Literatura académica sobre el tema "Nutrients spatial variability"
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Artículos de revistas sobre el tema "Nutrients spatial variability"
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Zhao, Gengxing, Chao Dong, Xiaona Chen y Baowei Su. "Scale Characteristics and Effects on Spatial Variability of Soil Available Nutrients". Applied Engineering in Agriculture 35, n.º 2 (2019): 221–30. http://dx.doi.org/10.13031/aea.12963.
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Abstract.The spatial variability of farmland soil nutrients on different scales is important for farming as it forms the basis for the efficient utilization of soil nutrients and precision fertilization. Survey points were distributed throughout the study area on three different scales (county, field, and block). Research on the scale effect of the spatial variability of available nitrogen (AN), available phosphorus (AP), and available potassium (AK) involved a combination of classical statistics, geostatistics, and Geographic Information System (GIS) techniques. Results indicated that the three kinds of nutrients presented moderate variation intensity on the three scales. All of the nutrients tested exhibited strong spatial autocorrelation, indicating that spatial variability was primarily affected by structural factors, including climate, soil type and topography. As the sampling scale decreased, the nutrients showing weak variation at the large scale exhibited great variation at the small scale; the spatial autocorrelation of these three nutrients first became greater and then weakened; the distance of the spatial autocorrelation shortened gradually. Furthermore, the patch density value of the soil nutrient map increased, which indicated that the distribution of nutrients tended to be more fragile. When combined, sampling methods on the multi-scale allowed us to obtain real and systematic soil information. This study explored scale characteristics and the effects of spatial variability with regards to the primary nutrients available on farmland and provided a theoretical basis to effectively understand the nutrient status of regional farmland and improve the efficacy of soil sampling. Keywords: Multi-scale, Geostatistics, Patch density, Fractal dimension, Kriging interpolation.
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Qin, Zi Han. "Research on the Spatial Variability of Soil Nutrients Prediction Based on GIS". Advanced Materials Research 791-793 (septiembre de 2013): 1681–85. http://dx.doi.org/10.4028/www.scientific.net/amr.791-793.1681.
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Soil is a necessary nutrition library of crop growth, its nutrient spatial variability exists the whole crop growth period with the characteristics of long and complex, so the spatial variability of soil nutrient prediction is one of the hot research problems to be urgently solved in precision agriculture. This paper first introduces GIS and statistical analysis organic combination of research method and model, on the basis of this, based on GIS spatial data level of analysis and point-line-side buffer, we will accurate analysis of point-line-sides mutation interval through the variation Euclidean distance and distance weighting interpolation method. Finally through the comparison of mean value and T test, we can predict the approximate interval of soil nutrients spatial variability, to a certain extent, it can provide theory and technology support for the scientific prediction of soil nutrients spatial variability.
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Zhao, Yue Ling, Hai Yan Han, Li Ying Cao y Gui Fen Chen. "The Nutrients Spatial Variability of Black Soil Based on GIS". Applied Mechanics and Materials 694 (noviembre de 2014): 580–83. http://dx.doi.org/10.4028/www.scientific.net/amm.694.580.
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The precision agriculture (PA) is the end product of the modern high tech's information technology and the agricultural production technology union. The soil nutrients are not only an important component of soil research, but also a critical determinant of its productivity. Some soil nutrients spatial distribution pictures were established based on important factors that affect crops production. The soil nutrient situation was understood by the paper in Jilin province black soil. The results can realized some information opening and sharing and helped some farmer and manager to understand some soil nutrient spatial distribution. They can speed up the development of Jilin province’s precision agriculture.
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Long, Linli, Ying Liu, Xiaoyang Chen, Junting Guo, Xinhui Li, Yangnan Guo, Xuyang Zhang y Shaogang Lei. "Analysis of Spatial Variability and Influencing Factors of Soil Nutrients in Western China: A Case Study of the Daliuta Mining Area". Sustainability 14, n.º 5 (27 de febrero de 2022): 2793. http://dx.doi.org/10.3390/su14052793.
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An understanding of the spatial variation and influence factors of soil nutrients in mining areas can provide a reference for land reclamation and ecological restoration. Daliuta was used as the study area. The spatial variability of soil nutrients was analyzed using traditional statistics and geostatistics. The effects of topography, mining history, and soil erosion were discussed. The results indicate that the soil pH of the Daliuta mining area is slightly acidic to slightly alkaline, and the soil organic matter, available nitrogen, available phosphorus, and available potassium belonged to the five levels (very low), six (extremely low), five (extremely low), and four (moderately low), respectively. The soil water and salt content indicated that the soil environment in the mining area is arid and has normal levels of salinity. The organic matter, available nitrogen, available phosphorus, available potassium, and soil salt varied moderately, and the pH did not change much, while the soil water varied strongly. The organic matter, pH, and soil salinity are moderately spatially autocorrelated, and the available nitrogen, available phosphorus, available potassium, and soil water are weakly spatially autocorrelated. Each nutrient index had a certain spatial trend effect. The slope, aspect, elevation, and topographic wetness index are the primary topographic factors that control the spatial distribution of soil nutrients. The organic matter, pH, and soil salinity are moderately spatially autocorrelated, and the available nitrogen, available phosphorus, available potassium, and soil water are weakly spatially autocorrelated. Each nutrient index had a certain spatial trend effect. The slope, aspect, elevation, and topographic wetness index are the primary topographic factors that control the spatial distribution of soil nutrients. Soil erosion and mining history are also important factors that lead to the spatial variation of soil nutrients.
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Carr, Geneviève M., Patricia A. Chambers y Antoine Morin. "Periphyton, water quality, and land use at multiple spatial scales in Alberta rivers". Canadian Journal of Fisheries and Aquatic Sciences 62, n.º 6 (1 de junio de 2005): 1309–19. http://dx.doi.org/10.1139/f05-044.
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The ability of land use to replace water quality variables in predictive models of periphyton chlorophyll a was tested with a 21-year data set for Alberta rivers. Nutrients (total dissolved P and NO2 + NO3) explained 23%24% of the variability in seasonal chlorophyll a, whereas land use (human population density) explained 25%28% of the variability. The best models included the combination of total dissolved P and population density, explaining 32%34% of periphyton chlorophyll a variability. However, analysis of variance of chlorophyll a by ecoregions and ecozones explained about as much variability (28%30%), and the inclusion of an ecoregion term into the regression models showed a diminished importance of land use as a predictor of chlorophyll a, with best models based on the combination of nutrients and ecoregion and explaining up to 43%44% of periphyton chlorophyll a variability. Within ecoregions, land use was sometimes a good surrogate for nutrient data in predicting chlorophyll a concentrations. Overall, land use is a suitable surrogate for nutrients in regression models for chlorophyll a, but its inclusion in general models may reflect regional differences in nutrientchlorophyll relationships rather than true land use effects on chlorophyll a.
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Behera, S. K., K. Suresh, K. Ramachandrudu, K. Manorama y B. N. Rao. "Mapping spatial variability of leaf nutrient status of oil palm (Elaeis guineensis Jacq.) plantations in India". Crop and Pasture Science 67, n.º 1 (2016): 109. http://dx.doi.org/10.1071/cp15029.
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Spatial variability of leaf nutrients in oil palm (Elaeis guineensis Jacq.) plantations in Goa, Karnataka, Mizoram and Gujarat states of India were examined for implementation of site-specific fertilisation programs. Georeferenced leaf samples were collected randomly for the oil palm plantations. The leaf nutrient concentrations were assessed and analysed statistically and geostatistically. The concentrations of leaf nutrients such as nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S) and boron (B) in oil palm plantations varied widely at different locations. Leaf P concentration was positively and significantly correlated with S concentration at Goa, Karnataka and Gujarat. Positive and significant correlation between leaf Ca and Mg concentration was recorded at Mizoram and Gujarat. Geostatistical analysis of leaf nutrients showed different distribution patterns at different locations. This study revealed the need to determine spatial variability of nutrient status of oil palm plantations before planning a differential fertiliser program. Therefore, saving of nutrients could be achieved by adopting site-specific nutrient-management strategies.
