Ecology of curlleaf mahogany in western and central Nevada: community and population structure

Abstract

Curlleaf mahogany is an important browse species for mule deer in the mountain brush zone of the Intermountain West. Past research on increasing browse availability of curlleaf mahogany has been inconclusive. This appeared to be directly related to limited understanding of community and population structure and dynamics. To obtain information on the community and population structure of curlleaf mahogany we sampled 25, 30 × 30-m macroplots in western and central Nevada. Data on mahogany density, maturity class structure, size, ages, and population growth rates were obtained. Understory cover and composition and percent rock, bare ground, and litter were also recorded. Mahogany density in central Nevada was one-half that in western Nevada, but mahogany cover and total cover were significantly (P lesser than or equal to 0.05) greater. Maturity class distribution in central Nevada was heavily skewed towards large mature mahogany, suggesting an older population dominated by fewer large individuals. This dominance resulted in significantly (P lesser than or equal to 0.05) lower population and relative growth rates and the necessity of canopy gaps for the survival of young mahogany. Range improvement of mature mahogany stands dominated by large individuals will require the removal of the mature and over mature individuals so that young forage producing plants are released from intraspecific competition.