The understorey palm Licuala (Arecaceae) suppresses tree regeneration in a lowland forest in Asia

The establishment and growth of a young tree requires a microsite that falls within a range of specific environmental conditions.Microsites will to some degree be modified by such neighbouring plants as are already established, a circumstance that will in turn lead to either a positive or negative spatial association among the individuals. Such patterns of spatial interactions are amenable to statistical inference. Positive associations may result when one species ameliorates overall hostile conditions, such as the shade and moisture provided the seedlings of long-leaf pine by the canopy of the saw palmetto (Allen 1956). Indeed, positive associations appear widespread in arid and cold habitats (reviewed in Tirado & Pugnaire 2003). However, on the forest floor of the humid tropics, negative associations are presumably more likely (Montgomery 2004). Harms et al. (2004) recently found a correlation between high density of small palms and a low density of tree saplings across four Neotropical sites, while Wang & gspurger (2004) demonstrated that dwarf palms and cyclanths reduce seedling recruitment on the forest floor in Costa Rica.