Дисертації з теми "Below ground"
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1
Butler, André Joseph. "Below ground functioning of tropical biomes." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5048.
Повний текст джерелаАнотація:
Within the field of ecosystem science, substantial progress has been made towards our knowledge of the factors which shape the global distribution of vegetation. However, factors which control the biogeography of belowground vegetation structure and function remain less understood than their aboveground counterpart. Vegetation types can differ substantially in terms of belowground processes such as root growth, root turnover, and resulting vertical root distributions. Fine roots provide an exchange surface, allowing transport of water and nutrients to the leaves. On the other hand they also represent a significant sink for photosynthetically fixed carbon to the soil in terms of maintenance and growth. Overall, root processes have a major influence on fluxes of water, carbon and nutrients within ecosystems. In this thesis, an electrical impedance method was used to determine the area of ‘active’ root in contact with the soil for the purpose of absorption. These measurements were compared to the leaf area of the trees, for the first time allowing the aboveground and the belowground resource exchange areas of plant to be contrasted. This approach was first developed to compare the exchange surface areas of leaves and roots within a Sitka spruce (Picea sitchensis) managed forest, making measurements in adjacent stands of differing tree density, but identical in age. Stem density was found to significantly influence the proportion of absorbing root area relative to leaves. Following the successful test of the method, it was used to compare the resource exchange areas of eight stands of forest and savanna vegetation in central Brazil. Across a broad gradient of vegetation structure, the results showed progressively more investment in fine root area relative to leaf area across the transition from dense forest to open savanna. However, a contrasting result showed that the forests had a higher absorbing root area to leaf area ratio than savannas. Furthermore, these measured ratios were strongly correlated with tree height across the eight structurally contrasting stands. It appears that absorbing root area index provides a physiologically meaningful way of characterising belowground water uptake ability, it is possible that excessive investment in fine root area, relative to leaf area, may reflect differences in the requirement for nutrient uptake in poor soils. Complementary to the analysis of root absorbing area, measurements of root activity and belowground carbon cycling were made by focussing on two of the eight tropical study sites. Here, the carbon costs of root growth and respiration were quantified to develop a belowground carbon budget for two structurally contrasting Brazilian savannas, using soil respiration measurements and a root presence/absence manipulation experiment. Annual estimates showed that at least 60% of the total CO2 efflux from the soil was contributed by autotrophic processes, with this value rising to 80% during the dry season. Seasonal fluctuations of soil respiration were strongly correlated with soil moisture for both the autotrophic (R2=0.79, pvalue< 0.05) and heterotrophic (R2=0.90, p-value<0.05) components, with maximum flux rates corresponding with 16.4 and 17.7% soil moisture content respectively. Furthermore, autotrophic respiration was found to varied with phonological patterns of fine root growth (R2=0.80, p-value<0.05). It follows that, the way in which phenological processes respond to a changing climate is of potential importance within seasonally dry regions. Diurnal fluctuations of heterotrophic CO2 efflux were correlated with soil temperature (R2=0.74, p-value<0.05), demonstrating a Q10 value of 1.6 across both sites. In contrast, total soil CO2 efflux was not correlated with temperature (p-value=0.31), suggesting that autotrophic respiration is predominantly limited by substrate supply.
2
McQuillan, Shane. "Above and Below Ground Assessment of Pinus radiate." Thesis, University of Canterbury. School of Forestry, 2013. http://hdl.handle.net/10092/9897.
Повний текст джерелаАнотація:
A comparison of above ground forest metrics with below ground soil CO₂ respiration was carried out in an attempt to reveal if any correlations exist. Above ground measurements of 2720 clonally propagated trees were taken assessing the silvicultural treatments of stocking, herbicide and fertiliser. These were compared to 480 below ground soil CO₂ respiration measurements. Using measurements of mean height, mean dbh and basal area the data was analysed and returned significant results for mean dbh and the interactions of herbicide and clones, and stocking and herbicide. Mean height returned a significant result for the interaction of stocking and herbicide. Below ground measurements showed an interaction between ripping and stocking; however these results were not ratified by the above ground results. Overall the results were encouraging and should aid in future experiments that seek to understand what effect above ground treatments have on below ground CO₂ activity.
3
Daluom, Abdulhakim A. M. "Optimal Sensor Geometries for Tomographic Below Ground Imaging." University of Dayton / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1543505143363275.
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Clemensen, Andrea K. "Understanding Plant Secondary Metabolites; Above and Below Ground." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7090.
Повний текст джерелаАнотація:
Plants naturally produce primary and secondary metabolites. Primary metabolites are directly involved with plant growth and metabolic function. Plant secondary metabolites (PSM) were once thought of as metabolic waste products, and more recently viewed as toxins to herbivores. However, ongoing research shows that PSM are beneficial to herbivores at low doses, and PSM aid plants by attracting pollinators, recovering from injury, protecting from ultraviolet radiation, increasing drought tolerance, and aid in defense against pathogens, diseases, and herbivores. Plant secondary metabolites also influence soil nutrient cycling, and can increase the sustainability of agroecosystems. Endophyte-infected tall fescue (Festuca arundinacea Schreb.) , which contains ergovaline, and reed canarygrass (Phalaris arundinacea L.), containing gramine, were studied along with the legumes alfalfa (Medicago sativa L.) which contains saponins, and tannin-containing sainfoin (Onobrychis viciifolia Scop.) and birdsfoot trefoil (Lotus corniculatus L.). This dissertation researches (i) how planting configuration (monocultures vs. two-way mixtures) influences PSM and total N in plants, (ii) how cattle grazing forages containing PSM affects soil quality, nutrient cycling, and PSM, and (iii) how cattle manure from different diets, containing different PSM, influences soil nutrient cycling.
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Bowes, Joshua S., Mark T. Newdigate, Pedro J. Rosario, and Davis D. Tindoll. "The enemy below: preparing ground forces for subterranean warfare." Thesis, Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/38883.
Повний текст джерелаАнотація:
Approved for public release; distribution is unlimited.This capstone project analyses subterranean threats in the contemporary operational environment. It identifies the doctrinal gap in the U.S. military regarding operations within tunnels, urban and natural cavities, and other underground facilities, and outlines the changes necessary to prepare ground forces to operate in these complex environments. This paper reviews historical cases spanning back over half a millennium, proposes a new typological classification system, and investigates the subterranean environment in terms of the United States Army doctrine, organization, training, matriel, leadership and education, personnel, and facilities process. Additionally, it provides analysis geared toward countering subterranean threats through indirect means to include: incendiary weapons, cyber-based attacks, and military information support operations. The capstone finds that: 1) Current U.S. military doctrine does not properly prepare units for operations in subterranean environments; 2) Future conflicts will require general purpose forces to deal with subterranean threats; and 3) Understanding the use of indirect approaches is critical in the conduct of subterranean operations. This research leads to the recommendation that the Training and Doctrine Command Intelligence Support Activity recognize subterranean as an operational environment. Additionally, this capstone provides guidance to commanders and staffs to assist in pre-mission training even before the doctrinal gap is filled.
6
Genney, David R. "Below-ground ecology of Calluna vulgaris and Nardus stricta." Thesis, University of Aberdeen, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325227.
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Pierce, Sarah. "Impacts of climate change on ecosystem functioning : linking above-ground and below-ground responses." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/49789.
Повний текст джерелаАнотація:
Climate change is expected to include changes to rainfall patterns. For southern England, this is likely to include decreased summer and increased winter rainfall patterns by the end of the 21st century. The aim of this research was to investigate the effects of altered precipitation patterns on ecosystem properties both above- and below-ground using a grassland experimental system in southeast England. The DIRECT experiments were established in 2008 and continued through 2013. This included three experiments assessing the effects of rainfall change on ecosystem functioning. The first crossed a summer rainfall reduction/winter rainfall increase scenario with plant functional trait diversity. The second considered the effects of two more extreme rainfall change scenarios, one an extended drought and one a shorter, more severe drought with occasional downpours. The third crossed rainfall change with increased nitrogen deposition in line with current levels experienced in parts of Europe. By concurrently measuring a broad range of above- and below-ground properties during the 2012 and 2013 growing seasons, I assessed the effects of changes in annual precipitation patterns. Drought during the growing season was linked to increased grass dominance and reduced ecosystem respiration, photosynthesis, and net ecosystem exchange, despite increases in winter precipitation. Effects on ecosystem functioning were most severe under extreme drought scenarios. Plant functional trait identity and diversity influenced response to drought, with increased diversity linked to higher plant cover in drought conditions. Increased nitrogen appeared to magnify the effects of drought on plant cover, while moderating the effects on CO2 flux. These results suggests that the levels of precipitation change predicted for England will negatively affect biodiversity and carbon cycling in grasslands, but factors such as trait diversity and nutrient inputs must be taken into account to understand the range of possible outcomes for ecosystem functioning.
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Koikkalainen, Riitta Katariina. "Influence of nitrogen on below ground dynamics in improved grasslands." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=33591.
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Namirembe, S. "Tree shoot pruning to control competition for below-ground resources in agroforestry." Thesis, Bangor University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297866.
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Orrell, Peter. "Linking above and below-ground interactions in agro-ecosystems : an ecological network approach." Thesis, University of Newcastle upon Tyne, 2018. http://hdl.handle.net/10443/4102.
