Patterns of Understory Plant Diversity in Response to Transmitted Solar Radiation in a Subtropical Forest

Abstract

In order to reveal how transmitted solar radiation affects understory plant diversity patterns, we carried out plant census in a subtropical forest in south China. We determined canopy structure and understory gap light regimes using hemispherical photography. The results showed that a total of 206 species and 14489 individuals occur in the understory vegetation of the 2-ha sampling plots. Canopy openness was found to be a good predictor for transmitted direct radiation, diffuse radiation, and total radiation. Indicator species analysis detected a number of indicators to varying canopy openness. Six of these indicator species with significant indicator values are tree seedlings, shrubs, or vine, which are shade-intolerant, or frequently occur in habitats with the greatest canopy openness. Our results demonstrated that understory plant species composition and diversity are affected by transmitted gap light and different species may have varying response to the radiation gradient, which will have implications for using plants from the natural environment in landscaping.