Alpine Vegetation of Wheeler Peak, New Mexico, U.S.A.: Gradient Analysis, Classification, and Biogeography

Abstract

The alpine vegetation in the Sangre de Cristo Mountains of northern New Mexico was studied using gradient analysis and numerical classification techniques. Ordinations produced using detrended correspondence analysis (DECORANA) correlated with two environmental gradients, a complex wind-related snow and surface rock distribution gradient, and a simple gradient in effective incident radiation. Complete linkage hierarchical cluster analysis was used to define ten community types. Nine of these communities are similar in dominant species, species composition, and environmental location to communities in the northern Colorado Front Range. A Festuca thurberi meadow type is apparently restricted to the western slope of the Rockies from central Colorado southward. Analysis of biogeographic distributional groups suggests the alpine in New Mexico to be similar to other parts ofso the southern Rockies in the percentage of the flora that is also found in the Arctic (32%o), and that is widespread in the western mountains (28%). Widespread western mountain species have greatest coverage in protected, snowy alpine habitats, while species restricted to the Rocky Mountain axis are most important in open windy and low radiation alpine habitats. This pattern may be related to (1) the common occurrence of protected, late-lying snow habitats throughout the west, and (2) the rarity in the west, outside the Rocky Mountain axis, of dry, windy habitats that have moisture replenished by growing season thundershowers.