Comparative Structural/Functional Features in Conifer Forests of Yosemite and Glacier National Parks, USA

Abstract

Structural/functional characteristics of the vegetative cover are used to provide common attributes for comparing vegetation patterns in Yosemite National Park, California, in the central Sierra Nevada, and Glacier National Park, Montana, in the northern Rocky Mountains. Ordinations based on composition allow identification of four forest types in Yosemite: ponderosa pine/incense-cedar forests on xeric, lower montane sites; white fir/incense-cedar forests on mesic, lower montane sites; red fir/white fir forests on mesic, upper montane sites, and lodgepole pine forests on subalpine sites. These types segregate along an elevational gradient. Compositional ordinations allow identification of three forest types in Glacier: red cedar/hemlock forests on moist sites; ponderosa pine/Douglas fir forests on dry sites; and lodgepole pine/larch forests on intermediate moisture sites. Within the limited elevation zone sampled, geographic moisture differences and associated disturbance phenomena overshadow the influence of elevation in controlling vegetation patterns in Glacier. Structural/functional ordinations produce stand arrangements similar to compositional ordinations for each region, and are interpreted according to variations in significant structural/functional factors along an elevational gradient in Yosemite and a successional gradient in Glacier. Differences in the control of forest structure between regions are attributed to climatic disparities and associated differences in disturbance regimes.