The Conservation Value of Small Fragments For Atlantic Forest Reptiles

Abstract

Loss and fragmentation of natural habitats are key contributors to the decline of populations and impoverishment of biological communities. The response to these disturbances can vary substantially among taxa and depends on spatial metrics of habitat fragments and the surrounding landscape. Herein we test how fragment area, shape, isolation, and matrix quality affect reptile richness, abundance, and occurrence in Brazilian Atlantic Forest fragments, a biodiversity hotspot with a poorly studied reptile fauna. We used 23 forest fragments, ranging from 2 to 30 hectares, surrounded by different matrix types, including sugarcane crop fields, cattle ranching, subsistence farmlands and rural communities. Species richness, total reptile abundance, population abundance, and occurrence probability of many species decreased with fragment area. Model selection suggested that fragment area is the main predictor of both richness and abundance, but matrix quality as well as fragment shape are also important predictors. For population abundance and occurrence probability, fragment area and proximity were the most important predictors followed by fragment shape and matrix quality, but the strength and even the sign of predictors varied substantially among species. We highlight that the value of small fragments should not be neglected for the conservation of Atlantic Forest reptiles.

Abundance and survival rates of three leaf-litter frog species in fragments and continuous forest of the Mata Atlântica, Brazil

“…Our findings support recent studies, indicating that small habitat patches can have an important conservation value (Bickford et al 2010, Lion et al 2016. This is especially true for taxonomic groups with limited spatial requirements that may also benefit from the absence of predators.…”

The contribution of theory and experiments to conservation in fragmented landscapes

“…But many were surprised to find that pollination (Dick 2001), and other interspecific interactions were often quite resilient in small and even highly degraded fragments (Bruna et al 2005). Although there has been no suggestion that preserving small fragments is sufficient to conserve biodiversity comparable to that in large fragments, they could also play key roles as relict habitats, stepping stones for dispersing species, building blocks for corridors, sources of seeds and pollen for regeneration, and reservoirs of genetic diversity (Aizen and Feinsinger 1994, Turner and Corlett 1996, Freudenberger 2001, Pardini et al 2005, Mueller et al 2014, Saura et al 2014, Lion et al 2016. Also, small fragments may contain unique subsets that was not severe, it could buffer against the degrading effects of fragmentation and it could be valuable habitat not only for species moving between fragments, but also for a diverse community of resident taxa (Mesquita et al 1999, Davies et al 2000, Laurance et al 2011, Mendenhall et al 2014.…”

Conservation value of small reserves

“…Lion et al. () hypothesized this result may reflect the variety of focal species or the potential of fragment edges to hold high densities of squamate species, possibly increasing the species richness of small reserves and fragments with more edge. Consistent with other taxa, reserve characteristics, such as vegetation structure and invasive species presence, affect species richness as much or more than reserve size (Jellinek et al.…”

“…Unfortunately, when Lion et al. () reviewed other studies of lizard species responses to habitat loss and fragmentation, they did not extract information on habitat quality as a predictor of these responses. Regardless of how reptile species richness relates to habitat area, small reserves and fragments are valuable for species conservation (McCoy & Mushinsky ; Rubio & Simonetti ; Lion et al.…”

“…Regardless of how reptile species richness relates to habitat area, small reserves and fragments are valuable for species conservation (McCoy & Mushinsky ; Rubio & Simonetti ; Lion et al. ). For example, squamate species richness in small Atlantic Forest patches (1.7–27.4 ha) matches the richness of areas with the highest species richness in the region (Lion et al.…”