Efeitos do tipo de floresta e da estrutura de habitat em assembléias de primatas no sudoeste da Amazônia

Abstract

Environmental heterogeneity of natural vegetation types is a key determinant of local primate species richness and abundance. In this study we investigate primate assemblages composition and structure in four types of forest: unflooded (terra firme) forest, open and dense igapó forests (those seasonally inundated by clear water rivers) and cerradão (dense savanna woodland) in the Guaporé Biological Reserve in southwestern Brazilian Amazonia. In addition, we evaluate associations between primate occurrence and abundance with structural differences between forests types. We carried out 617.8 km of line-transect census (~154 km per forest type) and evaluated vegetation structure in 108 200 m2 plots (0.54 ha per forest type). Ten primate species were recorded during the 11-month study. Terra firme forest presented the highest primate species richness and density, predominantly as it is the only habitat playing host to Callicebus moloch and has the highest abundance of Sapajus apella. The high density of Ateles chamek in open igapó forest led to this habitat recording the highest primate biomass of any forest type. In the open and dense igapós and terra firme forests, Ateles chamek and Sapajus apella together made up over 70% of primate biomass, whilst in cerradão Sapajus apella accounted for 68% of primate biomass. Differences across forest types in primate species composition and relative abundances were associated with flood regimes and with several habitat structure variables (such as understory and canopy tree densities, canopy openness, total canopy height, and palm and liana densities). Our results reinforce the importance of heterogeneous landscapes in Amazonia, since these areas tend to contribute to elevating species diversity on this spatial scale.