Дисертації: "Nutrient cycliing"

1

Ngai, Zoology. "Trophic effects on nutrient cycling." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2851.

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The top-down effects of consumers and bottom-up effects of resource availability are important in determining community structure and ecological processes. I experimentally examined the roles of consumers — both detritivores and predators — and habitat context in affecting nutrient cycling using the detritus-based insect community in bromeliad leaf wells. I also investigated the role of multiple resources in limiting plant productivity using meta analyses. The insect community in bromeliads only increased nitrogen release from leaf detritus in the presence of a predator trophic level. When only detritivores were present, the flow of stable isotope-labeled nitrogen from detritus to bromeliads was statistically indistinguishable from that in bromeliads lacking insects. I suggest that emergence of adult detritivores constitutes a loss of nitrogen from bromeliad ecosystems, and that predation reduces the rate of this nutrient loss. Hence, insects facilitate nutrient uptake by the plant, but only if both predators and detritivores are present. Moreover, predators can affect nutrient cycling by influencing the spatial scale of prey turnover. This mechanism results in a pattern opposite to that predicted by classic trophic cascade theory. Increasing habitat complexity can have implications for nutrient cycling by decreasing the foraging efficiency of both predators and their prey, and by affecting the vulnerability of predators to intraguild predation. Along a natural gradient in bromeliad size, I found that, depending on the relationship between community composition and habitat size, habitat complexity interacts with the changing biotic community to either complement or counteract the impact of predators on nutrient uptake by bromeliads. In contrast to the existing emphasis on single-resource limitation of primary productivity, meta-analyses of a database of 653 studies revealed widespread limitation by multiple resources, and frequent interaction between these resources in restricting plant growth. A framework for analyzing fertilization studies is outlined, with explicit consideration of the possible role of multiple resources. I also review a range of mechanisms responsible for the various forms of resource limitation that are observed in fertilization experiments. These studies emphasize that a wider range of predator and nutrient impacts should be considered, beyond the paradigm of single resource limitation or classic trophic cascades.

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McManamay, Ryan A. "The effect of resource stoichiometry on fish and macroinvertebrate nutrient excretion." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/30780.

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Consumer-driven nutrient cycling has been shown to be an important process in supplying inorganic nutrients to autotrophic and heterotrophic organisms in aquatic ecosystems. Theory indicates that consumer nutrient excretion is influenced primarily by an organismâ s nutrient composition; however, an organismâ s diet should also play an important role in nutrient excretion, especially if the consumer is nutrient limited. This study asks the question, how does diet influence nutrient excretion of consumers at different trophic levels? Macroinvertebrates and fish were collected from six streams and nitrogen (N) and phosphorus (P) excretion were quantified. Epilithon, leaf detritus, and seston (fine particulate organic matter in transport) were collected and analyzed for carbon (C), nitrogen (N), and phosphorus (P) content in an attempt to qualitatively assess the nutritional status of the diet of primary consumers. Macroinvertebrates were also analyzed for C, N, and P content to assess their nutritional composition in relation to their excretion and also to assess the nutritional composition of the diet of predatory insects and fish. Fish were also analyzed for C, N, and P.

Similar to theoretical predictions, fish and macroinvertebrate P excretion was negatively related to P content and the N:P excretion ratio was negatively related to the body N:P ratio. However, this relationship was driven primarily by two phosphorus rich species, mottled sculpin in the fish and crayfish in the macroinvertebrates. Some relationships did emerge between consumer excretion and diet. For example, hydropsychid caddisflies had the highest macroinvertebrate P excretion, possibly explained by the low N:P of seston. However, shredders, eating on a very low N and P diet of leaf detritus, had very low N and P excretion.

The relationship between consumers, their food, and nutrient excretion is a matter of mass balance. If the food N:P ratio is higher than that of the consumer, then the N:P excretion should be higher than the consumer N:P and the food N:P, especially if organisms are P-limited. However, N:P excretion by macroinvertebrates and fish were very similar despite large differences in diet. The majority of macroinvertebrates and fish had a lower N:P excretion ratio than the predicted N:P of their food, possibly indicating that 1) consumers were either selectively consuming more P-rich foods than the diets that I assigned them or 2) consumers are generally not N or P limited or influenced by the N or P in their diet. Mottled sculpin and crayfish were the only organisms with a higher N:P excretion than their resources and both had a higher %P than the other fish and macroinvertebrates, respectively. High N:P excretion along with high phosphorus content is indicative of P-limitation. Macroinvertebrates and fish, excluding mottled sculpin and crayfish, had a lower N:P excretion and the N:P ratio of the water column. If consumers do play a role in nutrient dynamics, then consumers could alter the relative abundance of nitrogen and phosphorus by supplying more phosphorus. However, the presence of a P-limited organism, such as mottled sclupin or crayfish, could alter the relative abundance of nitrogen and phosphorus by supplying less phosphorus.
Master of Science

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NASCIMENTO, Sandra Maria do. "Distribuição, exportação e ciclagem de nutrientes minerais em Cupiúva (Tapirira guianensis Aubl.), em um fragmento manejado de mata atlântica no município de Goiana - PE." Universidade Federal Rural de Pernambuco, 2006. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/5114.

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The Atlantic rainforest is one of the richest biomasses of the planet in terms of biodiversity, but has been compromised by considerable anthropogenic action. The present study investigated a managed fragment of the Atlantic rainforest in the city of Goiana, PE, Brazil, on the Megaó farmland, with the aim of evaluating the distribution and exportation of mineral nutrients in Tapirira guianensis Aulb. (cupiúva), a perennial, pioneering halophyte species belonging to the family Anacardiaceae. Analysis of the mineral nutrients in the vegetal biomass and litter was carried out at the Mineral Nutrition of Plant Laboratory (Chemistry Department) and the Soil Chemistry Laboratory (Agronomy Department); soil analysis was carried out at the Soil Physics and Soil Fertility Laboratories (Agronomy Department) of the Rural Federal University of Pernambuco. Macronutrient (N, P, K, Ca, Mg, S) and micronutrient (Cu, Fe, Mn, Zn) determinations were performed on the leaves, branches, bark and trunk. Pre-dried samples were submitted to nitro-perchloric digestion, with the exception of N, for which sulfuric digestion was performed. Colorimetry was used for the analytic determination of P, whereas turbidimetry was used for S; K was assessed using the flame photometric technique, and the Ca, Mg, Cu, Fe, Mn and Zn contents were determined by the atomic absorption spectrophotometric method. N concentration was determined by the Kjeldahl method. Results were submitted to variance analysis and the averages were compared through the Tukey test at 5 % probability. The concentration of nutrients in the Tapirira guianensis Aulb. biomass obeyed the following order: leaves>bark>branches>trunk. The distribution of macronutrients in the leaves, bark and branch were distributed in N>Ca>Mg>K>S>P, and in the trunk in N>Ca>S>P>Mg>K. Micronutrients followed the distribution sequence for all arboreal components: Fe>Zn>Mn. The leaves presented a greater accumulation of nutrients, despite their biomass being smaller than the remaining components. Leaf maintenance is therefore important in the management area, thereby ensuring the cycling of nutrients through litter and the adequate maintenance of the management area. The total of exported nutrients was 71 % at the time of the cutting of the tree when the trunk, bark and branches are removed from the site, which could compromise the sustainability of the site.
A mata Atlântica é um dos biomas mais ricos em biodiversidade do planeta, diversidade esta que se encontra comprometida por causa da forte ação antrópica, que entre outros problemas, produz a degradação do solo. O presente trabalho teve como área de estudo um fragmento manejado de mata Atlântica no município de Goiana – PE, na fazenda Megaó. O objetivo foi avaliar a distribuição e exportação de nutrientes minerais em Tapirira guianensis Aulb. (cupiúva), espécie perenifólia, pioneira, e heliófita, pertencente à família Anacardiaceae. As análises dos nutrientes minerais na biomassa vegetal e na serrapilheira foram realizadas no Laboratório de Nutrição Mineral de Plantas (Departamento de Química) e no Laboratório de Química do Solo (Departamento de Agronomia), e as análises do solo foram realizadas nos Laboratórios de Física do solo e Fertilidade do Solo (Departamento de Agronomia), da Universidade Federal Rural de Pernambuco. As determinações dos macronutrientes (N, P, K, Ca, Mg, S) e micronutrientes (Cu, Fe, Mn, Zn), foram realizadas nas folhas, galhos, casca e fuste. As amostras pré-secas foram submetidas à digestão nitroperclórica, com exceção do N, onde foi feita a digestão sulfúrica. A determinação analítica de P se deu por colorimetria e S por turbidimetria; K, foi avaliado através da técnica de fotometria de chama e os teores de Ca, Mg, Cu, Fe, Mn e Zn foram determinados pelo método de espectrofotometria de absorção atômica. Os teores de N foram determinados pelo método de Kjeldahl. Os resultados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey a 5 % de probabilidade. A concentração de nutrientes na biomassa da cupiúva obedeceu a seguinte ordem folhas>casca>galhos>fuste. A distribuição de macronutrientes nas folhas, casca e galho foi distribuídos em N>Ca>Mg>K>S>P e no fuste foi N>Ca>S>P>Mg>K. Os micronutrientes seguiram a seqüência de distribuição para todos os componentes arbóreos Fe>Zn>Mn. As folhas apresentaram maior concentração de nutrientes, apesar de sua biomassa ser menor que os outros componentes, sendo assim importante sua manutenção na área de manejo, garantindo a ciclagem de nutrientes via serrapilheira e a boa manutenção da área de manejo. O total de nutrientes exportados no momento do corte da árvore, em que são retirados o fuste, a casca e os galhos do sítio, é de 71 %, o que representa uma grande perda no total de nutrientes da área de manejo, e pode comprometer a sustentabilidade do sítio.

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Barthelemy, Hélène. "Herbivores influence nutrient cycling and plant nutrient uptake : insights from tundra ecosystems." Doctoral thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-120191.

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Reindeer appear to have strong positive effects on plant productivity and nutrient cycling in strongly nutrient-limited ecosystems. While the direct effects of grazing on vegetation composition have been intensively studied, much less is known about the indirect effect of grazing on plant-soil interactions. This thesis investigated the indirect effects of ungulate grazing on arctic plant communities via soil nutrient availability and plant nutrient uptake. At high density, the deposition of dung alone increased plant productivity both in nutrient rich and nutrient poor tundra habitats without causing major changes in soil possesses. Plant community responses to dung addition was slow, with a delay of at least some years. By contrast, a 15N-urea tracer study revealed that nutrients from reindeer urine could be rapidly incorporated into arctic plant tissues. Soil and microbial N pools only sequestered small proportions of the tracer. This thesis therefore suggests a strong effect of dung and urine on plant productivity by directly providing nutrient-rich resources, rather than by stimulating soil microbial activities, N mineralization and ultimately increasing soil nutrient availability. Further, defoliation alone did not induce compensatory growth, but resulted in plants with higher nutrient contents. This grazing-induced increase in plant quality could drive the high N cycling in arctic secondary grasslands by providing litter of a better quality to the belowground system and thus increase organic matter decomposition and enhance soil nutrient availability. Finally, a 15N natural abundance study revealed that intense reindeer grazing influences how plants are taking up their nutrients and thus decreased plant N partitioning among coexisting plant species. Taken together these results demonstrate the central role of dung and urine and grazing-induced changes in plant quality for plant productivity. Soil nutrient concentrations alone do not reveal nutrient availability for plants since reindeer have a strong influence on how plants are taking up their nutrients. This thesis highlights that both direct and indirect effects of reindeer grazing are strong determinants of tundra ecosystem functioning. Therefore, their complex influence on the aboveground and belowground linkages should be integrated in future work on tundra ecosystem N dynamic.

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5

Galli, Corina Verónica Sidagis. "Análise da função de uma várzea na ciclagem de nitrogênio." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/18/18139/tde-17022016-130159/.

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Para identificar a influência de uma área de várzea do ribeirão do Feijão (São Carlos-SP) sobre a ciclagem de nitrogênio e sobre a qualidade da água superficial e subsuperficial, foram analisadas as características físicas e químicas da água e determinadas as taxas de nitrificação e desnitrificação dos sedimentos da várzea. A maior concentração dos compostos nitrogenados foi observada na água de interface subsuperficial da várzea, região mais ativa em termos de fluxos de água e materiais. As taxas de nitrificação variaram de 0,145 a 0,068 μmol N-NO3-.g-1.dia-1 e a rota metabólica predominante foi a autotrófica, na qual as bactérias utilizaram amônio como substrato. As taxas de desnitrificação tiveram um valor médio de 0,0081 nmol N2O.g-1.dia-1. Mediante um modelo de estimativa foi calculado que 70% da água que circula no Ribeirão do Feijão provém do lençol que flui sob terras secas e o restante das áreas de várzea da bacia. Foi observado que existe uma considerável redução das concentrações dos compostos nitrogenados, principalmente do amônio, desde as zonas ripárias mais distantes do curso do rio até o canal, passando pela área de várzea. O funcionamento da várzea como sistema de filtro e depuração das águas subsuperficiais que alimentam o rio foi evidenciada pelas características físicas e químicas da água do rio em relação ao uso do solo na bacia.
In order to identify the influence of a floodplain area of the Feijão stream (São Carlos-SP) on surface and subsurface water quality, the physical and chemical characteristics of the water were analyzed and the floodplain sediment\'s nitrification and denitrification rates were determined. The highest concentration of nitrogen compounds was observed at the floodplain\'s subsurface water interface it being the most active region with respect to water and solute flow. Nitrification rates varied between 0.145 and 0.068 μmol N-NO3-.g-1.day-1 and the autotrophic metabolic route dominated, in which bacteria use ammonia as a substrate. Denitrification rate average was 0.0081 nmol N2O.g-1.day-1. Through a model it was estimated that 70% of the water flowing in the Feijão stream came from the water table flowing under dry land, the remainder coming from the floodplain of the area. A significant reduction of nitrogen compound concentration, mainly ammonium, was observed between the more distant riparian zones and the river\'s channel going through the floodplain. The floodplain\'s action as a filtering system for the water reaching the river was brought out through the physical and chemical characteristics of the river water relative to land use in the catchment area.

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Pimentel, Tania Pena. "Dinâmica do carbono em uma microbacia no extremo leste da Amazônia." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/91/91131/tde-01082016-175320/.

