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VARIABILITY IN NET PRIMARY PRODUCTION AND CARBON STORAGE IN BIOMASS ACROSS OREGON FORESTS - AN ASSESSMENT INTEGRATING DATA FROM FOREST INVENTORIES, INTENSIVE SITES, AND REMOTE SENSING. (R828309)
Citation:
Van, T. U., B. E. Law, D. Turner, AND A. Gitelman. VARIABILITY IN NET PRIMARY PRODUCTION AND CARBON STORAGE IN BIOMASS ACROSS OREGON FORESTS - AN ASSESSMENT INTEGRATING DATA FROM FOREST INVENTORIES, INTENSIVE SITES, AND REMOTE SENSING. (R828309). FOREST ECOLOGY AND MANAGEMENT 209(3):273-291, (2005).
Description:
We used a combination of data from USDA Forest Service inventories, intensive
chronosequences, extensive sites, and satellite remote sensing, to estimate biomass
and net primary production (NPP) for the forested region of western Oregon. The
study area was divided into four ecoregions differing widely in climatic conditions
and management regime. The forest age distributions (as derived from inventory
data) differed by ecozone with fewer old stands in the Coast Range and the East
Cascades, and a relatively uniform distribution of ages from 0 to 815 in the
Cascade Mountains. Age distributions also differed by land ownership, with fewer
old stands on non-federal lands than on national forest lands. Estimated biomass
increased rapidly in early stand development and tended to stabilize after about
200 years. Peak biomass in the semi-arid East Cascades was about one-third that
of the other ecoregions (median biomass at asymptote ~ 9 and ~ 25 kg C m-2,
respectively). The timing and magnitude of maximum net primary production also
varied by ecoregion,
with the high productivity Coast Range forests reaching a maximum NPP before
30 years of age (median ~ 1 kg C m-2 y-1), and the low
productivity East Cascades reaching a maximum NPP between 80 and 100 years (median
~ 0.3 kg C m-2 y-1). Productivity
was generally lower in older stands with the exception of the East Cascades ecoregion
where, contrary to the paradigm of age-related decline in forest growth, the
oldest stands had the highest NPP. The East Cascades also differed from the other
ecoregions in that the proportion of NPP allocated belowground decreased rather
than increased with stand age. This study demonstrates the value of combining
data from intensive and extensive measurement sites for improved estimates of
carbon stocks and fluxes as well as improved parameterization of process models
used in scaling carbon flux over broad regions.
Keywords: Biomass; Net primary production; Forest inventory; Carbon storage;
Carbon flux; Pacific Northwest