Повний текст джерелаАнотація:
Belowground microbial communities, such as arbuscular mycorrhizal fungi (AMF), may modify plant reproductive traits, although little is known about how this might then influence pollinator behaviour. This is important as pollinators provide an ecosystem service by contributing towards agricultural production. AMF also provide an ecosystem service by assisting plants with increased access to nutrients and water resources, thereby influencing yields. However, few studies have examined the combined effects of how AMF interact with crop cultivars to alter plant reproductive traits, pollination processes, and ultimately crop yield. Furthermore, the importance of both AMF and pollinators for human perceived crop quality has not been investigated. In this thesis, I examine the influence of manipulating AMF communities on plant-pollinator interactions, and the role of crop cultivars in mediating these effects, by growing three strawberry (Fragaria × ananassa) cultivars inoculated with four AMF communities, and measuring strawberry yield and quality (determined through human taste tests) in two 2-year experiments. The first experiment was conducted under greenhouse conditions and I found that pollen foraging visits by bumblebees (Bombus terrestris Audax) were influenced by both AMF community and strawberry cultivar, whereas nectar foraging visits were only influenced by AMF community. AMF community influenced strawberry yield, without any changes in fruit quality, and effects were consistent across each strawberry cultivar, while AMF community and strawberry cultivar interacted to influence strawberry appearance. The second experiment was similar to the greenhouse experiment but repeated under field conditions to examine the effects on the naturally occurring pollinator community. Here, I found that while AMF community may influence the visitation of some pollinator taxa, the wild pollinator community provided a high degree of functional redundancy, and strawberry yield was influenced in the same manner as in the greenhouse experiment when plants were exposed to the highly efficient pollinators used in commercial production. The potential to utilise the above and below-ground interaction data to improve yields relies on the opinions of end users. I conducted a socio-economic analysis of growers' and scientists' iv perceptions, which showed that key stakeholders believe that interactions between above- and below-ground organisms should be harnessed to improve crop production. These results show that manipulating a below-ground mutualistic community has effects that cascade through the network to influence plant-pollinator interactions, and alters strawberry yield without loss in quality, with largely predictable outcomes across multiple strawberry cultivars. The interdisciplinary nature of this research revealed that stakeholders believe AMF should be used to improve strawberry production. Understanding the dynamics of these interactions may form part of a toolset for sustainable increases in food security, as well as helping to gain a deeper understanding of the underlying biology that influences ecological networks.
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Sabtu, Nuridah. "Hydraulic interaction between the above and below ground drainage systems via gully inlets." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/11506/.
Повний текст джерелаАнотація:
The primary objective of this study was to complete an experimental programme to better understand the hydraulic performance of typical individual types of gully inlets and systems used in practice by analysing the interaction of flow into and from typical gully systems by determining the head-discharge relationship of each system. Therefore, a full scale laboratory system comprising of a testing platform with an inlet tank and an outlet tank on both ends of the platform has been designed to mimic the hydraulic interaction between the above and below ground drainage system via gully inlets and the designated catchment area. Longitudinal slope was later incorporated onto the initially flat testing platform to represent different road conditions. Tests were completed with the flow in one direction to the gulley (intermediate tests) and from both tanks such that the flow to the gulley is in two directions (terminal tests). Surcharged condition was also tested where two flows were released into the system – a primary flow coming from the primary inlet and a secondary flow coming from an alternative inlet straight into the gully system itself. A gully pot manufactured by Milton Precast with a diameter of 375mm and 750mm nominal depth was used for this study and was tested over a range of flowrates of 0 – 50 l/s. Another variable studied was two different longitudinal slopes (SL). Two different types of grates with BS EN 124 loading class of C250 representing different hydraulic characteristics were also used and were tested for a range of surcharged and non-surcharged flow conditions. The interaction – expressed in terms of head-discharge relationship, was determined for the different gully systems and flow conditions tested. Based on the head-discharge relationship, a range of coefficient of discharge, Cd was established. Cd is known to be a function of many parameters and hence to examine how Cd changes, a dimensional analysis approach has been used. This is followed by a review of the application of different types of equations in an attempt to link the dimensionless terms and hence define a universal equation that describes the performance of the system for a range of conditions. This analysis has resulted in a number of significant findings, which have formed the conclusions to the thesis and may be used to inform the way in which these coefficients are represented in water industry standard software.
12
Pillinger, Chad. "Effects of take all (Gaeumannomyces graminis var. tritici) on below ground resource capture and above ground growth of winter wheat." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273261.
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Yadav, Priyanka. "Below ground biological control in urban landscapes and assessment of factors influencing its abundance." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1332516989.
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Kaplan, Ian. "Inducible plant responses linking above- and below-ground herbivory ecological significance and underlying mechanisms /." College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/7779.
Повний текст джерелаАнотація:
Thesis (Ph. D.) -- University of Maryland, College Park, 2007.Thesis research directed by: Dept. of Entomology. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
15
Boddy, Elizabeth. "Impact of climate change on below-ground carbon storage in the Arctic and UK." Thesis, Bangor University, 2008. https://research.bangor.ac.uk/portal/en/theses/impact-of-climate-change-on-belowground-carbon-storage-in-the-arctic-and-uk(11cf9f66-2a76-43ad-b91b-41052ac98c66).html.
Повний текст джерелаАнотація:
Despite the large quantity of research on the sensitivity of soil organic matter (SOM) degradation to temperature change, there is still no consensus as to whether soil efflux Of C02 Will increase with elevated temperatures. Understanding the mechanisms that controIC02efflux from the soil is therefore critical for predicting the response of ecosystems to climate change, particularly in polar regions where warming is occurring at rates 2-3 times greater than in temperate regions. This thesis considered two methodologies for evaluating whether soil efflux0f C02 is driven by recent inputs from plants and, secondly, the degree of temperature sensitivity. Firstly, Part I (Chapter 2) considered basal C02 and nutrient limitations in these soils. Secondly, Part 11 (Chapters 3-6) utilized 14C -labelled glucose and amino acids to assesst he mineralization of low molecular weight (MW) C in soils from the UK and Arctic and the temperature sensitivity of mineralization. UK and Svalbard soils had similar respiration rates per gram of 0 horizon and metabolism of low MW C with an exponential decay coefficient ki averaging < 1.5 h in the laboratory. However, cycling of C through the microbial biomass was significantly slower in Svalbard soils than in UK grassland soils, though when Svalbard soils were incubated at 20 OC, turnover was similar to UK field rates. Respiration measurements undertaken on an area basis were also significantly different, with the UK having much greater respiration rates, highlighting the importance of the sampling methodology when considering results. Both soils were substrate limited, indicating that respiration rates were dominated by recent contributions of labile C from plants. Temperature changes did cause an increased respiratory loss of SOM, but not to the magnitude expected with the Qjo value being < 2. Temperature dependence of SOM degradation was shown to be C pool dependent; with mineralization of labile substrate-C insensitive to temperature, but microbial biomass-C turnover and mineralization of higher MW SOM fractions increased with elevated temperatures. Partitioning of 14C changed with elevated temperatures, with more C utilized for respiration rather than growth, indicating a possible decreasein efficiency of growth at higher temperatures. Further research is needed in the temperature-dependence of SOM degradation, particularly turnover of high MW SOM, in the laboratory and field.
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Twolan-Strutt, Lisa. "Competition intensity and its above- and below-ground components in two contrasting wetland plant communities." Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/9921.
Повний текст джерелаАнотація:
I used a field experiment to measure total competition intensity and its above- and below-ground components in two wetlands that represent extremes in habitat productivity: an infertile sandy shoreline and a fertile bay. Transplants of Lythrum salicaria and Carex crinita were grown with no neighbours, with roots of neighbours only and with all neighbours; their growth rates were used to estimate competition intensity. The experiment was carried out to answer the following main questions: (1) Is there a difference in total, above- and below-ground competition intensity in two wetlands that differ in standing crop? (2) Is there an effect of standing crop on total, above- and below-ground competition intensity when the data from the two wetlands are combined? Both total and above-ground competition intensity were found to be greater in the high standing crop wetland but below-ground competition did not differ between wetlands (CI$\rm\sb{TOTAL}$: p 0.00001, CI$\rm\sb{ABOVE}$: p = 0.0013 CI$\rm\sb{BELOW}$: p = 0.58). Mean total competition increased from 0.16 to 0.43, the above-ground component increased from $-$0.063 to 0.21 and the below-ground component was close to 0.20 in both wetlands. Total and above-ground competition intensity was significantly affected by standing crop in the wetlands studied but below-ground competition intensity was not (CI$\rm\sb{TOTAL}$: p = 0.0001, CI$\rm\sb{ABOVE}$: p = 0.0001, CI$\rm\sb{BELOW}$: p =0.89). The result that competition was predominantly below-ground in the low standing crop wetland supports previous work in agricultural pot experiments (Wilson 1988) and terrestrial field studies (Wilson and Tilman 1991, Putz and Canham 1992, Wilson and Tilman 1993, Wilson in press). The result that root and shoot competition were roughly equal in the high standing crop wetland is not typical of past studies. (Abstract shortened by UMI.)
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Morrow, Carl Dylan. "The effects of elevated atmospheric CO2 on below ground processes in fynbos and C4 ecosystems." Doctoral thesis, University of Cape Town, 2002. http://hdl.handle.net/11427/10901.
Повний текст джерелаАнотація:
Includes bibliography.This thesis investigated ways in which elevated atmospheric carbon dioxide (CO2) concentrations influence the plant: soil interface and soil biological processes. The studies focused on microbial populations associated with the plant rhizosphere, and how these responses could feed into changes in the soil carbon pool.
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Smith, Candice M. "Carbon, nitrogen and phosphorus additions to a temperate hardwood forest effects on below ground processes /." [Bloomington, Ind.] : Indiana University, 2008. 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:3344601.
Повний текст джерелаАнотація:
Thesis (Ph.D.)--Indiana University, School of Public and Environmental Affairs, 2008.Title from PDF t.p. (viewed on Oct. 7, 2009). Source: Dissertation Abstracts International, Volume: 70-02, Section: B, page: 0900. Adviser: J. C. Randolph.
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Weckbacher, Jason Yelderman Joe C. "Effects of recharge events below on-site wastewater drain fields as related to soil type." Waco, Tex. : Baylor University, 2007. http://hdl.handle.net/2104/5094.
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Williams, Alex. "Impacts of sub-ambient and elevated CO2 on above- and below-ground microbial interactions with Arabidopsis." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/20547/.
