Microenvironmental conditions as predictors of tree diversity and structure patterns in a Mexican temperate forest

Local perturbations modify environmental conditions and species distribution at fine spatial scales. We studied the effects of microenvironmental variables on the structure and diversity patterns of tree species in a temperate forest from central Mexico. Previously published data on diversity and recruitment were included; additionally, tree structure was estimated. The explanatory variables were grouped into three categories: edaphic, climatic, and landscape. Relationships between tree structure and species abundances and a set of non-collinear variables were analyzed using Nonmetric Multidimensional Scaling. Subsequently, a constrained ordination of statistically significant variables was performed using a Redundancy Analysis with Hellinger-transformed data. To assess the effects of the variables of interest on tree species distribution we used Joint Species Distribution Models. Finally, Generalized Linear Models were constructed to determine the microenvironmental influence on tree structure, diversity, abundance, recruitment and mortality. Temperature, humidity, anthropogenic disturbance, potassium concentration, and pH were the most influential variables affecting tree structure and community composition. Recruitment of <i>Abies religiosa</i> showed a negative response to potassium levels. Anthropogenic disturbance was associated with adult tree richness and typical species diversity. Recruitment was determined by relative humidity and environmental heterogeneity, while mortality was associated with humidity. Minimum temperature, relative humidity, and elevation affected tree structure. To enhance conservation efforts in Mexico’s temperate forest remnants, we recommend regulating key microenvironmental variables in future management plans and monitoring vulnerable species. Halting land-use changes is crucial to preserve biodiversity and the ecosystem services that sustain the remaining forest.