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O presente estudo objetiva avaliar os mecanismos de transferência de carbono entre os compartimentos atmosfera, vegetação, solo e igarapé em uma microbacia da Amazônia Ocidental. Dois igarapés drenandos, respectivamente, 2927 e 66,73 ha de floresta de terra firme, foram monitorados durante um ano. A área de estudo se encontra na zona de amortecimento de uma Unidade de Conservação de Uso Sustentável denominada Floresta Estadual do Amapá (FLOTA/AP), na região central do estado de mesmo nome. Foram coletadas as águas da chuva, da precipitação interna da floresta, do escoamento de água pelo tronco, do escoamento superficial pelo solo, da solução do solo, da água subterrânea e da água do igarapé. Os solos também foram investigados em relação a suas características físico-químicas. Para calcular a entrada e saída de C do sistema, foram determinadas as concentrações do carbono orgânico e inorgânico dissolvido (COD e CID, respectivamente) na água da chuva e do igarapé, em 16 eventos de chuva. As concentrações médias de COD na água da chuva foram de 1,6± 1,52 mg L-1, resultando em um aporte de 11,43 Kg C ha-1 ano-1. Na precipitação interna os valores médios observados foram de 9,1 ± 5,99 mg L-1, o que corresponde a um fluxo de 100,71 Kg C ha-1 ano-1. No escoamento do tronco, os valores médios observados foram de 17,4 ± 8,03 mg L-1 e no escoamento superficial do solo de 14,2 ± 6,4 mg L-1. Nos compartimentos amostrados abaixo do solo, solução do solo e água do lençol, as concentrações de COD foram relativamente mais baixas. A saída de COD pelo igarapé, os fluxos foram de 0,45 Kg C ha-1 ano-1. Em relação às concentrações de CID, o aporte pela água da chuva foi de 3,66 Kg C ha-1 ano-1, passando a 10,10 Kg C ha-1 ano-1 na precipitação interna e com uma saída pelo igarapé de 0,07 Kg C ha-1 ano-1. Os resultados mostram grande variabilidade espaço-temporal e retenção de C pelo sistema, seja na fase orgânica (COD) ou inorgânica (CID), demonstrando a importância destes processos para a compreensão do funcionamento destes ecossistemas.
This study aims to evaluate carbon transfer mechanisms between the atmosphere, vegetation, soil and stream in a microbasin of eastern Amazon. Two streams, draining respectively 2917 and 66.73 ha of \"terra firme\" forests were monitored during one year. The study area is located in a Conservation Unit named Amapá State Forest (FLOTA/AP), in the central region of the Amapá State. We sample rain water, throughfall, stemflow, soil surface flow, soil solution, groundwater and stream water. Physico-chemical characteristics of soils were also evaluated. To calculate inputs and outputs of C in this system, we determined the concentrations of dissolved organic and inorganic carbon (DOC and DIC, respectively) in rain and stream water during 16 rain events. Average concentrations of DOC in rain water were 1.6± 1.52 mg L-1, resulting in an input of 11.43 Kg C ha-1 year-1. Throughfall had average concentrations of 9.1 ± 5.99 mg L-1, which increased inputs to 100.71 Kg C ha-1 year-1. Stemflow had average concentrations of 17.4 ± 8.03 mg L-1 while those of soil surface flow were 14.2 ± 6.4 mg L-1. Bellow ground DOC concentrations were relatively lower. The export of DOC in stream water was 0.45 Kg C ha-1 year-1. In relation to DIC, the input from rain water was 3.66 Kg C ha-1 year-1, increasing to 10.10 Kg C ha-1 year-1 in throughfall and exiting the micro basin through the stream with a flux of 0.07 Kg C ha-1 year-1. The results show large spatiotemporal variations and C retention within the system, either in the organic (DOC) or inorganic (DIC) phases, showing the importance of these processes for the comprehension of the functioning of these ecosystems.

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Heggenstaller, Andrew Howard. "Productivity and nutrient cycling in bioenergy cropping systems." [Ames, Iowa : Iowa State University], 2008.

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8

Lammers, Peter J. "Energy and nutrient cycling in pig production systems." [Ames, Iowa : Iowa State University], 2009.

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9

Jabro, Nicholas Berman. "Microcosm studies of nutrient cycling in Bahamian stromatolites." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8594.

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Thesis (M.S.) -- University of Maryland, College Park, 2008.
Thesis research directed by: Marine, Estuarine, Environmental Sciences Graduate Program. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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Langi, Martina Agustina. "Nutrient cycling in tropical plantations and secondary rainforests /." St. Lucia, Qld, 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16357.pdf.

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11

Vaillant, Grace C. "Nutrient cycling at cattle feedlots field & laboratory study." Thesis, Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/318.

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Oates, Richard Hunter. "Phosphate-mineral interactions and potential consequences for nutrient cycling." Thesis, Online version of original thesis, 2008. http://hdl.handle.net/1912/2395.

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Mitchell, Mark E. "Nutrient Cycling Dynamics and Succession in Green Roof Ecosystems." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin150487303109878.

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14

Cottam, Nigel D. "Internal nutrient cycling in evergreen and deciduous tree species." Thesis, University of Aberdeen, 1990. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU027729.

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This thesis compares the cycling of nutrients (N, P, K, Mg and Ca) within twigs and foliage, between the evergreen species Pinus sylvestris L. (Scots pine) and Picea abies (L.) Karst. (Norway spruce), and the deciduous species Quercus petraea (Matt.) Liebl. (oak) and Betula pubescens Ehrh. (birch). In addition, the role of foliage produced in previous seasons as a source of nutrients for current growth, in young stands of Scots pine and lodgepole pine (Pinus contorta Loud.), was investigated by means of defoliation experiments, where various age-classes of foliage were removed. In both evergreen and deciduous species, the main areas of overwinter storage and sources of nutrients to support current growth appear to lie outside the twig/foliage system. Patterns of leaf litter production were similar in both Scots pine, oak and birch, however the deciduous species lost a greater amount of nutrients in leaf litter than did the evergreen species. In comparisons between Scots pine and oak, it was observed that foliage production in spring and summer is much slower, and takes place over a longer period, in the Scots pine, which also maintains a greater amount of nutrients within its foliar biomass. Results from the artificial defoliation experiments, suggested that older needle fractions do not play a major role in supplying nutrients to sites of current growth, however they do appear to provide an essential source of photosynthate to support new biomass production. A mechanism is proposed, whereby evergreen species are able to reduce the level of current nutrient demands in two main ways, firstly by means of their slower more extended growing period, and secondly by maintaining lower foliar nutrient concentrations (thereby reducing nutrient losses via leaf litterfall), at the expense of maintaining a greater amount of nutrients within their biomass.

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Bush, Timothy. "Response to environmental perturbations in microbial nutrient-cycling ecosystems." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/15789.

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The habitability of Earth is dependent upon the global recycling of elements essential for life, such as nitrogen, sulfur and carbon. Nutrient-cycling by micro-organisms is vital to these biogeochemical cycles because many key steps are mediated primarily, or exclusively, by microbial life. The dynamics of these cycles are highly complex, and environmental perturbations (such as changes in the oceanic oxygen concentration) can have unexpected or catastrophic effects; often causing abrupt switches between chemical states. Despite the importance of these environmental perturbations however, few theoretical models have addressed how they affect the dynamical behaviour of nutrient-cycling microbial ecosystems. In this work, we investigate the effect of environmental perturbations on microbially-mediated nutrient cycles and assess the likelihood of "sudden transitions" between chemical states of the ecosystem occurring in a variety of ecological contexts. To do this, we first use computational modelling of microbial nutrient-cycling, using a "box model" approach. We then move on to an experimental study using the microbial sulfur cycle as a model ecosystem, with freshwater pond sediment/water microcosms. These microcosms have the advantage of retaining many of the features of the real ecosystem (such as microbial diversity, spatial structure, and abiotic interactions) while allowing the controlled manipulation of environmental perturbations. We study these microcosms using a combination of chemical measurements and high-throughput sequencing of the microbial community. Finally, we return to the computational side, and attempt to reproduce chemical data from our experiments in a mathematical model containing realistic abiotic chemical interactions.

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Oliveira, Filho Romildo Lopes de. "Dynamics of phosphorus in mangroves impacted by the state of Ceará." reponame:Repositório Institucional da UFC, 2012. http://www.repositorio.ufc.br/handle/riufc/17165.

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OLIVEIRA FILHO, Romildo Lopes de. Dinâmica de fósforo em manguezais impactados por águas residuárias no Estado do Ceará. 2012. 62 f. Dissertação (Mestrado em ecologia e recursos naturais)- Universidade Federal do Ceará, Fortaleza-CE, 2012.
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Recent studies demonstrated the efficacy of mangrove retaining nutrients and, in particular, the ability of the mineral component of the buffer in its high soil phosphorus levels. In general, the mangroves have been considered as important sinks of nutrients due to its high capacity purification of effluents. However, depending on the geochemical conditions exist, these soils can act as a source of phosphorus to other environments and / or coastal waters. Given that the geochemical behavior of phosphorus and its role in eutrophication of water bodies, is best measured by the behavior of its different fractions, this paper aims at a fractionation of the different forms of phosphorus in wetlands impacted by different effluent. The objective of this project is to study three areas in order to assess how activities impacting interfere in the process of nutrient cycling (with special emphasis on the dynamics of phosphorus forms) and, as the marsh supports the stress caused by these activities. Also, if you evaluate the potential for eutrophication of each human activities. Taking into consideration the impact that these environments suffer as a result of separate activities, were established the following areas of study: a marsh impacted by effluents from shrimp, a marsh impacted by effluents, and a control area located in a preserved area that still finds is little affected by human impacts. The samples were determined pH, Eh, salinity, grain size and the total content of C and P. In addition, extraction was performed sequentially phosphorus which allows differentiation of fractions 7: P exchangeable (NaClP), P associated with iron oxides (Fe-P); organic P (AH-P), the bound phosphorus hydroxides Al (Al-P), P associated with compounds of calcium (Ca-P); phosphorus associated refracting matter (P-RES) and unreacted phosphorus (P-NR). The results indicate that the discharge of effluents in mangrove increases the amount of phosphorus in these environments, especially in organic form, the phosphorus bound to carbonate is the major inorganic fraction in these environments.
Estudos recentes demonstram a eficácia do manguezal em reter nutrientes e, em especial, a capacidade dos componentes minerais do seu solo em tamponar elevados teores de fósforo. Em geral, os solos dos manguezais têm sido considerados como importantes sumidouros de nutrientes devido a sua grande capacidade de depuração de efluentes. Entretanto, dependendo das condições geoquímicas existentes, esses solos podem funcionar como fonte de fósforo para outros ambientes e/ou para as águas costeiras. Tendo em vista que o comportamento geoquímico do fósforo, bem como seu papel na eutrofização dos corpos d'água, é melhor avaliado através do comportamento de suas diferentes frações, o presente trabalho visa realizar um fracionamento das diferentes formas de fósforo em manguezais impactados por distintos efluentes. O objetivo da presente dissertação é estudar três áreas a fim de se avaliar como as atividades impactantes interferem no processo de ciclagem de nutrientes (com especial ênfase na dinâmica das formas de fósforo) e, como o manguezal suporta o estresse ocasionado por estas atividades. Além disso, se avaliará o potencial de eutrofização de cada uma das atividades antrópicas. Levando-se em consideração os impactos que esses ambientes sofrem em consequência de distintas atividades, foram estabelecidas as seguintes áreas de estudo: um manguezal impactado por efluentes de carcinicultura; um manguezal impactado por efluentes urbanos; e uma área controle localizada em uma área preservada que ainda encontra-se pouco afetada por impactos antrópicos. Nas amostras foram determinados pH, Eh, salinidade, granulometria e teores totais de C e P. Além disso, foi realizada a extração seqüencial de fósforo que permite a diferenciação de 7 frações: P trocável (NaCl-P); P associado a óxidos de Fe (FeP); P orgânico (AH-P); fósforo ligado a hidróxidos de Al (Al-P); P associado a compostos de cálcio (Ca-P); fósforo associado à matéria orgânica refratária (P-RES) e fósforo não reativo (P-NR). Os resultados obtidos indicam que o descarte de efluentes nos manguezais aumenta a quantidade de fósforo nesses ambientes, principalmente nas formas orgânicas; o fósforo ligado aos compostos de cálcio é a principal fração inorgânica nesses ambientes. Palavras-chave: ciclagem de nutrientes; extração sequencial; carcinicultura; efluente domiciliar.

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Prior, Hannah. "Total nitrogen and total phosphorus cycling in riparian ecosystems." Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285963.

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Enoki, Tsutomu. "Topographic Variations of Nutrient Cycling in a Pinus Thunbergii Parl.Plantation." Kyoto University, 1997. http://hdl.handle.net/2433/160875.

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本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものである
Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第6616号
農博第907号
新制||農||734(附属図書館)
学位論文||H9||N2993(農学部図書室)
UT51-97-B287
京都大学大学院農学研究科林学専攻
(主査)教授岩坪五郎, 教授小﨑隆, 教授川那辺三郎
学位規則第4条第1項該当

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Viera, Márcio. "DINÂMICA NUTRICIONAL EM UM POVOAMENTO HÍBRIDO DE Eucalyptus urophylla x Eucalyptus globulus EM ELDORADO DO SUL-RS, BRASIL." Universidade Federal de Santa Maria, 2012. http://repositorio.ufsm.br/handle/1/3743.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
Understanding of the involved issues in nutritional dynamics process in eucalyptus stands is the base to sustainable management. Objective this study was to determine the nutritional dynamic in Eucalyptus urophylla x Eucalyptus globulus stand, Eldorado do Sul - RS. For this, was available: a) litter production (leaves, twigs diameter ≤ 1.0 cm, miscellaneous and thick branches diameter > 1.0cm) and nutrients uptake, from 6.5 to 9.5 years-old stand (2007 at 2010); b) leaf litter decomposition and nutrients release by litterbags method (adding 12g of dried leaves in nylon bags), for three years (2007 to 2009); c) aboveground biomass and nutrients amount in the eucalyptus (wood, bark, branches and leaves) and underground (wood and leaves) to ten-year-old stand (June 2010); d) interfere of different intensities of biomass removal (all aboveground biomass removal eucalyptus + underground; eucalyptus removal; wood with bark removal and only wood removal) in relation nutrients stock and; - silvicultural alternative for sustainable forestry management. Litter production was increasing with stand age increasing, showing seasonal behavior with deposition increasing with the air temperature increasing and being mainly composed by leaves fraction that also is main fraction nutrients return through litter. Accumulated litter showed decomposition coefficient of 0.54 with 1.86 years how time average renewal and 1.29 and 5.59 years to disappear 50 and 95% of the litter. Mass loss leaf showed positive correlation with nutrients concentration, indicating that the higher mass loss, higher the nutrients concentration in litter remaining. Litter leaf decay initially showed P, Fe, Mn and Zn immobilization and release of the others, in the second year occurred P release and in the third year occurred Mn and Zn release, with Fe exception. Eucalyptus biomass was allocated predominantly to stem (Wood + bark) with 93.7% and with the largest nutrients stock. Biomass components had different chemical composition, being generally higher in leaves and bark and smaller in wood and branches biomass. With the harvest of wood with the bark all the nutrients removal would suffer more than 45% of the total amount accumulated in aboveground biomass. However, removed just the wood, which has the highest nutrients utilization rate, the nutrients removed percentage, except by Cu and Zn, will be less than 50% and up to 10% in the case of Ca in relation the total biomass contained. Phosphorus and calcium can be the main nutrients became limiting in next rotation productivity, because the potential rotation estimates are close to one, when in the harvest of wood with the bark. Nutrients output through forestry harvest must be take account by companies during the planning of activities. Avoiding productivity decreasing with the next rotations, and also contributing sustainable management, because the nutrients exportation, Ca mainly, is high due to wood with bark harvest.
O entendimento dos aspectos envolvidos no processo da dinâmica nutricional em povoamentos de eucaliptos é a base para um manejo sustentável. O objetivo deste estudo foi determinar a dinâmica nutricional em um povoamento híbrido de Eucalyptus urophylla x Eucalyptus globulus em Eldorado do Sul RS, com dez anos de idade. Para isso, foi avaliado: a) a produção de serapilheira (folhas, galhos finos diâmetro ≤ 1,0 cm, miscelânea e galhos grossos diâmetro > 1,0 cm) e o aporte de nutrientes, dos 6,5 aos 9,5 anos de idade do povoamento (2007 a 2010); b) a decomposição da serapilheira foliar e liberação de nutrientes pelo método de litterbags (adição de 12g de folhas secas recém caídas em bolsas de naylon), durante três anos (2007 a 2009); c) o estoque de biomassa e nutrientes no eucalipto (madeira, casca, galhos e folhas) e sub-bosque (lenho e folhas) aos dez anos de idade do povoamento (junho de 2011); d) a influência de diferentes intensidades de remoção da biomassa (retirada de toda a biomassa eucalipto + sub-bosque; retirada de toda a biomassa de eucalipto; retirada da madeira com a casca e retirada apenas da madeira) sobre o estoque de nutrientes e; e) alternativas silviculturais para um manejo florestal sustentável. A produção de serapilheira foi crescente com o aumento da idade do povoamento, apresentando comportamento sazonal com maior deposição no período de aumento da temperatura do ar e sendo composta predominantemente pela fração folhas, que também é a responsável por maior parte do retorno de nutrientes via serapilheira. A serapilheira acumulada apresentou coeficiente de decomposição de 0,54 com tempo médio para a renovação de 1,86 anos e tempo médio para decomposição de 50 e 95% da serapilheira em 1,29 e 5,59 anos, respectivamente. A perda de massa foliar apresentou correlação positiva com a concentração de nutrientes, indicando que quanto maior a perda de massa, maior a concentração dos elementos no folhedo remanescente. A decomposição da serapilheira foliar apresentou inicialmente imobilização do P, Fe, Mn e Zn e disponibilização dos demais, a partir do segundo ano o P tornou-se disponível e a partir do terceiro ano o Mn e Zn também se tornaram disponíveis, com exceção do Fe. A biomassa do eucalipto encontra-se predominantemente alocada no fuste (madeira + casca) com 93,7% e com os maiores estoques de nutrientes. Os componentes da biomassa apresentaram composições químicas distintas, sendo geralmente maiores nas folhas e casca e menores nos componentes madeira e galhos. Com a colheita da madeira com casca todos os nutrientes sofreriam remoção superior a 45% de sua quantidade acumulada na biomassa total acima do solo. Entretanto, removendo apenas a madeira comercial, que apresenta o maior coeficiente de utilização de nutrientes, a porcentagem de remoção para os nutrientes, com exceção ao Cu e Zn, seria inferior a 50% e chegando até 10% no caso do Ca em relação ao total contido na biomassa. O fósforo e o cálcio poderão ser os principais nutrientes a tornarem-se limitantes na produtividade nas próximas rotações, pois as estimativas de rotações estão próximas a um, quando da colheita da madeira com casca. A saída de nutrientes do sítio via colheita florestal deve ser um componente levado em consideração por parte das empresas, durante o planejamento das atividades, e assim evitando que haja diminuição de produtividade nas próximas rotações e contribuindo para o manejo sustentável, pois a exportação de nutrientes, principalmente do Ca, é elevado devido à colheita da madeira com casca.

