Morphological Divergence between Conifer Forests of Yosemite and Glacier National Parks, U.S.A.

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Abstract
Discriminant analysis (DFA) was used to test for divergence in structural/functional characteristics between conifer forests of Yosemite National Park, California, and Glacier National Park, Montana. A pair of two-variable DFA models, one based on species composition and one on structural/functional characteristics, achieves comparably high classificatory success (96%), providing evidence for structural divergence of forests between regions. To attribute this structural divergence to interregional differences in environment and disturbance regime, a second pair of DFA models, one using environmentally sensitive characters and one using disturbance-adapted traits, is presented. The environmental model, linking specific structural/functional traits to heat, moisture, and nutrient regimes, suggests that, relative to Glacier forests, Yosemite forests display morphological and physiological traits suited to warmer more nutrient-poor sites. The disturbance model, which incorporates germination requirements for surface light, mineral seedbed, and dispersal efficiency, suggests that forested sites sampled in Glacier exhibit greater evidence of catastrophic disturbance, and support a more prominent suite of early successional structural/functional characters than sites sampled in Yosemite. This difference presumably emanates from the combined influence of interregional disparities in presettlement disturbance regimes and associated differences in the efficacy of subsequent fire suppression policies.