Spatial Distribution and Association Patterns of Two Dipterocarp Tree Species in a Tropical Moist Semi-Deciduous Forest, Southern Vietnam.

Studying the spatial pattern of plant species can improve understanding of ecological processes and mechanisms that maintain forest stand stability. To better understand the population dynamics of two dipterocarp species Dipterocarpus costatus and Dipterocarpus alatus, in the semi-deciduous forest in Southern Vietnam, we used the spatial point-pattern analysis methods to evaluate the spatial patterns and the interaction of these two species. The results showed that the population structure of D. costatus and D. alatus was similar; their diameter distributions were reverse J-shaped, and the numbers of trees were high at the juvenile and premature stages. The spatial patterns of two dipterocarp species tend to shift from aggregation to randomness and regularity as the tree diameter increases. We found negative interactions between mature and premature trees of two dipterocarp species at small scales. Mature and premature trees of two dipterocarp species showed no inhibition with their juveniles. Seed dispersal and natural self-thinning may be two main processes that control the spatial distribution and association patterns of two dipterocarp species. With the obtained results, our study contributes to simulate the population dynamics of tropical forest trees by using time-replacing space. [ABSTRACT FROM AUTHOR]