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Safi, Zikrullah [Verfasser]. "Nutrient cycling and nutrient use efficiency in urban and peri-urban agriculture of Kabul, Afghanistan / Zikrullah Safi." Kassel : Universitätsbibliothek Kassel, 2011. http://d-nb.info/1012867978/34.

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SILVA, Izabela Aline Gomes da. "Deposição e decomposição de serrapilheira de leguminosas arbóreas consorciadas com Brachiaria decumbens Stapff." Universidade Federal Rural de Pernambuco, 2015. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/6791.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
Studying about litter dynamics in silvopastoral systems is critical to estimate the natural return of nutrients to the soil and reduce the use of nitrogen fertilizers. This research evaluated litter deposition, litter decomposition, and nitrogen contents of gliricidia [Gliricidia sepium (Jacq.) Kunth ex Walp.] and sabia (Mimosa caesalpiniifolia Benth) intercropped with signal grass (Brachiaria decumbens Stapff.). The research was performed at the experimental research station of Itambe, conducted in the Agronomic Institute of Pernambuco (IPA).The randomized block design with a split plot arrangement was used. The main plots were the legumes intercropped with to grass and the subplots were the distances from the trees trunk. Senescent material was collected manually in a wood gatherers of 0.25m2 every month, in a perpendicular transect across the tree rows (between the tree rows, 2.0 m and 4.0 m away from the trees rows), during one year. The material collected was dried in a forced circulation oven for 72 h at 55°C, and later separated into four fractions (leaf, stem, reproductive structures and unrecognized), and weighed to determine the dry biomass, then the contents were milled in a grinder type Willey with 1 mm sieve for analysis of nitrogen content. Litter decomposition was evaluated by litter bag technique with a mesh of 75 μm and litter samples were collected from both species and incubated for 0, 4, 8, 16, 32, 64, 128 and 256 days. The bags were incubated in the same spots of wood gatherers. The litterbags were collected and dried in a forced circulation oven for 72 h at 55°C. The remaining material was used to determine N concentration. The annual deposition of litter fractions (leaves + branches + reproductive structures) between the rows of trees, two meters and four meters of rows of trees by sabia was (18,170 kg OM ha-1, 9,200 kg OM ha-1 OM and 4,200 kg ha-1) and by gliricidia (11,000 kg ha-1 OM, 2,480 kg OM ha-1 and 1,160 kg ha-1 OM). The annual contribution of these fractions in the three distances was 610 kg ha-1 of N by sabia and 450 kg ha-1 of N by gliricidia. For both legumes, the sheet fraction dominated entire contents of the litter, followed by the fraction branches, reproductive structures and unidentifiable structures. The annual deposit by unrecognized structures in the three respective distances, by sabia was (445 kg OM ha-1, 245 kg OM ha-1 and 90 kg OM ha-1) and by gliricidia (180 kg OM ha-1, 90 kg OM ha-1 and 45 kg OM ha-1). It was not quantified the nitrogen supply to these fractions. The sabia deposited larger amounts of litter in the months with less rainfall. The gliricidia litter deposition was not influenced by rain. The decomposition rates was greater to sabia (k=0,0055 g.g-1.dia-1) than gliricidia (k=0,0022 g.g-1.dia-1). The nitrogen mineralization to sabia was 77% and to gliricidia it was 50% leading a system contribution of 50 kg de N e 64 kg de N, respectively, during 256 days. The nitrogen from legume's litter is an important alternative to reduce chemical nitrogen use.
Estudar sobre a dinâmica de serrapilheira em sistemas silvipastoris é fundamental para estimar o retorno de nutrientes ao solo e diminuir o uso de fertilizantes nitrogenados. Dessa forma, objetivou-se avaliar a deposição, decomposição e teores de nitrogênio das serrapilheiras de sabiá (Mimosa caesalpiniifolia Benth) e gliricídia (Gliricidia sepium (Jack) Kunth ex Walp) em pastagens consorciadas com Brachiaria decumbens Stapff. O experimento foi conduzido na Estação Experimental pertencente ao Instituto Agronômico de Pernambuco-IPA, Itambé-PE. Foi utilizado o delineamento em blocos ao acaso com arranjo em parcelas subdivididas. As parcelas principais foram as duas leguminosas consorciadas com a gramínea, e as subparcelas foram as três distâncias das fileiras das árvores. A deposição de serrapilheira foi avaliada pelo uso de coletores de madeira que foram distribuídos entre as fileiras duplas das leguminosas, a dois e a quatro metros destas fileiras. O material depositado mensalmente durante um ano foi colocado em estufa a 55˚C por 72 horas, separado em quatro frações (folhas, ramos, estruturas reprodutivas e estruturas não identificáveis), e pesado para determinar a biomassa seca. O conteúdo foi triturado em moinho tipo Willey com peneira de 1mm para quantificar o aporte de nitrogênio depositado por cada fração nas três distâncias das fileiras das árvores. A avaliação da taxa de decomposição foi feita pela análise do desaparecimento de massa ao longo do tempo. Foram utilizados sacos de náilon 100% poliéster com 75 micrômetros de porosidade. As amostras de ambas as espécies de serrapilheira foram coletadas e incubadas durante 0, 4, 8, 16, 32, 64, 128 e 256 dias. Os sacos foram incubados nos mesmos pontos dos coletores de madeira. Após coleta, os sacos foram pré-secos em estufa a 55˚C por 72 horas. As concentrações de nitrogênio remanescente foram calculadas para serrapilheira retirada dos sacos após cada tempo de incubação. A deposição anual das frações de serrapilheira (folhas+ramos+estruturas reprodutivas) entre as fileiras das árvores, a dois metros e a quatro metros das fileiras das árvores para sabiá foi de (18.170kg MO ha-1, 9.200 kg MO ha-1 e 4.200 kg MO ha-1) e para a gliricídia (11.000 kg MO ha1, 2.480 kg MO ha-1 e 1.160 kg MO ha-1). O aporte anual dessas frações nas três distâncias foi de 610 kg ha-1 de N para sabiá e 450 kg ha-1 de N para a gliricídia. Para ambas as leguminosas, a fração folha dominou conteúdo total da serrapilheira, seguida da fração ramos, estruturas reprodutivas e estruturas não identificáveis. O depósito anual de estruturas não identificáveis nas três respectivas distâncias, para a sabiá foi de (445 kg MO ha-1, 245 kg MO ha-1 e 90 kg MO ha-1) e para a gliricídia de (180 kg MO ha-1, 90 kg MO ha-1 e 45 kg MO ha-1). Não foi quantificado o aporte de nitrogênio para essas frações. A sabiá depositou maiores quantidades de serrapilheira nos meses com menores precipitações pluviais. A deposição de serrapilheira de gliricídia não foi influenciada pelas chuvas. A taxa de decomposição para a sabiá (k=0,0055 g.g-1.dia-1), também foi maior que para a gliricídia (k = 0,0022 g.g-1.dia-1). A mineralização de N na serrapilheira de sabiá foi de 77% e da gliricídia foi de 50% proporcionando um aporte de 50 kg de N e 64 kg de N, respectivamente, durante os 256 dias. O maior porcentual de nitrogênio nas folhas e ramos de gliricídia contribuiu com o maior aporte desse nutriente. A contribuição de nitrogênio pelas serrapilheiras das leguminosas avaliadas representa uma importante alternativa para redução do uso de nitrogênio químico

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VALE, Clemeson Cardoso. "Desempenho produtivo do milho em função dos atributos químicos do solo, tendo em vista a intensificação ecológica." Universidade Federal do Maranhão, 2014. https://tedebc.ufma.br/jspui/handle/tede/tede/2039.

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CAPES
The constant concerns over the unsustainable use of natural resources, coupled with rapid population growth, direct them to the productive process of maximizing resources systems to provide greater increases in production to minimize impacts to the environment yields. The objective of this research was to evaluate the performance of maize in no-tillage in legume straw depending on the spatial variability of soil chemical properties and nutrient input in a Dystrophic cohesive oxisol. The experiment was conducted in a 0.6 ha area containing two environments (without legumes and pulses) and 170 sampling points regularly dispersed (7.0 x 5.0 m) for chemical soil variability and productive maize yields. Data were initially analyzed using descriptive statistics and later by geostatistical methods. The interaction between soil chemical properties and yield of corn production was assessed by Pearson correlation to 5%. There was an increase in levels of soil chemical properties in the area with legumes compared to the area without legumes, proving the applicability of this management system to improve the chemical quality of the soil due to continuous addition of plant residues. Found the presence of spatial variability for all soil chemical properties and productive yield with spatial dependence ranged from moderate to strong, allowing reveal through thematic maps the potentialities and limitations of the production system. The productive efficiency, productivity specifically, correlated positively with calcium, sum of bases, phosphorus, potassium, base saturation and cation exchange capacity.
As constantes preocupações com o uso insustentável dos recursos naturais, juntamente com o acelerado crescimento demográfico, direcionam os sistemas produtivos ao processo de maximização dos recursos a fim de proporcionar maiores incrementos nos rendimentos produtivos com minimização dos impactos ao ambiente. O objetivo da presente pesquisa foi avaliar o desempenho produtivo do milho em sistema de plantio direto na palha de leguminosas em função da variabilidade espacial dos atributos químicos do solo e do aporte de nutrientes num Latossolo Amarelo distrocoeso. O experimento foi conduzido numa área de 0,6 ha contendo dois ambientes (sem leguminosas e com leguminosas) e 170 pontos amostrais regularmente dispersos (7,0 x 5,0 m) para determinação da variabilidade química do solo e dos rendimentos produtivos do milho. Os dados foram inicialmente analisados por meio da estatística escritiva e posteriormente por métodos geoestatísticos. A interação entre os atributos químicos do solo e o rendimento produtivo do milho foi verificada pela correlação de Pearson a 5%. Verificou-se a elevação nos teores dos atributos químicos do solo na área com leguminosas quando comparado com a área sem leguminosas, comprovando a aplicabilidade desse sistema de manejo para a melhoria da qualidade química do solo em consequência da adição continuada de resíduos vegetais. Constatou-se a presença de variabilidade espacial para todos os atributos químicos do solo e rendimento produtivo, com grau de dependência espacial que variaram de moderado a forte, o que possibilitou revelar por meio de mapas temáticos as potencialidades e limitações do sistema de produção. O rendimento produtivo, especificamente a produtividade, apresentou correlação positiva com o cálcio, a soma de bases, o fósforo, o potássio, a saturação por bases e a capacidade de troca catiônica.

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Alves, Neto Alfredo José. "Uso de água residuária de suinocultura associada à adubação mineral no sistema de produção de grãos da Região Oeste do Paraná." Universidade Estadual do Oeste do Paraná, 2015. http://tede.unioeste.br:8080/tede/handle/tede/1264.

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Nutrients contained in swine wastewater (SW), are unbalanced and not fully available for the first crop, with the need for regionalized research, taking into account the characteristics of each site, such as rainfall, soil type and cropping systems of each region. With the objective of evaluating the influence of applications of ARS doses in soybean crop and second crop corn, chemical and physical properties of the soil, an experiment was conducted from september 2013 to august 2014, in the municipality of Cafelândia, western of Paraná, in the Copacol Center of Agricultural Research - CPA Copacol, in Dystroferric Red Latosol. In this experiment, was used five swine wastewater doses (0, 35, 70, 105 and 140 m3 ha-1 yr-1) and two sources of mineral fertilizer, absence and presence. The statistical design, was a randomized block with split plots, with four repetitions, allocated in the main plots factor doses, and in the subplots was allocated the mineral fertilizer factor, the soybean crop (summer 13/14) and maize second crop (winter 14/14). Biometric variables were evaluated, leaf levels of N, P, K, Cu and Zn in soybean and corn with their respective yields, with subsequent determination of economic analysis of SW doses. After second crop corn harvest, soil samples were collected in the layers 0 - 0,10 and 0,10 - 0,20 m to determine the C organic, P, K, Cu and Zn. Undisturbed soil core samples were collected in the layers 0 - 0,10, 0,10 - 0,20 and 0,20 - 0,30 m to determination of soil physical properties. With increasing of SW doses, a reduction in the biological nitrogen fixation in soybean, in contrast with increases in the weight of a thousand grains. In second crop corn, the SW doses increased productivity, thousand grain weight and grains moisture content. Identified an increase in the levels of P, K, Cu and Zn in the layer of 0 - 0,10 m, and increase in the P content in the layer of 0,10 - 0,20 m. The applications of SW doses kept the physical soil quality in layers sampled
Os nutrientes contidos na água residuária de suinocultura (ARS), são desbalanceados e não totalmente disponíveis no primeiro cultivo, havendo a necessidade de pesquisas regionalizadas levando em conta particularidades de cada local, como o regime pluviométrico, tipo de solo e os sistemas de cultivos. Com o objetivo de avaliar a influência das aplicações de doses de ARS nas culturas de soja e milho segunda safra, nos atributos químicos e físicos do solo, um experimento foi conduzido nos meses de setembro de 2013 a agosto de 2014, no município de Cafelândia, região oeste do Paraná, no centro de pesquisa agrícola Copacol CPA Copacol, em Latossolo Vermelho Distroférrico típico. Foram utilizadas cinco doses de água resíduária de suinocultura, (0, 35, 70, 105 e 140 m3 ha-1 ano-1), e duas fontes de adubação mineral, ausência e presença. O delineamento utilizado foi de blocos casualizados com parcelas subdivididas, com quatro repetições, sendo alocado nas parcelas principais o fator doses, e nas subparcelas alocado o fator adubação mineral, com os cultivos de soja (verão 13/14) e milho segunda safra (inverno 14/14). Foram avaliadas as variáveis biométricas, os teores foliares de N, P, K, Cu e Zn das culturas de soja e milho e as suas respectivas produtividades, com posterior determinação de análise econômica das doses de ARS. Após a colheita do milho segunda safra, foram coletadas amostras de solo nas profundidades de 0 - 0,10 e 0,10-0,20 m para determinação dos teores de C orgânico, P, K, Cu e Zn. Amostras indeformadas com anéis volumétricos foram retiradas nas profundidades de 0 - 0,10, 0,10 - 0,20 e 0,20 - 0,30 m, para determinação dos atributos físicos do solo. Com o aumento das doses de ARS, houve redução na fixação biológica de nitrogênio na cultura da soja, em contrapartida, com aumento na massa de mil grãos. Na cultura do milho, as doses de ARS aumentaram a produtividade, a massa de mil grãos e o teor de umidade dos grãos. Evidenciou-se aumento nos teores de P, K, Cu e Zn, na profundidade de 0 - 0,10 m, e aumento no teor de P na profundidade de 0,10 - 0,20 m. As aplicações das doses de ARS conservaram a qualidade física do solo

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24

Campos, Henrique Ferraz de. "Deposição e concentração de nutrientes da serapilheira de seis espécies nativas do Pontal do Paranapanema: uso da biodiversidade funcional em sistemas agroflorestais." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/11/11150/tde-26052015-094123/.

