Environmental and historical factors affecting red and white fir regeneration in ecotonal forests.

Abstract

Diameter-class distributions of 30 mixed Abies magnifica/A. concolor forests from Yosemite National Park, California, are used to examine patterns of canopy dominance and regeneration modes of these 2 zonal dominants. Successful regeneration of each species is associated with open canopies and nutrient rich substrates. Red fir regenerates in greater numbers on a wider range of sites, but suffers greater mortality than white fir. White fir tolerates canopy closure and dominates on nutrient-rich sites in montane forests, whereas red fir is less tolerant of shading and dominates on disturbed, nutrient-poor substrates in subalpine forests. These patterns are interpreted as adaptive responses to complex interactions of site factors, disturbance frequency, and biotic constraints along an elevational gradient. -from Author Yosemite National Park California Abies concolor Abies magnifica