We investigated variation in carbon stock in soils and detritus (forest floor and woody debris) in chronosequences that represent the range of forest types in the US Pacific Northwest. Stands range in age from <13 to >600 years. Soil carbon, to a depth of 100 cm, was highest in coastal Sitka spruce/western hemlock forests …
Journal: Global Change Biology, Volume 10 (9): 1470-1481 (2004). DOI: 10.1111/j.1365-2486.2004.00829.x Sites: US-Me1, US-Me2, US-Me3, US-Me4, US-Me5
As forests age, their structure and productivity change, yet in some cases, annual rates of water loss remain unchanged. To identify mechanisms that might explain such observations, and to determine if widely different age classes of forests differ functionally, we examined young (Y, 25 years), mature (M, 90 years) …
Journal: Tree Physiology, Volume 24 (7): 753-763 (2004). DOI: 10.1093/treephys/24.7.753 Sites: US-Me2
We used a spatially nested hierarchy of field and remote-sensing observations and a process model, Biome-BGC, to produce a carbon budget for the forested region of Oregon, and to determine the relative influence of differences in climate and disturbance among the ecoregions on carbon stocks and fluxes. The simulations suggest that …
Journal: Global Change Biology, Volume 10 (9): 1429-1444 (2004). DOI: 10.1111/j.1365-2486.2004.00822.x Sites: US-Me2, US-Me4, US-Me5
Biometric techniques were used to measure net ecosystem production (NEP) across three climatically distinct forest chronosequences in Oregon. NEP was highly negative immediately following stand-replacing disturbance in all forests and recovered to positive values by 10, 20, and 30 years of age for the mild and mesic Coast Range, …
Journal: Global Biogeochemical Cycles, Volume 18 (4): n/a-n/a (2004). DOI: 10.1029/2004gb002236 Sites: US-Me2, US-Me4
We investigated the relative importance of climatic versus biotic controls on gross primary production (GPP) and water vapor fluxes in seasonally drought-affected ponderosa pine forests. The study was conducted in young (YS), mature (MS), and old stands (OS) over 4 years at the AmeriFlux Metolius sites. Model simulations showed that …
Journal: Global Biogeochemical Cycles, Volume 18 (GB4007): n/a-n/a (2004). DOI: 10.1029/2004GB002234 Sites: US-Me2, US-Me4, US-Me5
To test the hypothesis that variation in soil respiration is related to plant production across a diverse forested landscape, we compared annual soil respiration rates with net primary production and the subsequent allocation of carbon to various ecosystem pools, including leaves, fine roots, forests floor, and mineral soil for 36 …
Journal: Global Change Biology, Volume 10 (11): 1857-1869 (2004). DOI: 10.1111/j.1365-2486.2004.00850.x Sites: US-Me2, US-Me4, US-Me5
Understanding the controls over ecosystem-respired δ13C (δ13CR) is important for applications of isotope-based models of the global carbon budget as well as for understanding ecosystem-level variation in isotopic discrimination (Δ). Discrimination may be strongly dependent on synoptic-scale variation …
Journal: Global Biogeochemical Cycles, Volume 18 (1): n/a-n/a (2004). DOI: 10.1029/2003gb002049 Sites: US-Me2, US-Me4