Influence of landscape heterogeneity and meteorological features on small mammal abundance and richness in a coastal wetland system, NW Portugal

Abstract

The abundance and distribution of small mammals are important factors for ecosystem structure and functioning, often affected by spatial heterogeneity and seasonal fluctuations. In this study, we tested the influence of habitat type, landscape composition and meteorological conditions on small mammal abundance and richness in the heterogeneous coastal wetland landscape of Baixo Vouga Lagunar (BVL), NW Portugal. Seven different habitats (Bocage, a mosaic composed of small agricultural and pasture fields separated by live fences of autochthonous vegetation, eucalyptus stands, maize fields, marshlands, reed beds, rice fields and rushes) were sampled every 2 months, between November 2011 and October 2012, resulting in a trapping effort of 18,665 trap-nights. We recorded a total of 1961 captures, including 566 recaptures, of which 1714 (87.4 %) were rodents and 247 (12.6 %) were shrews. Spatially, reed beds presented the highest values of small mammal diversity and favoured this fauna abundance, as well as rushes and marshlands. In contrast, Bocage and eucalyptus stands did not favour most of the species abundance and richness; eucalyptus stands were the habitat with the lowest diversity. Overall, cumulative precipitation favoured the abundance of most species, determining small mammal seasonal fluctuations. At a fine scale, landscape heterogeneity did not seem to influence small mammal abundance and richness. At a broader scale, the landscape matrix appeared to favour small mammal richness and diversity, because species have heterogeneous distribution throughout the patchy landscape. Conservation and management efforts should therefore be focused on wetland natural habitats, considering the remaining habitat types that compose the matrix.