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Na elaboração de arranjos de sistemas agroflorestais devem ser buscadas interações benéficas entre as espécies utilizadas, com o intuito de atingir os objetivos desses sistemas em otimizar a eficiência do uso dos recursos naturais como: luz solar, a água e os nutrientes. Essas interações benéficas em SAFs são, muitas vezes, obtidas através da utilização de princípios e funcionamentos semelhantes ao ecossistema natural da região. Um dos funcionamentos chaves para garantir a sustentabilidade dos ecossistemas florestais é a dinâmica da serapilheira. A dinâmica quantitativa e qualitativa da produção de serapilheira é fortemente influenciada pela composição de espécies. Poucos estudos evidenciam o papel individual de cada espécie, sobretudo das árvores nativas, nessa dinâmica. Nesse sentido, este estudo teve o objetivo de aprofundar o conhecimento do papel individual na deposição e concentração de nutrientes da serapilheira de 6 espécies nativas da floresta estacional semidecidual, para uso racional desse conhecimento em sistemas agroflorestais, principalmente para a agricultura familiar e assentamentos rurais da região do Pontal do Paranapanema. O experimento foi desenvolvido em um plantio de restauração ecológica no município de Presidente Epitácio, São Paulo, Brasil. A pesquisa foi realizada durante o período de maio de 2013 a abril de 2014. As espécies estudadas foram: Anadenanthera colubrina (angico), Enterolobium contortisiliquum (tamboril), Inga laurina (ingá), Luehea divaricata (açoita cavalo), Croton urucurana (sangra d\'água), Schinus terebentifolius (Aroeira pimenteira). Foram selecionados aleatoriamente, no talhão experimental, em área de restauração, 10 indivíduos de cada espécie. Para todos os 60 indivíduos selecionados foram instalados coletores de serapilheira. Durante o período de estudo, a cada 2 meses, todo o material coletado foi retirado dos coletores e teve o seu peso seco determinado. Em dois dos períodos de coleta parte do material foi submetido ao processo de análise química dos macronutrientes (N, P, K, Ca, Mg e S). As 6 espécies alvo deste estudo se comportaram de forma semelhante em termos de quantidade de deposição de serapilheira ao longo do ano. O fluxo anual de deposição de serapilheira não apresentou variações sazonais significativas, analisando-se cada espécie de forma separada. No entanto, na análise do conjunto das espécies verificou-se uma maior deposição de serapilheira durante o período mais seco do ano. A espécie Sangra d\'Água considerada pioneira quanto à classe sucessional , teve o maior valor de deposição anual seguido da aroeira pimenteira espécie também considerada de fase mais inicial na sucessão em comparação com as demais. Para todos os macronutrientes com exceção do enxofre houve interação significativa entre espécie e época de coleta. As espécies de início de sucessão aportaram mais nutrientes durante o ano de estudo que as espécies mais tardias. Uma maior diversidade de espécie proporciona maiores possibilidades de complementaridade na disponibilidade de recursos, visto que, houveram diferenças na dinâmica da concentração de macronutrientes na serapilheira das espécies. Estudos adicionais são necessários para contribuir no entendimento da dinâmica quantitativa e qualitativa de deposição da serapilheira de diferentes espécies, bem como suas interações em sistemas agroflorestais.
In the elaboration of Agroforestry Systems arrangements should be sought beneficial interactions among species used, in order to achieve the objectives of these systems by optimizing the efficiency of natural resources use, such as: sunlight, water and nutrients. These beneficial interactions in Agroforestry Systems are often obtained through the use of principles and functioning similar to the natural region ecosystem. One key functioning to ensure forest sustainability of ecosystems is the litterfall dynamics. The quantitative and qualitative dynamics of litter production is strongly influenced by species composition. Few researches have demonstrated the individual role of each species, mainly of native trees, on this dynamic. In this sense, the present study aimed to deepen the knowledge of the individual role in the deposition and concentration of nutrients from litter of 6 native tree species from the Semideciduous Mesophytic Atlantic Forest for rational use of this knowledge in agroforestry systems, mainly for family farms and rural settlements in the region of the Pontal do Paranapanema. The experiment was conducted in an ecological restoration planting in the city of Presidente Epitácio in São Paulo state, Brazil. The survey was also conducted during one year period, from May 2013 to April 2014. The species studied were: Anadenanthera colubrina, Enterolobium contortisiliquum, Inga laurina, Luehea divaricata, Croton urucurana, Schinus terebentifolius. It was selected randomly in the experimental field, 10 individuals of each species. For all 60 individuals selected were installed litter collectors. During the study period, every 2 months all collected litter material was removed from collectors and its dry weight determined. In two period of time collection part of the material was subjected to the process of chemical analysis of macronutrients (N, P, K, Ca, Mg, S). The 6 species targeted for this study behaved similarly in terms of amount of litter deposition throughout the year. The annual flow litter deposition has not shown significant seasonal variations by analyzing each species separately. However, in the analysis of all joint species there were a greater deposition of litter during the driest period of the year. The species considered pioneer as the successional class, the Croton urucurana had the greatest annual deposition followed by Schinus terebentifolius, species also considered in the Initial stage in the succession, in comparison to the others. For all macronutrients except sulfur there was significant interaction between species and time of collection. The early successional species supplied more nutrients than later species during the year of this research. Greater species diversity provide better possibility of complementary effects in resource availability, as there were differences on macronutrients concentration dynamics in litter of these species studied. Additional studies are needed to contribute on quantitative and qualitative dynamics understanding of litter deposition of different species as well as their interactions in agroforestry systems.

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Rosado, Jéssica Pedroso. "Cinza de casca de arroz e lodo de estação de tratamento de esgoto como fertilizantes." Universidade Federal de Pelotas, 2016. http://repositorio.ufpel.edu.br:8080/handle/prefix/3226.

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O uso de resíduos como fertilizante tais como cinza de casca de arroz (CCA) e lodo de estação de tratamento de esgoto (LETE) podem contribuir no fornecimento de nutrientes e reduzir custos de produção. Nesse sentido esta pesquisa objetivou avaliar o LETE como complemento da CCA no fornecimento de nutrientes para o milho e consequentemente no desenvolvimento das plantas. O experimento foi realizado em casa de vegetação de setembro a novembro. Adotou-se o delineamento em blocos ao acaso em esquema fatorial 6 x 6, tendo no primeiro fator as doses de CCA: 0; 4; 8; 16; 32; 64 g kg-1e no segundo as doses de LETE: 0; 2; 4; 8; 16; 32 g kg-1, com três repetições. As unidades experimentais foram constituídas de vasos plásticos com 12 dm³ de terra de um Argissolo Vermelho – Amarelo Eutrófico coletado no Centro Agropecuário da Palma-UFPEL, Capão do Leão, RS. Ao final do experimento, com setenta e sete dias, toda a parte aérea do milho foi colhida para quantificar a produção de massa seca e analisar macro (N, P, K, Ca e Mg) e micronutrientes (Fe, Mn, Cu e Zn). Os atributos químicos analisados no solo foram: pH em água, teores de cátions trocáveis (Ca, Mg, K e Na), teores de C, N, P, Si, Fe, Mn, Zn e Cu, bem como, a capacidade de troca de cátions (CTC) a pH 7. Os resultados indicaram que a CCA atuou na correção da acidez do solo, além de contribuir para o crescimento das plantas, se mostrando eficiente como fonte de fósforo e potássio. O uso do LETE contribui no suprimento de nitrogênio e fósforo, proporcionando o aumento da produção de matéria seca das plantas. Com o LETE houve aumento do Zn e Cu, enquanto que a CCA diminuiu a disponibilidade dos mesmos. Embora o LETE possa de fato suprir o N, carente na CCA, ela supre também o P, de modo que, pelo menos em solo bem suprido de K, não há vantagem em misturar CCA ao LETE para suprir estes macronutrientes, ou seja, aquilo que se busca completar na CCA usando o LETE pode ser atendido, mas ao usar o LETE a CCA pode ser dispensada.
The use of waste as fertilizer such as rice husk ash and sewage sludge treatment plant can contribute to the nutrient supply and reduce production costs. In this sense, this research aimed to evaluate the sewage sludge as the rice husk ash complement the supply of nutrients to corn and consequently in plant development. The experiment was carried out in September - November greenhouse. The design was adopted in randomized blocks in a factorial 6 x 6, with the first factor doses of rice husk ash: 0, 4, 8, 16, 32 and 64 g kg-1 and second doses of sewage sludge: 0; 2; 4; 8; 16; 32 g/kg, with three replications. The experimental units consisted of plastic pots with 12dm³ land Red-Yellow Pozolic soil (Ultisol). At the end of the experiment, seventy-seven days all aerial parts of the corn was harvested to quantify the dry matter yield and analyze macro (N, P, K, Ca and Mg) and micronutrients (Fe, Mn, Cu and Zn). Chemical characteristics analyzed in the soil were pH in water exchangeable cations (Ca, Mg, K and Na) contents of C, N, P, Si, Fe, Mn, Zn and Cu, as well as the ability to cation exchange (CTC) at pH 7. The results indicated that the rice husk ash acted to correct soil acidity and contributes to plant growth, proving efficient and phosphorus and potassium source. The use of sewage sludge contributes to the supply of nitrogen and phosphorus, providing increased production of dry matter of the plants. With sewage, sludge was increased Zn and Cu, while rice husk ash decreased availability. Although milk may in fact supply the N, lacking the CCA, it also supplies the P, so that at least well supplied ground K, there is no advantage to mix CCA to LETE to meet these macronutrients, namely that we are seeking to complete the CCA using LETE can be served, but to use the LETE CCA may be waived.

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26

Dubeux, Júnior José Carlos B. "Management strategies to improve nutrient cycling in grazed Pensacola bahiagrass pastures." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0011202.

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Stark, S. (Sari). "Reindeer grazing and soil nutrient cycling in boreal and tundra ecosystems." Doctoral thesis, University of Oulu, 2002. http://urn.fi/urn:isbn:9514266927.

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Abstract In northernmost Fennoscandia, grazing by reindeer (Rangifer tarandus L.) has a substantial impact on the vegetation of boreal forests and arctic-alpine tundra heaths, which are reflected in below-ground processes, such as nutrient mineralization and soil organic matter decomposition. In the present thesis, the effects of reindeer grazing on soil nutrient cycling were studied by comparing grazed situation with an ungrazed control area in ten boreal forests and six arctic-alpine tundra heaths. In boreal forests, reindeer grazing reduced microbial respiration in both the oligotrophic and mesotrophic study areas, indicating a deficiency of labile substrates for the soil microbes due to reindeer grazing. Simultaneously, there was heterogeneity in the impact on nitrogen mineralization rates as at some sites, mineralization was enhanced by grazing. The fertilization effect of urine and faeces can therefore be strong enough a factor to outweigh a reduction in quality of soil organic matter. In the oligotrophic forests, low soil moisture content in the grazed areas could sometimes limit the mineralization rates even when the potential for mineralization was enhanced by grazing. In the tundra ecosystems, there was spatial variation in the impact of grazing on microbial respiration and nitrogen mineralization. Low grazing intensity occurring outside the growing season had a retarding impact on nutrient cycling in both unfertilized, nutrient-poor and fertilized, nutrient-rich conditions. In contrast, a relatively high grazing intensity enhanced the mineralization rates in two nutrient-poor and two nutrient-rich tundra heaths. When three different grazing intensities were compared in one oceanic, nutrient-rich and one continental, nutrient-poor tundra heath, the strongest positive effect of grazing on soil nutrient cycling occurred in the heavily grazed areas. The data do not support the assumption that soil nutrient availability regulates whether herbivores enhance or retard nutrient cycling in the soil. Instead, the net effect of grazing is determined by the balance between the underlying mechanisms that may work at opposite directions. The most important of these mechanisms are the grazer-mediated impact on the decomposability of the dominant vegetation and fertilization by urine and faeces. The duration, intensity and seasonal timing of the grazing seem to be important factors that regulate whether reindeer grazing enhances or retards soil nutrient cycling in each specific area. Due to the high spatial and temporal variation in the effects of grazing observed in this study, it is not possible to generalize the overall impact of grazing. Further study is required in order to determine the exact conditions under which grazing enhances or it retards soil nutrient cycling.

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Kolm, Luciana. "Ciclagem de nutrientes e variações do microclima em plantações de Eucalyptus grandis Hill ex Maiden manejadas através de desbastes progressivos." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/11/11142/tde-30072002-151746/.

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O presente trabalho aborda a ciclagem de nutrientes e aspectos do microclima em plantações de Eucalyptus grandis de 20 anos, manejadas pelo método CCT, em 3 intensidades de desbaste (T0 = 0%, T1 = 67% e T2 = 83% de desbaste). As áreas de estudo localizam-se na Fazenda Santa Terezinha, propriedade da empresa Eucatex S.A., no município de Bofete SP. O clima da região é do tipo Cwa, segundo a classificação de Köpen, e o solo é classificado como Latossolo Vermelho-Amarelo transição para Areia Quartzosa. Em relação aos aspectos microclimáticos, verificou-se que os tratamentos desbastados (T1 e T2) interceptaram menos luz que os tratamento testemunha (T0). Seus valores de radiação fotossinteticamente ativa e ILR (%) foram, em geral, maiores que os do T0. As temperaturas mensais variaram pouco entre os tratamentos. O T2 apresentou a maior amplitude térmica, e as temperaturas médias foram ligeiramente superiores às dos demais tratamentos. Em todas as profundidades (0-5, 6-30 e 31-60 cm), o T0 manteve os maiores teores de umidade do solo. A deposição de serapilheira (estudada de outubro de 1998 a setembro de 1999) foi estatisticamente semelhante entre os tratamentos, embora os tratamentos com desbaste (T1 e T2) tenham depositado quantias ligeiramente maiores. Os teores de nutrientes e a sua transferência, pela deposição mensal de serapilheira, foram em geral mais altos nos tratamentos com desbaste. As taxas de deposição anual nos tratamentos T0, T1 e T2 foram de 10,2; 10,9; 10,4 t/ha/ano, respectivamente. A biomassa de serapilheira acumulada sobre o solo foi de 18,1 t/ha no T0, 13,4 t/ha no T1 e 14,8 t/ha no T2. Nos tratamentos com desbaste, os teores médios anuais de nutrientes da serapilheira acumulada foram geralmente iguais ou maiores que os do T0; porém, seus estoques foram inferiores aos do T0. A decomposição da serapilheira foi mais rápida nos tratamentos com desbaste, provocando menores acúmulos desta sobre o solo. Os estoques de P, K, Ca e Mg no solo foram superiores nos tratamentos desbastados (principalmente no T1). Devido à sua lenta velocidade de decomposição e imobilização dos nutrientes na camada de serapilheira, o T0 apresentou os menores estoques de nutrientes no solo (exceto para N). A aplicação de desbastes progressivos em povoamentos de eucaliptos, quando manejados em regimes de ciclos mais longos do que usualmente vem sendo aplicados atualmente (5 - 6 anos), podem favorecer a reciclagem dos nutrientes que entram no ecossistema, conservando mais eficientemente seus estoques no sistema (solo + serapilheira) e contribuindo para manter a produtividade do sítio.
This study characterizes nutrient cycling and microclimate conditions within a 20-year-old Eucalyptus grandis plantation with three thinning intensity treatments of Correlated Curve Trend (CCT) management method (T0 = 0%, T1 = 67% and T2 = 83% of thinning intensity). This project was located in Bofete SP, in the Santa Terezinha Farm, of Eucatex S.A. The climate of site is Cwa, according to Köpen classification, and the type soil is a Haplustox with a transition to Quartz Psamment. In respect to microclimate measurements, the thinned treatments (T1 and T2) intercepted less light than the non-thinned treatment (T0). Its photosynthetic radiation and IRL (%) were generally higher then the T0values. Montly temperature fluctuations were minimal among the treatments. T2 presented the highest thermical fluctuation, and their temperatures were higher than the other treatments. At all soil depths (0-5, 6-30 and 31-60 cm), the moisture contents were greater in T0. Litter production (measured from October, 1998 to September, 1999) was similar among the treatments, but there was somewhat more litterfall in thinned treatments (T1 and T2). Annual litterfall in treatments T0, T1 and T2 were 10.22, 10.87 and 10.39 t/ha/year respectively. The concentration of nutrients and their return through litterfall were generally greater in thinned treatments. Biomass of forest floor litter was 18.13 t/ha in T0, 13.43 t/ha in T1 and 14.83 t/ha in T2. Thinned treatments had equal to or higher than annual concentrations of forest floor litter when compared with T0. However, the amount of nutrients was less than T0. Litter decomposition was faster in the thinned treatments, and there was less forest floor litter in thinned treatments. Soil P, K, Ca and Mg contents were higher in thinned treatments, especially in T1. Due to its slow forest floor litter decomposition and its consequent nutrient immobilization, T0 had lower soil nutrient contents, except for N. The use of thinning practices in long rotation can improve nutrient cycling of atmospheric input, conserve the amount of nutrients in the soil-litter system and improve the site productivity.

