Seasonality in metacommunity structure: an empirical test in the Atlantic Forest

Abstract

The metacommunity concept helps to understand how local and regional processes regulate species distributions in landscapes. Metacommunity structure is often assumed as static, but may be rather dynamic, following temporal changes along environmental gradients. We present an empirical test of the temporal dynamics of metacommunity structure, using small mammals in an Atlantic Forest landscape as a model system. We analyzed incidence matrices using the Elements of Metacommunity Structure framework and evaluated whether local, landscape, and spatial factors structured the metacommunity during different climatic seasons (HS = humid; SHS = super-humid) and time periods (1 = 1999–2001; 2 = 2005–2009). We compared HS-1 and SHS-1 to evaluate if metacommunity structure varies between seasons, and HS-1 and HS-2 to evaluate if it varies between time periods. Metacommunity structure changed from Clementsian (HS-1) to random (SHS-1), but during HS-2 it was Clementsian again. This suggests that groups of species are responding similarly to the major gradient of variation during the HS only. Patch size structured the metacommunity during both humid periods, and local habitat structure only during HS-1. We suggest that during the SHS these gradients are lost due to increased matrix permeability to movement, which homogenizes local communities resulting in a random structure. Species habitat requirements and specializations determined metacommunity structure, but only during the HS. The Clementsian structure indicates that forest disturbances may result in the loss of whole groups of species during the HS. Alternating patterns of metacommunity structure may be associated to changes on matrix suitability between seasons.