Повний текст джерелаАнотація:
Over recent years, an increasing body of evidence has suggested that elevated atmospheric CO2 concentrations can alter plant microbial interactions. However, there is limited consensus whether these impacts will be positive or negative for plants in terms of disease resistance. Accordingly, there is a pressing need to gain a better understanding of the molecular and physiological mechanisms by which CO2 shapes the plant’s ability to interact with its biotic environment, which is essential to predict impacts of future climate scenarios on crop production. The work described in this thesis has used a range of CO2 concentrations, from past through present to future predicted concentrations, to study the immune response of the model plant Arabidopsis thaliana to aboveground pathogens and belowground rhizosphere bacteria. Furthermore, a novel developmental correction was established, which enables assessing the direct immunological effects of CO2 on microbial interactions without bias from age-related resistance arising from the stimulatory effects of CO2 on plant development. Changes in disease resistance at elevated CO2 (eCO2), against the necrotrophic fungus Plectosphaerella cucumerina (Pc) and the obligate biotrophic oomycete Hyaloperonospora arabidopsidis (Hpa) were associated with changes in production and sensitivity of the phytohormones jasmonic acid (JA and salicylic acid (SA), respectively. However, priming of SA-dependent defence was not the only mechanisms contributing to eCO2-induced resistance against Hpa. The increased resistance to Hpa at sub-ambient CO2 (saCO2) against Hpa operated independently of SA signaling and was associated with changes in cellular redox state and priming of pathogen-inducible intracellular ROS. Based on the defence phenotypes of knock-down mutants in glycolate oxidase, the H2O2-generating enzyme of the photorespiration cycle, and transcriptional profiling of the peroxisomal catalase gene CAT2, it is proposed that the enhanced Hpa resistance at saCO2 is controlled by photorespiratory ROS. Below-ground, the root colonisation of a specialised rhizobacterial strain Pseudomonas simiae WCS417 was found to be dependent on CO2 concentration vi and soil-nutritional status, whereas root colonisation by the soil saprophytic strain Pseudomonas putida KT2440 was largely unaffected by these variables. Hence, changes in atmospheric CO2 have a greater impact on specialist rhizosphere microbes. Furthermore, the ability of P. simiae WCS417 to promote plant growth and elicit an induced systemic resistance (ISR) was highly dependent on CO2 and nutritional status of the soil. These results suggest that the effects of atmospheric CO2 on rhizosphere microbes depend on the rhizosphere species in question and the nutritional status of the soil. To obtain a more global impression of the impacts of CO2 on rhizosphere interactions, rhizosphere soil was studied for bacterial community diversity and composition using PCR-based community profiling techniques. This revealed that CO2 has a measurable impact on microbial communities in a time-point dependent manner, whereby the effects of eCO2 are more pronounced at earlier stages and the effects of saCO2 are more pronounced at later stages. To study the biochemical basis of these CO2 effects on the rhizosphere effect, a new mass spectrometry-based method was developed to study quantitative and qualitative impacts of CO2 on non-sterile rhizosphere chemistry. These experiments revealed that the diversity of chemical signals greatly increases with rising CO2 concentrations, and that saCO2 and eCO2 are associated with rhizosphere enrichment of different classes of chemicals. Together, the results presented in this thesis provide novel insights into the mechanisms by which plants have adapted to past CO2 climates, and the potential impacts by which future CO2 scenarios will affect interactions with hostile and beneficial microbes. Further research is required to explore the combined impacts of eCO2 and other environmental changes due to global climate change, such as elevated temperatures and drought.
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Peng, Qicheng. "Impact of Precipitation Variability on Above- and Below-ground Carbon Allocation of Maize (Zea Mays. L.)." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1451865331.
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Mercado, Sofía Isabel Basto. "Soil seed banks and ecological restoration : above and below ground effects of environment, management and intraspecific variation." Thesis, University of Sheffield, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.574481.
Повний текст джерелаАнотація:
The aim of this thesis is to contribute to the understanding of how the response of communities (above and below ground) to environment degradation are reflected in seed banks and, how this knowledge can be used to suggest improved application of ecological restoration processes. Two study areas were selected, one at Buxton Climate Change Impacts Laboratory, a site near Buxton, and the other at Wardlow Hay-Cop, in Cressbrook Dale National Nature Reserve, both located in the Derbyshire, UK. This study is organized in the following four sections. I. Chapter 11 examines the impact of the long-term management and changes in precipitation on calcareous grassland seed banks. More than two decades of dereliction have had the largest effects followed by the effects of more than ten years of summer drought. Both changed species composition and, declined seed abundance. In addition, species richness decreased in dereliction. 3. Chapter III investigates the effects of the long-term nitrogen deposition on acid grassland seed banks. More than one decade of N deposition caused shifts in species composition. decrease richness, seed density and. the abundance of functional groups. Moreover, seed bank populations were unable to recover after more than 4 years of ceasing N deposition. 4. Chapter IV explores the effects of soil pH on seed persistence. Seed density, grasses seed abundance the probability that Hypericum pulchrum seeds persist declined as soil pH increased. 5. Chapter V investigates the extent to which the intraspecific trait variation in the same community differs between the components of mature plant population and seed bank, arising from a possible trade-off between investment in seed banks and vegetative growth. Seed bank were not representative of mature plant population. Overall, larger individuals invested more in sexual reproduction than the smaller and, per unit of total biornass, seed- originating individuals invested more in vegetative than in reproductive traits. Therefore, there is no evidence of the potential trade-off between investment in seed banks (via seed production) and vegetative growth in the calcareous grassland species at Buxton. We concluded that the potential of seed banks to assist the restoration is lower in calcareous than acid grass lands. Moreover, the relevance of seed banks is lower in those affected by dereliction and summer drought and, in acid grass lands affected by N deposition the potential is very limited. In addition, the genetic diversity of calcareous grassland species cannot be recovered by using seed banks. Therefore, the recovery of seed banks and above-ground vegetation should be integrated together into restoration programmes.
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Mills, Mystyn W. "Bringing light to below ground patterns| Arbuscular mycorrhizae fungi diversity along an elevation gradient in Southern California." Thesis, California State University, Long Beach, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1597781.
Повний текст джерелаАнотація:
Necessary for the diversity and survival of most terrestrial plants, arbuscular mycorrhizae (AMF) are fungi that form mutualistic symbiotic relationships with approximately 90 percent of terrestrial plant families. While the biodiversity and abundance of plants and animals have received much attention, these patterns for the belowground organisms on which they rely, such as AMF, remain poorly understood. While studies have found indications that AMF are fundamental to ecosystem structure and function, relatively few of these studies have been conducted in situ. In their ability to accommodate the complexity found in natural ecosystems, in situ studies may be vital in providing information relevant to the restoration and conservation of ecosystems. This thesis sought to explore in situ how AMF diversity and root colonization changed across ecosystems along an elevation gradient in Southern California. The findings indicate that certain soil parameters may be especially influential and that intra-species competition may play a role in AMF root colonization.
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Ahmad, Aqeel. "Effect of transgenic Bacillus thuringiensis corn expressing the Cry3Bb1 toxin on above and below ground nontarget organisms /." Search for this dissertation online, 2004. http://wwwlib.umi.com/cr/ksu/main.
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Schleip, Inga Verfasser], Johannes [Akademischer Betreuer] Schnyder, and Wolfgang W. [Akademischer Betreuer] [Weisser. "Carbon residence time in above-ground and below-ground biomass of a grazed grassland community / Inga Schleip. Gutachter: Wolfgang W. Weisser ; Johannes Schnyder. Betreuer: Johannes Schnyder." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/1036494896/34.
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Galambos, Istvan. "Improved understanding of performance of local controls linking the above and below ground components of urban flood flows." Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/4063.
Повний текст джерелаАнотація:
This work is devoted to investigation of the flow interaction between above and below ground drainage systems through gullies. Nowadays frequent flood events reinforce the need for using accurate models to simulate flooding and help urban drainage engineers. A source of uncertainty in these models is the lack of understanding of the complex interactions between the above and below ground drainage systems. The work is divided into two distinct parts. The first one focuses on the development of the solution method. The method is based on the unstructured, two- and three-dimensional finite volume method using the Volume of Fluid (VOF) surface capturing technique. A novel method used to link the 3D and 2D domains is developed in order to reduce the simulation time. The second part concentrates on the validation and implementation of the Computational Fluid Dynamics (CFD) model. The simulation results have been compared against 1:1 scale experimental tests. The agreement between the predictions and the experimental data is found to be satisfactory. The CFD simulation of the different flow configurations for a gully provides a detailed insight into the dynamics of the flow. The computational results provide all the flow details which are inaccessible by present experimental techniques and they are used to prove theoretical assumptions which are important for flood modelling and gully design.
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Pickles, A. R. "The application of critical state soil mechanics to predict ground deformations below an embankment constructed on soft alluvium." Thesis, City University London, 1989. http://openaccess.city.ac.uk/7404/.
Повний текст джерелаАнотація:
An embankment has been constructed to a maximum height of approximately twelve metres at Beckton, east London. The embankment is underlain by up to eight metres of alluvium and made ground. The embankment was monitored during construction. Centreline settlements of the order of O.6m and horizontal movements at the embankment toe of up to O.1Sm were measured. The excess pore pressures generated during construction were found to dissipate rapidly. Soil samples recovered from the site have been tested at city University. The alluvial clay is shown to have extremely variable compression characteristics and it is not possible to determine a single set of critical state soil parameters from the "undisturbed" soil samples. The use in design of parameters derived from reconstituted soil samples is investigated. Laboratory test results indicate that a small quantity'of organic matter in the soil has a large effect on the engineering properties of the alluvial clay. The importance of not dry~ng soils which contain organic matter is highlighted. It is shown that, despite the effects of the organic matter, critical state concepts and in particular the modified Cam clay soil model can be used to predict the behaviour of the alluvial clay in a wide variety of laboratory tests. standard methods of determining the yield stress or preconsolidation pressure are shown to be inadequate when used to analyse the results of compression tests performed at a constant rate of loading. An alternative method, the Lambda construction, is proposed and this is shown to be both reliable and objective. Two distinct testing methods have been used to probe the state boundary surface of the reconstituted alluvial clay samples. The results of these tests appear to indicate the existence of a single state boundary surface for both Ko and isotropically compressed samples. This surface has a shape similar to that predicted by the modified Cam clay soil model. This result conflicts with the findings of many other investigators. Finite element modelling of the embankment construction has been carried out. A single set of soil parameters derived from tests on the reconstituted clay were used to represent the alluvial stratum. The construction of the embankment was modelled as a drained event. The results are shown to compare favourably with the actual field data.
