Long-term persistence of midsized to large-bodied mammals in Amazonian landscapes under varying contexts of forest cover

Abstract

Both forest fragmentation and overhunting have profound effects on the structure of large-vertebrate assemblages in neotropical forests. However, the long-term value of habitat fragments for forest mammals remains poorly understood and few regional scale studies have replicated sampling across spatially independent landscapes. Here, we assess the species occupancy and abundance of midsized to large-bodied mammals within three neighbouring Amazonian forest landscapes varying widely in extent of forest cover. One of these consisted of forest fragments surrounded by semi-natural scrub savannahs that had been occupied by paleoindian populations for at least 7,000 years, whereas forest cover in the other two landscapes was either variegated or continuous. Data on species occurrence and abundance from diurnal and nocturnal line-transect surveys and local interviews in each landscape were used to examine the effects of forest cover and hunting pressure on mammal persistence within forest patches. The extent of forest cover was a key determinant of species persistence across the three landscapes, but populations of large-bodied species were either reduced or driven to local extinction by hunting even in the most forested and least fragmented landscape. Many game and non-game species persisted in forest isolates, even though, individually, these were likely too small to support viable populations. This study indicates that even small, long-term forest fragments may retain significant conservation value if they can be managed within the context of enhanced connectivity across wider fragmented landscapes

Assemblage of medium and large size mammals in an urban Semideciduous Seasonal Forest fragment in Cerrado biome

“…The impacts of habitat fragmentation limit the presence of various species in the fragment because they restrict the area of the fragment (Chiarello 1999, Michalski & Peres 2007. They also cause edge effects (Fahrig 2003) in the interaction between the fragment and the matrix (Murcia 1995, Stevens & Husband 1998 and decrease landscape connectivity (Fahrig & Merriam 1994, Sampaio et al 2010. Aside from these factors, there are also factors present related to the proximity of households and urban centers.…”

“…In this scenario the fragments are important to conserve despite their size or location, because although they are small, they may have conservation value in increasing connectivity (e.g. Crooks 2002, Lacerda et al 2009, Sampaio et al 2010.…”

Terrestrial mammal assemblages in protected and human impacted areas in Northern Brazilian Amazonia

“…In our previous studies (Mendes Pontes 2004, Mendes Pontes et al 2007, Mendes Pontes et al 2012, Melo et al 2015, we showed that in the highly heterogeneous vegetation mosaics of the northernmost Guyana shield the structure of the terrestrial mammalian assemblages was shaped by forest type and heterogeneity, which, in turn, is directly connected with resource availability. Species richness and diversity may vary between protected and impacted areas, with the latter in most studies presenting a lower number of species due to hunting (Lopes and Ferrari 2000, Peres and Nascimento 2006, Michalski and Peres 2007, Sampaio et al 2010, Ahumada et al 2011, Melo et al 2015, Meyer et al 2015. Accordingly, the richest area was PA Uatumã, located south of the Guyana shield, closest to central Amazonia, the natural vegetation cover for which is dense ombrophilous forests, followed by IA Entre Rios, which is located in the transition between the dense ombrophilous terra firme forests of the south of the Guyana shield, and the seasonally-dry forest mosaics of central Guyana shield, and the poorest areas were PA Maracá and IA Bom Jesus, in the northernmost Guyana shield, where the vegetation is mainly seasonally-dry forest mosaics interspersed with extensive areas of savannas (See Hoorn et al (2010)).…”

Análise espacial da distribuição da fauna de vertebrados de médio e grande porte frente a dois padrões de desmatamento típicos da floresta Amazônica, na região de Alta Floresta - MT

“…Indeed, pumas (Puma concolor) and jaguars (Panthera onca) need an area of at least 1000 ha to have 50% probability of occurrence in the same study region . These species require large areas effectively protected to maintain viable populations in the long term, disappearing in fragmented habitats that are not connected by corridors (Crooks 2002;Sampaio et al 2010;Sálek et al 2009). …”

“…Obtaining data of species occurrence through local interviews is an effective approach successfully tested with mid-sized and large bodied vertebrates (Gros 1998;Lawes et al 2000;Urquiza-Haas et al 2009;Sampaio et al 2010). …”