Local topographic and biotic neighborhood factors influence tree survival in a tropical dry forest, western Thailand

Abstract Background Understanding variations in tree mortality and survival is essential to interpreting community dynamics and demographic processes. Tree size and both biotic and abiotic factors are among the local-scale drivers proposed to be essential to explain patterns of tree survival. However, detailed studies of their actual importance are lacking, particularly in tropical dry forests. Methods We investigated the influence of local topographic (i.e., abiotic) and biotic factors on tree survival at the community, guild, and species levels using data from a 4 ha (200 m × 200 m) permanent plot established in a mixed deciduous tropical dry forest at the Mae Klong Watershed Research Station, western Thailand. Censuses were conducted within the plot in December every 2 years from 1994 to 2022, in which tree mortality was assessed and measurements were performed on all trees with diameter at breast height ≥ 2 cm. Factors influencing tree survival were analyzed using a generalized linear mixed model. Results We found that tree size was the most important factor influencing tree survival, with a significant positive relationship for all but the largest trees. Among abiotic factors, only elevation had a significant positive effect on the longevity of shade-tolerant species. Of the biotic factors examined, tree density and total basal area significantly impacted tree survival in certain guilds and/or species. Conclusions Overall, the relative significance of factors influencing tree survival patterns in these tropical dry forests differed significantly across species guilds, tree size classes, and shade tolerance groups. These findings inform forest management in the study region and offer essential data for further research on forest dynamics.