Research in biosphere - atmosphere interactions
We currently have several projects underway that examine the influence of the biosphere on the isotopic composition of CO2 and H2O in the atmosphere. These projects are directed at understanding how biological processes affect the stable isotopic composition of organic matter produced by photosynthesis in different ecosystems and in turn how respiratory processes influence the isotopic composition of CO2 that is then released back to the atmosphere.
LBA (NASA) Tutorial of 13C in organics
TCP (DOE) Tutorial on 13C in CO2
WLEF (NOAA)
BASIN (NSF) Tutorial on 18O in organics
Tutorial on 18O in CO2
Previous studies
BOREAS (NASA)
OTTER (USDA)
Utah forests (USDA)
WRCC (DOE)
LBA
The LBA project focuses on carbon stocks and on CO2 fluxes in forest and pasture sites across Amazonia. It is part of a larger Brazil-US project investigating the carbon dynamics within the Amazon Basin and how land-use changes influence carbon, water, and biogeochemical cycles.
TCP
At several AmeriFlux sites across the United States, we have established automated samplers to measure the isotopic composition of CO2 released by the atmosphere and the isotopic discrimination during photosynthesis. These parameters are linked with the net ecosystem exchange observations to better interpret the mechanistic bases for changes in the magnitudes of carbon fluxes during the year.
WLEF
In association with other investigators, we are examining the isotopic composition of CO2 in biosphere-atmosphere exchange and the biosphere-atmosphere relationships of CO2 and H2O concentrations and isotopic composition in the convective boundary and the vegetative layers.
BASIN
A network of studies focusing on isotopic aspects of biosphere - atmosphere interactions. The focus of the Biosphere Atmosphere Stable Isotope network (BASIN) is to develop a world-wide database of stable isotope data to be used in flux studies and to promote interactions among scientists interested in linking stables isotopes and the carbon cycle.
BOREAS
Our BOREAS project focused on characterizing the isotopic composition of both carbon stocks and fluxes in the dominant vegetation types in the northern and southern regions of the boreal forest in central Canada. These are the aspen, jack pine, and black spruce forests.
OTTER
The OTTER project examined the isotopic composition of carbon stocks and of CO2 fluxes in different coniferous forests in the Pacific Northwest along a precipitation gradient in Oregon (OTTER). Along this 200 mm to 2000 mm precipitation gradient, there are changes in conifer species composition, but all sites are dominated by coniferous tree species.
Utah
In the north, Utah forests are dominated by both deciduous (aspen, boxelder-maple) and evergreen (Douglas fir, lodgepole pine, and spruce) trees. The isotopic composition of phososynthesis and respiration of deciduous and evergreen components respond to changes in moisture availability.
WRCC
The Wind River Canopy Crane (WRCC) Project examined the isotopic composition of carbon stocks and of CO2 fluxes in an old growth coniferous forest in the Pacific Northwest and in adjacent forests that have been harvested at selected intervals in the past.