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Mahieu, Stéphanie. "Assessment of the below ground contribution of field grown pea (Pisum sativum L. ) to the soil N pool." Angers, 2008. http://www.theses.fr/2008ANGE0030.
Повний текст джерелаАнотація:
La difficulté d'estimer avec fiabilité la contribution des cultures de légumineuses au pool azoté du sol est un frein à l'accroissement de l'utilisation de ces cultures en tant qu'alternative aux engrais azotés chimiques. D'une part, il est difficile de prévoir la quantité d'azote (N) fixé en fonction des conditions de culture. D'autre part, il existe une grande incertitude sur la quantité d'azote provenant des parties souterraines et principalement de l'N rhizodéposé. Dans ce contexte, le premier objectif de mon travail de thèse était d'adapter et d'affiner une méthode de marquage utilisant le tracer 15N pour mesurer la quantité d'N rhizodéposé par une culture de pois. Deux méthodes « split-root » et « cotton-wick » ainsi que plusieurs conditions de marquage ont été testées. Les effets de la disponibilité en azote du sol, d'un stress hydrique et des sources d'azote sur ce processus ont également été étudiés chez différentes variétés et lignées isogéniques de pois. L'estimation de la rhizodéposition est influencée par la fréquence de marquage et la concentration de la solution de marquage. Cependant, des résultats fiables ont été obtenus avec les deux méthodes de marquage lorsque les plantes étaient soumises à un marquage continu avec une solution diluée d'urée. Pour des raisons pratiques, la méthode « cotton-wick » a été adaptée pour les expérimentations en conditions de plein champ. La proportion d'azote allouée aux parties souterraines n'était influencée ni par un stress hydrique, ni par la disponibilité en azote du sol ou les sources d'azote. L'N rhizodéposé représentait 90% de l'azote total des parties souterraines. De ce fait, l'azote des parties souterraines devrait être intégré dans le calcul du bilan N après une culture de légumineuse ainsi que pour la prédiction des économies en N pour les cultures suivantes dans les systèmes de cultures basés sur les légumineusesIn order to use grain legumes as a means of N acquisition in cropping systems, estimates of biological N2 fixation, N balances and the N benefit for following crops need to be improved. These estimates remain unclear, mainly because of difficulties in assessing below ground N (BGN = Root N + N rhizodeposition), especially N rhizodeposition. The aim of my Ph. D. Was to adapt and refine a 15N labelling method to measure the amount of N derived from rhizodeposition by a pea and to design a protocol for field studies. Two methods (split-root and cotton-wick) and a variety of labelling conditions were tested in the field and in the greenhouse. In addition, effects of water stress, N availability and sources of N nutrition (nitrogen fixation or inorganic N uptake) on this process were investigated on different pea varieties and isolines. The labelling frequency and concentration of the labelling solution were shown to influence the assessment of N rhizodeposition. However, results obtained with both methods were reliable when plants were labelled continuously with a diluted labelling solution. The 15N cotton-wick technique was easier to adapt and monitor in the field than the split-root method and was chosen for further field studies. The results suggest that N source and water stress have no specific effect on the proportion of total plant N allocated to the below ground parts. In the field, rhizodeposition represented around 90% of the total plant N. This should be taken into account when estimating N benefits from biological N2 fixation by a grain legume crop and for the prediction of N economies for succeeding crops in legume-based cropping systems
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Londoño-Flórez, Beatriz Elena. "Ultracold stable ground state RbCs molecules through photoassociation below the Rb(5s)Cs(6p 1/2) dissociation limit." Paris 11, 2010. http://www.theses.fr/2010PA112263.
Повний текст джерелаАнотація:
Le but de cette thèse est l'exploration théorique, sur l'exemple de la molécule RbCs, de la formation par voie optique de dimères alcalins hétéronucléaires dans leur niveau d'énergie le plus bas, à partir d'atomes ultrafroids. On a analysé le spectre lié et le continuum près du seuil de dissociation des états électroniques stables X et a, ainsi que les derniers niveaux liés des états 0+,0- et 1 sous la limite de dissociation Rb(5s)Cs(6p 1/2). Une description 'universelle' des résonances de forme de molécules diatomiques montre le rôle crucial de la longueur de diffusion en onde s. Les facteurs de Franck-Condon (FCF) liés aux processus de photoassociation (PA) ou de désexcitation par émission spontanée (RS) sont calculés de façon systématique. Comme observé expérimentalement, le niveau le plus peuplé par PA suivie de RS est le niveau v=37 de l'état triplet le plus bas. Le rôle important du couplage 'résonnant' est mis en évidence. Les durées de vie des niveaux 0+ sont calculées de façon systématique. Les FCF liés au transfert de population du niveau v=37 vers l'état fondamental absolu sont calculés : le chemin par un niveau intermédiaire 0+ est le plus efficace. L'emploi de sources femtoseconde et de trains d'impulsions femtoseconde pour le transfert de population vers des niveaux très liés des états électroniques stables à été exploré en analysant, dans une approche dépendant du temps, la dynamique de l'excitation depuis le régime champ faible jusqu'au régime champ fort. La Méthode de Représentation de l'Hamiltonien sur une Grille de Fourier à pas ajusté a été étendue avec succès à l'étude de la dynamique des transitions entre niveaux liés et états de diffusionThe main goal of this thesis is to explore theoretically, on the example of the RbCs molecule, the formation, by optical means, of heteronuclear dialkali molecules in the lowest vibrational level of the ground electronic state, starting from ultracold atom pairs. The bound spectrum and the continuum close to threshold of the ground and lowest triplet electronic states are analyzed together with the levels 0+, 0- and 1 below the Rb(5s)Cs(6p 1/2) limit. A 'universal' description of the profiles of shape resonances, valid for any diatomic molecule, points out the crucial role of the s-wave scattering length. Calculations of Franck-Condon factors (FCF) relevant to photoassociation (PA) and spontaneous radiative decay (RS) are presented, showing, in agreement with experiment, that the v=37 level of the triplet electronic state is most favorably populated after PA followed by RS. The so-called 'resonant' coupling is examined in great detail, underlying its crucial influence on PA and RS. Radiative lifetimes are systematically calculated. The FCF associated with optical two-color population transfer from the triplet v=37 level toward the absolute ground level are also calculated, showing that the path through levels of 0+ symmetry is the most efficient. The possibilities offered by femtosecond sources for the population transfer toward deeply bound levels are explored and the dynamics is analyzed, from the low field up to the high field regime. Trains of femtosecond pulses are considered. The Mapped Fourier Grid Hamiltonian method, cornerstone of this study, proves its efficiency to accurately analyze the dynamics of transition processes between bound and scattering levels
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Baumer, Marilyn Cabrini. "Tree Seedling Establishment Under the Native Shrub, Asimina Triloba." Wright State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=wright1183587955.
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Schmelz, Eric Alexander. "The role of phytoecdysteroids in spinach (Spinacia oleracea): Physiological responses to below ground herbivory support a plant defense hypothesis." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/288960.
Повний текст джерелаАнотація:
Polyhydroxylated steroids with insect molting hormone activity were discovered in plants over thirty years ago. The major endogenous molting hormone of insects is believed to be 20-hydroxyecdysone (20E) and interestingly, it is also the most commonly encountered phytoecdysteroid (PE) in plants. Ecdysteroids control developmental programs in both immature and adult insects however, the role of PEs in plants has not been demonstrated. PEs are hypothesized to function as either plant hormones or plant defenses against phytophagous insects. Many toxic secondary metabolites are concentrated in apical meristems where herbivory would result in the greatest reduction in plant fitness. Similarly, the highest concentrations of 20E in spinach were associated with the stems and vasculature while old leaves and roots displayed low levels. In plants, concentrations of toxic or deterrent metabolites are often rapidly induced following attack. In spinach roots, both mechanical damage and insect herbivory resulted in rapid increases in 20E concentrations. The plant wound signal, jasmonic acid was strongly implicated in signaling this response. Known plant hormones and chemical defenses are regulated differently. Pulse chase studies with [2-¹⁴C] mevalonic acid demonstrated that de novo root 20E biosynthesis occurred during the induction and, once synthesized, 20E was stable for over one month. This result is does not support the plant hormone hypothesis, as plant hormones typically undergo rapid conjugation or catabolism. The induction of root 20E concentrations occurred without similar changes in related membrane phytosterols. Simply, pathway specificity was demonstrated as increased 20E accumulation was not part of an overall increase in steroids. To empirically examine the hypothesis that PEs function as plant defenses against insects, a series of experiments were designed with the fungus gnat Bradysia impatiens. Results indicated that root herbivory by larvae induced 20E levels in roots, larval preference for diets containing induced 20E levels was reduced, larval survivorship on 20E containing diets was lower, and plants with induced root 20E levels were better protected from attack. Together, these results support the plant defense hypothesis at both the physiological and ecological level.
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Barnes, Christopher James. "Characterizing environmental, temporal and spatial scaling of Rhizosphere fungi in bioenergy crops : and their role in below-ground carbon cycling." Thesis, University of Warwick, 2014. http://wrap.warwick.ac.uk/72734/.