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Kumar, Hemendra, Puneet Srivastava, Jasmeet Lamba, Brenda V. Ortiz, Thomas R. Way, Laljeet Sangha, Bijoychandra S. Takhellambam, Guilherme Morata y Roberto Molinari. "Within-Field Variability in Nutrients for Site-Specific Agricultural Management in Irrigated Cornfield". Journal of the ASABE 65, n.º 4 (2022): 865–80. http://dx.doi.org/10.13031/ja.15042.
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HighlightsPhosphorus and nitrogen in soil and plants varied during the growing season across the cornfield.Spatial variability in nutrients caused spatial variability in plant growth and crop yield across the cornfield.Hydrological characteristics and soil hydraulic properties were responsible for spatial variability in nutrients.Need to consider spatial variability in nutrients in delineating management zones before adopting management practices.Abstract. The adoption of precision agricultural practices in Alabama has been increasing in recent years. Although challenging, understanding nutrient variability in agricultural fields is important for site-specific management. This study investigated phosphorus (P) and nitrogen (N) variability in an irrigated cornfield located in the Town Creek Watershed of Tennessee Valley Region of Alabama, USA during the 2019 growing season. Three different irrigation management zones (high yield-HY, moderate yield-MY, and low yield-LY) were delineated based on ten years of historical records of crop yield, soil texture, and measured topography using the Management Zone Analyst (MZA) software. The soil samples at 0 to 15 cm, 15 to 30 cm, and 30 to 60 cm depths were collected five different times during the 2019 growing season. Both manure and inorganic fertilizer were uniformly applied during the growing season. At all soil depths, HY and MY zones had higher soil nutrient concentrations than the field average nutrient concentration. However, the LY zone had below field average soil nutrient concentration in the entire soil profile. The plants (above-ground) in HY and MY zones had higher than average nutrient concentrations and the plants in the LY zone had lower than average nutrient concentrations throughout the cornfield. This site-specific nutrient variation in these zones was due to within-field terrain attributes, differences in soil properties, and surface runoff losses. A significant difference was recorded in the corn yield in the HY and LY zones of the field. Two extreme groups of nutrients were found in the cornfield similar to irrigation management zones (HY and LY). A zone with a higher yield also had higher soil and plant nutrients in the zone (HY), and a zone with a lower yield also had lower soil and plant nutrients in the zone (LY). Incorporating nutrient variability for site-specific management in management zone delineation can help with reducing nutrient application, nutrient loss, and improving yield. This study supports the adopting of precision agricultural management practices based on in-field nutrient variability. Keywords: Corn, Crop yield variability, Irrigation, Management zones, Nitrogen, Nutrient variability, Phosphorus, Site-specific management, Topographical wetness index (TWI).
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Siswanto, Eko, MD Latifur Rahman Sarker y Benny N. Peter. "Spatial variability of nutrient sources determining phytoplankton Chlorophyll-a concentrations in the Bay of Bengal". APN Science Bulletin 2022, n.º 1 (30 de julio de 2022): 56–64. http://dx.doi.org/10.30852/sb.2022.1834.
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Primary production is a key marine ecosystem driver in the Bay of Bengal and is important for the societies and economies of the surrounding countries. Although the availability of inorganic nutrients is known to control primary production in this region, the specific nutrient sources that affect primary production in different parts of the bay have not been identified. In this study, we assess the importance of nutrients from different sources in determining chlorophyll-a concentration, an indicator of primary production, in the Bay of Bengal by conducting multiple linear regression of satellite-derived chlorophyll-a concentration, sea surface height anomaly, and sea surface temperature; modelled dust deposition; and in situ river discharge from 1997 to 2016. River-borne nutrients were important up to approximately 200 km from the coast. Deep-ocean nutrients influenced chlorophyll-a concentrations mainly in the south-western and western bay, whereas wind-borne nutrients were more important in the central and eastern bay. Any attempt to understand the impact of nutrients from a certain source should also consider the potential impacts of other nutrient sources. Although climate impacts on chlorophyll-a concentrations through river discharge were observed in our study, future studies should investigate climate-change impacts through atmospheric aerosols and mesoscale eddies.
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Neatrour, Matthew A., Robert H. Jones y Stephen W. Golladay. "Correlations between soil nutrient availability and fine-root biomass at two spatial scales in forested wetlands with contrasting hydrological regimes". Canadian Journal of Forest Research 35, n.º 12 (1 de diciembre de 2005): 2934–41. http://dx.doi.org/10.1139/x05-217.
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We investigated the relationship between soil nutrients and fine-root biomass at broad (among ecosystem types) and fine (within a 20 m × 20 m plot) spatial scales in forested wetlands of the southeastern United States. We selected three replicates each of high-fertility floodplain swamps, low-fertility depressional swamps, and intermediate-fertility river swamp sloughs and measured soil nutrient availability (NO3-N, NH4-N, and PO4-P) and fine-root biomass. At one replicate of each wetland type, a dense network of sampling points was used to measure variability (variance and coefficient of variation) of soil nutrients and fine-root biomass. At the broad scale, fine-root biomass was lower in floodplain swamps than in either river swamp sloughs or depressional swamps. Also, multiple linear regression and Spearman's rank correlations indicated a negative relationship between soil nutrient availability and fine-root biomass. Fine-scale correlates between soil nutrient availability and fine-root biomass were generally weak. Fine-scale variability of NO3-N and NH4-N was greatest in the floodplain swamps, but nutrients were not spatially patchy at any of the sampled sites. We conclude that soil nutrient availability may control fine-root biomass at the broad scale, but it is unclear if the same is true at fine spatial scales.
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Kambale, J. B. y H. V. Rudramurthy. "Application of Geographical Information System to Understand Spatial Variability of Soil Available Nutrients in Northern Karnataka, India". Current World Environment 12, n.º 1 (25 de abril de 2017): 169–73. http://dx.doi.org/10.12944/cwe.12.1.20.
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It is very important to distinguish the spatial variability in soil fertility for site specific nutrient application. To know the status, 25 soil samples were collected from Vandurga Village, Yadgir District, Karnataka, India. Samples were analysed for electrical conductivity (EC), power of hydrogen (pH), organic carbon (OC), Nitrogen (N), Phosphorous (P2O5) and Potassium (K2O). Further, SPSS (ver. 19) was used to execute conventional statistical analysis and ArcGIS to get the information about distribution and spatial variability of soil available nutrients. The analysis results showed that the EC of soil varied from 0.13 to 0.25 dS/m with a mean of 0.18 dS/m. The PH ranged from 6.62 to 8.82 with an average of 7.89. Available OC ranged from 0.14 % to 1.90 % with mean of 0.78 %. Similarly mean values for N, P2O5 and K2O observed 215.3 kg/ha, 31.5 kg/ha, and 513.4 kg/ha, respectively. The SD and CV for EC was 0.031 and 16.69%, respectively, while for pH, OC, N, P2O5 and K2O it was found to be 0.56 and 7.04, 0.39 and 51.16, 100.9 and 46.86, 19.12 and 60.61, 160.88 and 31.33 respectively. Spatial variability maps for various nutrients prepared shows the huge variation in the soil nutrients availability. This variability appeared due to lack of balanced application of fertilizers. It was suggested that an appropriate applications of nutrients necessary for selected land based on soil nutrients.
Tesis sobre el tema "Nutrients spatial variability"
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Dias, Jos? Eduardo. "Monitoramento do uso da terra e dos n?veis de nutrientes do solo no Sistema Integrado de Produ??o Agroecol?gica utilizando geoprocessamento". Universidade Federal Rural do Rio de Janeiro, 2007. https://tede.ufrrj.br/jspui/handle/tede/549.
