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 20 of 23 for “"gross primary production (GPP)"”.
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Remote sensing-based assessment of Gross Primary Production (GPP) in agricultural ecosystems
… form of food products, e.g. agricultural yield. Gross primary production (GPP) of agricultural ecosystems is the amount of total carbon assimilated by the planted crops and the driver of useful biomass production. To assess the GPP of croplands, this study combines information from flux …
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The Effect of Elevated Carbon Dioxide and Ozone on Soybean Development, Leaf Anatomy and Productivity
… increase in canopy photosynthesis or gross primary production (GPP). A draw-back of FACE is that GPP cannot be measured directly. Measurements of micrometeorology, leaf photosynthetic properties and canopy structure were combined in an adapted version of the Integrated Scientific …
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A joint analysis of gross primary production and evapotranspiration of Australia using eddy covariance, remote sensing and land surface modelling approaches
… aim of this thesis is to analyze the patterns of gross primary production (GPP) and evapotranspiration (ET) across Australian biomes in combination of eddy covariance, remote sensing and land surface model (LSM) methods, taking advantage of their respective applicability on different space and …
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Uncertainty quantification and calibration of physical models
… and underlying parameters, and the outputs are gross primary production (GPP), net ecosystem production (NEP) and other variables. To make predictions of future outputs from the computer model, I also estimate the under- lying parameters. With an efficient Bayesian approximation, statistical …
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Seasonal Variation in Whole Stream Metabolism across Varying Land Use Types
… from 2010-2011. I used these data 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. …
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Evaluation and Application of the Community Land Model for Simulating Energy and Carbon Exchange in Agricultural Ecosystems
… parameters was developed to better simulate crop gross primary production (GPP), ecosystem respiration (ER) and leaf area index (LAI). The key parameters include the maximum carboxylation rate at 25 oC (Vcmax25), specific leaf area at the top of the canopy (slatop) and a parameter determining the …
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Ecosystem metabolism in coastal plain streams of southeast Louisiana : environmental and watershed effects
… light, nutrients, and stable substrates for gross primary production (GPP) and a source of organic matter (OM) for ecosystem respiration (ER). Stream size is important at mediating these factors through the presence or absence of a riparian canopy where small streams tend to have an intact …
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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
… stream metabolism. Understanding how gross primary production (GPP) and ecosystem respiration (ER) respond to salinity, stream flow, and their association is needed to characterize the consequences of salinization on stream processes. To assess the role of salinization and discharge on …
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Recent changes in land use and productivity in agro-pastoral Inner Mongolia, China
… means to buy them as more critical for crop production than soil erosion. This indicates the increase in use of and dependence on agro-chemicals, a trend confirmed by regional statistics, and concern is raised regarding the sustainability of the rapid agricultural development. The …
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Recovery of southern Appalachian streams from historical agriculture
… Agricultural streams had higher rates of gross primary production (GPP) and GPP to respiration (P/R) ratios than forested streams, indicating that agriculture enhances autotrophic metabolism in streams. Agriculture did not have a significant effect on wood breakdown or microbial biofilm …
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Canopy structural and meteorological influences on CO2 exchange for MODIS product validation in a boreal jack pine chronosequence
… Finally, the fourth objective was to model gross primary production (GPP) from airborne lidar. Lidar estimates of GPP were then compared with those from the EC system at the jack pine chronosequence and with the MODIS GPP (Collection 5) product.
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Effects of Landscape Disturbances on Autotrophic Processes Within Arkansas Ozark Streams
… that can promote increased algal growth and primary production. Natural gas (NG) infrastructure development, a recent land use change in many regions, may also stimulate forested stream primary production, by reducing forest cover and increasing sediments and nutrient transport. I sampled …
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Nitrogen spiraling in stream ecosystems spanning a gradient of chronic nitrogen loading
… gradient of N concentration. Across all streams, gross primary production (GPP) accounted for most NO3-N demand. Uptake of NO3-N was also related to GPP but was limited by N availability when N concentrations were low. A combination of GPP and NO3-N explained 80% of the variance in uptake. In …
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Modeling lake ecosystem change within coupled human-natural systems to improve water resources management
… lake to examine variability in site-specific gross primary production (GPP) and respiration (R), two fast-changing variables that serve as robust indicators of slowly-changing trophic state. I found that higher rates of near-shore GPP and R were partially due to stream-related variables, …
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The Flow Regime of Function: Influence of flow changes on biogeochemical processes in streams
… Stream metabolism is estimated from the production (gross primary production; GPP) and consumption (ecosystem respiration; ER) of dissolved oxygen. With these data, I evaluated how low and elevated flows differentially impact water quality (e.g., turbidity, conductivity) and metabolism …
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Land-atmosphere exchange of carbon in a high-Arctic wet tundra ecosystem
… was well correlated with soil temperature, gross primary production (GPP), active layer thickness and soil organic acids. The spatial variability in CH4 fluxes was closely correlated to water table depth (WtD), species compo-sition and soil organic acids. The CH4 fluxes remained low during …
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Water balance and productivity of a Mediterranean oak woodland : Quantifying understory vegetation impacts by development of a stable oxygen isotope partitioning approach
… world-wide and contribute about 40% to global gross primary production (GPP). The major driving factor of GPP in these ecosystems is water availability; since annual precipitation pattern show periodical summer droughts and evapotranspiration losses are high. Hence, understanding seasonal …
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The effects of terrestrial sediment inputs on ecosystem functions in seagrass meadows and unvegetated sediments
… elevated terrestrial sediment inputs on benthic primary production and nutrient cycling in intertidal seagrass meadows (Zostera muelleri) and microphytobenthos-dominated unvegetated habitats. To investigate the effects of reduced seafloor light availability and prolonged submergence periods …
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Carbon metabolism and dissolved organic carbon (DOC) fluxes on seagrass communities: insights from plant colonization states, eutrophication and global change related factors
… marine carbon cycle as an important driver of primary production for other compartments of the food web. While there has been extensive research on DOC dynamics in the open ocean, the role of coastal ecosystems in the global DOC cycle is still inadequately understood, even though these habitats …
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Environmental and developmental regulation of carbon cycling in a warm-temperate forest
… composition and an expected decline in Net Primary Production (NPP) with increasing age. To examine the effect of elevated atmospheric CO2 concentrations on ecosystem C loss via autotrophic respiration (Ra), I measured rates of fine root respiration at the Duke Free Air CO2 Enrichment (FACE) …
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