There is much interest in the role that agricultural practices might play in sequestering carbon to help offset rising atmospheric CO2 concentrations. A number of management methods that might increase soil C levels have been suggested, but there are scant available data to properly support recommendations or policy changes. …
Journal: Agricultural And Forest Meteorology, Volume 128 (3-4): 163-177 (2005). DOI: 10.1016/j.agrformet.2004.11.005 Sites: US-Ro1
Carbon dioxide exchange was quantified in maize–soybean agroecosystems employing year-round tower eddy covariance flux systems and measurements of soil C stocks, CO2fluxes from the soil surface, plant biomass, and litter decomposition. Measurements were made in three cropping systems: (a) irrigated continuous maize, …
Journal: Agricultural And Forest Meteorology, Volume 131 (1-2): 77-96 (2005). DOI: 10.1016/j.agrformet.2005.05.003 Sites: US-Ne1, US-Ne2, US-Ne3
Using eddy covariance flux measurements, gross primary production (GPP) and ecosystem respiration (Re) of irrigated maize and soybean fields were quantified and examined in terms of relevant controlling variables. Even though the peak green leaf area index (GLAI) of the maize and soybean canopies was comparable …
Journal: Agricultural And Forest Meteorology, Volume 131 (3-4): 180-190 (2005). DOI: 10.1016/j.agrformet.2005.05.007 Sites: US-Ne1, US-Ne2, US-Ne3
Whether the goal is to fill gaps in the flux record, or to extract physiological parameters from eddy covariance data, researchers are frequently interested in fitting simple models of ecosystem physiology to measured data. Presently, there is no consensus on the best models …
Journal: Agricultural And Forest Meteorology, Volume 131 (3-4): 191-208 (2005). DOI: 10.1016/j.agrformet.2005.05.008 Sites: US-Ho1, US-Ho2
Operational monitoring of global terrestrial gross primary production (GPP) and net primary production (NPP) is now underway using imagery from the satellite-borne Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. Evaluation of MODIS GPP and NPP products will require site-level studies across a range of biomes, with close …
Journal: Global Change Biology, Volume 11 (4): 666-684 (2005). DOI: 10.1111/j.1365-2486.2005.00936.x Sites: US-Me4, US-Me5
The dynamics of forest-atmosphere CO2 carbon isotope exchange were examined in a coniferous forest in Colorado, United States. Tunable diode laser absorption spectrometry provided extensive characterization of the carbon isotope content (δ13C) of CO2. Observed patterns in δ13C of forest …
Journal: Global Biogeochemical Cycles, Volume 19 (3): n/a-n/a (2005). DOI: 10.1029/2004gb002394 Sites: US-NR1
Old-growth forests are often assumed to exhibit no net carbon assimilation over time periods of several years. This generalization has not been typically supported by the few whole-ecosystem, stand-scale eddy-covariance measurements of carbon dioxide exchange in old-growth forests. An eddy-flux tower installed in a >300-year-old …
Journal: Agricultural And Forest Meteorology, Volume 128 (1-2): 33-55 (2005). DOI: 10.1016/j.agrformet.2004.09.005 Sites: US-Syv, US-WCr
This paper discusses the advantages and disadvantages of the different methods that separate net ecosystem exchange (NEE) into its major components, gross ecosystem carbon uptake (GEP) and ecosystem respiration (Reco). In particular, we analyse the effect of the extrapolation of night-time values of ecosystem …
Journal: Global Change Biology, Volume 11 (9): 1424-1439 (2005). DOI: 10.1111/j.1365-2486.2005.001002.x Sites: US-Bo1, US-Bo2
This paper summarizes the energy and water vapour fluxes for the first 14 months at a newly initiated flux tower site at a 65-year-old temperate conifer forest (Pinus strobus …
Journal: Hydrological Processes, Volume 19 (1): 27-49 (2005). DOI: 10.1002/hyp.5758 Sites: CA-TP1, CA-TP3, CA-TP4
The spatial upscaling of soil respiration from field measurements to ecosystem levels will be biased without studying its spatial variation. We took advantage of the unique spatial gradients of an oak–grass savanna ecosystem in California, with widely spaced oak trees overlying a grass layer, to study the spatial variation in soil …
Journal: Biogeochemistry, Volume 73 (1): 183-207 (2005). DOI: 10.1007/s10533-004-5889-6 Sites: US-Ton