Vegetation Patterns in a Virgin Subalpine Forest at Crawford Notch, White Mountains, New Hampshire

Abstract

Woody vegetation in a 667 ha virgin subalpine forest in the White Mountains of New Hampshire was examined with direct gradient analysis, incorporating the natural distribution of disturbance-created vegetation patches, over the elevational range of 600-1100 m and sampling specifically in old-age vegetation patches. Disturbance patches exerted a major influence on vegetation patterning, occupying 39% of the total study area. They were formed primarily by windthrow: mass movements and fire were of minor importance. In the gradient analysis, density of live stems .gtoreq. 5.0 cm DBH [diameter breast height] generally increased with elevation. Basal area rose to a maximum at 890 m elevation, then decreased towards higher elevations. Species'' importance distributions changed independently with elevation. Old-age vegetation patches were dominated by red spruce and balsam fir and averaged 1189 stems ha (.gtoreq. 2.5 cm DBH), a value lower than those reported from other old-age spruce-fir stands in New England, and 44.0 m2 ha basal area. The recent spruce mortality reported by Siccama et al. (1982) is a widespread form of disturbance of Crawford Notch.