Search Results for: gross n
Assessing the relationship between microwave vegetation optical depth and gross primary production
At the global scale, the uptake of atmospheric carbon dioxide by terrestrial ecosystems through photosynthesis is commonly estimated through vegetation indices or biophysical properties derived from optical remote sensing data. Microwave observations of vegetated areas are sensitive to different components of the vegetation layer than observations in the optical domain […]
Contrasting changes in gross primary productivity of different regions of North America as affected by warming in recent decades
Ecosystem responses to the increasing warming in recent decades across North America (NA) are spatially heterogeneous and partly uncertain. Here we examined the spatial and temporal variability of warming across different eco-regions of NA using long-term (1979–2010) climate data (North America Regional Reanalysis (NARR)) with 3-hourly time-step and 0.25° × 0.25° spatial […]
Stimulation of grassland nitrogen cycling under carbon dioxide enrichment
Nitrogen (N) limits plant growth in many terrestrial ecosystems, potentially constraining terrestrial ecosystem response to elevated CO2. In this study, elevated CO2 stimulated gross N mineralization and plant N uptake in two annual grasslands. In contrast to other studies that have invoked increased C input to soil as the mechanism […]
Elevated CO2 and nutrient addition after soil N cycling and N trace gas fluxes with early season wet-up in a California annual grassland
We examined the effects of growth carbon dioxide (CO2)concentration and soil nutrient availability on nitrogen (N)transformations and N trace gas fluxes in California grasslandmicrocosms during early-season wet-up, a time when rates of Ntransformation and N trace gas flux are high. After plant senescenceand summer drought, we simulated the first fall […]
Elevated CO2 increases nitrogen fixation and decreases soil nitrogen mineralization in Florida scrub oak
We report changes in nitrogen cycling in Florida scrub oak in response to elevated atmospheric CO2 during the first 14 months of experimental treatment. Elevated CO2 stimulated above-ground growth, nitrogen mass, and root nodule production of the nitrogen-fixing vine, Galactia elliottii Nuttall. During this period, elevated CO2 reduced rates of gross […]
Global change, nitrification, and denitrification: a review
[1] We reviewed responses of nitrification, denitrification, and soil N2O efflux to elevated CO2, N availability, and temperature, based on published experimental results. We used meta-analysis to estimate the magnitude of response of soil N2O emissions, nitrifying enzyme activity (NEA), denitrifying enzyme activity (DEA), and net and gross nitrification across experiments. […]
Stable isotope discrimination during soil denitrification: Production and consumption of nitrous oxide
[1] Measuring the stable isotope composition of nitrous oxide (N2O) evolved from soil could improve our understanding of the relative contributions of the main microbial processes (nitrification and denitrification) responsible for N2O formation in soil. However, interpretation of the isotopic data in N2O is complicated by the lack of knowledge of […]
Interactions between plant growth and soil nutrient cycling under elevated CO2: A meta‐analysis
Free air carbon dioxide enrichment (FACE) and open top chamber (OTC) studies are valuable tools for evaluating the impact of elevated atmospheric CO2 on nutrient cycling in terrestrial ecosystems. Using meta-analytic techniques, we summarized the results of 117 studies on plant biomass production, soil organic matter dynamics and biological N2 […]
Does deep soil N availability sustain long‐term ecosystem responses to elevated CO2?
A scrub-oak woodland has maintained higher aboveground biomass accumulation after 11 years of atmospheric CO2 enrichment (ambient +350 μmol CO2 mol−1), despite the expectation of strong nitrogen (N) limitation at the site. We hypothesized that changes in plant available N and exploitation of deep sources of inorganic N in soils have sustained greater […]