The Effect of the Light Environment on Population Size of the Epiphytic Herb, Lepanthes Rupestris (Orchidaceae)

Abstract

The demographic dynamics of plant populations will depend on the relative role of density-dependent versus density-independent factors on population regulation. Density-independent factors (i.e. changes in climate, fire, hurricanes) will affect plant survival and reproduction within a population in a manner that is independent of the density of individuals. The amount of light that a plant receives is one such factor that will affect its mode of development, growth and reproduction independent of plant density. Life history traits may evolve when light requirements are a limiting factor in the survival of plant populations. Our research group has used the orchid Lepanthes rupestris, a common miniature orchid that inhabits riparian habitats mountain forests of Puerto Rico (Ackerman 1995, Tremblay 1997) as a model to understand the factors that affect the persistence of epiphytic orchids. In this study we were interested in determining if population size is affected by the amount of light perceived by the population.