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Menoyo, Molins Alexandra. "Nutrient availability regulates cell cycle through a Pho85 CDK-dependent control of Cln3 cyclin stability." Doctoral thesis, Universitat Internacional de Catalunya, 2012. http://hdl.handle.net/10803/101414.

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Cell cycle control by trophic factors has a key role in regulation of cell proliferation in all organisms. Nutrients are one of these important factors needed by cells to reproduce, so very well regulated mechanisms must exist that connect nutrient availability to cell cycle. Hence the importance on studying how exactly nutrient-dependent signaling pathways work. Cln3, the most upstream G1 cyclin in Saccharomyces cerevisiae, is one well demonstrated common effector of multiple nutrient-dependent signaling pathways. Moreover, its role in cell cycle is crucial. So it is a good candidate to regulate cell cycle progression in response to nutrient availability. One important question is to find the protein that could directly modulate Cln3 levels in response to nutrient availability. This protein could play as a nutrient sensor and as a cell cycle regulator at the same time. In the present thesis, Pho85 is founded to be the protein that could run these two highly different tasks, because of its well-characterized properties on sensing phosphate availability and the well-known functions on modulating cell cycle as CDK. The results of the present work clearly demonstrate that when phosphate is present, Pho85 regulates Cln3 levels by increasing the stability of the cyclin through specific phosphorylations, promoting cell cycle progression. Contrary, under phosphate depletion conditions, Pho85 become inactive and Cln3 is rapidly degraded, leading to a cell cycle arrest in order to maintain cell chronological lifespan.
El control del cicle cel•lular per factors tròfics té un paper important en la proliferació cel•lular de tots els organismes. Els nutrients són uns d’aquests factors importants requerits per les cèl•lules per reproduir-se, per tant deuen existir mecanismes molt ben regulats que connecten la disponibilitat de nutrients amb el cicle cel•lular. Per això, l’estudi de com funciona la senyalització cel•lular de nutrients i com afecta a la progressió del cicle és altament rellevant. Cln3, la ciclina de G1 més primerenca a Saccharomyces cerevisiae, és un efector comú de múltiples vies de senyalització de nutrients. A més, el seu paper en el cicle cel•lular és crucial. Per tant aquesta proteïna és una bona candidata per regular la progressió del cicle cel•lular en resposta a la disponibilitat de nutrients. Una qüestió important a resoldre és trobar la proteïna que podria modular directament els nivells de Cln3 depenent de la presència de nutrients. Aquesta proteïna actuaria com a sensor de nutrients i com a reguladora del cicle cel•lular alhora. A la present tesi, es mostra a Pho85 com la proteïna que pot fer aquestes dues tasques, tant per les seves propietats ben conegudes en la detecció de fosfat, com per les seves funcions de CDK modulant el cicle cel•lular. Els resultats d’aquesta tesi demostren clarament que quan el fosfat és present, Pho85 modula els nivells de Cln3 incrementant l’estabilitat de la ciclina mitjançant fosforilacions específiques, promovent la progressió del cicle cel•lular. Per altra banda, sota condicions de manca de fosfat, Pho85 esdevé inactiva i Cln3 és degradada ràpidament, conduint a un arrest del cicle cel•lular per mantenir la longevitat de la cèl•lula.
El control del ciclo celular por factores tróficos tiene un papel importante en la proliferación celular de todos los organismos. Los nutrientes son uno de estos factores importantes requeridos por las células para reproducirse, por lo tanto deben existir mecanismos muy bien regulados que conecten la disponibilidad de nutrientes con el ciclo celular. Por ello, el estudio de cómo funciona la señalización celular de nutrientes y cómo afecta a la progresión del cicle es altamente relevante. Cln3, la ciclina de G1 más temprana en Saccharomyces cerevisia, es un efector común de múltiples vías de señalización de nutrientes. Además, su papel en el ciclo celular es crucial. Por lo tanto esta proteína es una buena candidata para regular la progresión del ciclo celular en respuesta a la disponibilidad de nutrientes. Un tema importante a resolver es encontrar la proteína que podría modular directamente los niveles de Cln3 dependiendo de la presencia de nutrientes. Esta proteína actuaría como sensor de nutrientes y como reguladora del ciclo celular. En la presente tesis, se muestra a Pho85 como la proteína que puede hacer estas dos tareas, tanto por sus propiedades bien conocidas en la detección de fosfato, como por sus funciones de CDK modulando el ciclo celular. Los resultados de esta tesis demuestran claramente que cuando el fosfato está presente, Pho85 modula los niveles de Cln3 incrementando la estabilidad de la ciclina mediante fosforilaciones específicas, promoviendo la progresión del ciclo celular. Por otro lado, bajo condiciones de ausencia de fosfato, Pho85 es inactivada y Cln3 se degrada rápidamente, conduciendo a una parada del ciclo celular para mantener la longevidad de la célula.

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30

Brockett, Beth. "Patterns in forest soil microbial community composition across a range of regional climates in Western Canada." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/486.

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Soil microbial communities can be characterized by community structure and function (community composition) across a spectrum of spatial scales, and variation in soil microbial composition has been associated with a number of environmental gradients. This study investigates the structure and function of soil microbial communities under mature, undisturbed forested sites across a range of regional climates in British Columbia and Alberta, and also examines the variation in community composition within sites. Phospholipid fatty acid analysis was used to investigate the structure of soil microbial communities and total soil microbial biomass at each site. Extra-cellular enzyme assays established the functional potential of the soil microbial community at each site. Multivariate analysis of the data showed that the soil microbial communities under different forest types did significantly separate along the regional climate gradient by both community structure and function, despite high local variation in the communities. Soil moisture content and soil organic matter concentration consistently exhibited the strongest relationship with microbial community characteristics, although the functional and structural responses to the external drivers were different. Microbial community function and structure also changed with soil depth but not with time of sampling. Microbial community function was related to the regional annual average precipitation gradient. Most of the locations exhibited unique microbial community functional profiles in their soil layers; however the enzyme activities in the samples from the driest (Ponderosa Pine) and wettest (Mountain Hemlock) locations were notably different from each other and from those of the other locations, especially in the organic layers. The moist maritime-influenced Coastal Western Hemlock (CWH) forest exhibited microbial community structural characteristics which were unique from those of the other forest locations. The higher abundance of bacteria relative to fungi in the CWH forest soils may be related to the significantly higher available nitrogen concentrations at this site.

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31

Barbosa, Vanessa Virginia. "Decomposição anaeróbia de Egeria densa Planch e Chara braunii Gmel em sistemas aquáticos sob diferentes estados tróficos." Universidade Estadual da Paraíba, 2015. http://tede.bc.uepb.edu.br/tede/jspui/handle/tede/2242.

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In this study there were three motivating questions: (i) are there differences in the decomposition kinetics of E. dense and C. braunii? (ii) in which trophic state the decomposition is faster? (iii) wthat is the magnitude of nutrients release in the water during decomposition? The hypothesis tested is that the decomposition kinetics is faster for C. braunii releasing few nutrients, because it is a seaweed, however, with both species faster decomposing in eutrophic water due to the greater microbial activity in the environment. Water samples were taken from eutrophic reservoirs with low nutrient content of the Paraiba semi-arid region. The in vitro study in which anaerobic conditions were analyzed: the decay of organic matter and release of nutrients during decomposition. Both species showed similar biphasic decay of organic matter and carbon mineralization and the trophic state did not influence this process. Nutrient release was high for both species, independent of the trophic state. The trophic state of Paraiba semi-arid water is not a limiting factor for the debry decay of E. dense and C. braunii. The species are from different families, but for being submerged macrophytes have similar content of plant fibers, as a consequence significant differences in weight loss was observed.
Neste estudo as três questões motivadoras foram: (i) existem diferenças na cinética de decomposição entre E. densa e C. braunii? (ii) em qual estado trófico a decomposição ocorre mais rapidamente? (iii) qual a magnitude da liberação de nutrientes na água durante a decomposição? A hipótese testada e que a cinética de decomposição é mais rápida para C. braunii, liberando pouco nutrientes, por ser uma macroalga, no entanto, ambas as espécies se decompõem mais rapidamente em águas eutróficas devido à maior atividade microbiana nesse meio. Para isso, foram realizadas coletas de águas em reservatórios eutrófico e oligotrófico do semiárido paraibano. O estudo foi realizado in vitro em condições anaeróbias no qual se analisou o decaimento de matéria orgânica e a liberação de nutrientes durante a decomposição. As duas espécies apresentaram o mesmo padrão bifásico de decaimento da matéria orgânica e de mineralização do carbono e o estado trófico não influenciou esse processo. A liberação de nutrientes foi elevada por ambas às espécies, independente do estado trófico. O estado de trofia da água do semiárido paraibano não representa um fator limitante para o decaimento dos detritos de E.densa e C.braunii. As duas espécies são de famílias distintas, mas por serem macrófitas submersas, possuem teor de fibras vegetais semelhantes, uma vez que não apresentaram diferenças significativas na perda de massa.

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32

Aquino, Deodato do Nascimento. "Cycling carbon and spectrum characterization at thinned and native tropical dry forest - Caatinga." Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=16051.

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nÃo hÃ
The aim of this study was to evaluate the effects in the Caatinga biome of the technique of thinning on the dynamics of herbaceous phytomass productivity; fine roots; the deposition, accumulation and rates of decomposition of litter; aggregate stability; respirometry of the soil; stocks of carbon and nitrogen; and characterisation of changes in the spectral behaviour of the canopy. The study was carried out in two stages: the first in watersheds in the town of Iguatu, in the south central region of the State of CearÃ, Brazil, and the second in the watershed of the CaxitorÃ River, in the northern region of the state. The Iguatu experimental area comprised two watersheds, one under thinning for 5 years (CR5) and the other preserved with natural vegetation for 35 years (CS35). The variables to be sampled were: productivity of herbaceous biomass; fine roots; gravimetric moisture; isotope δ13C (â); aggregate stability; deposition, accumulation and rates of decomposition of litter; and stocks of total organic carbon and total nitrogen in the 0-20, 20-40 and 40-60 cm layers, from April 2013 to March 2014. The data were submitted to the analysis of means test and compared by t-test (p≤ 0.05). The increase in the intensity of herbaceous plants resulting from thinning contributed to an increase in stocks of total organic carbon (249% and 139% in the 20-40 cm and 40-60 cm layers respectively) and of total nitrogen (142% and 137% respectively), in relation to the area under preservation. The 0-10 cm layer of CR5 stored double the amount of fine roots found in CS35. In the topsoil (0-20 cm) of CR5, aggregates with a size 2.15 times greater than those found in CS35 were obtained. The greater conservation of litter on the soil of CR5 is associated with the greater input of lignified woody biomass from thinning, and consequently with the lower rates of decomposition and respirometry, which are evidenced by the low CO2 emissions into the atmosphere. Thinning in a Vertisol of the Caatinga biome has an influence on soil structure and on the stocks of carbon and nitrogen, making possible lower rates of CO2 emission and improving conditions for the infiltration of water. In the second phase of the experiment, SRTM (Shuttle Radar Topography Mission) data were used to evaluate the effect of the illumination geometry on the spectral characterisation of the canopy, as well as images from the OLI/Landsat 8 sensor, representative of the rainy and dry seasons of 2013. The images were converted into physical values (surface reflectance factors), the NDVI was calculated, and with the technique of principal component analysis images PC1 and PC2 were generated. Dispersion for the values of PC1 and PC2 from the different canopies was evaluated in a two-dimensional space. It was found that the reflectance intensity of the incident electromagnetic radiation in canopies of the caatinga biome is not only influenced by seasonality, but also by the illumination geometry arising from the topographical characteristics of the terrain. The effect of shading was predominant during the dry season, especially under low lighting conditions, irrespective of the structure of the plant cover. The NDVI proved to be unsuitable for detecting changes in the spectral behaviour of the Caatinga biome during the rainy season.
Objetivou-se com este trabalho avaliar os efeitos da tÃcnica de raleamento do bioma caatinga sobre a dinÃmica da produtividade de fitomassa herbÃcea; raÃzes finas; deposiÃÃo, acumulaÃÃo e taxas de decomposiÃÃo da serapilheira; estabilidade de agregados; respirometria do solo; estoque de carbono, nitrogÃnio e caracterizaÃÃo das alteraÃÃes no comportamento espectral do dossel. O estudo foi conduzido em duas etapas: a primeira em microbacias hidrogrÃficas no municÃpio de Iguatu, regiÃo centro sul e a segunda na bacia hidrogrÃfica do rio CaxitorÃ, regiÃo norte, ambas no estado do CearÃ. A Ãrea experimental de Iguatu consistiu de duas microbacias adjacentes, sendo uma raleada por 5 anos (CR5) e a outra conservada com vegetaÃÃo natural hÃ 35 anos (CS35). As variÃveis amostradas foram: produtividade de fitomassa herbÃcea, raÃzes finas, umidade gravimÃtrica, isÃtopo δ13C (â), estabilidade de agregados, deposiÃÃo, acumulaÃÃo e taxas de decomposiÃÃo da serapilheira, estoque de carbono orgÃnico total e nitrogÃnio total nas camadas de 0-20, 20-40 e 40-60 cm entre abril/2013 e marÃo/2014. Os dados foram submetidos Ã anÃlise de teste de mÃdia e confrontados pelo Teste T (p≤0,05). O aumento da intensidade de plantas herbÃceas decorrente da tÃcnica de raleamento contribuiu para o acrÃscimo nos estoques de carbono orgÃnico total (249% e 139% nas camadas 20-40 cm e 40-60 cm, respectivamente) e do nitrogÃnio total (142% e 137%, respectivamente) em relaÃÃo Ã Ãrea conservada. A camada de 0-10 cm da parcela CR5 armazenou o dobro do quantitativo de raÃzes finas encontradas em relaÃÃo a CS35. Na camada superficial do solo (0-20 cm) da CR5 foram obtidos agregados com tamanho de 2,15 vezes acima dos obtidos na CS35. A maior conservaÃÃo de serapilheira no solo da CR5 estÃ associada aos maiores aportes de fitomassa lenhosa lignificada proveniente do raleamento, e consequentemente das menores taxas de decomposiÃÃo e respirometria, constatada pelas baixas emissÃes de CO2 Ã atmosfera. O raleamento em Vertissolo do bioma Caatinga exerce influÃncia na estruturaÃÃo do solo, no estoque de Carbono e NitrogÃnio, possibilitando as menores taxas de emissÃo de CO2 e melhorando as condiÃÃes para a infiltraÃÃo de Ãgua. JÃ na segunda etapa do experimento, foram utilizados dados do SRTM (Shuttle Radar Topography Mission) para avaliaÃÃo do efeito da geometria de iluminaÃÃo na caracterizaÃÃo espectral do dossel, alÃm de imagens do sensor OLI/LANDSAT 8 representativas da estaÃÃo chuvosa e seca de 2013. As imagens foram convertidas em valores fÃsicos (fatores de reflectÃncia de superfÃcie), calculado o Ãndice NDVI e, a partir da tÃcnica de componentes principais, geradas imagens PC1 e PC2. Foram avaliadas as dispersÃes dos valores de PC1 e PC2, em um espaÃo bidimensional, provenientes dos diferentes dossÃis. Os resultados indicaram que a intensidade de reflectÃncia da radiaÃÃo eletromagnÃtica incidente em dossÃis do bioma caatinga Ã influenciada tanto pela sazonalidade climÃtica quanto pela geometria de iluminaÃÃo decorrentes das caracterÃsticas topogrÃficas do relevo. O efeito sombreamento foi predominante durante o perÃodo seco, principalmente para condiÃÃo de pouca iluminaÃÃo independentemente da estrutura de cobertura vegetal. O NDVI nÃo se mostrou adequado para detectar alteraÃÃes no comportamento espectral do bioma caatinga durante a estaÃÃo chuvosa.

