Neighborhood competition and spatial patterns of tree species in an evergreen broadleaved forest of Bidoup-Nui Ba National Park, southern Vietnam

Abstract Competitive interactions significantly impact plant diversity, playing a crucial role in community assembly. This study, conducted in the evergreen broadleaved forest of Bidoup-Nui Ba National Park in southern Vietnam, aimed to investigate neighborhood competition and spatial patterns of tree species. In 2024, a 4-ha study plot was established within the strictly protected zone of the national park for data collection purposes. A total of 7,666 trees with a diameter at breast height (DBH) ≥2.5 cm, representing sixty-six species from thirty-one families, were identified, measured for DBH, and mapped for stem location. Unmarked and marked point-pattern analyses were employed to examine the spatial patterns of the most abundant species. The results revealed that the fifteen most abundant species exhibited an aggregated distribution at small scales (0–30 m), with their spatial patterns correlating with their life-history stages. Specifically, the spatial arrangements shifted from aggregation during the juvenile stage to randomness or regularity at the subadult and adult stages. Intra- and interspecific competition were found to be closely tied to spatial scale, showcasing instances of both symmetric and asymmetric competition. Notably, interspecific associations mainly exhibited spatial independence, especially at 0–50 m scales. This study identified several vital ecological processes governing the spatial distribution and neighborhood competition among broadleaved tree species in the study area, including dispersal limitations, symmetric and asymmetric competition, and self-thinning of tree species.