Local environmental controls of Atlantic Forest tree community assembly on a coastal continental island in southeastern Brazil

Felipe Cito Nettesheim,Mário Luís Garbin,Dorothy Sue Dunn De Araujo,Marcos Gervasio Pereira

doi:10.1590/0102-33062018abb0025

Abstract

ABSTRACT Tropical forests with high species diversity are commonly found in rugged montane areas. We investigated causes of local tropical forest tree community assembly on a continental island with heterogeneous terrain. We recorded tree community (absolute species abundance), topography, soil, litter and location in 40 sampling units on two opposite sides of the island with similar heterogeneous terrain. We used transformation based Redundancy Analyses and variation partitioning to determine the contribution of environment (topography, soil and litter), spatial structure (geographic location and Moran Eigenvector Maps) and the shared effects of these to explain community assembly. The environment made a significant contribution to explain tree community patterns (species composition and abundance) across all models. Conversely, spatial structure showed minor impact. Contribution of strictly environmental effects and spatially structured environmental effects varied when evaluating each site independently as well as when evaluating the combined data. Evidence suggests that local tropical tree community assembly on heterogeneous terrain may be located much closer to the niche end of the hypothetic niche-neutral continuum. Findings indicate additionally that heterogeneity of environmental factors present in dissected mountainous terrain can affect the way tropical community assembly processes are perceived.

Highlights

Understanding the ecological processes that control species distributions and natural community assembly is a fundamental goal of community ecology deeply rooted in the theoretical foundations of this discipline (Tilman 2004)
* Corresponding author: felipe@citos.net disentangling the relative contribution of environmental filters and stochastic processes that originate spatially structured species distributions (Chave 2008; Clark 2012; Dray et al 2012; Rosindell et al 2012). This understanding is represented by hypotheses such as the niche-neutrality continuum, which suggests communities are located somewhere on a hypothetical axis according to the inputs that niche and neutral processes provide to their assembly (Tilman 2004; Gravel et al 2006; Leibold & Mcpeek 2006)
We address the causes of tree community assembly at the local-scale by evaluating a tropical continental island that displays the typically heterogeneous terrain of a mountain range covered by Atlantic Forest in southeastern Brazil

Summary

Introduction

Understanding the ecological processes that control species distributions and natural community assembly is a fundamental goal of community ecology deeply rooted in the theoretical foundations of this discipline (Tilman 2004). A long lasting debate over which perspective (niche or neutral) is more suitable to explain community assembly leads to a focus on disentangling the relative contribution of environmental filters ( environmental conditions) and stochastic processes (e.g. dispersal-limitation) that originate spatially structured species distributions (Chave 2008; Clark 2012; Dray et al 2012; Rosindell et al 2012) This understanding is represented by hypotheses such as the niche-neutrality continuum, which suggests communities are located somewhere on a hypothetical axis according to the inputs that niche and neutral processes provide to their assembly (Tilman 2004; Gravel et al 2006; Leibold & Mcpeek 2006). Determining where communities lie within this continuum is a key question in ecology to advance comprehension of the mechanisms behind species distribution and community assembly

Methods

Results

Conclusion