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Agroecological production systems are more complex than conventional ones, since a series of crops follow in sequence or are intercropped to achieve high diversity and maximize soil nutrient recycling. The full understanding of these systems require systemic analyses and therefore, adequate tools. To understand soil fertility evolution, heterogeneity should also be considered. This thesis was performed at Integrated Agroecological Production System, located at Serop?dica, Rio de Janeiro, an area that has been organically managed for 14 years. The first chapter consisted of studying land use from 2003 to 2005. Each land unit use was annotated every three months to generate 12 maps. The information gathered was processed to generate three maps: (i) cultivated species richness; (ii) fallow intensity and (iii) green manure use. High cultivated species richness was observed. In some land units up to 40 plant species were recorded. However, this diversity was not uniformly distributed throughout the terrain. A high intensity of land use, mostly with annuals was also observed in a large part of the area. In most cases, fallow periods were up to 3 months in 3 years. The use of legumes was less frequent on the land units used for annual crops. They were not uniformly distributed throughout the terrain. The objectives of the second chapter were: (i) to generate maps of spatial distribution of soil nutrients (Ca++, Mg++ K++ and P), pH and organic matter; at two soil depths 0-20 and 20-40 cm, in 2004 and 2005 (ii) evaluate the difference of those soil attributes in two years (iii) evaluate the difference of soil fertility between the layers of 20-40 cm and 0-20 cm, (iv) generate two maps of fertility potential , one for each year, for the 0-20 cm layer; (v) to combine maps of all attributes in order to generate maps of potential of gain/loss of nutrients . In general, soil nutrient levels were high and very high, indicating that the 14 years of organic management has built up soil fertility. There was a trend of decreasing soil fertility from 2004 to 2005. The area with higher loss potential coincided with a high intensively used portion of the system. However, on the area used as a control, losses also occurred, in lower intensity. From all nutrients studied, phosphorus was the most spatially and temporally variable.
Sistemas de produ??o com base agroecol?gica s?o mais complexos que os convencionais. A heterogeneidade ? uma regra nesses sistemas, pois muitas culturas se sucedem no tempo e no espa?o, compondo assim, alta biodiversidade. A compreens?o desses sistemas requer an?lises de car?ter sist?mico e, portanto, necessita de ferramentas compat?veis. Da mesma forma, estudos de fertilidade do solo, que consideram a heterogeneidade espacial e temporal s?o imperativos para se compreender a din?mica dos nutrientes. O presente estudo foi conduzido no Sistema Integrado de Produ??o Agroecol?gica - SIPA, uma ?rea que vem sendo manejada organicamente por catorze anos, situada no munic?pio de Serop?dica RJ. O primeiro cap?tulo constou do estudo do uso da terra, entre 2003 e 2005. Foram feitos registros trimestrais do uso das glebas, gerando doze mapas de uso. As informa??es contidas nesses mapas foram processadas de forma a gerar tr?s novos mapas: (a) riqueza de esp?cies cultivadas; (b) intens idade de pousio e (3) utiliza??o de leguminosas. Foi verificada alta riqueza de esp?cies cultivadas, havendo algumas glebas com at? 40 esp?cies vegetais. Por?m, esta diversidade encontra-se desuniformente distribu?da no terreno. Houve uma alta intensidade de uso da terra, sendo o per?odo de pousio, em grande parte, relativamente curto, ou seja, de at? tr?s meses, em tr?s anos. Nesses casos, predominaram cultivos anuais. O uso de leguminosas, no sistema, foi menor nas glebas de cultivos anuais e estava desuniformemente distribu?do no terreno. O segundo cap?tulo teve como objetivos: (1) gerar mapas da distribui??o espacial de MO, pH. Ca++, troc?vel, Mg++ troc?vel e K++ troc?vel em quatro glebas selecionadas do SIPA, para as camadas de 0 a 20 e de 20 a 40 cm, nos anos 2004 e 2005; (2) avaliar a evolu??o dos teores daqueles elementos nos dois anos; (3) avaliar a diferen?a de teores entre as camadas 0- 20 cm e 20-40 cm; (4) gerar dois mapas de fertilidade potencial qu?mica , um para cada ano, combinando-se os mapas de todos os nutrientes, para a camada de 0 a 20 cm e (5) gerar dois mapas de potencial de perda/ac?mulo de nutrientes, um, pela combina??o dos mapas de evolu??o da fertilidade e outro, pela combina??o dos mapas de potencial de 2005 e 2004. Os resultados indicaram n?veis dos nutrientes, na faixa de alto a muito alto, na maioria da extens?o da ?rea de estudo, nos dois anos, indicando que o manejo do SIPA, nos catorze anos, desde a sua cria??o, tem constru?do a fertilidade do solo. No entanto, detectou-se uma tend?ncia de diminui??o dos n?veis de nutrientes de 2004 para 2005. O potencial de perda coincide com ?rea de alta intensidade de uso, entretanto a ?rea controle, de uso m?nimo, tamb?m indicou perdas, contudo em propor??es menores.
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Smucker, Nathan J. "Using Diatoms and Biofilms to Assess Agricultural and Coal Mining Impacts on Streams, Spatio-Temporal Variability, and Successional Processes". Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1276285170.
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Malecki, Lynette. "Temporal and spatial variability of nutrient fluxes from sediment in the lower St. Johns River". [Gainesville, Fla.]: University of Florida, 2002. http://purl.fcla.edu/fcla/etd/UFE0000568.
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Oelsner, Gretchen Pauline. "Spatial and Temporal Hydrologic Variability as a Control on the Nutrient Dynamics of the Upper Rio Grande". Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/194215.
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Large rivers in semiarid regions provide valuable resources for municipalities, agriculture, and adjacent ecosystems, yet the limited nature of the resource requires a concerted effort to understand the controls on water quality. To address this issue I continued and adapted biannual geochemical synoptic sampling of the Rio Grande from Del Norte, CO to Elephant Butte Reservoir between August 2003 and 2006 which had started in 2001. During average to drought conditions, river discharge was derived primarily from snowmelt in the headwaters region, total dissolved solutes increased downstream, and wastewater treatment plants were the largest source of nitrogen to the river. Surprisingly, return flows of river water diverted for agriculture had lower average nitrogen concentrations than the original river water, indicating that the agricultural system is a sink for nitrogen. When summer climatic conditions changed to a persistent monsoon regime, both the water and solute sources changed as the river was reconnected to its uplands and floodplain. Stable isotope data indicate that monsoon precipitation represented 10-50% of surface flow and that discharge increases were entirely due to ephemeral flows. An analysis of solute concentrations suggested that 80-100% of the increases in sulfate, chloride, DOC and nitrate were due to ephemeral flows. Ephemeral flows replaced wastewater treatment plants as the largest source of nitrogen to the river.Using data from the synoptic sampling, I developed both a simple chloride mixing model and a dynamic simulation model of nitrate to evaluate the controls on nutrient cycling within the Rio Grande. Results from the chloride mixing model indicate that both abiotic hydrologic processes and biotic processes provide important controls on nutrient concentrations. River characteristics that increase surface water/groundwater exchange are important for determining nutrient retention, a result commonly identified in smaller streams, but never before quantified in a large river. Dynamic simulation modeling indicates that both plant uptake and denitrification remove nitrate within the Middle Rio Grande with denitrification accounting for 55-100% of the nitrate removal downstream of Albuquerque. The results of this dissertation provide a conceptual model for the hydrologic and biologic controls on nutrient concentrations in a heavily managed large semiarid river.
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Fernández-Martínez, Marcos. "On the role of nutrients, climate and anthropogenic impacts in spatio-temporal variability of forest productivity". Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/385914.
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Els boscos són dels ecosistemes terrestres més importants en termes de fotosíntesi i segrest de carboni, perquè n’acumulen i en segresten en grans quantitats, com a biomassa i com a matèria orgànica del sòl. A més, els boscos proporcionen polsos de recursos, a traves de la producció de fruits, que poden comportar efectes en cascada a través de la xarxa tròfica de l’ecosistema.
L’objectiu d’aquesta tesi és caracteritzar l’estructura i el funcionament dels boscos i quantificar llurs productivitats ecosistèmiques. La nostra recerca s’ha centrat en entendre els controls del balanç de carboni i de la producció de fruits en ecosistemes forestals. En aquesta tesi, hem intentat discernir entre els efectes de la disponibilitat de nutrients, del clima, de la variabilitat meteorològica interanual i dels impactes antropogènics en la variabilitat espai-temporal de la productivitat forestal.
