Determining light requirements of groundcover plants from subtropical natural forest using hemispherical photography

In order to determine light requirements of indigenous groundcover plants for potential use in urban landscaping, we conducted a plant census in Yinpingshan Nature Reserve, Dongguan, China, and measured canopy structure and understory light regimes using hemispherical photography. We found that canopy openness, transmitted direct solar radiation, and transmitted diffuse solar radiation exhibited highly significant spatial heterogeneity. Species composition and diversity of groundcover plants were highly dependent on canopy structure and understory light condition. Greater diversity and more stems of groundcover plants were associated with greater canopy openness and understory radiation in most cases. Highly significant differences in species composition were detected along canopy openness, transmitted direct solar radiation, and transmitted diffuse solar radiation gradients, respectively. We also detected indicator species for specific understory light regimes, which will provide useful information when applying such species in urban greening under various light environments.