Ferns, frogs, lizards, birds and bats in forest fragments and shade cacao plantations in two contrasting landscapes in the Atlantic forest, Brazil

Abstract

The traditional shade cacao plantations (cabrucas) of southern Bahia, Brazil, are biologically rich habitats, encompassing many forest-dwelling species. However, a critical question for the conservation management of this specific region, and the highly fragmented Atlantic forest in general, is to what extent the conservation value of cabrucas relies on the presence of primary forest habitat in the landscape. We investigated the relative importance of cabrucas and forests for the conservation of five diverse biological groups (ferns, frogs, lizards, birds and bats) in two contrasting landscapes in southern Bahia, one dominated by forest with some interspersed cabrucas, and one dominated by cabrucas with interspersed forest fragments. The community structure (richness, abundance and diversity) of all biological groups differed between cabrucas and forests, although these differences varied among groups. A high number of forest species was found in the cabrucas. However, there were pronounced differences between the two landscapes with regard to the ability of cabrucas to maintain species richness. Irrespective of the biological group considered, cabrucas located in the landscape with few and small forest fragments supported impoverished assemblages compared to cabrucas located in the landscape with high forest cover. This suggests that a greater extent of native forest in the landscape positively influences the species richness of cabrucas. In the landscape with few small forest fragments interspersed into extensive areas of shade cacao plantations, the beta diversity of birds was higher than in the more forested landscape, suggesting that forest specialist species that rarely ventured into cabrucas were randomly lost from the fragments. These results stress both the importance and the vulnerability of the small forest patches remaining in landscapes dominated by shade plantations. They also point to the need to preserve sufficient areas of primary habitat even in landscapes where land use practices are generally favorable to the conservation of biodiversity.

Land-use effects on local biodiversity in tropical forests vary between continents

“…The magnitude of the effects varied among continents and with land-use intensity: intensively used plantations in Asia and Africa had particularly low species richness. These results agree with previous studies that found plantations to be highly detrimental to biodiversity (Barlow et al 2007b;Brühl and Eltz 2010;Edwards et al 2010;Freudmann et al 2015;Gilroy et al 2015), especially if they are managed intensively (Faria et al 2007;Clough et al 2009;Tadesse et al 2014;Newbold et al 2015). The low biodiversity in intensive plantations is likely to reflect the lack of structural complexity and the homogeneity in the age of the stands (Fitzherbert et al 2008;Clough et al 2009;Foster et al 2011;Freudmann et al 2015).…”

“…Differences in site-level diversity might be attributable to stand age (Bremer and Farley 2010;Taki et al 2010;Wang and Foster 2015), or might reflect differences in at least two other factors. First, plantations that are managed less intensively, such as those including shade trees, could retain more of the original biodiversity than more intensive plantations (Faria et al 2007;Clough et al 2009; but see la Mora et al 2013). Such an effect may occur either within a crop type (e.g., cacao plantations with more shade trees often support higher species richness: Clough et al 2009) or between crop types (e.g.…”

Biodiversity, Species Interactions and Ecological Networks in a Fragmented World

“…The abundance and diversity of many taxa (including frogs, lizards, small mammals and birds) are generally positively affected by the surrounding matrix , and see also Faria et al, 2006Faria et al, , 2007, whereas the richness and abundance of shade-tolerant trees are negatively affected and decline from large to small fragments ). This indicates that increasing landscape heterogeneity might allow the maintenance of higher diversity of animals, but that specialist tree species depend on the maintenance of native forest patches Ribeiro et al, 2009).…”

Genetic assessment of the Atlantic Forest bristle porcupine, Chaetomys subspinosus (Rodentia: Erethizontidae), an endemic species threatened with extinction

“…This apparently paradoxical situation may be partially explained by the fact that most of the forest cover in southern Bahia comprises extensive areas of shaded cacao plantations. In these so-called "cabrucas", the native canopy forest is thinned whereas the cacao shrubs largely replace the original understory, not allowing enough connectivity among the patches (Faria et al, 2007).…”