Els resultats indiquen que l’edat del bosc, la disponibilitat d’aigua i la llargada de l’època càlida són els controls més importants dels estocs i fluxos de carboni i les eficiències en l’ús dels recursos. Malgrat això, el balanç del carboni dels boscos ve fortament determinat per la disponibilitat de nutrients del sòl. Els boscos fèrtils segresten el 33 ± 4% del carboni fotosintetitzat, mentre que els boscos infèrtils en segresten només el 6 ± 4%. A més, un cop tingut en compte l’efecte de l’edat, la relació biomassa-producció primària neta de les branques, tiges i arrels gruixudes estava positivament relacionada amb la disponibilitat de nutrients, contràriament al que passava amb les arrels fines. D’altra banda, vam trobar que l’augment de concentració del CO2 atmosfèric ha contribuït a augmentar la producció primària bruta i el segrest de carboni en un 1% anual des de l’any 1995 fins al 2011. Els resultats indiquen que, a Europa i els Estats Units, la reducció en la deposició de sofre ha comportat un augment més gran en la respiració que no pas en la fotosíntesi de l’ecosistema.
Els resultats mostren que la producció de fruits en boscos centre-Europeus oscil·la entre els 10 i els 40 g C m-2 any-1 i fa servir entre el 0.5 i el 3% del carboni fotosintetitzat. Els boscos amb elevades concentracions foliars de zinc i fòsfor produeixen més fruits i presenten una irregularitat interanual menor. A més, vam trobar que la producció interanual de fruits estava controlada per la variabilitat de la Oscil·lació de l’Atlàntic Nord, amb una importància major que les condicions atmosfèriques locals predint la producció de fruits. En boscos de Quercus ilex i Quercus pubescens vam trobar que l’estrès hídric de la primavera era el factor més rellevant explicant la variabilitat interanual en la producció d’aglans, mentre que la variabilitat en la producció de pol·len no presentava cap efecte. També vam demostrar que la producció de fruits pot ser predita fent sevir índexs de vegetació mitjançant la teledetecció per satèl·lit com l’”enhanced vegetation index” (EVI). Les grans produccions d’aglans en Quercus ilex van ser determinades per unes bones condicions de la vegetació durant els mesos previs a la collita i per unes bones condiciones hídriques primaverals. Finalment, vam demostrar la utilitat de l’índex de disparitat consecutiva (D) i les seves avantatges respecte el coeficient de variació (CV) en avaluar la variabilitat temporal. Vam trobar que D era menys depenent que la mitjana que el CV, a banda de tenir en compte l’autocorrelació de les sèries temporals.
Els resultats d’aquesta tesi obren la porta a un bon nombre de noves hipòtesis que mereixen ser testades en un futur proper. A més, aquesta tesi suposa un bon exemple del que les grans bases de dades poden oferir al camp de l’ecologia.Forests are among the most important terrestrial ecosystems in terms of photosynthesis and carbon sequestration because they accumulate and sequester large amounts of carbon, both as living tissues and as soil organic matter. Forests also provide large resource pulses through fruit crops that may present cascading effects through the food web of the ecosystem. The objective of the thesis was to characterize the structure and functioning of forests and to quantify ecosystemic productivity. We focused our research on understanding the main controls of carbon balance and fruit production in forest ecosystems. In this thesis, we try to disentangle the effects of nutrient availability, stand characteristics, climate and weather variability and anthropogenic impacts on spatio-temporal variability in forest productivity. We found that stand age, water availability, and length of the warm period were the main factors controlling forest carbon stocks, fluxes and resource-use efficiencies. Standing biomass and carbon fluxes were strongly correlated to each other at the global scale and both were controlled by climate (mainly water availability and temperature) and stand characteristics such as the age of the stand or leaf type. However, carbon balance of the ecosystem strongly depended on the nutrient availability. We found that, nutrient-rich forests sequester 33 ± 4% of photosynthesized carbon while nutrient-poor forests only sequester 6 ± 4% of it. At the ecosystem level, this effect of nutrient availability was independent of climate, stand age or the management of the stand. In addition, once the effect of stand age was removed the biomass-to-net primary production ratio of woody tissues (branches, stems, and coarse roots) was positively influenced by nutrient availability, but it had a negative effect on the fine root fraction. Regarding temporal variability of carbon fluxes, we found that increasing CO2 has increased gross primary production and carbon sequestration, on average, by 1% annually from 1995 to 2011. We also found that the reduction of sulphur deposition in Europe and the USA involves a higher recovery in ecosystem respiration than in gross primary production. Regarding fruit production, we found that fruit production ranges from 10 to 40 g C m-2 y-1 and uses around 0.5 - 3% of the photosynthesized carbon in European forests. We found that forests with higher foliar zinc and phosphorus concentrations, produced larger fruit crops and presented less irregularity in interannual fruit crop size. Additionally, we found interannual fruit variability to be controlled by the interannual variability of the North Atlantic Oscillation, having a more prominent importance than local weather variables in predicting it. In Quercus ilex and Quercus pubescens stands we found that spring water deficit was the most relevant factor in explaining interannual variability in acorn production and that interannual differences in pollen production did not influence acorn crop size. We demonstrated that fruit production can be predicted using remotely sensed vegetation indices, such as the enhanced vegetation index (EVI). Our results suggested that fruit crop size in Quercus ilex was driven by a combination of two factors, i.e. good vegetation conditions during several months prior to fruit harvest, and wet weather during spring. Finally, we demonstrated the usefulness of the consecutive disparity index (D) and its advantages with respect to the coefficient of variation (CV). We found D to be less dependent on the mean than the CV while also taking into account the autocorrelation of the time series. The results of this thesis open the door to a wide range of new ideas and hypotheses worth to test in the near future. This thesis is also a good example of what the so called “big data” can offer to ecologists and environmental scientists.
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Klasner, Laura M. y Laura M. Klasner. "The influence of spatial and temporal hydrologic variability on nutrient fluxes and transformations, San Pedro River, Arizona, USA". Thesis, The University of Arizona, 2006. http://hdl.handle.net/10150/626916.
Texto completoResumen
Pre-monsoon (June) and monsoon (August) sampling campaigns were conducted
on a gaining and a losing reach in the San Pedro River in 2005 to quantify the effects of
variability in hydrologic conditions on carbon and nitrogen cycling in an N-limited semi
arid stream. Nutrient concentrations decrease along the gaining reach, while new
groundwater inputs, rapid N03-N uptake and net production of organic DOC and DON
occurs. In contrast, the losing reach experiences little spatial variability suggesting the
presence of a large, well-mixed alluvial aquifer as a single source. However, so/
concentrations and S04:Cl ratios decrease between gaining and losing systems with
isotope mixing models indicating uptake of S04 2- and suggesting biological sulfate
reduction between reaches. Diurnal cycles of increases in nighttime stage, er and
nutrients indicate change in riparian vegetation transpiration demand and bank drainage
of relatively N rich water at night. Monsoon stream flow becomes a roughly equal
mixture of groundwater and monsoon precipitation with nutrient concentrations
exhibiting little spatial variability. However, a decrease in DON concentrations and DON
between the two reaches indicates nutrient processing occurs at much larger spatial scales. These data illustrate several examples of how hydro logic variability at different
spatial and temporal scales controls nutrient fluxes and transformations.
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Montiel, Luis Ramiro Samaniego. "Balanço e evolução temporal de teores de fósforo e potássio no solo em áreas manejadas com agricultura de precisão". Universidade Federal de Santa Maria, 2011. http://repositorio.ufsm.br/handle/1/5540.
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The need for improving nutrient use efficiency and increase savings demand a better
knowledge of soils and production systems. The objective of this study was to
evaluate the soil P and K budget and its relationships with their temporal evolution on
site-specific management areas. The experiments were carried out in four cropland
areas from the Medium Plateau region of the Rio Grande do Sul state, located at the
cities of Almirante Tamandaré do Sul, Tio Hugo, Não-Me-Toque and Vitor Graeff.