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33

Campbell, Jocelyn. "Relationships between cyanolichen communities and nutrient cycling in sub-boreal spruce forests." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/23238.

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Cyanolichens (lichens with cyanobacterial symbionts) form a distinct assemblage of epiphytes strongly associated with humid microclimatic conditions in inland British Columbia. Disparate abundance patterns in sub-boreal forests are examined in relation to the influence of overstorey tree species. A comparison of lichens on conifer saplings beneath five overstorey tree species revealed that saplings beneath Populus support a disproportionately abundant and species-rich community of cyanolichens. Cyanolichens also grew more rapidly and had lower rates of mortality beneath Populus than beneath conifer overstorey trees. That cyanolichens were observed beneath Populus in stands that were otherwise climatically unsuitable suggests that Populus facilitates cyanolichen communities by providing a factor that compensates for sub-optimal conditions. Chemical analyses of throughfall precipitation from beneath Populus, Picea, Abies, Pseudotsuga and Betula failed to explain the variation in lichen community structure. However, glucose-rich nectar, exuded from extrafloral nectaries on Populus leaves, may instead be supporting cyanolichen communities. The nectar accumulates during dry periods, is washed off during subsequent rain events, and may be intercepted and metabolized by cyanolichens on conifer saplings beneath mature Populus canopies. C-flux measurements and phospholipid fatty-acid analyses with experimental applications of ¹³C₆-labelled glucose revealed a strong physiological response to glucose and a rapid incorporation of exogenous-¹³C into cyanolichen fatty-acid tissues. Field evidence further supports this hypothesis with higher rates of cyanolichen establishment observed on Picea branches under treatment of 2% glucose solution compared to water. The exogenous C may enable cyanolichens to become established in regions that are otherwise too dry to support them by providing a source of C despite drought-induced inactivity of the cyanobacterial partner. The abundant communities of nitrogen-fixing cyanolichens in wet, mature forests and beneath Populus are important to ecosystem function. The contribution of cyanolichens to N-cycling is calculated at sites with varying lichen abundances from measured rates of lichen litter deposition, decomposition and nutrient release. Cyanolichen litter biomass represents up to 11.5% of the total N-input from aboveground litterfall and is estimated to release 2.1 kg N ha⁻¹ yr⁻¹ of newly-fixed N that would otherwise be unavailable in these mature sub-boreal forests.

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34

O'Reilly, Andrew M. "Biogeochemical Cycling and Nutrient Control Strategies for Groundwater at Stormwater Infiltration Basins." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5360.

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Elevated concentrations of nutrients, particularly nitrate, in groundwater and springs in Florida are a growing resource management concern. Stormwater infiltration basins, which are a common stormwater management practice in the well-drained karst terrain areas of Florida, are a potentially important source of nutrients to the groundwater system because stormwater exits the basin by only evaporation or infiltration. To better understand the biogeochemical processes integrating stormwater infiltration impacts on groundwater resources in a field-scale setting, a combination of hydrologic, soil chemistry, water chemistry, dissolved and soil gas, isotope, and microbiological data was collected from 2007 through 2010 at two stormwater infiltration basins receiving runoff from predominantly residential watersheds in north-central Florida. Substantially different biogeochemical processes affecting nitrogen fate and transport were observed beneath the two stormwater infiltration basins. Differences are related to soil textural properties that deeply link hydroclimatic conditions with soil moisture variations in a humid, subtropical climate. During 2008, shallow groundwater beneath the basin with predominantly clayey soils (median 41% silt+clay content) exhibited decreases in dissolved oxygen from 3.8 to 0.1 mg/L and decreases in nitrate-nitrogen from 2.7 mg/L to less than 0.016 mg/L, followed by manganese and iron reduction, sulfate reduction, and methanogenesis. In contrast, beneath the basin with predominantly sandy soils (median 2% silt+clay content), aerobic conditions persisted from 2007 through 2009 (dissolved oxygen of 5.0–7.8 mg/L), resulting in nitrate-nitrogen of 1.3–3.3 mg/L in shallow groundwater. Soil extractable nitrate-nitrogen was significantly lower and the copper-containing nitrite reductase gene density was significantly higher beneath the clayey basin. Differences in moisture retention capacity between fine- and coarse-textured soils resulted in median volumetric gas-phase contents of 0.04 beneath the clayey basin and 0.19 beneath the sandy basin, inhibiting surface/subsurface oxygen exchange beneath the clayey basin. Subsurface biogeochemical processes at the clayey stormwater infiltration basin were further analyzed to better understand the effects of the highly variable hydrologic conditions common in humid, subtropical climates. Cyclic variations in biogeochemical processes generally coincided with wet and dry hydroclimatic conditions. Oxidizing conditions in the subsurface persisted for about one month or less at the beginning of wet periods with dissolved oxygen and nitrate showing similar temporal patterns. Reducing conditions in the subsurface evolved during prolonged flooding of the basin. At about the same time oxygen and nitrate reduction concluded, manganese, iron, and sulfate reduction began, with the onset of methanogenesis one month later. Reducing conditions persisted up to six months, continuing into subsequent dry periods until the next major oxidizing infiltration event. Evidence of denitrification in shallow groundwater at the site is supported by median nitrate-nitrogen less than 0.016 mg/L, excess nitrogen gas up to 3 mg/L progressively enriched in delta-15N during prolonged basin flooding, and isotopically heavy delta-15N and delta-18O of nitrate (up to 25 and 15 per mil, respectively). Isotopic enrichment of newly infiltrated stormwater suggests denitrification was partially completed within two days. Soil and water chemistry data suggest a biogeochemically active zone exists in the upper 1.4 m of soil, where organic carbon was the likely electron donor supplied by organic matter in soil solids or dissolved in infiltrating stormwater. The cyclic nature of reducing conditions effectively controlled the nitrogen cycle, switching nitrogen fate beneath the basin from nitrate leaching to reduction in the shallow saturated zone. Soil beneath the sandy stormwater infiltration basin was amended using biosorption activated media (BAM) to study the effectiveness of this technology in reducing inputs of nitrogen and phosphorus to groundwater. The functionalized soil amendment BAM consists of a 1.0:1.9:4.1 mixture (by volume) of tire crumb (to increase sorption capacity), silt and clay (to increase soil moisture retention), and sand (to promote sufficient infiltration), which was applied to develop an innovative best management practice (BMP) utilizing nutrient reduction and flood control sub-basins. Construction and materials costs, excluding profit and permit fees, for the innovative BMP were about $US 65 per square meter of basin bottom. Comparison of nitrate/chloride ratios for the shallow groundwater indicate that prior to using BAM, nitrate concentrations were substantially influenced by nitrification or variations in nitrate input. In contrast, for the new basin utilizing BAM, nitrate/chloride ratios indicate minor nitrification and nitrate losses with the exception of one summer sample that indicated a 45% loss. Biogeochemical indicators (denitrifier activity derived from real-time polymerase chain reaction and variations in major ions, nutrients, dissolved and soil gases, and stable isotopes) suggest nitrate losses are primarily attributable to denitrification, whereas dissimilatory nitrate reduction to ammonium and plant uptake are minor processes. Denitrification was likely occurring intermittently in anoxic microsites in the unsaturated zone, which was enhanced by increased soil moisture within the BAM layer and resultant reductions in surface/subsurface oxygen exchange that produced conditions conducive to increased denitrifier activity. Concentrations of total dissolved phosphorus and orthophosphate were reduced by more than 70% in unsaturated zone soil water, with the largest decreases in the BAM layer where sorption was the most likely mechanism for removal. Post-BAM orthophosphate/chloride ratios for shallow groundwater indicate predominantly minor increases and decreases in orthophosphate with the exception of one summer sample that indicated a 50% loss. Differences in nutrient variations between the unsaturated zone and shallow groundwater may be the result of the intensity and duration of nutrient removal processes and mixing ratios with water that had undergone little biogeochemical transformation. In order to quantify potential processes leading to observed nitrogen losses beneath the innovative BMP, an integrated infiltration basin–nitrogen reduction (IBNR) system dynamics model was developed. Based on two simulation periods, the IBNR model indicated denitrification accounted for a loss of about one-third of the total dissolved nitrogen mass inflow and was occurring predominantly in the BAM layer. The IBNR model results in combination with the field-based biogeochemical assessment demonstrated that the innovative BMP using the functionalized soil amendment BAM is a promising passive, economical, stormwater nutrient-treatment technology. Further field- and laboratory-scale research on the long-term sustainability of nutrient losses and further elucidation of causative physicochemical and biogeochemical mechanisms would contribute to improved BAM performance and green infrastructure development in the future.
ID: 031001572; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Adviser: Ni-Bin Chang.; Title from PDF title page (viewed August 26, 2013).; Thesis (Ph.D.)--University of Central Florida, 2012.; Includes bibliographical references (p. 246-263).
Ph.D.
Doctorate
Civil, Environmental, and Construction Engineering
Engineering and Computer Science
Civil Engineering

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35

Chuyong, George Bindeh. "Nutrient cycling in ectomycorrhizal legume-dominated forest in Korup National Park, Cameroon." Thesis, University of Stirling, 1994. http://hdl.handle.net/1893/2640.

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Patterns and rates of nutrient input to the forest floor in litterfall, throughfall and stemflow were investigated in plots of low and high abundance of ectomycorrhizal species. The aim of the study was to examine the comparative advantage of the ectomycorrhizal species in nutrient acquisition and cycling on nutrient-poor soils in Korup. Litterfall was similar in both forests with annual estimates of 9.00 and 8.33 t ha-1 yr-1 for LEM and HEM forests respectively. Litterfall distribution followed a mono-modal pattern, with peaks in the dry season in both forests and the HEM forest showing stronger seasonality. The concentrations N, K and Ca in total litterfall were higher in the LEM forest while those of P and Mg were higher in the HEM forest. The bulk of nutrients in total litterfall was in leaf litter with the reproductive fractions having the highest concentrations of nutrients. Ectomycorrhizal species showed lesser internal redistribution of nutrients than non-ectomycorrhizal species which resulted in their higher leaf litter concentrations of nutrients. Breakdown of litter was relatively faster in the LEM forest with an annual decomposition constant (KL) of 3.21 compared to 2.43 for the HEM forest. The reproductive fractions had relatively higher annual decomposition constants of 8.20 and 4.27 in the LEM and HEM forests respectively compared to the other fractions. The overall element mobility in decomposing leaf litter was similar in both forests and in the following order: Mg>K>Ca>P>N. Mineralization of N, P and K in the decomposing leaf litter was similar in both forests and higher in the HEM forest for Mg and Ca. Throughfall was 96.6% and 92.4%, and stemflow 1.5% and 2.2%, of gross rainfall in LEM and HEM forests respectively. Considerable amounts of Ca, Mg and P were brought to the forest canopy in gross rainfall (24-45% of total input through this route) with higher amounts of K and Ca leached from plant parts by the rainwater. The amounts of P, K and Ca in stemflow and throughfall were of the same magnitude in both forests with the enhancement of N slightly higher in the LEM forest and Mg in the HEM forest.

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36

Laruelle, Goulven Gildas. "Quantifying nutrient cycling and retention in coastal waters at the global scale." Doctoral thesis, Utrecht University, Utrecht, 2009. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/282551.

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37

Tavakol, M. Hossien. "Production and nutrient cycling in three Scottish oak woods on contrasting soils." Thesis, University of Stirling, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317316.

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38

Meyers, Emily. "Phosphate Cycling in the Presence of Biogenic Iron Oxides and Iron-Reducing Bacteria." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37306.

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Nutrient pollution from industrial activity is an environmental problem that persists in water bodies near urban settings, and has been a primary contributor to eutrophication, bacterial contamination, and harmful algal blooms. Biogenic iron oxides offer a potential solution to the treatment of lakes and rivers containing high concentrations of phosphate, the limiting nutrient in aquatic systems. Soluble ferrous iron can act as an electron donor for iron-oxidizing bacteria, which thrive in low-oxygen environments. This results in the formation of insoluble ferric iron minerals, ideal adsorbents for negatively charged phosphate. Conversely, iron-reducing bacteria reduce ferric iron to form ferrous iron, resulting in the formation of secondary minerals depending on the chemistry of the particular environment. This project investigates the chemical conditions at which biogenic iron oxides have the maximum adsorptive capacity, especially with respect to organic carbon content. A simplified model of natural biogenic iron oxides was synthesized by co-precipitating the mineral ferrihydrite (a common iron oxide) with the polysaccharide alginate, an analogue to bacterial exopolysaccharides. At the levels of carbon investigated, organic matter was not found to affect the adsorptive capacity of iron oxides at the C/Fe ratios analyzed. Similarly, organic matter did not appear to significantly influence the rate of reduction of ferrihydrite by the iron-reducing bacterium Shewanella putrefaciens CN32. Presence of organics did however influence rates of reduction and the mineralogy of the post-reduction precipitates. Phosphate adsorbed to iron oxides prior to microbial reduction greatly increased both the rate and the extent of ferric iron reduced, and also had an impact on the secondary minerals that formed (vivianite, green rust). An improved understanding of these conditions could contribute to a more efficient process by which iron-oxidizing bacteria are used for large-scale industrial water treatment.

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39

Andersson, Sara. "Nutrient cycling by the herbivorous insect Chrysomela tremulae : Nutrient content in leaves and frass and measurements of ingestion, egestion and exuviation rates." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-125632.

