Patterns and metacommunity processes of epiphytic bromeliad assemblages along a coastal‐inland gradient in a subtropical Brazilian geographic corridor

Abstract

AbstractMetacommunity ecology investigates how drivers of regional and local scales cause compositional variation in a network of communities potentially linked by dispersal. We examined the metacommunity structure of epiphytic bromeliad assemblages along a coastal‐inland gradient in a subtropical geographic corridor extending from the Atlantic coast to near the Uruguay River, in the central depression of Rio Grande do Sul State, in southernmost Brazil. We surveyed floristic and environmental data on a sequence of 71 testimonial hills. We used elements of metacommunity structure to identify metacommunity patterns (i.e. random, checkerboard, nested, Clementsian, Gleasonian, evenly spaced and quasi‐structured). We ran a canonical correspondence analysis to evaluate how coastal‐inland gradient influenced species distribution. Finally, we employed variation partitioning to determine archetype‐based metacommunity structuring processes (i.e. species sorting, neutral dynamics, patch dynamics and mass effects). We found that temperature‐ and moisture‐based gradients generated environmental heterogeneity that established species filtering, determining the formation of cohesive groups of epiphytic bromeliads with coincidentally occurring boundaries (i.e. quasi‐Clementsian structure). As a result, we identified four metacommunity structures embedded along the coastal‐inland gradient: In the eastern and east‐central metacommunities, species distributions were idiosyncratic due to individual species' responses to environmental gradients (i.e. quasi‐Gleasonian structure), and in the western and west‐central metacommunities, we observed Clementsian and Gleasonian structures, respectively. Habitat heterogeneity and dispersal sufficiency (i.e. species sorting archetype) were the foremost drivers establishing metacommunity structures. Ultimately, and surprisingly, in the east‐central metacommunity, we detected source‐sink dynamics among the testimonial hills (i.e. mass effects archetype). Our findings suggest that epiphytic bromeliad assemblages are linked to a gradient‐driven pattern with moderate heterogeneity (i.e. low turnover) and identify four embedded metacommunity structures. Moreover, they indicate that the species sorting archetype best represents the processes of establishing metacommunity structures.