The strength of coupling between canopy gas exchange and root respiration was examined in ~15-yr-old ponderosa pine (Pinus ponderosa Doug. Ex Laws.) growing under seasonally drought stressed conditions. By regularly watering …
Journal: Biogeochemistry, Volume 73 (1): 271-282 (2005), ISBN . DOI: 10.1007/s10533-004-2564-x Sites: US-Me2, US-Me5
From 1999 to 2002, the variations in carbon flux due to management practices (shrub removal, thinning) and climate variability were observed in a young ponderosa pine forest originated from clear-cutting and plantation in 1990. These measurements were done at the Blodgett Forest Ameriflux site located in the Sierra Nevada Mountains …
Journal: Agricultural And Forest Meteorology, Volume 130 (3-4): 207-222 (2005), ISBN . DOI: 10.1016/j.agrformet.2005.04.001 Sites: US-Blo
The spatial and temporal dynamics of soil temperature (TSOIL) strongly influence a wide range of biotic and abiotic processes in boreal forests. Relatively few spatial and temporal TSOIL measurements have been made in these systems; in addition, not all ecosystem models take into account the …
Journal: Agricultural And Forest Meteorology, Volume 131 (1-2): 27-40 (2005), ISBN . DOI: 10.1016/j.agrformet.2005.04.008 Sites: CA-NS2, CA-NS3, CA-NS5, CA-NS6, CA-NS7
We present a new soil respiration model, describe a formal model testing procedure, and compare our model with five alternative models using an extensive data set of observed soil respiration. Gas flux data from rangeland soils that included a large number of measurements at low temperatures were used to model soil CO2 …
Journal: Biogeochemistry, Volume 73 (1): 71-91 (2005), ISBN . DOI: 10.1007/s10533-004-0898-z Sites: US-GLE
The diurnal variation of net ecosystem exchange (NEE) showed an unusual pattern at the Blodgett Forest Ameriflux site, with late afternoon NEE lower than early morning (indicating more uptake), while air temperature and atmospheric vapor pressure deficit were much higher. …
Journal: Agricultural And Forest Meteorology, Volume 129 (1-2): 69-83 (2005), ISBN . DOI: 10.1016/j.agrformet.2004.11.008 Sites: US-Blo
The development of carbon (C) and nitrogen (N) simulations is one of the ongoing efforts in the land surface schemes of climate models. The C- and N-coupled Canadian Land Surface Scheme (C-CLASS) was recently modified to better represent grassland ecosystems. Improvements include revised plant growth and senescence calculations that …
Journal: Ecological Modelling, Volume 181 (4): 591-614 (2005), ISBN . DOI: 10.1016/j.ecolmodel.2004.07.007 Sites: CA-Let
We recommend an automated statistical method (Moving Point Test, or MPT) to determine the friction velocity (u*) thresholds in nighttime eddy flux filtering. Our intention is to make the determination of the u* thresholds objective and reproducible and to keep flux treatment consistent over …
Journal: Agricultural And Forest Meteorology, Volume 128 (3-4): 179-197 (2005), ISBN . DOI: 10.1016/j.agrformet.2004.11.006 Sites: BR-Sa1, CA-Oas, US-Shd, US-Ton, US-Var
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), ISBN . 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), ISBN . 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), ISBN . DOI: 10.1016/j.agrformet.2005.05.007 Sites: US-Ne1, US-Ne2, US-Ne3