Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 19 of 19 for “"ecosystem respiration"”.
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Mesoscale Wind and Temperature Changes over Peatlands of the Hudson Bay Lowlands: impacts on the Surface Energy Balance and Net CO2 Exchange
… combined response of plant productivity and ecosystem respiration to global warming and moisture changes. The Hudson Bay Lowlands (HBL) region of Canada is the second largest peat-accumulating complex in the world that is strongly influenced by the cold air masses originating off the Hudson …
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Forest respiration from eddy covariance and chamber measurements under high turbulence and a bark beetle epidemic
… has resulted in major advances in understanding ecosystem-scale biogeochemical cycling. However, long-term sums of net ecosystem exchange, photosynthesis and respiration fluxes have uncertainties because of potential measurement biases in respiration fluxes at night. Many studies have …
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Carbon dynamics in restiad peatlands across different timescales
… of internal feedbacks which tend to dominate ecosystem response over long-timescales and may amplify or dampen external influences. This has made predicting the effects of environmental change, beyond a few years, highly challenging. Here we use CO₂ fluxes and down-core measurements of carbon …
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Ecosystem-atmosphere exchange of carbon dioxide and water vapour in typical East-Asian croplands
… and environmental changes, the role of cropland ecosystems in the surface-atmosphere energy and matter exchange has drawn a lot of attention. This thesis investigated the potential change on ecosystem-atmosphere exchange of heat, water vapour and carbon dioxide if crop species planted or …
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Investigation of high nighttime CO2-fluxes at the Wetzstein spruce forest site in Thuringia, Germany
… with the ones obtained at similar spruce ecosystems (Rebmann, 2004; Grünwald and Bernhofer, 2007). The site is located on a hill and subject to strong winds and high levels of turbulence for continuous periods. The unusual high fluxes of CO2 are predominantly associated with these …
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Seasonal Variation in Whole Stream Metabolism across Varying Land Use Types
… to estimate gross primary production (GPP) and ecosystem respiration (ER). GPP and ER were compared to stream chemistry, light, land cover, and storms. I found that there is greater influence of local riparian land cover than watershed land cover on GPP and ER. Streams had varying annual GPP, …
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Assessment of grassland ecosystem functioning: Carbon dioxide exchange and the dynamics of carbon and nutrient pools in temperate and Mediterranean grasslands
… extreme weather events, management methods and ecosystem heterogeneity on grassland ecosystem functioning in the context of the variables CO2 exchange, nutrient dynamics, production, nitrogen and carbon pools. Two sites were selected in Central Europe, to represent temperate grassland, namely a …
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Interactive effects of climate change and management on grassland greenhouse gas emissions
… gas (GHG) emissions and a range of other ecosystem functioning in grasslands. This will be particularly important for the sustainability of agricultural ecosystems due to its role in global food security and soil C sequestration. The interaction between climate warming and grassland …
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Carbon fluxes at an upland blanket bog in the north Pennines
… stores of carbon. The degree to which these ecosystems are currently functioning as sinks or sources of carbon is not clear. There is a paucity of measurements from suitable sites but the available evidence suggests that certain sites might be close to being carbon neutral or acting as a net …
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Stress-induced alterations in ecosystem function: the role of acidification in lotic metabolism and biogeochemistry
… of microbial compartments responsible for these ecosystem processes. Microcosm incubations of leaf biofilms from streams of differing pH revealed greater rates of fungal biomass-specific respiration (i.e. the stress metric <i>q</i>CO₂) and biomass-specific N uptake (i.e. <i>q</i>N) with …
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Evaluation and Application of the Community Land Model for Simulating Energy and Carbon Exchange in Agricultural Ecosystems
… the interactions between the atmosphere and ecosystems, understanding biophysical feedback processes, and predicting future climate. Most state-of-the-art LSMs assessed in the fifth phase of the Coupled Model Inter-comparison project (CMIP5), however, did not include process-based crop models …
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Ecosystem metabolism in coastal plain streams of southeast Louisiana : environmental and watershed effects
… oxygen curves for estimating the components of ecosystem metabolism in the lotic setting have been important in determining the current ecosystem theory of streams, both spatially among multiple systems and longitudinally within the same system, as well as identifying potentially impaired …
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Evaluating the role of flow and specific conductivity on stream metabolism across a mining-induced salinity gradient in the Appalachian Coalfield
… have been well documented in freshwater ecosystems, but there are few measurements assessing how salinity effects on organisms influence whole-ecosystem processes, specifically stream metabolism. Understanding how gross primary production (GPP) and ecosystem respiration (ER) respond to …
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Modeling Neotropical Ecosystems during the Last Glacial Maximum
… has long motivated research on Neotropical ecosystems, though regionally-focused modeling studies remain relatively sparse and limited in scope. Three individual projects were performed to address potential issues in the modeling of Neotropical ecosystems in past and present contexts with …
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Controls on terrestrial carbon and nutrient cycling in Arctic permafrost environments
… will largely depend on the response of Arctic ecosystems to positive and negative feedbacks, which has implications for the global climate system and the people that inhabit the Arctic region. Improving our understanding of the biogeochemical cycles that influence Arctic terrestrial systems …
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Modelling Stream Metabolism and Fish Biomass in Headwater Streams of the Eastern Cascades Mountains
… by the average fish mass, and I estimated ecosystem metabolism on three occasions using the single station method with a diel oxygen curve and inverse modeling. I estimated the critically important air-water gas exchange values based on stream slope, using an empirical relationship from a …
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The Flow Regime of Function: Influence of flow changes on biogeochemical processes in streams
Streams are ecosystems organized by disturbance. One of the most frequent disturbances within a stream is elevated flow. Elevated flow can both stimulate ecosystem processes and impede them. Consequently, flow plays a critical role in shifting the dominant stream function between biological …
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Headwater stream network connectivity: biogeochemical consequences and carbon fate
Headwaters may be small relative to other aquatic ecosystems, but they are neither simple nor static environments. Heterogeneous stream corridors constitute the majority of river network length and regulate cycling of carbon and oxygen as they expand and contract their connections across the …
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Effects of environmental warming on lentic freshwater communities and the behavioral and physiological responses by fishes to warming
… for ectotherms across all habitats. Freshwater ecosystems are threatened by anthropogenic warming, and with projected increases in global temperatures, understanding the impacts of warming on aquatic communities and organism success is important. Many studies have examined the effects of future …