Topographic Effects on the Spatial Species Associations in Diverse Heterogeneous Tropical Evergreen Forests

Nguyen Hong Hai,Trinh Hien Mai,Van Bac Bui,Ion Catalin Petritan,Yousef Erfanifard,Yousef Erfanifard,Any Mary Petritan

doi:10.3390/su13052468

Abstract

Studying spatial patterns and habitat association of plant communities may provide understanding of the ecological mechanisms and processes that maintain species coexistence. To conduct assessments of correlation between community compositions and habitat association, we used data from two topographically different plots with 2 ha area in tropical evergreen forests with the variables recorded via grid systems of 10 × 10 m subplots in Northern-Central Vietnam. First, we tested the relationship between community composition and species diversity indices considering the topographical variables. We then assessed the interspecific interactions of 20 dominant plant species using the nearest-neighbor distribution function, Dij(r), and Ripley’s K-function, Kij(r). Based on the significant spatial association of species pairs, indices of interspecific interaction were calculated by the quantitative amounts of the summary statistics. The results showed that (i) community compositions were significantly influenced by the topographic variables and (ii) almost 50% significant pairs of species interactions were increased with increasing spatial scales up to 10–15 m, then declined and disappeared at scales of 30–40 m. Segregation and partial overlap were the dominant association types and disappeared at larger spatial scales. Spatial segregation, mixing, and partial overlap revealed the important species interactions in maintaining species coexistence under habitat heterogeneity in diverse forest communities.

Highlights

One of the main goals of community ecology is to explain the mechanisms of plant species associations which regulate their spatial distributions and the significant variations in complex communities of natural forests [1,2,3]
Interspecific associations such as spatial segregation, partial overlap, and mixing were dominant interaction types at small spatial scales up to 30 m, while the effects of habitat heterogeneity occurred at larger scales
We found that partial overlapping and segregation dominate the entire species association at small spatial scales

Summary

Introduction

One of the main goals of community ecology is to explain the mechanisms of plant species associations which regulate their spatial distributions and the significant variations in complex communities of natural forests [1,2,3]. Previous studies have shown that the main drivers regulating the spatial patterns of plant communities are biotic (e.g., plant–plant interactions) and abiotic factors, such as effect of environmental conditions [4,5,6,7]. Effects of biotic and abiotic factors can occur simultaneously; the relative importance of the drivers may often vary at different spatial scales [8,9]. The effects of abiotic factors seem to be more important at large spatial scales, while the effects of biotic factors may be more important at small scales [10,11]. Previous investigation on plant communities [7,12,13]

Methods

Discussion

Conclusion