CARNIVOROUS MAMMALS IN A MOSAIC LANDSCAPE IN SOUTHEASTERN BRAZIL: IS IT POSSIBLE TO KEEP THEM IN AN AGRO-SILVICULTURAL LANDSCAPE?, pp. 317-332
Authors: (Maria Carolina Lyra-Jorge, Giordano Ciocheti, Leandro Tambosi, Milton César Ribeiro, Vânia Regina Pivello, Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, Brazil)
Abstract: Habitat fragmentation can be defined as a process where continuous areas of natural habitats are broken into small patches separated by other habitats different from the original ones (Wilcove et al. 1986; Andrén 1994). Today, habitat fragmentation is a common issue to almost every ecosystem in the world, since anthropogenic land uses transformed initially continuous habitats into mosaic landscapes represented by isolated native patches surrounded by man-altered environments (Nagendra et al. 2003). Anthropogenic matrices usually act as selective filters to species movements among native patches in the landscape (Gascón et al. 1999), and therefore, the persistence of animal and plant populations in fragmented habitats will depend to a great extent on the matrix permeability (Ricketts 2001). Landscapes are commonly classified into continuous or fragmented (Fahrig 2003) however, the landscape is not a binary mosaic formed by natural habitat and matrix – or habitat and non-habitat – and the species certainly do not perceive it that way (presence/ absence of resources), as we will discuss later on in this chapter (Fahrig, 2003) Despite being a rather controversial issue, several authors have shown the importance of protecting small native patches resulted from habitat fragmentation, as in the landscape context they are able to keep a significant portion of local biodiversity (Saunders et al. 1991; Lindenmayer & Nix 1993; Bodin et al. 2006). Andrèn (1994) states that landscape biodiversity may increase considerably when several small fragments are close to each other and permit animal and plant fluxes as in a continuous habitat. The ability of a species to move throughout the landscape is related to habitat connectivity (); it refers to the functional linkage among patches either due to patch proximity or to matrix permeability (With 1997; Uezu et al. 2005). Therefore, the degree of habitat connectivity, which depends on matrix quality, is essential to maintain native species in a fragmented landscape (Forman & Gordon 1986; With 1997; Tischendorf & Fahrig 2000; Ewers & Didham 2005). Besides affecting species movements throughout the landscape, matrix quality also controls the permanence time of individuals in it, according to the resources it offers (Aberg et al. 1995), thus matrices of good quality may characterize a type of habitat effectively used by the species both in search for resources or traveling among preferential habitats (Smallwood & Fitzhugh 1995; Wagner & Fortin 2005). The quality of a matrix, however, is differently perceived by different species; some species may benefit from agricultural lands while others may be excluded (Gehring et al. 2003; Laurance 1994). As examples of the former case, some studies show the regular use of coffee plantations in Mexico (Moguel et al. 1999), banana and cocoa plantations in Costa Rica (Harvey et al. 2006), cocoa plantations in Brazil (Faria et al. 2006) and subsistence agriculture in Nepal (Acharya 2006) by the native fauna. On the other hand, species that required large territories and have small populations are particularly vulnerable to habitat fragmentation and can be locally extinct (Crooks 2002). The increasing fragmentation and loss of natural areas, associated to changes in ecological processes and species extinctions demand urgent integration of human needs and the preservation of essential ecosystem processes. Approaches focused on the interactions between nature and man should be the basis for a transition to a more sustainable agriculture (Bignal 1998). The challenge of achieving development in a sustainable way was first globally discussed in the Brundlandt Commission (World Commission on Environment and Development – WCED), in 1983, and it has become a central question ever since. However, practical sustainable actions are being implemented very slowly although numerous studies have shown that the preservation of many species could be ensured if agricultural systems incorporated ecological concepts. On the other hand, conservationists have tried to find ways to integrate human land uses and native fauna needs (Vandermeer et al. 1997; Bignal 1998). In this chapter, we intend to show the use of both natural and agricultural (silvicultural) habitats by the native carnivore fauna, and to demonstrate the possibility to maintain these populations in a fragmented landscape, provided that some large native patches are left and the matrix is permeable to the native fauna.