Growing at the forest edges: how natural regeneration develops under fragmentation

Abstract

Environmental changes caused by edge effects and matrix land use can interfere with plant community resilience and, consequently, alter forest succession. Here, we aimed to (i) investigate whether species composition, density and richness in a forest’s regeneration layer vary in its edge-to-interior gradient and (ii) analyze the relationship between regeneration and local abiotic variables. We conducted the study in the lowland rainforest of the Atlantic Forest biodiversity hotspot at the Córrego Grande Biological Reserve, Espírito Santo state, Brazil. We sampled the regeneration layer in two edge environments with different matrices (forest and road) and the fragmented interior to link vegetation structure with environmental variables. In each environment, we set up 12 plots of 5 × 10 m size and recorded, in each plot, the height and stem base diameter of all living individuals above 50 cm of height and below 2.5 cm of diameter at breast height (1.30 m height). We applied different multivariate analyses to assess the influence of environmental data, such as canopy openness and physical-chemical soil variables. The three environments shared 22 out of the 174 morphospecies recorded, and the forest-side edge had the lowest species richness among all environments. The environmental variables that better explained the distribution of species across the three environments were: canopy openness, soil penetration resistance, zinc, and calcium content. Our results revealed significant environmental differences among the forest edges and the forest interior of the study site, highlighting the relevant role of the forest surrounding matrix for the maintenance of protected remnants.