Edge effects and landscape matrix use by a small mammal community in fragments of semideciduous submontane forest in Mato Grosso, Brazil

Abstract

A community of small mammals was studied in seasonal semideciduous submontane forest in the state of Mato Grosso, Brazil. This study evaluated the use of edge and matrix pasture, by different small mammal species. Overall, 31 areas were studied, with a total sampling effort of 33,800 trap x nights. Only seven of the 25 species captured in the study sites were able to use the pasture matrix; we classified these species as generalists. Fourteen species were found to be intermediate in habits, being able to use forest edges. We found only four species habitat specialists, occurring only on transect lines in the interior of the fragment, at least 150 m from the edge. Transects located in the pasture matrix and 50 m from the edge had significantly lower species richness and abundance than transects located in the fragment edge or in the interior of the fragment. All transects located within the fragment had similar species richness and abundance, but transects located 50 m from the edge had slightly lower, but non-significant, species richness than transects located 100 m apart from edges. Rarefaction curves demonstrated that only medium-sized fragments (100-300 ha) reached an asymptote of species accumulation. The other areas require further sampling, or more sampling transect, before species accumulation curves stabilize, due to a continued increase in species number.Keywords: edge effects, matrix of pasture, small mammals, forest fragments, Mato Grosso.Efeitos de borda e uso da matriz por uma comunidade de pequenos mamíferos em fragmentos de floresta semidecidual submontana no Mato Grosso, Brasil ResumoUma comunidade de pequenos mamíferos foi estudada em fragmentos de floresta estacional semidecidual submontana no Estado de Mato Grosso, Brasil. Nesse estudo, buscou-se avaliar o uso da borda e da matriz de pastagem pelas diferentes espécies. No total, 31 áreas foram estudadas, com um esforço total de 33.800 armadilhas x noite. Apenas sete das 25 espécies capturadas foram capazes de utilizar a matriz de pastagem, sendo estas consideradas generalistas. Quatorze foram consideradas intermediárias no uso do habitat, sendo capazes de utilizar habitats de borda. Encontramos apenas quatro especialistas, ocorrendo somente nas transecções do interior do fragmento, a aproximadamente 150 m da borda. Dentre todas as transecções utilizadas para amostragem, a disposta na matriz de pastagem, a 50 m da borda, demonstrou ser significativamente menos rica e abundante que as dispostas na borda e no interior dos fragmentos. Todas as transecções localizadas dentro do fragmento tiveram riqueza e abundância de espécies similares, porém a transecção localizada a 50 m da borda teve uma tendência a ser menos rica que a transecção a 100 m. Através de ajustes das curvas de rarefação, somente uma das áreas considerada de médio porte, entre 100 a 300 ha., atingiu uma assíntota. As outras áreas necessitam de um maior número de transecções, a fim de se obter uma estabilização das curvas, pois continuaram a acrescentar espécies.Palavras-cha...

Edge effects and the impact of wildfires on populations of small non-volant mammals in the forest-savanna transition zone in Southern Amazonia

“…A similar pattern was observed by Santos-Filho et al (2008), who recorded the highest richness and abundance in transects within forest fragments (300 m from the edge) compared to those located closer to the pasture (50 m from the edge) and at the edge of the forest. However, Pardini (2004) recorded a significantly higher species richness of small mammals at the edge of forest fragments in Atlantic Forest, while Malcolm (1997) Neotrop.,vol.…”

“…By contrast, M. nudicaudatus was only captured in transects at least 250 m from the edge, which suggests they prefer forest habitats. Santos-Filho et al (2008) classified this species as "intermediate" in terms of habitat use, while the classified H. megacephalus as a "generalist", present throughout the forest, as observed in the present study. However, R. nitela, which was classified as an "intermediate" species by Santos-Filho et al (2008) was also captured at all distances from the edge in the present study, even though this is an arboreal species, which was likely undersampled in this study.…”

“…Santos-Filho et al (2008) classified this species as "intermediate" in terms of habitat use, while the classified H. megacephalus as a "generalist", present throughout the forest, as observed in the present study. However, R. nitela, which was classified as an "intermediate" species by Santos-Filho et al (2008) was also captured at all distances from the edge in the present study, even though this is an arboreal species, which was likely undersampled in this study. The reduced number of specimens captured for some species, in particular scansorial and/or arboreal forms such as Micoureus demerarae (Thomas, 1905) and Oligoryzomys cf.…”

“…In the same ecosystem, Pardini (2004) found significantly richer small mammal community in edge habitats in comparison with the interior of mature forest and concluded that arboreal species are more affected by edge effects. In all cases, edge effects have different consequences for different species (Figueiredo & Fernandez 2004, Santos-Filho et al 2008.…”

Use of habitats by non-volant small mammals in Cerrado in Central Brazil

“…In forest fragments in southwest Mato Grosso, this species was the second most captured, also occurring in forest fragments' edges, but never in pasture (Santos-Filho et al, 2008b); in the Amazon, however, some individuals were observed crossing short pasturelands (about 300 m) surrounded by forest (MNFS, unpublished data). Necromys lasiurus was captured only in Cerrado sensu stricto areas in Cerrado in Alter do Chão (Magnusson et al, 1995), however Ribeiro and Marinho-Filho (2005) captured that species in murundus fields (grassland) in the Brazilian Federal District.…”