Soil tests were used to verify the spatial variability, budget and temporal evolution of
soil P and K levels by the comparison of the years of 2005 and 2009. Regression
analysis was performed by the software JMP IN v.3.2.1 to evaluate the relationship
between P and K budget and the temporal evolution of soil P and K levels. Cropland
areas showed high spatial variability for P and K soil test levels at the beginning of
the study, which was decreased by applying precision farming techniques.
Relationships between P and K budget and the temporal evolution of soil P and K
test levels were positive with the exception of the Vitor Graeff area which showed
negative P and K budget. P and K fertilization were 30 and 25% higher in relation to
their exportation, respectively. On average, soybean extracted 44 kg P2O5 ha-1 and
63 kg K2O ha-1, while the maize exported 78,5 kg P2O5 ha-1 and 59 kg K2O ha-1.
Temporal evolution of soil P and K test levels was high when P and K budget was
low and there was a low temporal evolution when the P and K budget was high. On
the average of the four cropland areas there were necessary the input of 12,0 kg
P2O5 ha-1 to increase 1 mg dm-3 of soil P test levels and the input of 4,1 kg K2O ha-1
to increase 1 mg dm-3 of soil K test levels.A necessidade de aproveitar melhor os insumos e economizá-los na maior medida possível leva à obrigação de conhecer a fundo os solos e sistemas de produção. O objetivo deste trabalho foi avaliar o balanço nutricional de fósforo (P) e potássio (K) no solo e sua relação com a evolução temporal, em áreas manejadas com auxilio da agricultura de precisão. Os experimentos foram conduzidos no Planalto Médio do Rio Grande do Sul, em quatro áreas situadas nos municípios de Almirante Tamandaré do Sul, Tio Hugo, Não-Me-Toque e Vitor Graeff. Por meio da análise das amostras de solo foi verificada a evolução dos teores de P e K comparando os anos de 2005 a 2009. Análises de regressão realizadas pelo software JMP IN v.3.2.1 foram utilizadas para avaliar a relação entre saldo e evolução de P e K. Determinaram-se a variabilidade espacial, o balanço nutricional e a evolução temporal de P e K no solo. As áreas apresentaram no inicio do estudo uma grande variabilidade espacial, as quais foram reduzidas mediante uso de práticas de agricultura de precisão. As relações entre os saldos e as exportações foram positivas em todos os locais com exceção da área situada em Vitor Graeff onde também se obtiveram saldos negativos. As fertilizações fosfatadas e potássicas foram 30 e 25 % superiores em relação as exportações, respectivamente. A soja extraiu em média 44 kg ha-1 de P2O5 e 63 kg ha-1 de K2O já o milho exportou 78,5 kg ha-1 de P2O5 e 59 kg ha-1 de K2O. A evolução dos teores foi alta quando os saldos eram baixos e, baixa quando o saldo se encontrava em níveis altos. Em média para os quatro locais foram necessários aplicar 12,0 kg ha-1 de P2O5 para elevar 1 mg dm- 3 de P no solo, assim como 4,1 kg ha-1 de K2O para elevar 1 mg dm-3 de K no solo.
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Nogueira, Rafaella da Silva. "DistribuiÃÃo espacial de carbono, nutrientes e solo em Luvissolos sob sistemas agrÃcolas tradicionais e agroflorestais no municÃpio de Sobral-CE". Universidade Federal do CearÃ, 2009. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=3335.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoO objetivo desse estudo foi avaliar os teores e estoques de carbono orgÃnico nas formas: total (COT), particulada (COP), associada (COA) e solÃvel em Ãgua (CSA), P disponÃvel, K e Na trocÃveis, assim como a possÃvel redistribuiÃÃo destes elementos e das partÃculas do solo pela erosÃo hÃdrica em sistemas agroflorestais, comparativamente ao sistema de cultivo tradicional e intensivo. O estudo foi desenvolvido em Ãrea experimental localizada na Fazenda Crioula, pertencente ao Centro Nacional de Pesquisa de Caprinos da EMBRAPA, no municÃpio de Sobral-CE. A partir de projeto desenvolvido desde 1997 foram selecionadas as seguintes Ãreas: Agrissilvipastoril (AGP), Silvipastoril (SILV), Tradicional 1 (TR1), Tradicional 2 (TR2), Cultivo Intensivo em Pousio (CIP), VegetaÃÃo Natural 1 (VG1) e VegetaÃÃo Natural 2 (VG2). A Ãrea estudada foi georeferenciada, nos transectos as amostras foram coletadas a profundidade de 0-5 cm a cada 20, 10 ou 5 m de acordo com o relevo. Os teores de COT foram determinados por oxidaÃÃo Ãmida, o CSA por centrifugaÃÃo seguida de oxidaÃÃo Ãmida, o fÃsforo (P) disponÃvel, K+ e Na+ trocÃveis por extraÃÃo com Mehlich I e colorimetria. Determinou-se tambÃm a densidade e a textura do solo, onde na fraÃÃo areia o COP foi quantificado por oxidaÃÃo Ãmida enquanto que o COA foi obtido por diferenÃa entre o COT e o COP. Os resultados foram avaliados atravÃs de medidas descritivas e tÃcnicas geoestatÃsticas. As Ãreas sob manejo agroflorestal apresentaram teores e estoques de carbono e nutrientes superiores, mesmo em condiÃÃes de relevo favorÃveis a perdas por processo erosivo. A fraÃÃo areia foi comumente alterada pela aÃÃo dos agentes erosivos nos sistemas conservadores, enquanto que nos sistemas mais intensivos a argila foi mais afetada devido à erosÃo està promovendo perdas do horizonte Bt nestas Ãreas. As estimativas de perdas e incrementos de solo e nutrientes confirmaram a eficiÃncia do SAFâs em reduzir os efeitos da erosÃo enquanto que as Ãreas tradicionais promoveram maiores perdas de nutrientes e solo. AlÃm disso, observou-se o predomÃnio de uma maior variabilidade espacial nos SAFâs, quando comparado as Ãreas manejadas de forma convencional que apresentaram um aspecto uniforme devido à maior aÃÃo dos agentes erosivos.
The objective of this study was to evaluate the content and stocks of: organic carbon in the form total (TOC), particulate (COP), associated (COA) and soluble in water (CSA), available P, K and Na exchangeable, as well as possible redistribution of these elements and soil particles by water erosion in agroforestry systems, compared to the traditional system of cultivation and intensive. The study was developed in an experimental area located at the Crioula Farm, CNPC â EMBRAPA, in Sobral County, CE. The following systems were evaluated: Agrisilvipastoril (AGP), Silvipastoril (SILV), Traditional 1(TR1), Traditional 2(TR2), Fallow Intense Cropping (CIP), Natural Vegetation 1 (VG1) and Natural Vegetation 2 (VG2). The studied field was georeferenced in transects and soil samples were collected to a depth of 0-5 cm every 20, 10 or 5 m, according to the condition of terrain. The TOC content was determined by wet oxidation, the CSA for centrifugation followed by wet oxidation, phosphorus (P) available, K and Na exchangeable was extracted by Mehlich-1 and determined colorimetrially. Was determined also the soil density and texture, where it was determined in the sand fraction COP by wet oxidation while the COA was obtained by the difference between the TOC and COP. The results were analyzed using descriptive statistic and geostatistic technique. The areas under management and agroforestry showed content of carbon stocks and superior nutrients, even under conditions favorable for significant losses for the erosion process. The sand fraction was commonly altered by the action of agents in erosive systems conservatives, while more intensive systems in the clay was most affected due to erosion is causing great losses of Bt horizon in these areas. Estimates of losses and gains of soil nutrients and confirmed the efficiency of the SAF's to reduce the effects of erosion while the traditional areas promoted stronger loss of nutrients and soil. Moreover, there is predominance bigger spatial variability in the SAF's, compared the areas managed in a way that presented a conventional uniform appearance due to greater erosive action of the agents.
