Twenty-five-year response of Larix occidentalis stem form to five stand density regimes in the Blue Mountains of eastern Oregon
occidentalis in the Blue Mountains of eastern Oregon were collected over a 25 year period
with an optical dendrometer. The following hypotheses were tested with these data: 1)
stand density regime has a significant effect on stem form; and 2) crown size controls the
response of stand density regime to stem form. The five stand density regimes
corresponded to five different growing-stock levels (GSLs) defined by bole surface area.
A variable exponent taper model was fit to the data from each individual tree and the
resulting parameters were treated as indices of stem form for comparisons among density
regimes. MANOVA performed on these parameters estimates confirmed statistically
significant differences in stem form both between the two lowest levels-of-growing stock
and between these two treatments and all three regimes with higher levels of growing
stock. The individual tree parameter estimates were also tested in the context of a
seemingly-unrelated regression (SUR) analysis. The two stem profile parameter estimates
were closely related to diameter! height ratio and crown ratio, respectively. Indicator
variables for the different density regimes did not contribute any explanatory power
beyond diameter/height ratio for the first parameter or crown ratio for the second
parameter. DBH, height and crown ratio are concluded to account for the variation in stem
form imposed by differences in stand density management.
Advisor:Maguire, Douglas A.
School:Oregon State University
School Location:USA - Oregon
Source Type:Master's Thesis
Keywords:western larch oregon growth blue mountains or and wash
Date of Publication:07/09/1999