Choosing between human trash and trashed forests: Resilience in nonvolant Atlantic Forest small mammals

Open pit rubbish dumps generate serious environmental problems both in Brazil and elsewhere. The goal of this study was to evaluate the occurrence patterns of an assemblage of small flightless mammals in the area of a landfill deactivated 19 years ago. During nine campaigns, three different sites located in a subtropical protected area near the city of Matinhos, Paraná coast, southern Brazil, were sampled. The selected places were an artificial clearing where urban waste had previously been dumped (Area 1), a site with less anthropic influence with tree species and a poorly developed understorey (Area 2), and a site with well-formed vegetation, with herbaceous, shrubby and tree strata well developed (Area 3). The total capture effort was 5210 trap-nights; 109 captures were made of 82 individuals from five species of Rodentia (all from the subfamily Sigmodontinae) and three species of marsupials (Order Didelphimorphia). The most conserved site (Area 3) had higher abundance than areas 1 and 2 (binomial test; P<0.05). Area 1, considered the most affected, showed less species richness (n=6) than the other two areas (7 and 8 species), although this may be affected by the lower number of captures. The diversity in Area 1, estimated by the Shannon index, was lower than in areas 2 and 3 (Hutcheson’s t tests; H’=1.26 for Area 1 vs. 1.76 and 1.68 for Areas 2 and 3, respectively), although the composition of the assemblage did not differ significantly between the areas (PERMANOVA; P=0.085). Our results show that even after 19 years of inactivity, the deposited waste is still having a negative impact on the environment, and highlight the resilience of some native small mammal species in exploiting the resources of degraded areas.