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Causse, Jean. "Temporalité des transferts de nutriments dans les bassins versants à algues vertes". Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1B012/document.
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En Bretagne, les « marées vertes » sont récurrentes depuis le début des années 70 et occupent une place importante dans le débat public en terme sanitaire, politique et économique. Lors de cette thèse, une large revue bibliographique a été réalisée sur l’export d’azote et une méthodologie innovante a été mise en place afin d’étudier la variabilité spatio-temporelle de l’export de nutriments dans 2 bassins versants à algues vertes à une échelle intra-annuelle et pendant des évènements extrêmes (évènements pluvieux, période touristique de basses eaux,…). Les bassins versants sélectionnés pour les expérimentations de terrain sont l’Ic et le Frémur (Côtes d’Armor). 3 types d’expérimentations ont été réalisées sur ces bassins versants : 1) Des campagnes de prélèvements ponctuels par temps sec et par temps de pluie (32 stations, 27 campagnes) ; 2) des prélèvements automatiques en crue (3 stations, 8 crues) ; et 3) la mesure haute fréquence (2 stations, en continu). Les paramètres hydrologiques et physico-chimiques classiques, les matières en suspension, les spectres UV et toutes les formes de macronutriments (carbone, azote, phosphore) ont été analysés lors de ces expérimentations. Les résultats obtenus confirment pour une part un certain nombre de résultats de la littérature. D’autre part, il met en lumière la relation carbone/nitrates, jusqu’à présent peu étudiée à différentes échelles spatio-temporelles et pendant des évènements pluvieux, qui semble pourtant primordiale dans la compréhension des phénomènes d’export de nitrates à l’échelle de l’année. Enfin, l’analyse de toutes les formes de nutriments révèle l’importance des formes particulaires issues de l’érosion des sols. Ces résultats soulèvent de nombreuses questions de recherche qui mériteraient un approfondissement afin d’améliorer la connaissance des transferts de nutriments dans les bassins versants et prioriser les actions de remédiations. Les perspectives de ce travail sont à la fois scientifiques et pratiques. Au niveau scientifique, les efforts de recherche sur la relation carbone/nitrate et l’identification de la fraction de carbone organique assimilable par les organismes dénitrifiants doivent être poursuivis. De même, l’amélioration des connaissances sur l’export de nutriments en crue passe par l’identification précise des sources de nutriments particulaires pendant les crues printanières. Au niveau pratique, il doit contribuer à l’amélioration des pratiques agricoles, à la reconnaissance de l’intérêt des zones humides naturelles et à l’amélioration des types de traitement utilisés par les stations d’épuration. Les résultats obtenus lors de cette étude devraient notamment être mis en relation avec la dynamique des nutriments observée dans l’estran pendant la période de développement des algues vertes. Enfin, un effort d’amélioration de l’accès à certains type de données sur les bassins versants est nécessaire afin d’améliorer la compréhension des transferts de nutrimentsIn Brittany (Western France), "green tides" are recurrent since the early 70s and have an important place in public debate in health, political and economic terms. In this thesis, a wide bibliographic review was performed on the export of nitrogen, and an innovative methodology has been set up to study the spatial and temporal variability of nutrient export in two coastal watersheds on an intra-annual basis and during extreme events (rainfall events, tourist periods of low water, ...). Watersheds selected for the field experiments are Ic and Frémur (Côtes d'Armor). 3 types of experiments were performed on these watersheds: 1) Campaigns of grab samples by dry and wet weather (32 stations, 27 campaigns); 2) automatic sampling during floods (3 stations, 8 floods); and 3) high frequency measurement (2 stations, continuous). Conventional hydrological and physicochemical parameters, suspended solids, UV spectra and all forms of macronutrients (carbon, nitrogen, phosphorus) were analyzed during these experiments. The results confirm in part a number of results of the literature. Furthermore, it highlights the relationship carbon / nitrates far little studied at different spatial and temporal scales and during rainfall events, which however seems to be crucial in understanding of nitrate export. Finally, the analysis of all forms of nutrients reveals the importance of particulate forms from soil erosion. These results raise many research questions that merit further development in order to improve knowledge on nutrient transfers in watersheds and prioritize remediation actions. The prospects of this work are both scientific and practical. At the scientific level, research efforts on the relationship carbon / nitrate and identification of the assimilable fraction of organic carbon by denitrifying organisms must be continued. Similarly, the knowledge on nutrient export must be improved through the precise identification of particulate nutrient sources during the spring floods. On a practical level, it should contribute to the improvement of agricultural practices, the recognition of the interest of natural wetlands and improvement of the types of treatment used by treatment plants. The results obtained in this study should in particular be linked to the dynamics of nutrients in the foreshore observed during the development of green algae. Finally, an effort to improve access to certain types of data on watersheds is needed to improve understanding of nutrient transfers
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Lee, Alyce R. "Response of Benthic Microalgal Community Composition at East Beach, Galveston Bay, Texas to Changes in Salinity and Nutrients". 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-05-625.
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Benthic microalgal community composition on an ephemerally submerged sandflat at East Beach, Galveston Island, Texas was studied to determine the spatial and temporal variability of total biomass and community composition and its responses to experimental manipulations of two environmental factors (salinity and nutrients). Four field studies were conducted between August 2004 and February 2005. The community consisted of two major algal groups, diatoms, and cyanobacteria with two less abundant groups, green algae, and phototrophic bacteria. Spatial variability showed that patch sizes of 12 - 25 m were detected over larger scales with smaller scale (cm) patches of approximately 28 - 201 cm^-2 contained within the larger patches. The second study examined the spatio-temporal variability of BMA over a 21-month period in a 1,000 m^2 area. Sampling location and date explained a significant amount of the variability in the abundances of algal groups, which were positively correlated with the water content of the sediments and negatively correlated with temperature (sediment and water). All of the algal groups showed a seasonal pattern with higher abundances measured in the winter months and lower abundances found during the summer. BMA biomass (100 mg Chl a m^-2 or greater) maxima occurred at temperatures less than 22 degrees C and sediment water content greater than 15% (g water g sediment^-1).
BMA response to different salinities and nutrient (N+P) amended sediments was assessed in four bioassays conducted over a 6-month period (Aug. 2004, Oct. 2004, Dec. 2004, and Feb. 2005). In the salinity study, the treatments that were either 100% or partially diluted with deionized water had the lowest BMA biomass over all. Chlorophyll a and fucoxanthin were significantly affected by salinity with higher abundances found in salinities that averaged 15 with a preference for salinities greater than 22. Chlorophyll b was affected by salinity with higher abundances measured in the treatments with lowest salinity (DL and DI); and was affected by the time of year. This would suggest that this algal group prefers an environment with salinity less than 2 but can easily adapt to environments with higher salinities. BMA abundances were not significantly affected by the nutrient amended sediment, but were significantly affected by stations with higher water content, and during the cooler months (Dec. 2004 and Feb. 2005).
Libros sobre el tema "Nutrients spatial variability"
1
Rinella, Frank A. Seasonal and spatial variability of nutrients and pesticides in streams of the Willamette Basin, Oregon, 1993-95. Portland, Or: U.S. Dept. of the Interior, U.S. Geological Survey, 1998.
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2
Rinella, Frank A. Seasonal and spatial variability of nutrients and pesticides in streams of the Willamette Basin, Oregon, 1993-95. Portland, Or: U.S. Dept. of the Interior, U.S. Geological Survey, 1998.
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3
Rinella, Frank A. Seasonal and spatial variability of nutrients and pesticides in streams of the Willamette Basin, Oregon, 1993-95. Portland, Or: U.S. Dept. of the Interior, U.S. Geological Survey, 1998.
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4
Maluk, Terry L. Spatial and seasonal variability of nutrients, pesticides, bacteria, and suspended sediment in the Santee River Basin and coastal drainages, North and South Carolina, 1995-97. Columbia, S.C: U.S. Dept. of the Interior, U.S. Geological Survey, 2000.
