Vanishing bird species in the Atlantic Forest: relative importance of landscape configuration, forest structure and species characteristics

Abstract

Patch size, isolation, and vegetation structure are expected to strongly affect species persistence in fragmented landscapes, particularly for those with \30% of native habitat remaining. Those influences should be modulated by species characteristics, resulting in complex relationships. In order to investigate how species, habitat structure and landscape factors are related and how they affected species persistence, we studied bird communities in a fragmented Atlantic Forest region. Patch size strongly affected species richness and population abundances. However, some functional groups were more affected than others, particularly endemic and understory insectivores, species that are near the limits of their geographical distribution, those using few forest types, and those with their center of abundance in high altitude tropical forests. The effect of vegetation structure was mainly at the species level, reflecting specific responses to habitat quality. The importance of landscape variables varies according to the species group. For the most affected ones, which usually have low dispersal capacity, patch size and quality were the most relevant factors, whereas patch isolation was associated with the richness of groups with more generalist species. This pattern is due to the limited structural connectivity in the study region, composed of low matrix permeability (e.g. pastures and sugar cane), which isolate the most affected species, making them more dependent on local factors. In such a fragmented landscape, the largest patches should be prioritized for conservation purposes, as they aggregate the most vulnerable species and present the highest alpha diversity. Landscape management, as such, should also reconnect large fragments through corridors Electronic supplementary material The online version of this article (or matrix improvements, promoting better conditions for long-term persistence of the most affected species.

Sensitivity to fragmentation and spatial distribution of birds in forest fragments of northern paraná

“…(G-test). Uezu & Metzger, 2011). Their habitat specialization is thought to be the reason for such higher vulnerability (Stratford & Stouffer 1999, Hansbauer et al 2008a, 2010, Sodhi et al 2011, which seems to be corroborated by the data presented here.…”

“…We considered these distinct groups of species because they seem to present different levels of sensitivity to forest fragmentation. Subcanopy species seem to be more sensitive than canopy ones, while climbers seem to have intermediate sensitivity levels (Aleixo & Vielliard 1995, Anjos & Soares 1999, Ribon et al 2003, Uezu & Metzger 2011.…”

“…Probably the broad potential of habitat occupancy (homogeneous spatial distribution) contributed to their low sensitivity to forest fragmentation (e.g. Karr 1982, Ribon et al 2003, Uezu & Metzger 2011.…”

“…Thus, a species could be found in certain habitats within a forest whilst being rare, or even absent, in others. Fragmentation can negatively affect the availability of those habitats for most specialized species, decreasing the chances of their survival in forest fragments (Uezu & Metzger 2011). Therefore, habitat-specialist species may have their survival compromised due to the loss or alteration of vegetation heterogeneity (Cerqueira et al 2003).…”

Biodiversity of leaf-litter ants in fragmented tropical rainforests of Borneo: the value of publically and privately managed forest fragments

“…The persistence of species within forest fragments may be influenced by vegetation structure in addition to fragment area, but the interactions between these factors and their impacts within different landscapes and species assemblages are poorly understood (Laurance and Cochrane 2001 ;Prugh et al 2008 ), especially within complex systems such as tropical forests (Carvalho and Vasconcelos 1999 ;Hill et al 2011 ;Uezu and Metzger 2011 ). For instance, many studies have examined biodiversity in fragments of near-primary rainforest (Kattan et al 1994 ;Benedick et al 2006 ;Muñoz et al 2013 ), yet agricultural crops usually replace forest that has already been highly degraded by activities such as timber extraction (McMorrow and Talip 2001 ;Edwards et al 2011 ).…”