Influence of land-use/land-cover change on landscape connectivity for an endemic threatened amphibian (Argenteohyla siemersi pederseni, Anura: Hylidae)

Abstract

Context Modifications in natural landcover generally result in a loss of habitat availability for wildlife and it's persistence will depend largely on their spatial configuration and functional connections. Argenteohyla siemersi is a threatened and endemic amphibian whose habitat is composed of forest patches near rivers and water bodies edges. Objectives This study aimed to analyse the accessible habitat for this species and identify key elements to maintain its ecological network in two different types of land uses: an anthropized area with extensive cattle raising and a protected area. Methods The structural and functional characteristics of both landscapes were analyzed. The connectivity at landscape level and the contribution of each habitat patch were evaluated through simulation models with different dispersion distances in the context of the graph theory. Results In both landscapes, nine types of landcover were identified with different compositions. Remarkable differences were found in habitat connectivity for this amphibian species between both landscapes. As the percentage of dispersion distance increases, reachable habitat increases as well, although with higher percentages in the protected area. Two corridors were identified in the protected landscape and one in the rangeland one; patches and key links constituted all of them. Conclusions The present work provides spatially explicit results with a quantitative basis. It could be useful as a tool for the development of management plans aimed at guaranteeing the functionality of the ecological network for this endangered species and, therefore, contribute to its long-term conservation.

Integrating dispersal, breeding and abundance data with graph theory for the characterization and management of functional connectivity in amphibian pondscapes

“…Functional connectivity in amphibian population dynamics has been assessed with different approaches, including the characterization of genetic structure at the landscape scale (Richardson 2012 ; Watts et al 2015 ), occupancy models (Brooks et al 2019 ), electric circuit theory (Beaujean et al 2021 ; Costa et al 2021 ), and graph theory (Ribeiro et al 2011 ; Matos et al 2019 ; Schivo et al 2020 ). The latter has been successfully applied for the study of patterns of connectivity in fragmented landscapes (Bunn et al 2000 ; Jordán et al 2003 , 2007 ; Bodin and Norberg 2007 ; Vasas et al 2009 ), and is a promising tool for characterizing the structure and dynamics of pond-breeding amphibian metapopulations.…”

“…Additionally, connectivity studies are often conducted at geographical scales that are much larger than the typical dispersal distances of amphibians (Sinsch 2012 ). Therefore, when modelling graphs, researchers must rely on sequential thresholds (Fortuna et al 2006 ) or records of maximum dispersal from other studies, often obtained from different geographic areas (Ribeiro et al 2011 ; Clauzel et al 2013 ) or from different species (Schivo et al 2020 ). This approach is limited and prone to biases of unknown magnitude due to the high interspecific variation of dispersal distances described in amphibians, even among species from the same family (Cayuela et al 2020 ).…”

Quantitative Spatial Ecology to Promote Human-Wildlife Coexistence: A Tool for Integrated Landscape Management

“…Our framework is suitable when animal movements can be predicted within a patch network. For example, a network approach was used to clarify the link between habitat changes and landscape connectivity for species ranging from small frogs (Schivo et al, 2020) to African elephants (Bastille-Rousseau and Wittemyer, 2020). As with these studies, our framework involves knowledge of how animals adjust their interpatch movements in response to landscape changes; however, here we suggest to actively manipulate landscape features to alter interpatch functional connectivity in a way that results in suitable management or conservation outcomes.…”

Remote sensing of wildlife connectivity networks and priority locations for conservation in the Southern Agricultural Growth Corridor (SAGCOT) in Tanzania

“…Graph theory combined with the habitat availability concept is a widely embraced approach to assess connectivity aiming to support management decisions (De la Fuente et al., 2018; Dondina et al., 2018; Gurrutxaga et al., 2011; Saura et al., 2017; Schivo et al., 2020). Graphs are data structures composed of nodes (suitable habitat units surrounded by inhabitable land) and links (potential connections between nodes) that allow simple but effective representations of the landscape to conduct complex connectivity analyses (Adriaensen et al., 2003; Bunn et al., 2000; Saura & Torne, 2009).…”