Abstract
Spatial variations in demographics of tree communities are influenced by multiple factors,
among which topography and canopy openness are important elements. Topographic
factors can serve as proxies that represent variations in the micro-climatic and edaphic
factors in a forest. Canopy openness is closely associated with the light regime in the
understory. However, in forests frequently disturbed by typhoons, canopy openness and
understory light levels tend to be higher than in those without disturbances. It is not clear
whether the effect of canopy openness remains the same in typhoon-disturbed forests as
in other regions. In this study, we analyzed spatial variations in tree demographics of a
subtropical rain forest to investigate the effects of topographic factors and canopy openness
on forest dynamics. Our results showed that there were significant effects of topographic
factors on tree mortality, recruitment, and relative growth rates. In contrast, canopy openness
was only significantly correlated with tree recruitment, and its effect was weaker than the
effects of topographic factors. These results imply that in frequently typhoon-disturbed
forests, other factors such as topography may be more important in driving forest dynamics
than light variations caused by canopy openness.