Повний текст джерелаАнотація:
The rhizosphere consists of plant roots and the adjoining soil, which contains a functionally and genetically rich fungal community. The obligate plant symbionts, the mycorrhizal fungi, have been shown to receive substantial quantities of plant-derived C and play an important role in belowground C dynamics. The flux and residence time of C is however likely to be highly species-specific for rhizosphere fungi, and therefore their abundance and composition will likely have important implications on C storage belowground. Rhizosphere fungal community formation is extremely complex and despite being an area of intense research, current understanding is limited. The composition and abundance of rhizosphere fungi have been shown to vary with temporal and environmental parameters, and potentially geographical separation. However, no studies to date have analysed these parameters simultaneously to isolate the independent effects of each. Clone libraries in conjunction with TRFLP were performed before progressing to 454-pyrosequencing to profile the rhizosphere fungal community of a short rotation coppice (SRC) willow filed site. In this work, distinct seasonal fungal assemblages were shown, with N availability having a large effect in summer and geographical distance effects in autumn sampling points. Additionally, a rare large transition in the composition of the rhizosphere fungi was also demonstrated, which was most likely driven by extreme rainfall earlier in the growing season of the year of transition. Finally, using ₁₃C-labelled-CO₂ the belowground movement of recently derived photo-assimilates was shown to differ between Miscanthus x giganteus and SRC willow, however no significant fluxes were associated with rhizosphere fungal pathways in either crop. Results from this work demonstrate that some of the considerable complexity of microbial communities could have between overlooked in previous community analyses, whilst the flow of C within through mycorrhizal pathways maybe less important in bioenergy cropping systems compared to other ecosystems.
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Krüger, Inken [Verfasser], and Werner [Akademischer Betreuer] Borken. "Potential of above- and below-ground coarse woody debris as a carbon sink in managed and unmanaged forests / Inken Krüger. Betreuer: Werner Borken." Bayreuth : Universität Bayreuth, 2013. http://d-nb.info/1060009609/34.
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West, Eric. "Effects Of Both Above And Below Ground Biomass On Soil Chemical, Physical And Biological Properties On A Coastal Plain Soil In North Carolina." NCSU, 2010. http://www.lib.ncsu.edu/theses/available/etd-02222010-194850/.
Повний текст джерелаАнотація:
The literature has shown the possibility to enhance many of the soil properties that improve production with additions of plant biomass to the soil in conjunction with long-term conservation tillage. Since it has been proven that reduced tillage is extremely beneficial to a soilâs health, the key question is if the incorporation of deep rooted cover crops and/or large quantities of above ground biomass over a two-year period would result in extensive improvements on a soilâs natural properties throughout the effective rooting depth, or is this too short of a time period for any beneficial effects to occur to the chemical, physical and biological properties of the soil? While SOC additions to the soil surface through decaying biomass can make measurable improvements to a soil in the humid, tropical southeastern U. S., the dynamics of total carbon (total SOC), total nitrogen (TKN), particulate organic matter (POM), potentially mineralizable nitrogen (PMN), CEC and bulk density (Db) in the 0-5, 5-10, and 10-18 cm depths in a production system that incorporates deep rooted cover crops and/or additions of organic matter from cover crops at rates >6 Mg/ha/yr (3 T/ac) are unknown. The objectives of this research were to determine what effect rye (Scale cereale), barley (Hordeum vulgare), alfalfa (Medicago sativa), wheat (Triticum aestivum), triticale (Triticale hexaploide Lart.), annual white sweetclover (Melilotus officinalis), blue lupine (Lupinus angustifolius), rye/hairy vetch (Scale cereale/Vicia villiosa) and alfalfa/rye (Medicago sativa/Scale cereale) would have on the following parameters: total SOC, POM, TKN, PMN, CEC, and Db after two (2) years of seeding. Significant spatial/temporal interactions and main effects were found in Db, PMN, POM and CEC while significant main effects were found in total C and total N. Significant treatment interactions were found in Db, total C, PMN, POM and CEC. Relative to treatment biomass, significant effects were seen between treatments and treatment*year interaction. Results on Db found spatial variability with depth but not with season and a minimal treatment effect depending on surface texture. Total C and total N decreased with depth but were independent spatially and temporally; however, treatment effect on total C was <5 months. Between Db and total C, the two parameters were inversely correlated. PMN either fluctuated between sampling times or declined with time. Notably, rye and rye/hairy vetch effected PMN in the 0-5 cm depth where other treatments showed no effect. POM declined with time regardless of depth implying a priming effect was occurring; however, rye/hairy vetch appeared to show an early reversal trend. As for CEC, there was no consistent trend. Additionally, CEC exhibited a moderate correlation to POM but not total C. Biomass measurements indicated no treatment consistently exceeded >6 Mg/ha/yr. Rye and rye/hairy vetch more often produced the most biomass and lupine achieved the overall maximum yield. Relationships between biomass and N parameters found a moderate, positive effect from the biomass inputs that appeared to compound with time. Overall, rye and rye/hairy vetch were the best cover crop treatments but two years of biomass inputs were not enough to prevent declines in POM. Conversely, PMN fluxed from applied N, and biomass with low C:N ratios oxidized quickly resulting in less carbon. Total C, total N and Db were not responsive to short term management indicating more effort is needed to define and/or develop a cover crop that will consistently reach the >6 Mg/ha/yr.
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Lytle, William. "Coupled Evaluation of Below- and Above-Ground Energy and Water Cycle Variables from Reanalysis Products Over Five Flux Tower Sites in the U.S." Thesis, The University of Arizona, 2015. http://hdl.handle.net/10150/595636.
Повний текст джерелаАнотація:
Reanalysis products are widely used to study the land-atmosphere exchanges of energy, water, and carbon fluxes, and have been evaluated using in situ data above or below ground. Here measurements for several years at five flux tower sites in the U.S. (with a total of 315,576 hours of data) are used for the coupled evaluation of both below- and above-ground processes from three global reanalysis products and six global land data assimilation products. All products show systematic errors in precipitation, snow depth, and the timing of the melting and onset of snow. Despite the biases in soil moisture, all products show significant correlations with observed daily soil moisture for the periods with unfrozen soil. While errors in 2 meter air temperature are highly correlated with errors in skin temperature for all sites, the correlations between skin and soil temperature errors are weaker, particularly over the sites with seasonal snow. While net shortwave and longwave radiation flux errors have opposite signs across all products, the net radiation and ground heat flux errors are usually smaller in magnitude than turbulent flux errors. On the other hand, the all-product averages usually agree well with the observations on the evaporative fraction, defined as the ratio of latent heat over the sum of latent and sensible heat fluxes. This study identifies the strengths and weaknesses of these widely-used products, and helps understand the connection of their errors in above- versus below-ground quantities.
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Moore, Timothy E. "The role of water and nutrient availability in determining above and below ground allocations in a C4 grass Stipagrotis ciliata desf. de Winter." Bachelor's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/26459.
Повний текст джерелаАнотація:
In order to understand the impacts climate change will have on plants it is important to understand the role of functional diversity in determining plant success across a range of environments. Two populations of Stipagrostis ciliata were compared at two sites - drier coastal and wetter inland - that varied in their water and nutrient availability. Analysis indicates an inverse relationship between rainfall and N availability, with the drier coastal site having significantly lower soil and plant δ¹⁵N (Zadi= -1.964, p<0.05). Plant percent N decreased by 63% between the coastal and inland site. Mean root: shoot ratios also differed significantly between sites (Zadi= -1.964, p<0.05). Although total rooting depth did not appear to differ between sites, in total more root material was found per plant at the inland site, with 40% of all root material occurring directly below the plant. At the coastal site, a greater proportion of root material was allocated laterally in the upper 10cm of soil. As expected, water use efficiency, based on δ¹³C, was higher at the drier coastal site. It is proposed that plants will alter above and below- ground allocation depending on the nature of the limiting resource. In dry environments, more root material in upper soil layers, and a faster growth rate associated with higher shoot allocation, may enhance water uptake. Where nutrients are limiting, increased root biomass might increase nutrient, especially N interception. Competition may also be higher at low nutrient sites.
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Metcalfe, Daniel Benjamin. "Understanding the effects of drought upon carbon allocation and cycling in an Amazonian rain forest." Thesis, University of Edinburgh, 2007. http://hdl.handle.net/1842/6574.
Повний текст джерелаАнотація:
The Amazon rain forest plays an important role in regional and global biogeochemical cycling, but the region may undergo an increase in the frequency and severity of drought conditions driven by global climate change, regional deforestation and fire. The effects of this drought on carbon cycling in the Amazon, particularly below-ground, are potentially large but remain poorly understood. This thesis examines the impacts of seasonal and longer-term drought upon ecosystem carbon allocation and cycling at an Amazon rain forest site with a particular focus upon below-ground processes. Measurements are made at three one-hectare forest plots with contrasting soil type and vegetation structure, to observe responses across a range of Amazon primary forest types. A fourth plot is subjected to partial rainfall exclusion to permit measurement of forest responses to a wider range of soil moisture levels than currently exists naturally. An analysis of the number of samples required to accurately quantify important ecosystem carbon stocks and fluxes is used to guide the sampling strategy at the field site. Quantifying root dynamics, in particular, presents methodological challenges. Thus, I critically review existing methods, and develop techniques to accurately measure root standing biomass and production. Subsequently, these techniques are used to record root responses, in terms of standing biomass, production, morphology, turnover and nutrient content, to variation in soil moisture across the four rain forest plots. There is substantial environmental variation in root characteristics. However, several responses remain consistent across plots: root production of biomass, length, and surface area, is lower where soil is dry, while root length and surface area per unit mass show the opposite pattern. The other major component of the below-ground carbon cycle is soil carbon dioxide efflux. I partition this efflux, on each plot, into contributions from organic ground surface litter, roots and soil organic matter, and investigate abiotic and biotic causes for observed differences within and between plots. On average, the percentage contribution of soil organic matter respiration to total soil carbon dioxide efflux declines during the dry season, while root respiration contribution displays the opposite trend. However, spatial patterns in soil respiration are not directly attributable to variation in either soil moisture or temperature. Instead, ground surface organic litter mass and root mass account for 44 % of observed spatial heterogeneity in soil carbon dioxide efflux. Finally, information on below-ground carbon cycling is combined with aboveround data, of canopy dynamics and stem wood production and mortality, to analyze the potential effects of drought upon carbon cycling in an Amazon forest ecosystem. Comparison of the rainfall exclusion plot with a similar, but unmodified, control plot reveals potentially important differences in tree carbon allocation, mortality, reproduction, soil respiration and root dynamics. The apparent net consequence of these changes is that, under drier conditions, the amount of CO2 moving out of the forest and into the atmosphere is diminished. This synthesis of above-ground and below-ground data advances understanding of carbon cycling in rain forests, and provides information which should allow more accurate modelling of the response of the Amazon region to future drought. Additional measurements at other sites, and of other ecosystem carbon fluxes, should further refine modelling predictions.