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Debrewer, Linda M. Factors affecting spatial and temporal variability in nutrient and pesticide concentrations in the Surficial Aquifer and the Delmarva Peninsula. Reston, Va: U.S. Dept. of the Interior, U.S. Geological Survey, 2007.
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Akana, Palani Robert. Patterns, mechanisms, and implications of spatial variability in the ecological processes regulating nutrient access by forest trees. [New York, N.Y.?]: [publisher not identified], 2022.
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Jacobsen, Dean y Olivier Dangles. Living conditions in high altitude waters. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198736868.003.0003.
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Chapter 3 deals with the abiotic environment in high altitude lakes and streams worldwide. It searches for general patterns in relation to altitude, without overlooking the enormous variability, both temporally as well as at small and large spatial scales. Overall, environmental conditions in high altitude waters may be regarded as harsh. Indeed, certain features such as low temperature, low oxygen pressure, and high ultraviolet radiation (all a direct result of high altitude) as well as transparent and ion-poor waters with low nutrient concentrations are typical of high altitude aquatic systems. However, streams and lakes turbid from inflow of glacial meltwater loaded with glacial mineral flour and peatbogs with deep brown water from a high concentration of coloured dissolved organic matter are equally prominent. So, evidently, environmental conditions in aquatic systems are probably just as variable at high as at low altitudes.
Capítulos de libros sobre el tema "Nutrients spatial variability"
1
Zhao, Yueling, Haiyan Han, Liying Cao y Guifen Chen. "Study on Soil Nutrients Spatial Variability in Yushu City". En Computer and Computing Technologies in Agriculture V, 1–7. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-27278-3_1.
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Cui, Bei, Wude Yang, Meichen Feng, Wenjiang Huang y Xiaoyu Song. "Study on the Spatial – Temporal Variability of Soil Nutrients during Winter Wheat Growth Season". En Computer and Computing Technologies in Agriculture VI, 238–47. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-36137-1_29.
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Nolin, M. C., S. P. Guertin y C. Wang. "Within-Field Spatial Variability of Soil Nutrients and Corn Yield in a Montreal Lowlands Clay Soil". En Proceedings of the Third International Conference on Precision Agriculture, 257–70. Madison, WI, USA: American Society of Agronomy, Crop Science Society of America, Soil Science Society of America, 2015. http://dx.doi.org/10.2134/1996.precisionagproc3.c26.
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Weber, L. H. y S. Z. El-Sayed. "Spatial Variability of Phytoplankton and the Distribution and Abundance of Krill in the Indian Sector of the Southern Ocean". En Antarctic Nutrient Cycles and Food Webs, 284–93. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-82275-9_41.
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Bannister, Jacob M., Ellen R. Herbert y Christopher B. Craft. "Spatial Variability in Sedimentation, Carbon Sequestration, and Nutrient Accumulation in an Alluvial Floodplain Forest". En The Role of Natural and Constructed Wetlands in Nutrient Cycling and Retention on the Landscape, 41–55. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-08177-9_4.
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Honea, Jon M. "Challenges for Diadromous Fishes in a Dynamic Global Environment". En Challenges for Diadromous Fishes in a Dynamic Global Environment, editado por Robert J. Naiman, James M. Helfield, Krista K. Bartz y Deanne C. Drake. American Fisheries Society, 2009. http://dx.doi.org/10.47886/9781934874080.ch26.
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<em>Abstract</em>.-We review the current understanding of major pathways, mechanisms, and consequences of salmon-borne marine-derived nutrients (MDN) in estuarine, freshwater, and riparian ecosystems. Semelparous Pacific salmon <em>Oncorhynchus </em>spp. acquire most of their body mass while at sea before returning to spawn and die in natal streams. The annual spawning migrations transport substantial quantities of MDN from the fertile North Pacific Ocean to relatively nutrient-poor coastal freshwater and terrestrial ecosystems. People have been long aware of the importance of salmon-borne MDN for the productivity of freshwater ecosystems in western North America, and the rapidly increasing knowledge base supports this notion. Nevertheless, many details associated with nutrient pathways, cycling processes, and the ecosystem-scale consequences of MDN transfer remain to be elucidated. The collective data suggest that freshwater portions of the salmon production system, as well as the dynamics of local terrestrial plant and animal communities, are intimately linked to MDN in complex ways. At the same time, the ecological importance of MDN, relative to other major nutrient sources, is temporally and spatially dependent and influenced by the life histories and abundances of salmonid stocks. Although interactions among climate cycles, salmon, riparian vegetation, predators, and MDN flowpaths and feedbacks are complex, they also form a wonderfully integrated ecological system with a high degree of resilience and productivity. Understanding this complex system and its inherent temporal and spatial variability requires a holistic scientific perspective that values important interactions among the salmonid life cycle, the physical setting, and the numerous linkages to other ecosystem components.
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Reynolds, James F. y Paul R. Kemp. "Modeling the Unique Attributes of Arid Ecosystems: Lessons from the Jornada Basin". En Structure and Function of a Chihuahuan Desert Ecosystem. Oxford University Press, 2006. http://dx.doi.org/10.1093/oso/9780195117769.003.0020.
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The Jornada Basin is typical of arid ecosystems of the Southwestern United States and many other regions of the globe: It is water-limited with low annual net primary production (ANPP) and low-standing crop (Szarek 1979; Ludwig 1987). Yet paradoxically, arid ecosystems are structurally and functionally quite complex, exhibiting a remarkable range of species compositions and system behaviors. This can be attributed in part to the presence of complex topography and landscape physiography (Mabbutt 1997; see also chapter 2) which, when combined with extreme variability in precipitation (Cavazos et al. 2002; Weltzin et al. 2003; see also chapter 3), produces striking spatial and temporal heterogeneity in the availability of essential limiting resources, such as water and mineral nutrients (MacMahon and Wagner 1985; see also chapters 5 and 6). In view of these complexities, one of the long-term objectives of the research in the Jornada Basin is to develop a synthetic understanding of the mechanisms and processes governing the complex patterns of arid land structure and functioning. It is clear that understanding and predicting potential cause–effect relationships will require considerable insights at multiple spatial and temporal scales (chapter 18). Models are expected to play an important role in this synthesis because most experiments and observations tend to take place at small spatial (e.g., 1–100 m2) and brief temporal scales (e.g., days, months, one to five years) (Levin 1992), whereas many ecosystem responses are the result of interacting factors and feedbacks operating over larger spatial and longer time periods (O’Neill et al. 1989; Levin 1992). In this chapter, we present a summary of some of the mechanistic models we developed as part of the Jornada Basin research program. Although our initial goal was largely focused on the relationship between precipitation and ecosystem functioning in the Jornada Basin, our work is sufficiently general that it should be applicable to other arid land regions of the world. Simulation modeling has a key role to play because it is difficult to experimentally examine even a partial spectrum of ecosystem-level responses that could result from abrupt perturbations, such as overgrazing and especially longer term external forcings, such as shifts in precipitation.
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Palis, Gary A. y Michael D. Rose. "Island Food Webs". En Island Biogeography in the Sea of Cortés II. Oxford University Press, 2002. http://dx.doi.org/10.1093/oso/9780195133462.003.0019.