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Insect herbivory on forest canopies strongly affects ecosystem nutrient cycling and availability in a variety of ways, e.g. by changing the quantity, quality and timing of nutrient input to forest soils. A qualitative method for measurements of ingestion, egestion and exuviation rates of the insect Chrysomela tremulae on leaves of the hybrid Populus tremula x tremuloides were tested in this study with the aim to detect differences in relative nutrient cycling efficiencies. The assimilation efficiency (AD), efficiency of conversion of digested food (ECD) and efficiency of conversion of ingested food (ECI) increased from 1st, through 2nd and 3rd instar larvae with generally higher efficiencies for nitrogen than carbon. Effects on nutrient limitations for the insect were also tested by increasing the C:N ratio of insect diet. A carbohydrate solution was painted onto leaves which resulted in a significant increase in C:N (p<0.0001). This lead to a trend of lengthened developmental time for each ontogenetic stage, as well as higher ingestion rate and lower egestion- and exuviation rates. However, a different method of increasing the C:N ratio is recommended in future experiments since the leaves never truly absorbed the solution.

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40

Silveira, Éliton Rodrigo da. "Recuperação da mata ciliar do córrego Tarumã (Tarumã, SP): aspectos estruturais, florísticos e ambientais de quatro diferentes modelos florestais, dez anos após o plantio." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/18/18139/tde-06022017-102458/.

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A recomposição das matas ciliares pode vir a ser a solução mais eficaz e duradoura para reverter o acelerado processo de degradação dos recursos hídricos. Não há, no entanto, consenso sobre técnicas e espécies adequadas para a recomposição e nem critérios e indicadores para avaliar o êxito dos plantios. Esta pesquisa tratou do estudo de reflorestamento efetuado em 1990, às margens do córrego Tarumã, município de Tarumã, SP. No plantio foram utilizadas 29 espécies, sendo 28 nativas da região e uma introduzida de valor comercial (Pinus elliottii var. densa). As árvores foram plantadas em quatro módulos distintos, caracterizados por diferentes combinações de espécies, como segue: Módulo A - 100% pioneiras; Módulo B - 50% pioneiras + 50% não pioneiras; Módulo C - plantio misto aleatório de espécies nativas (pioneiras ou não) e módulo D - 100% Pinus. Avaliou-se a floresta formada, dez anos após o plantio, com base no desempenho das espécies plantadas e comparando-se os módulos entre si e com fragmento natural remanescente - (E), quanto à estrutura do estrato arbóreo, densidade, diversidade e riqueza florística da regeneração natural, características químicas do solo superficial e deposição de folhedo ao longo do ano. Verificou-se que há diferença entre os módulos de plantio para boa parte dos parâmetros avaliados. Do ponto de vista da estrutura da floresta, todos os módulos de plantio apresentam área basal, diâmetro médio e altura máxima inferiores ao fragmento natural. Por outro lado, a densidade do plantio foi superior à densidade da floresta natural e, mesmo com a mortalidade ao longo desses dez anos, a densidade nos diferentes módulos ainda é superior à da floresta natural (árvores com DAP maior ou igual 5 cm). Em síntese, dez anos não foram suficientes para que, nas condições ambientais deste experimento, a floresta plantada adquirisse a estrutura de uma floresta natural. Comparando-se entre si as espécies plantadas quanto ao seu desempenho, destacaram-se pela sua sobrevivência: Inga uruguensis, Croton urucurana e Schinus terebinthifolius. Pelo crescimento em altura e diâmetro, as espécies com melhor desempenho foram: Anadenanthera macrocarpa, Enterolobim contortisiliquum, Croton urucurana e Pinus elliottii var. densa. Comparando-se os quatro módulos entre si, verifica-se que o plantio misto aleatório apresentou maior densidade e riqueza de espécies em regeneração, seguido do plantio com 50% não pioneiras, plantio puro de pioneiras, e no último lugar, o plantio puro de Pinus. Predominam espécies zoocórias na regeneração natural, sendo que 62% das espécies não foram plantadas, devendo ter sido trazidas por dispersores. No que se diz respeito à ciclagem de nutrientes, o plantio puro de Pinus, embora tenha depositado a maior quantidade de folhedo/ha/ano, proporciona baixo retorno de nutrientes ao solo de modo geral, já que a concentração desses nutrientes no folhedo é baixa. Além disso, a análise química da camada superficial do solo mostrou que sob o Pinus o solo é mais ácido e há menor disponibilidade para a maior parte dos nutrientes, o modelo que mais se aproximou da floresta natural foi o plantio misto aleatório com essências nativas. No outro extremo, com piores resultados, esteve o plantio puro com Pinus elliottii var. densa, para as condições ambientais da área estudada.
Riparian forests restoration can be the best way to stop the degradation process of the water resources. However, there is no agreement about how to do that, what are the best species and planting techniques and how to evaluate the planted forests. This study was based upon a planted riparian forest, along Tarumã River, Tarumã municipality, São Paulo State. Twenty nine species were planted, being 28 native and one introduced species. Trees were planted in four different species combinations, as follows: Module - A 100% pioneer species; Module - B 50% pioneer and 50% no pioneer species; Module - C mixed; Module - D 100% Pinus. The four modules were evaluated ten year after planting, considering: forest structure, density, richness and diversity of natural regeneration, litter deposition and chemical properties of surface soil. These results of the planted forest were compared with a forest remnant - (E) located close to the experimental area. Differences were found among treatments and in comparison with the natural forest, for most of the parameters considered. Basal area, DBH, and maximum height were lower than in the forest fragment. Trees density is still higher in the planted forest than in the natural one, even the mortality rates have been high. Ten years were not enough to make the planted forest structure similar to the natural forest. Comparing the planted species performance, there is a group of high survival rates: Inga uruguensis, Croton urucurana and Schinus terebinthifolius. Another group presented species with high increment in height and diameter: Anadenanthera macrocarpa, Enterolobium contortisiliquum, Croton urucurana and Pinus elliottii var. densa. Natural regeneration density and richness under the planted forest were also different among treatments, in decreasing order: mixed planting - 50% pioneer + 50% no pioneer - 100% pioneer - pure Pinus. Among the species surveyed, zoochory is the main dispersion syndrome and 62% of the species were not planted. They were, probably, brought by animal dispersers. Litter production was higher in pure Pinus planting than in the other treatrnents. However, nutrients concentration is lower than in treatments with native species. So, total quantity of mineral elements that return to the soil is higher in those forests planted with native species. In addition, chemical properties of surface soil under Pinus forests (H + AI, pH, Ca, Mg, etc.) are worse than under other treatments. This study leads to conclusion that, among the tested treatments, the mixed planting with native species (C) was the most similar to the native forest in structure, diversity and natural regeneration. The worst result, under the environmental conditions of this study, was obtained with the pure stand of Pinus elliottii var. densa.

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Arnaudin, Mary Elin. "Benefits of Dung Beetles (Coleoptera: Scarabaeidae) on Nutrient Cycling and Forage Growth in Alpaca Pastures." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/31419.

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Alpacas have been gaining prominence in the U.S. since the early 1980s. In pastures, dung beetle activity has been shown to enhance the degradation and incorporation of dung into the soil. The benefits of this activity have been quantified for cattle, but not for alpacas. The objectives of this study were to document the dung beetle species present in alpaca pastures, and to evaluate the impact of dung beetle activity on the growth of a common summer annual grass. In 2010 and 2011, dung beetle species present in alpaca pastures located at Virginia State University (VSU), were evaluated weekly from late May until late August. Eleven species of dung beetles were found, with Onthophagus taurus Schreber being the most dominant. In 2011, a greenhouse study was conducted at Virginia Techâ s Southern Piedmont Research Station. Treatments included a control (no dung, no beetles), dung only, dung with five pairs of O. taurus, and dung that was allowed to be colonized in alpaca pastures at VSU. The addition of O. taurus and the field colonization both significantly increased total yield over the no dung control by 10% and 14%, respectively. These results indicate that healthy and diverse dung beetle communities occur in alpaca pastures in the mid-Atlantic region, and that the presence of these beetles would likely enhance nutrient cycling and pasture growth. However, it is important to remember that dung beetles are just one component of many found in a healthy grassland ecosystem, and the functions of these components are interrelated.
Master of Science

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42

Wilks, Melissa Kimberly. "Predation Mediated Carbon Turnover in Nutrient-Limited Cave Environments." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1384803278.

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Finkler, Nícolas Reinaldo. "Dinâmica da retenção de nitrogênio e fósforo em riachos tropicais do bioma Cerrado (SP)." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-20062018-105639/.

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Os serviços ecossistêmicos se traduzem em benefícios diretos e indiretos obtidos pelos seres humanos do ambiente natural graças ao papel imprescindível dos ecossistemas para o seu bem-estar, saúde e desenvolvimento socioeconômico. Considerando o serviço ecossistêmico de purificação da água, a retenção de nitrogênio e fósforo pelos ecossistemas aquáticos depende de uma combinação de mecanismos físicos, químicos e biológicos que transformam o nutriente no sentido longitudinal de um curso de água. A retenção é majoritariamente estudada em ambientes temperados, mas ainda pouco se sabe sobre como as características ambientais de sistemas tropicais podem afetá-la. O objetivo principal dessa pesquisa foi estimar a retenção de macronutrientes em riachos localizados no bioma Cerrado (SP). Avaliaram-se, além das características físicas e químicas, as taxas de retenção de nitrato, amônio e fosfato em trechos de quatro riachos caracterizados por gradientes de concentrações ambientais para testar hipóteses vinculadas ao nível de enriquecimento por nutrientes e ao papel de riachos tropicais sobre a retenção ecossistêmica. No período de janeiro a outubro de 2017, foram realizados pulsos de nutrientes, segundo o método Tracer Additions for Spiraling Curve Characterization, para modelagem e quantificação de métricas de retenção desses nutrientes (distância, taxa e velocidade de retenção em condições ambientais), além do comportamento cinético de cada adição. Os riachos foram hierarquizados conforme o nível de enriquecimento por fosfato, variável utilizada como discriminante de tal enriquecimento em função de sua significativa variação inter-riachos. Com relação às métricas de retenção, foram encontradas diferenças espaciais significativas entre riachos, enquanto que não foram observadas diferenças temporais entre coletas. Em geral, riachos não enriquecidos apresentaram distâncias de retenção em geral menores (8-418 m para nitrato, 38-172 m para amônio e de 60-560 m para fosfato) em comparação a ambientes enriquecidos (56-508 m para nitrato, 35-253 m para amônio e de 77-391 m para fosfato). Além disso, os riachos não enriquecidos apresentaram maior velocidade de retenção (máximas de 123 mm min-1 para nitrato, 68 mm min-1 para amônio e 17 mm min-1 para fosfato), além de taxas de retenção (µg m-2 min-1) superiores em comparação aos enriquecidos. O nitrato apresentou maiores taxas ambiental de retenção (média geométrica de 999,3 µg m-2 min-1), enquanto o amônio apresentou menor distância ambiental de retenção (média geométrica de 85,7 m) e maior velocidade ambiental de retenção (média geométrica de 6,9 mm min-1). No ajuste cinético da retenção, não foi evidenciada a saturação de concentrações para nenhum caso. O modelo Efficiency-Loss mostrou melhor ajuste cinético aos dados experimentais que os modelos cinéticos de Michaelis-Menten e primeira ordem. As métricas de retenção obtidas são de magnitudes superiores às normalmente reportadas na literatura para riachos de pequeno porte em outros biomas, o que reforça a importância da preservação e conservação de riachos tropicais. Para isso, sugere-se especial atenção ao controle e disciplinamento das formas de uso e ocupação do solo nestas bacias. Concluiu-se que os riachos analisados desempenham um papel relevante como sumidouros de N e P, o que os permite colocar na categoria de cursos de água estratégicos em relação ao serviço ambiental de retenção de nutrientes. .
Aquatic systems are responsible for key ecosystems services, providing direct and indirect benefits for human beings such as well-being, health and socio-economic development. The ecosystem service of water purification is one of their main functions. Nutrient uptake in surface waters is a combination of physical, chemical and biological mechanisms which transform the nutrient in a downstream direction. The nutrient uptake has been mostly studied in temperate environments, but little is known about how the environmental characteristics of tropical systems could affect it. The main objective of this study was to estimate the nutrient uptake in streams located in the Cerrado biome (SP). In addition to the physical and chemical characteristics, nitrate, ammonium and phosphate uptake rates were evaluated in reaches of four streams characterized by gradients of environmental concentrations. Also we tested hypotheses regarding the level of nutrient enrichment and the role of tropical streams on the whole ecosystem uptake. From January to October 2017, nutrient additions were carried out according to the Tracer Additions for Spiraling Curve Characterization method, in order to model and quantify nutrient uptake metrics (uptake lenght, uptake rate and uptake velocity under ambient conditions) and to characterize the kinetics of each addition. The streams were ranked according to the level of enrichment by phosphate, since its concentrations showed significant variation across streams. Significant spatial differences were found across streams, while no temporal differences were observed among sampling periods. In general, non-enriched streams generally had lower uptake lengths (8-418 m for nitrate, 38-172 m for ammonium and 60-560 m for phosphate) in comparison to enriched streams (56-508 m for nitrate, 35 -253 m for ammonium and 77-391 m for phosphate). Non-enriched streams showed higher uptake velocities (maximum of 123 mm min-1 for nitrate, 68 mm min-1 for ammonium and 17 mm min-1 for phosphate), as well as uptake rates (µg m-2 min-1) greater than enriched streams. Nitrate had higher ambient uptake rates (geometric mean of 999.3 µg m-2 min-1), while ammonium had lower ambient uptake length (geometric mean of 85.7 m) and higher ambient uptake velocity (geometric mean of 6.9 mm min-1). The uptake kinetics modelling suggested that no nutrient saturation occurred in any case. The Efficiency-Loss kinetic model had better fit to the experimental data than Michaelis-Menten and first-order kinetic models. The retention metrics obtained are higher than those normally reported in the literature for low-order streams in other biomes, which highlights the importance of preservation and conservation of tropical streams. Special attention should be given to the control and management of the land use forms in these watersheds. The studied streams play a relevant role as sinks of N and P, indicating they are strategic watercourses regarding the environmental service of nutrient uptake.

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Aikio, S. (Sami). "Plant adaptive strategies in relation to variable resource availability, soil microbial processes and ecosystem development." Doctoral thesis, Oulun yliopisto, 2000. http://urn.fi/urn:isbn:9514256824.

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Abstract Plants have evolved various adaptive strategies for balancing the benefits and costs of having a high affinity for resources, plasticity of growth allocation and mycorrhizal symbiosis. The relative growth rates of mycorrhizal and non-mycorrhizal plants were modelled for stable and variable nutrient availability. Mycorrhizal plants had higher growth rates at low and non-mycorrhizal plants at high nutrient availability. Variation in nutrient availability reduced the growth rate of mycorrhizal plants due to a high affinity for nutrients. However, mycorrhizal plants may be able to buffer against external fluctuations and therefore experience less environmental variation than non-mycorrhizal plants. Non-mycorrhizal plants may even benefit from variation. The optimal allocation of growth between shoot and roots depends on the availability of energy and nutrients. The optimisation model predicted that the requirement for phenotypic plasticity of shoot/root allocation is greatest in environments with low resource availability. Plants with a high affinity for resources required more plasticity in order to tolerate variation than plants with a low affinity. The model predicted a trade-off between the ability to deplete resources and the ability to tolerate resource fluctuations. Changes in the availability and ratio of resources lead to changes in the structure and composition of vegetation during primary succession. The field study of the forested phases of the land uplift island Hailuoto showed a successional change in the vegetation from the dominance of bryophytes and deciduous dwarf shrubs to dominance by lichens and evergreen dwarf shrubs. The humus layer became thinner and the availability of nutrients declined, while the C/N ratio of soil organic matter increased during succession indicating a decline in the quality of organic matter. The increased soil respiration rate indicates a successional increase in the energetic costs of decomposing organic matter. Nutrients mediate both direct and indirect trophic interactions. Indirect interactions of nutrient cycling are not explicit in continuous time models. A transformation to a discrete time model was shown to make the indirect interactions explicit as transition probabilities and allowed their dynamic contribution to be evaluated with an elasticity analysis. The importance of indirect interactions was greater in tundra than temperate forest and increased with the rate of nutrient cycling.