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Shadwell, Eleanor. "Rivalry for nutrient resources : is there competition below ground between leguminous trees and grasses in a mesic and arid savanna in the Kruger National Park?" Bachelor's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/25558.
Повний текст джерелаАнотація:
As described in the resource-based co-existence theory, trees and grasses are able to co-occur due to partitioning of the edaphic environment in savannas. This study describes the fine root-distribution of dominant leguminous C₃ trees and C₄ grasses relative to soil nitrogen, phosphorus and water profiles using stable carbon and nitrogen isotope ratios (of the fine roots). The study occurs on a mesic savanna (737 mm MAP) site on sandy-loam soils and an arid savanna (547 mm MAP) site on clay-rich soils in the Kruger National Park, South Africa. We show that most tree and grass roots are located in the upper layers of the soil and both are present to the bottom of the profile. Root biomass is positively correlated to soil nitrogen and phosphorus and negatively to soil moisture and there were significant differences between sites, but very few of the results were significantly different down the soil profile. Therefore, the niche-separation hypothesis was not supported. The Scheiter & Higgins (2007) model illustrates that even though rooting niche separation is not an essential precondition for grass-tree coexistence, competition in the rooting zone can shape patterns of tree dominance in savannas, which may help in dealing with the problem of bush encroachment in savannas.
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Hesford, Nicholas James. "An above and below ground approach to understanding the impacts of the cultivation and management of short rotation coppice willow on biodiversity and ecosystem processes." Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.707229.
Повний текст джерелаАнотація:
Concerns over anthropogenic climate change coupled with reduced availability and rising prices of domestic fossil fuels have led a drive towards a low carbon economy and have seen increasing interest from Governments in the development of renewable energy technologies. In 2009, a Government strategy proposed by the Renewable Energies Directive, outlined that by 2020, 15% of the UK’s total energy consumption should come from renewable resources. Part of the initiative in meeting this target, and in helping mitigate greenhouse gas emissions, includes the increased production of energy crops, such as Short Rotation Coppice (SRC) willow (Salix spp.). Although SRC willow cultivation could contribute towards the renewable energies target set for 2020, its growth on a large-scale would result in significant changes to the agricultural landscape. Through employing both an above and below ground approach this thesis demonstrates how the cultivation and management of SRC willow can impact upon locally occurring ecological communities. The conversion of traditional pastoral farming systems to SRC willow is shown to be beneficial for avian communities from a biodiversity perspective, although the thesis highlights the potential for this novel crop to act as an ecological trap for locally breeding species. Furthermore, the results of this research illustrate how changing the management of the SRC willow crops, to facilitate the bioremediation of municipal wastewaters, affect the composition of invertebrate communities that have not previously been studied in this system, and can lead to changes to an essential ecosystem process, decomposition. Together, these findings provide a novel insight into the agro-ecology of commercial SRC willow cultivation.
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Ott, Emily Thomas. "Soil Genesis and Vegetation Response to Amendments and Microtopography in Two Virginia Coastal Plain Created Wetlands." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/83529.
Повний текст джерелаАнотація:
Wetlands serve important ecosystem functions such as carbon sequestration but are often affected by disturbances like urban development, agriculture, and road building. For wetlands created to mitigate losses, it is important that the ecosystem functions successfully replicate those of natural wetlands. Created wetlands have frequently not provided these functions due to issues including low organic carbon (OC), high soil bulk density (BD), lost topsoil, incorrect hydrology, and failure of targeted vegetation establishment. Organic matter (OM) amendments help created wetlands attain these functions quicker, but, their long-term effects are seldom reported. This research's purpose was to measure the long-term effects of treatments at a sandy tidal freshwater wetland created in 2003 (WWE) and a fine-textured, non-tidal wetland created in 2002 (CCW). We tested OM treatments, topsoil amendment, and microtopography effects on soil and vegetation properties at WWE and OM treatments at CCW. Pedogenic changes in soil morphology, physical and chemical properties were detected by comparing data to previous studies at these sites. At both sites, litter and biomass parameters were measured to estimate total mass C. Herbaceous biomass was measured at WWE. At WWE, no long-term OM treatment effects from 78 or 156 Mg ha-1 were observed. Soils in pits had higher OC, lower BD, and lower chroma than soils on mounds. Sandy and loamy HSFI's developed at WWE within four years, but there were fewer sandy indicators after 12 years. Loamy HSFI's were lost at CCW from 2003 to 2016. Plots at WWE that were amended with topsoil had higher soil mass C than the sandy soil due to a finer texture, but total mass C did not vary. At CCW, long-term OM treatment effects were observed, including lower BD, higher soil mass C, and higher tree mass C with increasing compost rates up to 224 Mg ha-1. Overall, the ideal compost loading rate for constructed wetlands varied with wetland type and mitigation goals. Compost rates of 112 Mg ha-1 are sufficient for short term establishment of wetland vegetation and hydric soil properties, but higher rates near 224 Mg ha-1 may be required for effects that last over 10 years.Ph. D.
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Kho, Lip Khoon. "Carbon cycling in a Bornean tropical forest : exploring carbon allocation and cycling of tropical forest in the 52-ha Lambir Hills forest dynamics plot." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:bfa1f206-97bf-4bcd-a148-521506225c90.
Повний текст джерелаАнотація:
The tropical forests on the island of Borneo are among of the richest in the world in terms of tree diversity, and their capacity to store a large reservoir of carbon. The Southeast Asian forests are fundamentally different from Neotropical and African forests, with their single-family dominance by dipterocarp trees, and with inherently greater stature and biomass. The carbon productivity and allocation in Asian tropical forests is still poorly quantified, and their responses to environmental drivers are still poorly understood. Almost all recent advances in tropical forest carbon cycling research have occurred in the Neotropics, with very few studies in Asia. The principal aim of this thesis is to quantify the carbon budget of a lowland dipterocarp forest in the Lambir Hills National Park, Miri, Sarawak, Malaysian Borneo. I examined and explored the productivity and carbon cycling processes and their responses to environmental factors across two major and contrasting soil types, in particular the clay and sandy loam soils. I recorded and analysed the Net Primary Productivity (NPP) and respiration for the above- and below-ground components, and observed the responses to seasonal variation and environmental drivers. Total soil respiration was relatively high and contributed a great deal to ecosystem respiration. Variation in soil respiration rates appeared closely related to soil moisture content. I found a strong diurnal cycle in soil respiration. On the basis of the first soil carbon dioxide (CO2) efflux partitioning study undertaken in a tropical forest, the diurnal cycle in total soil respiration appeared to be entirely driven by the diurnal cycle in litter respiration, and in turn litter is strongly controlled by moisture. There was little seasonal variation in allocation of net primary productivity (NPP), but there was evidence showing potential inter-annual variability for several components of NPP. Further, the allocation of NPP showed a strong seasonal shift between the forest plots on clay and sandy loam soils. Combining all the data measured and obtained in this D.Phil. thesis, the overall carbon budget assessed in this lowland dipterocarp forest showed a high level of agreement with other studies in Asia using micrometeorological techniques and the situation appears to be comparable to tropical forests in Amazonia. The key difference is that the aboveground NPP is higher and is the largest component contributing to the overall carbon budget, with relatively higher carbon use efficiency (CUE). The lowland dipterocarp forest in Lambir shows higher allocation in the above-ground NPP, and there were also differences in NPP and its allocation between sandy and clay-rich plots.
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Fragoso, Variluska Verfasser], Ian T. [Akademischer Betreuer] [Baldwin, Ralf [Akademischer Betreuer] Oelmüller, and John G. [Akademischer Betreuer] Jelesko. "Integrating below- and above-ground signaling in Nicotiana attenuata : root oxylipins systemically regulate leaf responses to attack and increase plant resistance / Variluska Fragoso. Gutachter: Ian Thomas Baldwin ; Ralf Oelmüller ; John G. Jelesko." Jena : Thüringer Universitäts- und Landesbibliothek Jena, 2015. http://d-nb.info/1066238529/34.
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Fragoso, Variluska [Verfasser], Ian T. [Akademischer Betreuer] Baldwin, Ralf [Akademischer Betreuer] Oelmüller, and John G. [Akademischer Betreuer] Jelesko. "Integrating below- and above-ground signaling in Nicotiana attenuata : root oxylipins systemically regulate leaf responses to attack and increase plant resistance / Variluska Fragoso. Gutachter: Ian Thomas Baldwin ; Ralf Oelmüller ; John G. Jelesko." Jena : Thüringer Universitäts- und Landesbibliothek Jena, 2015. http://d-nb.info/1066238529/34.
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Schwindt, Daniel [Verfasser], Christof [Gutachter] Kneisel, and Birgit [Gutachter] Terhorst. "Permafrost in ventilated talus slopes below the timberline - A multi-methodological study on the ground thermal regime and its impact on the temporal variability and spatial heterogeneity of permafrost at three sites in the Swiss Alps / Daniel Schwindt. Gutachter: Christof Kneisel ; Birgit Terhorst." Würzburg : Universität Würzburg, 2013. http://d-nb.info/111204003X/34.
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Rozak, Andes. "Vers une meilleure estimation des stocks de carbone dans les forêts exploitées à Diptérocarpées de Bornéo." Thesis, Paris, AgroParisTech, 2018. http://www.theses.fr/2018AGPT0008/document.
