Coexistence Mechanisms of Tree Species in an Evergreen Forest on Con Dao Islands, Vietnam

The configuration of trees and their interplay offer vital perspectives into a forest community's spatial structure and plant species' coexistence mechanisms. This study aimed to investigate the spatial patterns and interactions of woody plant species in an evergreen broadleaved forest on the Con Dao Islands, Vietnam. A 4-ha study plot was established in 2022, and all trees with a diameter breast height (DBH) >= 5 cm were measured, identified species, and mapped. The spatial point pattern analysis method was employed to explore the spatial distribution and interactions of woody plant species in the study plot. The findings indicated that saplings (DBH < 10 cm) were mainly aggregated at a small scale of 0-10 m, whereas intermediate (10 cm <= DBH <= 20 cm) and adult (DBH > 20 cm) trees were randomly distributed. Species-area relationships and spatial patterns varied according to the life-history stages of each species and spatial scales. The results also suggested that species coexistence within the plant community was achieved through the overall effects of the diversity accumulator species, diversity repeller species, and neutral species. The ecological niche theory, unified neutral theory, and asymmetric competition principle were deemed appropriate for explaining the coexistence of woody plant species in the evergreen broadleaved forest on Con Dao Islands, Vietnam.