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Forest fragmentation is the main cause of biodiversity loss in the Anthropocene and it is triggering a top-down cascade effect that may influence leaf litter decomposition. However, the link between biodiversity loss and changes in ecosystem processes is not fully understood. We conducted an experiment to evaluate whether the exclusion of vertebrates affects the decomposition rates of different litter types (grass, a pioneer species and a mix of litters from a well preserved secondary forest). To answer this question, we placed litter bags inside artificial exclusion plots that were built in two types of vegetation coverage (abandoned pastureland and preserved forest) in the Atlantic forest of southeast Brazil. Our hypothesis is that vertebrate exclusion will change decomposition rates of different litter types due to the top-down cascade effect on soil invertebrates. We found out that vertebrate exclusion did not affect decomposition rates, possibly due to the overlap of ecological functions in the soil fauna responsible for the decomposition process. Furthermore, grass litter was decomposed faster (k value), possibly due to its initial nutrient content and hence litter quality which plays a significant role on decomposition rates. [ABSTRACT FROM AUTHOR]

Edge effects are ubiquitous landscape processes influencing over 70% of forest cover worldwide. However, little is known about how edge effects influence the vertical stratification of communities in forest fragments. We combined a spatially implicit and a spatially explicit approach to quantify the magnitude and extent of edge effects on canopy and understorey epiphytic plants in the Brazilian Atlantic Forest. Within the human-modified landscape, species richness, species abundance and community composition remained practically unchanged along the interior-edge gradient, pointing to severe biotic homogenisation at all strata. This is because the extent of edge effects reached at least 500 m, potentially leaving just 0.24% of the studied landscape unaffected by edges. We extrapolated our findings to the entire Atlantic Forest and found that just 19.4% of the total existing area is likely unaffected by edge effects and provide suitable habitat conditions for forest-dependent epiphytes. Our results suggest that the resources provided by the current forest cover might be insufficient to support the future of epiphyte communities. Preserving large continuous 'intact' forests is probably the only effective conservation strategy for vascular epiphytes. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article in previous issue regarding John Kirkland's review of "Toward a Global PhD?."