FOREST BIOME - ScholarsArchive at Oregon State University

TITLE: Estimation of the Biomass of Old-Growth Douglas-Fir Trees
8.34
Descriptions of forest structure are essential for understanding the processes
of photosynthesis, respiration, nutrient uptake and return, micrometeorological
energy fluxes, and water relations of intact forest stands. The quantity and
distribution of forest plant organs contributing to these processes is an integral
part of the research program of the Western Coniferous Forest Biome.
The literature germane to this investigation contains a number of papers from
many ecosystems which describe the methodology and resultant data of similar
studies. However, without exception, these experiments have been conducted in
relatively young, vigorously growing forest stands.
Therefore, we have little
reason to believe that the regressions relating weights of crown and bole
components to bole measurements in these stands are germane to the old-growth
%
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ouglas-fir trees found in the Pacific Northwest.
Not only do the old-growth
Douglas-fir stands represent a major part of the forest resources of the United
States, but they also afford a. unique opportunity to measure growth processes
in an ecological system developed over several hundred years. However, the
range of tree diameters on the study plots (see proposal for nutrient cycling),
106 to 183 cm,is too great to permit extrapolation of volumes from conventional,
published yield tables. It will be necessary, therefore, for us to develop all
the data required to characterize the biomass of old-growth Douglas-fir trees.
OBJECTIVE:
To employ both destructive sampling and optical measurement techniques to measure
the biomass of the bole, branches, and foliar components of 450-year-old Douglasfir
trees to permit generalization of the biomass of these components on a unit
area basis within desired limits of precision and accuracy.
APPROACH:
Old-growth Douglas-fir trees will be selected for harvest and destructive analysis
according to the following criteria:
1. Diameters of the trees selected will span the range of 106 to 183 cm at
as uniform an interval as possible.
2. Tree crowns will be free from major injury, such as spike top,and will
have a form generally typical of the study stands.
3. The tree location will permit harvest with a minimum of breakage.
Prior to harvest, sufficient measurements of the standing tree will be made
with the laser-beam theodolite system developed by the U. S. Army Corps of
Engineers to permit an accurate description of the bole and branches. The
tree will then be harvested, utilizing high-climbing techniques to permit
removal of the crown, whorl by whorl, prior to felling the bole. Since both
the quantity and distribution of foliage are of major importance for process
studies, harvest techniques will be employed to yield an accurate inventory
of foliage ages and quantities by whorls.