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Mettam, Colin. "Nutrient cycling and oxygen availability in ancient oceans : extinction events and evolutionary opportunities." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/16334.

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Bilal, Ruba Candiga. "Soil Carbon and Nutrient Cycling Across Cover Types in Southern Appalachian Hardwood Forests." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/85625.

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Appalachian mixed hardwood stands along south facing slopes of the Ridge and Valley physiographic province were used to determine fine scale soil respiration (Rs ) and nutrient dynamics among four distinct cover types, white oak (WO, Quercus alba L.), scarlet oak (SO, Quercus coccinea Muech.), chestnut oak (CO, Quercus montana Wild.) and a pine-oak co-dominant cover (PO, Pinus spp. and Quercus spp. (primarily Pinus pungens Lamb. and Q. montana)). Null hypotheses were that: (1) Rs and its relationship to environmental drivers would not differ among the cover types, (2) water and nutrient use efficiencies (WUE and NUE) would not differ among the cover types, and (3) litter decomposition would not differ among the diverse cover types. In 0.02 ha plots, replicated four times, Rs and associated variables (e.g., soil temperature and moisture) were measured. Measurements occurred in three sub-sample locations per plot, from July 2014 - December 2015. In each plot, foliage from two trees of the dominant species were collected to determine WUE using δ¹³C isotope discrimination. Nutrient (N, P and K) content of this fresh foliage was compared with that of litterfall to determine NUE. Litterbags, collected over a one and half year period were used to determine decomposition rate constants for each dominant species. Soil temperature and moisture explained 71% of the variability in Rs. Although only slight, there were statistically significant differences in the Rs models due to cover type. At the same soil temperature, the PO cover type had the highest Rs while the SO, WO cover types had the lowest Rs. WUE, and NUE varied among cover types. SO had significantly greater WUE than the other species, including Table mountain pine, which had the highest NUE. Higher elevation cover types (i.e., PO and CO) ad greater decomposition rate constants. Among the factors driving decomposition, soil C: N ratio had the strongest correlation to decomposition. Correlations between decomposition and productivity variables of total above ground biomass, total stand biomass, and aboveground net primary production also exist. In conclusion, carbon and nutrient cycling varies across the level of cover type within the southern Appalachian hardwood forests. Future efforts to focus on carbon and nutrient dynamics in the context of land use or global change should consider these finer-scale differences.
Ph. D.

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47

Altinalmazis, kondylis Andreas. "Tree diversity effects on root production, decomposition and nutrient cycling under global change." Thesis, Bordeaux, 2021. http://www.theses.fr/2021BORD0067.

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L'hypothèse de l'assurance prévoit que les forêts composées de mélanges d'espèces d'arbres pourraient mieux résister aux conditions environnementales stressantes que les forêts composées d'une seule espèce d'arbre. La majorité des travaux antérieurs ont testé cette hypothèse en se focalisant sur la productivité et les variables de réponse associées sans prendre en compte les processus souterrains. L’objectif principal de ma thèse était d’étudier l’effet de la diversité des espèces d’arbres sur les processus souterrains impliqués dans la décomposition des racines à travers des gradients climatiques. J'ai émis l'hypothèse que le mélange d'espèces ayant des systèmes racinaires contrastés entraînerait une faible compétition souterraine, et se traduirait par la production de plus biomasse de racines fines. En outre, j'ai émis l'hypothèse que les racines ayant des caractéristiques chimiques et morphologiques contrastées dans les peuplements mixtes se décomposent plus rapidement. Dans des conditions de stress hydrique, j'ai émis l'hypothèse d'une décomposition plus lente mais d’une atténuation des mélanges d'arbres sur la décomposition en raison de l'amélioration des conditions micro-environnementales. Pour tester ces hypothèses, j'ai examiné la variation des caractéristiques fonctionnelles des racines et leurs conséquences sur les flux de C, N et P à l'échelle de l'écosystème à travers l’étude de : 1) la ségrégation verticale des racines et la biomasse des racines fines, 2) la dynamique des racines fines et les flux de nutriments associés et 3) la décomposition des racines fines et des feuilles mortes. Dans ce cadre, trois deux expériences de terrain ont été réalisé, l'une avec une expérience de plantation d'arbres de 10 ans avec du bouleau et du pin près de Bordeaux (expérience ORPHEE), la seconde le long d'un gradient latitudinal de forêts de hêtres matures dans les Alpes françaises (expérience BIOPROFOR).Les résultats obtenus montrent que les racines de bouleaux et de pins présentaient une distribution verticale similaire et une biomasse souterraine similaire de racines dans les mélanges d'arbres par rapport aux monocultures, contrairement à ma première hypothèse. Cependant, l'attribution plus importante du pin mais pas du bouleau à la croissance des racines dans les horizons du sol supérieur dans des conditions moins limitatives en eau suggère des conditions localement favorables qui peuvent conduire à une compétition asymétrique à la profondeur du sol. De plus, la production et la décomposition des racines fines étaient similaires dans les mélanges et dans les monocultures, en contradiction avec ma deuxième hypothèse. Il est intéressant de noter que les racines de bouleau, mais pas les racines de pin, ont libéré du P pendant leur décomposition, ce qui suggère un rôle important du bouleau dans le cycle du P et pour la nutrition en P des arbres sur ces sols sableux limités en P. Conformément à ma troisième hypothèse, j'ai observé une décomposition plus lente de la litière de feuilles et des racines fines en réponse à une sécheresse estivale prolongée, tout au long du gradient latitudinal dans les Alpes. Cependant, cette décomposition plus lente sous la sécheresse n'a pas été atténuée dans les peuplements forestiers à essences mixtes par rapport aux peuplements à essences uniques. Il est intéressant de noter qu’il y a une libération nette d'azote dans les racines fines en décomposition mais pas dans la litière de feuilles en décomposition, ce qui suggère un rôle distinct des racines fines dans le cycle de l'azote. En conclusion, j'ai constaté que le mélange des espèces d'arbres n'atténue pas les effets négatifs du changement climatique. Cette thèse démontre que la promotion de mélanges peut toujours être bénéfique pour au moins une des espèces d'arbres mélangées, par l'ajout d'espèces, car une espèce d'arbre peut en faciliter la nutrition minérale d’une autre par des flux souterrains de N et de P
The insurance hypothesis predicts that forests with tree species mixtures may resist better to stressful environmental conditions than forests composed of only one tree species. Most of the currently available literature tested this hypothesis for aboveground productivity and its related response variables, but less is known about belowground processes. In my PhD thesis, I studied the drivers of belowground productivity and decomposition across climatic gradients and how they are affected by tree mixtures. I hypothesized that mixing of tree species with contrasting rooting patterns and fine root morphologies, would result in a release of competitive pressure belowground, and translate into higher fine root standing biomass and increased fine root productivity. Moreover, I hypothesized that roots with contrasting chemical and morphological characteristics in mixed stands would decompose faster, which may be particularly important under nutrient-limited conditions. Under water-limiting conditions, such as during extreme summer drought, I hypothesized overall slower decomposition but an attenuating effect of tree mixtures on decomposition due to improved micro-environmental conditions, in particular for leaves, since roots decompose in a more buffered soil environment. To test these hypotheses I examined the variation in tree root functional traits (across- and within-species), and its consequences for fluxes of C, N and P at the ecosystem scale. I addressed three main objectives and associated research questions to quantify the interactive effect of tree mixtures and climate on: 1) vertical root segregation and fine root standing biomass, 2) fine root dynamics and their associated nutrient fluxes and 3) fine root- and leaf litter decomposition. I could benefit from two different field experiments for my work, one with a 10-year-old tree-plantation experiment with birch and pine close to Bordeaux (ORPHEE experiment), the second along a latitudinal gradient of mature beech forests in the French Alps (BIOPROFOR experiment).I observed that roots from the birch and pine tree-plantation showed similar vertical distribution and similar belowground root standing biomass in tree mixtures compared to monocultures, contrary to my first hypothesis. However, the greater allocation of pine but not of birch to root growth within the top soil horizons under less water-limiting conditions suggests locally favourable conditions that may lead to soil depth-specific asymmetric competition. In the same experiment, fine root production and decomposition were similar in mixtures and in monocultures, in contradiction with my second hypothesis. Moreover, I did not observe any interactive effects of tree mixtures with stand density or water availability. Interestingly though, birch roots, but not pine roots released P during root decomposition, which suggests an important role of birch in the P-cycle and for P nutrition of trees on these P-limited sandy soils. In line with my third hypothesis, I observed a slower decomposition of leaf litter and fine roots in response to reinforced and prolonged summer drought, irrespective of the position along the latitudinal gradient in the Alps. However, this slower decomposition under drought was not attenuated in forest stands with mixed tree species compared to single species stands. Compared to leaf litter, fine roots decomposed slower and released less C. Interestingly, I found a net N release in decomposing fine roots but not in decomposing leaf litter, which suggests a distinct role of fine roots in the N cycle. In conclusion, I found that mixing tree species did not attenuate negative effects of climate change. However, this thesis demonstrates that promoting mixtures can still be beneficial for at least one of the admixed tree species, through species addition (i.e., complementing one tree species with another tree species), as one tree species may facilitate another via belowground fluxes of N and P

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48

West, Elizabeth Jane. "The Influence of Zooxanthellate and Non-zooxanthellate Jellyfish on Nutrient Cycling and Trophodynamics." Thesis, Griffith University, 2009. http://hdl.handle.net/10072/366387.

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The appearance and disappearance of large numbers of medusae is a common characteristic of jellyfish populations. Blooms of jellyfish can attain very large biomasses that cover wide areas and can be short-lived, after which time the population may crash rapidly. The sheer biomass of jellyfish during bloom periods and the ‘boom and bust’ population dynamics are likely to have considerable impacts on the surrounding ecosystem. Some species of jellyfish contain symbiotic dinoflagellates called zooxanthellae. Zooxanthellae are able to assimilate nutrients from the surrounding water and transfer photosynthetic products to the host jellyfish. Zooxanthellate jellyfish are likely to acquire and recycle nutrients very differently to non-zooxanthellate species, and are therefore likely to have contrasting influences on nutrient cycling and trophodynamics. However, there are large gaps in our understanding of these processes. This thesis directly compares the role of zooxanthellate and non-zooxanthellate jellyfish on nutrient cycles and trophodynamics, by investigating these processes in zooxanthellate jellyfish, Cassiopea sp. and Phyllorhiza punctata, and the non-zooxanthellate jellyfish, Catostylus mosaicus. An important step in understanding the influence of jellyfish on ecosystem processes is to determine how nutrients are cycled within individual medusae. To do this, the exchanges of nutrients with the surrounding water were compared between zooxanthellate and non-zooxanthellate jellyfish. Experiments were done to compare the net exchanges (uptake and excretion) of organic and inorganic nitrogen and phosphorus with the surrounding water. Changes in nutrient concentrations were measured in tubs housing zooxanthellate Cassiopea sp., non-zooxanthellate C. mosaicus, and water control (no jellyfish). Experiments were repeated during the day, when photosynthesis and respiration could occur, and at night when only respiration could occur. Organic nutrients were found to comprise 25 - 43 % of the total excretion by non-zooxanthellate jellyfish. Organic nutrient excretion by blooms (506 t km-2) of non-zooxanthellate jellyfish were estimated to potentially support 62 – 120 mg C m-2 of bacterial production per day. In addition, excretion of inorganic nutrients by blooms of non-zooxanthellate jellyfish were estimated to potentially support 201- 423 mg C m-2 of primary production per day. In contrast, zooxanthellate jellyfish excreted minimal amounts of inorganic and organic nutrients or took them up from the water column. Therefore, nutrients assimilated by zooxanthellate jellyfish are likely to be retained and temporarily stored in the biomass of the population. The assimilation and retention of nitrogen were compared between zooxanthellate and non-zooxanthellate jellyfish. To do this, firstly, the assimilation and retention of nitrogen were directly compared between Cassiopea sp. and C. mosaicus. Jellyfish were labelled with isotopic nitrogen (15N) from two different sources, 15N-labelled Artemia prey and dissolved ammonium (15NH4+). The incorporation and retention of 15N was measured in the jellyfish tissues over nine days. Secondly, experiments were done to measure the influence of the availability of prey and concentrations of nutrients on the retention of nitrogen by Cassiopea sp. To do this, Cassiopea sp. were labelled with 15NH4+ and then placed in pools that had different combinations of high and low nutrient concentrations and high and low feeding regimes. The retention of 15N was measured in jellyfish over 37 days. Respiration and excretion rates were also measured for animals at the end of the experiment. Cassiopea sp. was found to assimilate nitrogen from both NH4+ and prey, and recycle this nitrogen internally. In contrast, C. mosaicus only assimilated nitrogen from prey and quickly excreted this nitrogen to the external environment, resulting in a short retention time. Cassiopea sp. retained nitrogen more than five times longer than C. mosaicus. Further, the nitrogen retention time of Cassiopea sp. was influenced by the availability of prey and dissolved nutrients, with the availability of prey having the greatest effect. Specifically, medusae exposed to low feeding retained nitrogen twice as long as medusae exposed to high feeding, which suggests that ingestion of prey by the host jellyfish is an important source of nitrogen in Cassiopea sp. Further, daily rates of photosynthesis and respiration suggest that photosynthesis by the zooxanthellae can potentially supply all of the carbon required for respiration and growth of the entire medusa. Jellyfish populations can hold considerable proportions of carbon and nutrients in an ecosystem and when a population crashes, jellyfish may sink to the benthos and decompose. An experiment was done that measured the changes in sediment oxygen demand as well as inorganic and organic nutrients during the decomposition of dead jellyfish, C. mosaicus. Fluxes were measured in tubs housing dead jellyfish over nine days as the jellyfish tissue decomposed. The decomposition of C. mosaicus resulted in a rapid leaching of organic nutrients from the dead tissues. Following this, microbial mineralisation dominated, which consumed oxygen and released dissolved inorganic nutrients. Although this release of nutrients may serve as a trophic link to pelagic primary producers, it may also lead to environmental problems associated with low oxygen concentrations depending on the size of the bloom and the degree of mixing in the system. Lastly, the influence of zooxanthellate and non-zooxanthellate jellyfish on plankton communities was compared. An in situ mesocosm experiment was done to compare the influence of C. mosaicus (non-zooxanthellate) and P. punctata (zooxanthellate). Changes in primary production and plankton assemblages were measured in mesocosms containing C. mosaicus, P. punctata, a combination of these species and compared to controls over six days. Catostylus mosaicus was found to increase chlorophyll a and productivity in the water column due to the large amount of nutrients excreted, causing a bottom-up influence on primary producers. This was in contrast to P. punctata, which were found to have little influence on chlorophyll a and production. This study provided direct experimental evidence that unlike C. mosaicus, P. punctata does not enhance primary production due to the minimal excretion of nutrients. Both P. punctata and C. mosaicus also had a large top-down predation pressure on zooplankton communities, causing significant declines in most species. This was with the exception of bivalve veligers, which were not consumed by either species, and gastropod veligers, which were not consumed by P. punctata. The major findings of this research have been integrated into a conceptual model that compares the influence of zooxanthellate and non-zooxanthellate jellyfish on nutrient cycles and trophodynamics. This model has been discussed in context to existing literature and recommendations have been made for future research. Overall this research found that zooxanthellate and non-zooxanthellate jellyfish assimilate, retain and release nutrients very differently and therefore have contrasting impacts on the nutrient cycling and trophodynamics of their surrounding ecosystem.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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49

Liptzin, Daniel. "Soil nutrients and biogeochemical cycling in the forest-alpine tundra ecotone." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3273655.

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50

Gardolinski, Paulo Cesar Ferreira da Costa. "In situ monitoring and biogeochemical cycling of nutrients in estuarine waters." Thesis, University of Plymouth, 2002. http://hdl.handle.net/10026.1/497.

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Дисертації з теми "Nutrient cycliing"

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