نتایج جستجو برای: gpp
تعداد نتایج: 1505 فیلتر نتایج به سال:
Responses of autotrophic and heterotrophic processes to nutrients and trace elements were examined in a series of experimental estuarine food webs of increasing trophic complexity using twenty 1-m3 mesocosms. Nutrients (nitrogen and phosphorus) and trace elements (a mix of arsenic, copper, cadmium) were added alone and in combination during four experimental runs spanning from spring 1997 to sp...
weak response after 10 days of ciclosporin and the immediate need to control the systemic disease. After 4 weeks, the patient was free of pustules but a slight erythema was still present. At week 14, the patient was free of lesions, and, after the 5th infusion, she requested the suspension of infliximab. Efa lizumab was reintroduced with the maintenance of the excellent results (PASI-100) until...
Gross primary production (GPP) can be separated from flux tower measurements of net ecosystem exchange (NEE) of CO2. This is used increasingly to validate processbased simulators and remote-sensing-derived estimates of simulated GPP at various time steps. Proper validation includes the uncertainty associated with this separation. In this study, uncertainty assessment was done in a Bayesian fram...
The effect of elevated CO2 on photosynthesis, respiration, and growth ef®ciency of sun ̄ower plants at the whole-stand level was investigated using a whole-system gas exchange facility (the EcoCELLs at the Desert Research Institute) and a C natural tracer method. Total daily photosynthesis (GPP), net primary production (NPP), and respiration under the elevated CO2 treatment were consistently hig...
H. T. Odum’s influential Limnology and Oceanography 1956 publication compared gross primary production (GPP) and ecosystem respiration (ER) among aquatic ecosystems. Few syntheses of aquatic ecosystem metabolism have been completed since. We used Odum’s conceptual framework to compare GPP and ER from open-water diel oxygen curves in lakes, wetlands, estuaries, and streams (n 5 350). We also doc...
Uncertainty about responses of vegetation index, aboveground biomass (AGB) and gross primary production (GPP) limits our ability to predict how climatic warming will influence plant growth in alpine regions. A field warming experiment was conducted in an alpine meadow at a low (4313 m), mid- (4513 m) and high elevation (4693 m) in the Northern Tibet since May 2010. Growing season vapor pressure...
To predict forest response to long-term climate change with high confidence requires that dynamic global vegetation models (DGVMs) be successfully tested against ecosystem response to short-term variations in environmental drivers, including regular seasonal patterns. Here, we used an integrated dataset from four forests in the Brasil flux network, spanning a range of dry-season intensities and...
Uncertainty in simulating gross primary production of cropland ecosystem from satellite-based models
Accurate estimates of gross primary production (GPP) for croplands are needed to assess carbon cycle and crop yield. Satellite-based models have been developed to monitor spatial and temporal GPP patterns. However, there are still large uncertainties in estimating cropland GPP. This study compares three light use efficiency (LUE) models (MODISGPP, EC-LUE, and VPM) with eddy-covariance measureme...
The notion that less productive marine planktonic communities tend to be heterotrophic was tested by synthesizing reported estimates of the relationships between the net community production or community respiration and gross primary production (GPP), allowing calculation of the threshold GPP separating less productive, heterotrophic communities from more productive, autotrophic ones. A total o...
The quantitative simulation of gross primary production (GPP) at various spatial and temporal scales has been a major challenge in quantifying the global carbon cycle. We developed a light use efficiency (LUE) daily GPP model from eddy covariance (EC) measurements. The model, called EC-LUE, is driven by only four variables: normalized difference vegetation index (NDVI), photosynthetically activ...
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