Non-volant small mammals from the Morro Grande Forest Reserve: distribution of species and diversity in an Atlantic Forest area

Abstract

Non-volant small mammals, the most diverse ecological group of mammals in Neotropical forests, play an important role in forest dynamics and are good indicators of both local and landscape alterations. However, little is known about species and diversity distribution and only a few of the largest Atlantic Forest remnants have been adequately sampled. Based on a survey we carried out in the Morro Grande Forest Reserve, São Paulo State, and on other 20 Atlantic forest inventories, this study aims at (1) describing the non-volant small mammal list and community structure of the Reserve, (2) describing how species and diversity are distributed in space and time in the Reserve and (3) investigating how diversity is affected by capture methods. The non-volant small mammal fauna of the Reserve includes several rare and mature forest species, besides common species from genera that are usually abundant in other well preserved forests. The total number of species is high, in part due to the use of large pitfall traps in the sampling protocol, but also probably due to the Reserve location and altitude. The additive partitioning of diversity indicates that a major part of diversity is found locally in sample sites, a second part among sample sites within the same habitat type and just a minor part among habitats, suggesting the importance of micro-scale forest heterogeneity to the distribution of non-volant small mammals. Abundance and richness did not vary between the two sampled years and it is possible that continuous forest areas may present more temporally stable populations and communities. However, they varied seasonally, with high values found at the end of the wet season and low values at the end of the dry season. Pitfall traps showed to be extremely efficient for capturing non-volant small mammals.