David. T. Tingey and Peter A. Beedlow, U.S. Environmental Protection Agency
Western Ecology Division Corvallis, OR 97333
Dendrometers are used to periodically measure the changes in bole circumference in mature Douglas fir (Pseudotsuga menziesii) trees growing at ~ 600 meters in the Cascade Mountains of Oregon. Dendrometers are located at ~dbh, ~15m, low canopy (~38 m) and upper canopy (~48 m) above the ground. Concurrent climate and soil variables are measured. The data are being collected to determine the time and amount of growth at different locations below and within the canopy.
The annual basal area increment decreases with height in the tree; declining from ~ 80 cm2 at dbh to 20 cm2 near the top of the tree. Stem enlargement starts earlier and persists longer below the canopy than within the canopy. During late summer there is typically a shrinkage in the lower stem that is not seen in the canopy portion of the stem. Relative growth rate, was ~1%-year--1 on the stem below the canopy and increasing to ~ 9%-year-1 in the upper canopy.
Reading a dendrometer in a ~ 50 m tall Douglas fir tree in the Cascade mountains of Oregon. The graphs illustrate the increase in basal area at several heights in a Douglas fir tree.
David T. Tingey E-mail: email@example.com
Peter A. Beedlow E-mail: firstname.lastname@example.org
Agricultural Electronics Corporation - Dendrometer User Group