The relationship between environmental disturbances and structural diversity on aboveground biomass in tropical forests of Vietnam's Central Highlands and Southern regions

In Vietnam's tropical forests, while previous research has primarily focused on the influence of stand structure and species diversity on aboveground biomass (AGB), the effects of environmental factors remain underexplored. We used a field experiment to quantify the relationship between environmental disturbances and structural diversity on aboveground biomass in tropical forests of Vietnam's Central Highlands and Southern regions. AGB was estimated from 1555 field plots from evergreen broadleaved forests and deciduous forests. The results showed that adding variables associated with environmental disturbances improved the accuracy of the AGB model, which included only structural diversity. The precipitation of the driest quarter, human footprint, distance to the sea, and volumetric fraction of coarse fragments were the most important variables explaining the estimated variation in AGB. Stand structural diversity (ddiv and hdiv) had a significant positive association with AGB. In addition, our results highlight the coordinated effects of environmental disturbances on AGB, operating primarily via the mediation role of stand structural diversity. The potential applicability of these results can improve the accuracy of AGB modelling while supporting decision-making in nature conservation and forest management.