Повний текст джерелаАнотація:
Les forêts tropicales constituent le principal réservoir de biodiversité et de carbone (C). Cependant, la plupart des forêts tropicales, en particulier les forêts de Bornéo en Asie du Sud-Est, subissent une pression intense et sont menacées par des activités anthropiques telles que l'exploitation forestière, l'industrie minière l’agriculture et la conversion en plantations industrielles. En 2010, la superficie des forêts de production de Bornéo était de 26,8 millions d’ha (environ 36% de la superficie totale de l’île, dont 18 millions ha (environ 24%) déjà exploités. Par conséquent, les forêts de production occupent donc une place importante à Bornéo et jouent un rôle essentiel dans la compensation des biens fournis et la maintenance des services écosystémiques, tels que la conservation du C et de la biodiversité.L’exploitation sélective réduit la biomasse aérienne et souterraine par l’élimination de quelques grands arbres, et augmente les stocks de bois mort par des dommages collatéraux. En créant des trouées dans la canopée, le microclimat dans les sous-étages et au sol change localement et accélèrent la décomposition de la litière et de la matière organique. L'importance des dégâts, de l'ouverture de la canopée et de la rapidité du rétablissement du C s'est avéré principalement liée à l'intensité de l'exploitation forestière. Cependant, les évaluations empiriques de l'effet à long terme de l'intensité de l'exploitation forestière sur l'équilibre du C dans les forêts de production restent rares.La présente thèse se concentre principalement sur l'évaluation de l'effet à long terme de l'intensité de l'exploitation forestière sur la séquestration de carbone dans une forêt à Diptérocarpées de Nord Bornéo (District de Malinau, Kalimantan Nord) exploitée en 1999/2000. Cinq principaux réservoirs de C, à savoir le C aérien dans les arbres vivants (AGC), le C souterrain dans les arbres vivants (BGC), le bois mort, la litière et le C organique du sol (SOC) ont été estimés le long d’un gradient d'intensité d'exploitation (0-57% de la biomasse perdue).Nos résultats ont montré que les stocks totaux de C, 16 ans après l'exploitation, variaient de 218 à 554 Mg C ha-1 avec une moyenne de 314 Mg C ha-1. Une différence de 95 Mg C ha-1 a été observée entre une faible intensité d'exploitation forestière (<2,1% de la biomasse initiale perdue) et une intensité d'exploitation élevée (>19%). La plus grande partie du C (environ 77%) était présente dans les arbres vivants, suivie par les stocks du sol (15%), les stocks de bois mort (6%) et une fraction mineure des stocks de litière (1%). L'empreinte de l'intensité de l'exploitation forestière était encore détectable 16 ans après l'exploitation et a été le principal facteur expliquant la réduction des AGC>20, BGC>20, du bois mort et des stocks de C et une augmentation du bois mort. L'intensité de l'exploitation expliquait à elle seule 61%, 63%, 38% et 48% des variations des AGC>20, BGC>20, du bois mort et des stocks de C totaux, respectivement. L'intensité de l'abattage a également réduit considérablement les stocks de SOC dans la couche supérieure de 30 cm. Pour l'ensemble des stocks de SOC (0-100 cm), l'influence de l'intensité de l'exploitation était encore perceptible, en conjonction avec d'autres variables.Nos résultats quantifient l'effet à long terme de l'exploitation forestière sur les stocks de C forestier, en particulier sur les AGC et les bois morts. L'intensité élevée de l'exploitation forestière (réduction de 50% de la biomasse initiale) a réduit les stocks totaux de C de 27%. La récupération de l'AGC était plus faible dans les parcelles d'intensité d'exploitation forestière élevée, ce qui suggère une résilience plus faible de la forêt à l'exploitation forestière. Par conséquent, une intensité d'exploitation forestière inférieure à 20%, devrait être envisagé afin de limiter l'effet à long terme sur les AGC et le bois mortTropical forests are a major reservoir of biodiversity and carbon (C), playing a pivotal role in global ecosystem function and climate regulation. However, most of the tropical forests, especially Bornean forests in Southeast Asia, are under intense pressure and threatened by anthropogenic activities such as logging, mining industry, agriculture and conversion to industrial plantation. In 2010, the area of production forests in Borneo was 26.8 million ha (approx. 36% of the total land area of Borneo) including 18 million ha (approx. 24%) of logged forests. Production forests are thus emerging as a dominant land-use, playing a crucial role in trading-off provision of goods and maintenance of ecosystem services, such as C and biodiversity retention.Selective logging is known to reduce both above- and below-ground biomass through the removal of a few large trees, while increasing deadwood stocks through collateral damages. By creating large gaps in the canopy, microclimates in the understory and on the forest floor change locally speeding up the decomposition of litter and organic matter. The extent of incidental damages, canopy openness, as well as the speed of C recovery, was shown to be primarily related to logging intensity. However, empirical evaluations of the long-term effect of logging intensity on C balance in production forests remain rare.The present thesis aims to assess the long-term effect of logging intensity on C sequestration in a north Bornean Dipterocarp forests (Malinau District, North Kalimantan) logged in 1999/2000. Five main C pools, namely above-ground (AGC) and below-ground (BGC) carbon in living trees, deadwood, litter, and soil organic carbon (SOC) were estimated along a logging intensity gradient (ranging from 0 to 57% of initial biomass removed).Our result showed that total C stocks 16 years after logging, ranged from 218-554 Mg C ha-1 with an average of 314 Mg C ha-1. A difference of 95 Mg C ha-1 was found between low logging intensity (<2.1% of initial biomass lost) and high logging intensity (>19%). Most C (approx. 77%) was found in living trees, followed by soil (15%), deadwood (6%), and a minor fraction in litter (1%). The imprint of logging intensity was still detectable 16 years after logging, and logging intensity thus was the main driver explaining the reduction of AGC>20, BGC>20, deadwood, and total C stocks and an increase in deadwood. Solely, logging intensity explained 61%, 63%, 38%, and 48% of variations of AGC>20, BGC>20, deadwood, and total C stocks, respectively. Logging intensity also significantly reduced SOC stocks in the upper 30 cm layer. For total SOC stocks (0-100 cm), the negative influence of logging intensity was still perceptible, being significant in conjunction with other variables.Our results quantify the long-term effect of logging on forest C stocks, especially on AGC and deadwood. High logging intensity (50% reduction of initial biomass) reduced total C stocks by 27%. AGC recovery was lower in high logging intensity plots, suggesting lowered forest resilience to logging. Our study showed that maintaining logging intensity, below 20% of the initial biomass, limit the long-term effect of logging on AGC and deadwood stocks
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Müller, Malin. "Functional workwear for miners working in the worlds largest underground mine : In what way can the future workwear for an extreme mine environment improve safety, facilitate the work flow as well as increase the comfort for workers situated more than 1045 meter below ground?" Thesis, Umeå universitet, Institutionen Designhögskolan, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-91808.
Повний текст джерелаАнотація:
PROBLEM This is my graduating thesis from the bachelor program in Industrial Design from Umeå Institute of design. In this project I have looked at in what way the future work wear for an extreme mine environment could improve safety, facilitate the workflow as well as increase the comfort for workers situated more than 1045 meters below ground. I have collaborated with LKAB in Kiruna, Sweden. LKAB is a mining company, exporting iron ore from the worlds largest underground iron ore mine. In the Kiruna mine, a new main level was recently opened at the level of 1365 meters. The extreme conditions down at this depth have created new challenges when it comes to work wear for the employees. METHODS AND FINDING RESULT During the project I have used several methods, all following a typical Industrial Design methodology. I started with visiting the mine, having a look at the entire process and talking to workes. After this I wrote a brief for the project, containing information on what the problem is today. I made an other trip to the mine to host a Pin-Point meeting and a workshop together with workers from different positions and work places within the mine. This to gain a further and more specific understanding in the problem -s. The workshop I hosted was to see what they themselves thought would be good solutions. Other methods I've used is survey, sketch ideation, evaluations with users, interviews, observations, visits to manufacturers, visit to the industrial wash / warehouse and mock-ups. I divided the problems in to categories: The fit of the clothes Ability to carry tools Material Functions / Adjustments The project has resulted in a concept of a new trouser and a new jacket for the workers at the LKAB iron or mine in Kiruna. The garments are of a lighter more durable material than the garments used today. The jacket and the trouser have now more specific pockets and are placed in better positions than earlier. I also tried to place seams better, this to avoid any discomfort and work related injuries. One of the problems today was that the jacket for some, created a pressure over the neck. I've added adjustment possibilities to the garments and inserted "softed" materials in some places to increase level of comfort. The result is portrayed as a full size model, in a women’s fit. RESULT The project has resulted in a concept of a new trouser and a new jacket for the workers at the LKAB iron or mine in Kiruna. The garments are of a lighter more durable material than the garments used today. The jacket and the trouser have now more specific pockets and are placed in better positions than earlier. I also tried to place seams better, this to avoid any discomfort and work related injuries. One of the problems today was that the jacket for some, created a pressure over the neck. I've added adjustment possibilities to the garments and inserted "softed" materials in some places to increase level of comfort. The result is portrayed as a full size model, in a women’s fit.
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Smith, Daniel Robert. "Soil respiration in a fire scar chronosequence of Canadian boreal jack pine forest." Thesis, University of Leicester, 2009. http://hdl.handle.net/2381/8268.