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Most of this book focuses on the biogeography and ecology of plants and various animal taxa on islands in the Sea of Cortés. These chapters highlight the historical and biogeographical factors that contributed to the patterns of species distribution and co-occurrence among islands. However, these patterns also reflect the action of ecological processes because the species present interact, directly or indirectly, within the food web that occurs on any given island. Island food webs may also be unique from other communities in the degree to which their structure and dynamics are also strongly influenced by the surrounding ocean. We believe that a deeper appreciation of the trophic connections between the sea and the land, and the resulting effects on the structure and dynamics of island food webs, is key to understanding the biogeography of species on islands. Many factors that operate through the food web can enhance or depress populations in a way that affects their local distribution and persistence, and, as a consequence, affects patterns of diversity on a biogeographical scale. Of these, we recognize three as being particularly important: the availability and quality of resources, competition, and consumption (i.e., by herbivores, predators, parasites). Bottom-up factors (nutrients, primary productivity, and food availability to consumers) set limits on island productivity and hence on the potential abundance of a particular group. Within a given community, secondary productivity and population density are subsequently constrained by top-down (i.e., consumption) and competitive effects. One of our goals in this chapter is to show how processes that influence productivity of gulf islands determine patterns of abundance of organisms on islands and affect interactions among species and trophic levels in these systems. Our second goal is to demonstrate the importance of spatial and temporal variability in productivity in determining the structure and dynamics of island food webs. Using our long-term studies of plants and consumers on islands in the northern gulf, we show that productivity varies greatly, both among years and islands, as a result of both local conditions and global climatic factors. Such variable productivity markedly affects food web dynamics and ultimately the abundance of species on the islands in the Sea of Cortés.
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Changa, Taity, Jane Asiyo Okalebo y Shaokun Wang. "Spatio-Temporal Dynamics of Soil Microbial Communities in a Pasture: A Case Study of Bromus inermis Pasture in Eastern Nebraska". En Agrometeorology [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.93548.
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Today’s intensified agricultural production is characterized by crop and pasture monocultures, which have a significant impact on soil microbial diversity and abundance. This chapter provides a case study in which the relative importance of brome grass (Bromus inermis) monoculture pasture versus intra-site microhabitat diversity is explored using fatty acid methyl ester (FAMEs) assay to delineate the presence and abundance of several classes of soil microbes instrumental in soil nutrient cycling, plant health, plant organic matter decomposition, and soil stabilization. The chapter explores spatio-temporal variability of bacteria, actinomycetes, saprophytes, mycorrhizae, and micro-eukaryotes over two durations (summer and fall) collected using two distinct sampling methods. One of the methods is commonly employed, namely, transect-based, while the other is informed by soil electroconductivity measurements conducted over the entire pasture site from a previous survey.
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Boose, Emery R. "Hurricane Impacts in New England and Puerto Rico". En Climate Variability and Ecosystem Response in Long-Term Ecological Research Sites. Oxford University Press, 2003. http://dx.doi.org/10.1093/oso/9780195150599.003.0008.
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Hurricanes have a profound effect on many coastal ecosystems. Direct impacts often include wind damage to trees, scouring and flooding of river channels, and salt-water inundation along shorelines (Simpson and Riehl 1981; Diaz and Pulwarty 1997). In some areas, secondary impacts may include landslides triggered by heavy rains (Scatena and Larson 1991) or catastrophic dry-season fires resulting from heavy fuel loading (Whigham in press). This chapter will focus on the longterm impacts of hurricane wind damage at two LTER sites, the Harvard Forest (HFR) in central New England and the Luquillo Experimental Forest (LUQ) in northeastern Puerto Rico. These two sites, both located in the North Atlantic hurricane basin and occasionally subject to the same storms, provide interesting examples of tropical and temperate hurricane disturbance regimes. Wind damage from a single hurricane is often highly variable (Foster 1988). Damage to individual trees can range from loss of leaves and fine branches, which can significantly alter surface nutrient inputs (Lodge et al. 1991), to bole snapping or uprooting, which can significantly alter coarse woody debris and soil microtopography (Carlton and Bazzaz 1998a and b). At the stand level, damage can range from defoliation to individual tree gaps to extensive blowdowns, creating different pathways for regeneration (Lugo 2000). At landscape and regional levels, complex patterns of damage are created by the interaction of meteorological, topographic, and biological factors (Boose et al. 1994). Adding to this spatial complexity is the fact that successive hurricanes are not necessarily independent in terms of their effects. A single storm lasting several hours may have effects that persist for decades (Foster et al. 1998). And forest susceptibility to wind damage is strongly influenced by composition and structure, which in turn are strongly influenced by previous disturbance history (Foster and Boose 1992). Thus, the impacts of a single hurricane may depend in part on the impacts of earlier storms as well as on other previous disturbances and land use. Hurricanes, like other disturbances, both create and respond to spatial heterogeneity (Turner et al. 2003). To understand the long-term ecological role of hurricanes at a given site, we must consider these three sets of questions: (1) What is the hurricane disturbance regime?
Actas de conferencias sobre el tema "Nutrients spatial variability"
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Wang, Zilong, Qiang Fu y Qiuxiang Jiang. "Spatial Variability Analysis of Reclaimed Wetland Soil Nutrients in Sanjiang Plain, China". En 2008 4th International Conference on Wireless Communications, Networking and Mobile Computing (WiCOM). IEEE, 2008. http://dx.doi.org/10.1109/wicom.2008.2976.
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Singha, Chiranjit y Kishore C. Swain. "Assessing The Spatial Variability of Soil Nutrients Prediction Using GIS-based Interpolation Techniques". En 2022 IEEE World Conference on Applied Intelligence and Computing (AIC). IEEE, 2022. http://dx.doi.org/10.1109/aic55036.2022.9848951.
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Tan, Qiujin, Fuping Zeng, Haisheng Chen, Zhenshi Qin, Hu Du, Wenlin Wang y Hao Zhang. "Spatial variability of soil nutrients in Juglans regia plantations in depressions between karst hills". En International Conference on Advances in Energy, Environment and Chemical Engineering. Paris, France: Atlantis Press, 2015. http://dx.doi.org/10.2991/aeece-15.2015.68.
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Yong He, HaiYan Song, ShuJuan Zhang y Hui Fang. "Study on the Spatial Variability and the Sampling Scheme of Soil Nutrients in the Field Based on GPS and GIS". En 2005 IEEE Engineering in Medicine and Biology 27th Annual Conference. IEEE, 2005. http://dx.doi.org/10.1109/iembs.2005.1615844.
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Curcio, Christine A. "Aging and topography of human photoreceptors". En OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/oam.1986.wc1.
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Age-related decrements in acuity and contrast sensitivity are only partially explained by the combined effects of pupillary constriction and lens opacification. The notion of a neural origin for these visual deficits remains controversial. Limited quantitative data on photoreceptors in aging suggest disorganization of both rod and cone outer segments, displacement of nuclei, and outright cell loss, particularly in the fovea. The relationship of these phenomena to nonpathological changes in retinal supporting tissues which may impair transport of nutrients across the outer blood–retinal barrier is unclear. The effects of age-related point deletions in the photoreceptor mosaic on spatial sampling characteristics of the retina are unknown. Recent studies of photoreceptor distribution in human retina show that individual variability in foveal cone density is much greater than previously appreciated. The implications of this finding for aging studies are (1) sample size must take into account high variability; (2) anatomical data need to be viewed in relation to functional and clinical data from the same individual; (3) photoreceptor counts alone are probably not sufficiently sensitive to detect age-related cell loss, and some measure of mosaic disorder is likely to be more informative.
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Zheng, Hongbo, Jianping Wu y Shan Zhang. "Study on the Spatial Variability of Farmland Soil Nutrient Based on the Kriging Interpolation". En 2009 International Conference on Artificial Intelligence and Computational Intelligence. IEEE, 2009. http://dx.doi.org/10.1109/aici.2009.137.
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Shen, Guangrong, Zhenhua Qian, Jingjing Xu y Apostolos Sarris. "Spatial Variability of Soil Nutrient in Chongming of Shanghai, China by Using GIS and Kriging Method". En 2009 WRI Global Congress on Intelligent Systems. IEEE, 2009. http://dx.doi.org/10.1109/gcis.2009.72.
Texto completoInformes sobre el tema "Nutrients spatial variability"
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Seasonal and spatial variability of nutrients and pesticides in streams of the Willamette Basin, Oregon, 1993-95. US Geological Survey, 1998. http://dx.doi.org/10.3133/wri974082c.
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Spatial and seasonal variability of nutrients, pesticides, bacteria, and suspended sediment in the Santee River basin and coastal drainages, North and South Carolina, 1995-97. US Geological Survey, 2000. http://dx.doi.org/10.3133/wri004076.
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