Distribuição e abundância de pequenos mamíferos em relação à paisagem da bacia do Rio Passa-Cinco, São Paulo, Brasil

Abstract

Distribution and abundance of small mammals in relation to the landscape of the Passa-Cinco River basin, São Paulo, Brazil.The Corumbataí Basin is used as the main source of water supply for the municipal districts of Piracicaba and Rio Claro, being the Passa-Cinco River its main tributary. The Passa-Cinco river basin can be considered as a convenient model for the study of the conservation of biodiversity for it contains the main existing agroecosystems in the state of São Paulo. So that conservationist strategies can be established, some information is required, such as how biodiversity is affected, and which strategies the population of wild species use to keep themselves in the altered forest remainings. Small mammals, such as rodends and marsupials can be considered a good group to help answer these questions, for this group develops an important ecological role in forest environments, through the predation and dispersion of seeds. From August 2003 to January 2005 surveys on small mammals were carried out using 160 Sherman type traps distributed in lines, in 16 sample country properties, being 4 in each type of environment that is predominant in the landscape: native forest, Eucalyptus plantation, sugar-cane plantation and pastures. In this period, 177 rodend and marsupial individuals were captured, which were distributed in 8 species, with a 0,77% rate of success in capture. There was significative difference among the studied environments in terms of abundance, but not in terms of the richness of the species. Also, we could observe a clear distinction between forest and non-forest habitats. Apparently, the native forest remainings in the region lost their species which are the most demanding in relation to the quality of habitat, in such a way that the current community is basically formed of generalists, which are a characteristic of degraded areas. The loss of forest species not only alters the community of small mammals, but also favors the occurrence of species from non-forest areas which can bring, among other things, problems related to public health. Eventhough, the small mammal community from the Passa-Cinco river basin is worth conservationist efforts which must give priority to studies relating the environmental law enforcement to the changes this might generate to the community of small mammals.

Terrestrial non-volant small mammals in agro-silvicultural landscapes of Southeastern Brazil

“…Furthermore, the present alpha diversity is similar to that detected in other silvicultural landscapes of São Paulo State, (Gheler-Costa, 2006;Gheler-Costa et al, 2002;Umetsu and Pardini, 2007), although the used method may be relatively less efficient to detect arboreal (e.g. Rhipidomys mastacalis -Gheler-Costa, 2006) or aquatic (Lutreolina crassicaudata - Bonvicino et al, 2002) species (Caceres et al, 2011;Lyra-Jorge and Pivello, 200;Santos-Filho et al, 2006), present in other agricultural landscapes of São Paulo.…”

“…Moreover, all the published studies regarding small mammals' distribution and abundance patterns in silvicultural landscapes were carried out in mature Eucalyptus plantations (Cademartori et al, 2008;Dietz et al, 1975;Gheler-Costa, 2006;Gheler-Costa et al, 2002;Stallings, 1989Stallings, , 1991Umetsu and Pardini, 2007), which may bias sampling results (Silva, 2007).…”

Trophic categories in a mammal assemblage: diversity in an agricultural landscape

“…The post hoc test indicated that sugar cane plantations harbor a significantly higher abundance compared to pastures (p = 0.03). This result could be related to the availability of prey items, since small mammal abundance in the Passa-Cinco region is also higher in sugar cane than in pastures (Gheler-Costa 2006). Moreover, the presence of cattle itself could be chasing away some species from the pastures.…”

Microestruturas de pêlos de pequenos mamíferos não-voadores: chave para identificação de espécies de agroecossistemas do estado de São Paulo, Brasil

“…Na Bacia do Passa-Cinco, utilizaram-se armadilhas do tipo Sherman distribuídas em 16 sítios de amostragem, igualmente distribuídos entre fragmentos de floresta semidecídua, plantios de eucalipto, pastagens e canaviais (Gheler-Costa 2006). Nas Fazendas Ibiti e Santa Isabel, utilizaram-se armadilhas de interceptação e queda (pitfall) distribuídas em 9 sítios de amostragem, sendo 6 áreas de eucalipto (borda e interior), 2 fragmentos de floresta semidecídua e 1 fragmento de cerrado.…”

“…Estes trabalhos foram aplicados para identificação de presas e/ou predadores de áreas florestadas e conservadas. Estudos referentes a pequenos mamíferos em agroecossistemas são insipientes (Barros-Batesti et al 2000, Bonvicino et al 2002, Bush et al 2001, Gheler-Costa et al 2002, Gheler-Costa 2006, se considerarmos agroecossistema como um conjunto que compreende ecossistemas naturais e ambientes modificados pelo homem (Odum et al 1988). A grande parte dos estudos de ecologia de pequenos foram realizados em áreas conservadas ou com porcentagem de vegetação natural acima de 20% (Castro & Fernandez 2004, Fonseca & Robinson 1990, Pardini 2004, Pardini et al 2005, Pires et al 2002, Pires et al 2005.…”