Functional attributes change but functional richness is unchanged after fragmentation of Brazilian Atlantic forests

Abstract

Federal de Vic ßosa, Vic ßosa, Minas Gerais, Brasil Summary 1. Fragmentation of tropical forests is one of the greatest threats to global biodiversity. Understanding how biological and functional attributes of communities respond to fragmentation and, in turn, whether ecosystem functioning is impacted upon are critical steps for assessing the long-term effects and conservation values of forest fragments. Ecosystem functioning can be inferred through functional diversity metrics, including functional richness, evenness and divergence, which collectively quantify the range, distribution and uniqueness of functional traits within a community. 2. Our study was carried out in forest remnants of the Brazilian Atlantic rain forest, which is a global hotspot of threatened biodiversity that has undergone massive deforestation and fragmentation. We focus on trees, which play critical functional roles in forest structure, food provisioning and carbon storage, to examine community organization and functional diversity across a gradient of fragmentation, from small to large fragments and at edge versus interior habitats. 3. The interiors of small fragments have marginally higher species richness, but similar community structures, to the interiors of bigger fragments. In contrast, fragment edges suffered significant losses of species and changes in community structure, relative to fragment interiors. 4. Despite shifts in community organization, functional richness was not impacted by fragmentation, with the same number of functions provided independent of fragment size or proximity to edge. However, functional evenness and functional divergence both increased with decreasing fragment size, while fragment edges had lower functional evenness than interiors did, indicating that the abundance and dominance of functional traits has changed, with negative implications for functional redundancy and ecosystem resilience. At fragment edges, large-fruited trees, critical as resources for fauna, were replaced by early successional, small-seeded species. The influence of fragment size was smaller, with a reduction in very large-fruited trees in small fragments counterbalanced by increased numbers of fleshy-and medium-fruited trees. Wood density was not impacted by fragmentation. 5. Synthesis. These results suggest that the interiors of even small fragments can contain important biodiversity, ecosystem functions and carbon stores, offering potential opportunities for cobenefits under existing carbon markets. Retaining forest fragments is an important conservation strategy within the highly threatened Brazilian Atlantic forest biome.

Atlantic forest bird communities provide different but not fewer functions after habitat loss

“…We used the metrics proposed by Villéger et al [27], because they are independent from each other (Pearson r ¼ 20.02, p ¼ 0.89), are easy to calculate [42] and are often used in the literature (e.g. [7,8,11]), which makes our results more comparable to other studies. Higher values for these metrics correspond to higher functional trait diversity.…”

“…Current knowledge, however, does not point to a simple pattern, as some studies have found that functional diversity remained unchanged or was even positively affected (e.g. [5,[8][9][10][11]). Existing evidence thus suggests that the consequences of environmental changes for ecological functions are complex and far from being well understood.…”

Structure and composition of altered riparian forests in an agricultural Amazonian landscape

“…Inhibited regeneration may have consequences for the future of altered riparian zones, but it remains to be seen if reductions in seedling and sapling abundance will propagate to larger size classes of trees. Because tree longevity in tropical forests is high, reduced seedling and sapling abundance suggests the possibility of an extinction debt, or inevitable future extinctions caused by past events (Magnago et al 2013).…”

Uma revisão sobre a controversa classificação fisionômica da Floresta de Linhares, norte do Espírito Santo

“…Devido à influência desses mapas sobre a organização de iniciativas oficiais de conservação e pesquisa da biodiversidade, desde então muitos estudos ecológicos têm optado por retratar a Floresta de Linhares como uma "floresta ombrófila densa" ou dense rain forest (por exemplo, Oliveira- Magnago et al 2014). Todavia, na contramão dessa tendência, alguns estudos têm considerado observações de campo ou análises do clima local para adotar o termo "floresta estacional semidecidual" (por exemplo, Rolim & Nascimento 1997;Rolim et al 1999;Kindel & Garay 2002;Saiter et al 2015), uma denominação disponível no sistema de Veloso et al (1991).…”