Evaluation of multi-causal dynamics of edge effects in a highly fragmented temperate forest

The available literature on landscape ecology documents the relationship between ecological conditions in patch edges (species richness, diversity and biological composition) and microenvironmental conditions that, in turn, are modified by spatial attributes and anthropogenic disturbances at the landscape level. The understanding of the interactions between these factors has been complex, because the issue becomes more complex and dynamic as more variables are considered, leading to a sensible variability in composition between patch edges. Determining the multi-causal dynamics that result in the formation of multiple edge composition types is key to extrapolate or predict edge effects in different patches and landscapes. In this study, we examine the effect of 13 microenvironmental variables, 3 landscape variables and 8 anthropogenic pressure variables on species richness, abundance and diversity in three distinct edge composition types using multivariate methods (DCA, CCA and SEM). The results of a comprehensive analysis of multi-causal dynamics differed from those derived from the analyses of the separate effect of each variable on edge composition types. The results obtained from the structural equation model showed that microenvironmental variations determine, to a large extent, the species composition of edges, and that landscape properties are correlated with these environmental variations but anthropogenic pressures had no significant effect on them. This final model can be used as a tool for the application of management and conservation strategies in fragmented forests, as it contributes to identify the direct and indirect effects with the largest impacts on floristic variation.