Повний текст джерелаАнотація:
This research investigates soil respiration (Rs) in a boreal jack pine (Pinus banksiana Lamb.) fire scar chronosequence at Sharpsand Creek, Ontario, Canada. During two field campaigns in 2006 and 2007, Rs was measured in a chronosequence of fire scars in the range 0 to 59 years since fire. Mean Rs adjusted for soil temperature (Ts) and soil moisture (Ms) (Rs T,M) ranged from 0.56 μmol CO2/m2/s (32 years post fire) to 8.18 μmol CO2/m2/s (58 years post fire). Coefficient of variation (CV) of Rs adjusted for Ts and Ms ranged from 20% (16 years post fire) to 56% (58 years post fire). Across the field site, there was a significant exponential relationship between Rs adjusted for soil organic carbon (Cs) and Ts (P = 1.24*10-06; Q10 = 2.21) but no effect of Ms on Rs adjusted for Cs and Ts for the range 0.21 to 0.77 volumetric Ms (P = 0.702). Rs T,M significantly (P = 0.030) decreased after burning mature forest, though no significant (P > 0.1) difference could be detected between recently burned and unburned young forest. Rs was measured in recently burned boreal jack pine fire scar age categories that differed in their burn history and there was a significant difference in Rs T,M between previously 32 v 16 year old (P = 0.000) and previously 32 v 59 year old (P = 0.044) scars. There was a strong significant exponential increase in S R T,M with time since fire (r2 = 0.999; P = 0.006) for the chronosequence 0, 16 and 59 years post fire, and for all these age categories, Rs T,M was significantly different from one another (P < 0.05). The Joint UK Land Environment Simulator (JULES) was used to model vegetation re-growth over successional time at Sharpsand Creek, though it appeared to perform poorly in simulating leaf area index and canopy height. JULES probably over estimated heterotrophic Rs at Sharpsand Creek when Ts corrected simulated values were compared with measured Rs T,M. The results of this study contribute to a better quantitative understanding of Rs in boreal jack pine fire scars and will facilitate improvements in C cycle modelling. Further work is needed in quantifying autotrophic and heterotrophic contributions to soil respiration in jack pine systems, monitoring soil respiration for extended time periods after fire and improving the ability of JULES to simulate successional vegetation re-growth.
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MARTANI, ENRICO. "Conversion of perennial cropping systems to arable land: keyelements for an ecologically sustainable transition." Doctoral thesis, Università Cattolica del Sacro Cuore, 2021. http://hdl.handle.net/10280/96576.
Повний текст джерелаАнотація:
La coltivazione dei sistemi colturali poliennali su terreni marginali combina la produzione sostenibile di biomassa per diversi utilizzi a benefici di carattere ambientale come il sequestro del C atmosferico nel suolo. La limitata longevità di questi sistemi colturali (10-20 anni), fornisce la possibilità di sfruttarli come una tecnica temporanea per rigenerare la fertilità dei terreni marginali e di studiare il loro effetto nel lungo periodo sul carbonio del suolo. Con questa tesi, avevo l'obiettivo di studiare l'effetto della riconversione a coltura annuali dei sistemi agricoli poliennali sul carbonio del suolo: per raggiungere questo obiettivo, ho combinato ad una meta-analisi di letteratura sull'effetto della riconversione, con un esperimento di campo di lungo periodo, un esperimento di incubazione in laboratorio e l'uso di un modello matematico del carbonio del suolo. L'uso combinato di questi approcci mi ha permesso di mostrare il potenziale che i sistemi colturali poliennali hanno nel sostenere il sequestro del C ne suolo anche dopo la loro riconversione. Quindi i sistemi colturali poliennali sono una pratica sostenibile promettente che può essere integrata in rotazioni agricole di 13 anni sui terreni marginali del nord d'Italia per ripristinare il carbonio del suolo.The cultivation of perennial cropping systems on marginal lands combines the production of sustainable biomass for multiple uses with environmental benefits such as carbon (C) sequestration in soil. In this thesis, we studied the effect of perennial cropping system on soil C considering the scenario of perennial cropping systems reversion to arable land. The limited longevity (10-20 years) of perennial cropping systems, gives the possibility of using these crops as a temporary- option to restore soil fertility of marginal lands and to study the long-term legacy of these cropping systems on soil C. In this thesis I aimed to study the effect of perennial cropping systems reversion to arable land on soil C: to achieve this objective, I combined a literature meta-analysis on the effect of reversion of perennial cropping systems on soil C, with a long-term field experiment on perennial cropping systems, an incubation experiment and the use of a process-based soil C model. The combined use of these approaches gave me the chance to show the potential of perennial cropping systems to support C sequestration even after their reversion. Therefore, perennial cropping systems are a promising sustainable practice which could be integrated on a 13-year agricultural rotation on marginal lands of northern Italy to restore soil C.
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De, almeida Tania. "Impact d’une espèce ingénieure de l’écosystème et son utilisation en restauration écologique : Le cas de Messor barbarus (L.) dans les pelouses méditerranéennes Above- and below-ground effects of an ecosystem engineer ant in Mediterranean dry grasslands Harvester ants as ecological engineers for Mediterranean grassland restoration: impacts on soil and vegetation A trait-based approach to promote ants in restoration ecology." Thesis, Avignon, 2020. http://www.theses.fr/2020AVIG0358.
Повний текст джерелаАнотація:
L’objectif principal de cette thèse était double : (i) mesurer l’impact d’une espèce de fourmi sur son écosystème, afin (ii) d’en déduire des applications potentielles dans le domaine de la restauration écologique.Les fourmis sont parmi les organismes les plus abondants des écosystèmes terrestres et occupent des zones géographiques très variées. Elles jouent des rôles écologiques clés dans de nombreux écosystèmes comme ingénieurs du sol, prédateurs ou régulateurs de la croissance et de la reproduction des plantes. Cependant les données collectées localement sont souvent parcellaires et ne permettent pas d’avoir une vision complète de l’impact d’une espèce sur son milieu.Messor barbarus (L.), connue pour redistribuer les graines et pour modifier les propriétés physico-chimiques du sol, est largement répandue dans le Sud-Ouest de l’Europe notamment au sein des pelouses méditerranéennes. Elle pourrait donc jouer un rôle majeur dans la composition et structuration de ces pelouses caractérisées par une forte biodiversité mais dont le nombre et la superficie ont drastiquement diminué ces dernières décennies.Dans un premier temps, par une étude multi-compartiments, nous avons confirmé l’hypothèse selon laquelle M. barbarus est une ingénieure de l’écosystème au sein des pelouses méditerranéennes. Elle transforme cet habitat en modifiant, comme attendu, les propriétés physico-chimiques du sol. Ces modifications sont associées à une augmentation de la biomasse et de l’hétérogénéité des communautés végétales ainsi qu’à des changements dans les faunes épigée et endogée (abondance, occurrence et structure des communautés). De plus, M. barbarus modifie profondément les relations trophiques et non trophiques interspécifiques et entre les espèces et leur habitat. L’hétérogénéité créée à l’échelle locale par l’activité de cette fourmi, entraine une diversification des niches écologiques au sein de ces pelouses.Malgré leur rôle souvent majeur sur le fonctionnement des écosystèmes, les fourmis ne sont que très rarement considérées en restauration écologique. Sur notre site d’étude, un chantier de réhabilitation d’une pelouse sèche après une fuite d’hydrocarbures et un transfert de sol, M. barbarus a permis d’accélérer la restauration des propriétés physico-chimiques du sol mais aussi de la banque de graines à moyen terme - sept ans après la réhabilitation du site. Ces résultats font donc de cette espèce une bonne candidate en ingénierie écologique.Afin de généraliser l’utilisation des fourmis en restauration écologique, nous proposons une méthodologie à destination des gestionnaires basée sur l’utilisation de traits fonctionnels et d’histoire de vie. Pour cela nous avons évalué le potentiel des fourmis en écologie de la restauration, puis nous avons listé l’ensemble des traits connus pour affecter les compartiments abiotiques et biotiques et/ou pertinent pour effectuer un suivi du succès de la phase de restauration. La méthodologie proposée permet une première sélection des espèces potentiellement utilisables en fonction des objectifs de restaurationThe main objective of this thesis was double: (i) to assess the impact of an ant species on its ecosystem, in order to (ii) deduce potential applications in the field of ecological restoration.Ants are among the most abundant organisms in terrestrial ecosystems and occupy a wide range of geographical areas. They play key ecological roles in many ecosystems as soil engineers, predators or regulators of plant growth and reproduction. However, the information collected locally is often fragmented and does not provide a complete overview of the impact of a species on its environment.Messor barbarus (L.), known to redistribute seeds and to modify the soil physico-chemical properties, is widespread in South-Western Europe, particularly in Mediterranean grasslands. Therefore, it may play a major role in the composition and structuring of these ecosystems, which are characterised by high biodiversity but whose abundance and surface area have decreased drastically in recent decades.Through a multi-compartment study, we confirmed the hypothesis that M. barbarus is an ecological engineer in Mediterranean grasslands. This species changes this habitat by modifying, as expected, soil physico-chemical properties. These modifications are associated with an increase in both biomass and heterogeneity of plant communities, as well as changes in above- and belowground fauna (abundance, occurrence and structure of communities). Messor barbarus profoundly changes trophic and non-trophic relationships within and between species and their habitat. The heterogeneity created locally by the activity of M. barbarus leads to a diversification of ecological niches within these grasslands.Despite their major role in the functioning of ecosystems, ants are rarely considered in restoration ecology. In our study site, corresponding to a dry grassland rehabilited after an oil leak and a soil transfer, M. barbarus contributed to accelerate the restoration of the soil physico-chemical properties but also of the seed bank in the medium term - seven years after the rehabilitation. These results make this species a good candidate for ecological engineering.In order to generalise the use of ants in restoration ecology, we propose a trait-based methodology for stakeholders. We evaluated the potential of ants in restoration ecology, then listed all the traits known to affect abiotic and biotic compartments and/or relevant to monitor the success of the restoration phase. The proposed methodology provides a first selection of potentially relevant species according to the restoration objectives
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Effenbergerová, Petra. "Mateřská školka." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240248.
Повний текст джерелаАнотація:
The purpose of this diploma thesis is to prepare the project documentation of the construction part for the building of the kindergarten according to the legal decree number 499/2006 Coll. on construction documentation. Projected building is a detached two-storey building located on the plots number 534/3,534/4, 536, 540/13 in the cadastre unit of Brno-Ivanovice. It is designed as building with storey partly below ground level and has wheechair access to both floor. The structural system of the building is combination of RC wall structures and columns and clay internal masonry. The roofs are designed as intensive green roofs. Designed kindergarten includes three classes for total of 75 children.