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Title
Comparing site quality indices and productivity in ponderosa pine stands of western Montana
Document Type
Article
Publication Title
Canadian Journal of Forest Research
Publication Date
1988
Volume
18
Issue
3
First Page
346
Last Page
352
Abstract
Four indices of site quality were compared with volume growth of pure, ideal ponderosa pine (Pinusponderosa Laws.) stands in western Montana. Indices based on quantifying the biophysical factors or physiological processes that control productivity (available water index and a relative index of seasonal photosynthesis from computer simulations) worked as well as those based on tree or stand measurements (site index and leaf area index). The following correlations of mean annual stem volume increment were found: with leaf area index, R2 = 0.93; with available water index, R2 = 0.95; with site index, R2 = 0.98; with gross photosynthesis R2 = 0.96. The available water and photosynthesis indices were also highly correlated to site index (R2 > 0.95). However, the tree-dependent site quality indices varied by stand density. Leaf area index and volume growth increased with stand density while site index decreased. Simulations indicated that depletion of soil water effectively halted transpiration and photosynthesis by midsummer and illustrated that even with adequate water, cold spring and fall temperatures ultimately defined the length of the growing season and hence site quality. We conclude that an ecosystem process model can provide an index to site quality independent of tree or stand measurements.
DOI
http://dx.doi.org/10.1139/x88-052
Rights
© 1988 NRC Research Press
Recommended Citation
McLeod, Scott D. and Running, Steven W. Comparing site quality indices and productivity in ponderosa pine stands of western Montana. Canadian Journal of Forest Research, 1988, 18:346-352, 10.1139/x88-052