We
measured components of ecosystem respiration and biomass from wood, foliage and
roots in two stands in an old-growth hemlock-northern hardwood forest.
Respiration was measured by the chamber method and upscaled to the stand level.
Wood production was calculated from the increase in tree size. Foliage biomass
was measured from litterfall. Root production was measured from in-growth root
cores. Based on the measurements of respiration and biomass we calculated gross
primary production (GPP) and net ecosystem production (NEP).
The annual GPP was estimated as 1144 and 1089 g C m2 y-1
in the hardwood and hemlock stands, respectively. GPP was partitioned into 131,
115, 270, 168, 257, 203 g C m2 y-1 of wood, foliage, and
root respiration, and wood, foliage, and root production, respectively, in the
hardwood stand, and 206, 72, 155, 190, 139, 327 g C m2 y-1 of
wood, foliage, and root respiration, and wood, foliage, and root production,
respectively, in the hemlock stand. The percentage of GPP allocated to wood,
foliage and roots for growth and respiration was 20%, 23%, and 57%,
respectively, for the hardwood stand, and 31%, 14%, and 55%, respectively, for
the hemlock stand. The ratio of net primary production (NPP)/GPP was 30% in the
hardwood stand and 33% in the hemlock stand.
Author: J. Tang, and P.V. Bolstad (jtang at umn dot edu)
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