DOI: 10.1594/pangaea.771405
title: Potential connections (least-cost paths) between existing and potential bison habitat patches in the Carpathian Mountains

description: Habitat connectivity is important for the survival of species that occupy habitat patches too small to sustain an isolated population. A prominent example of such a species is the European bison (Bison bonasus), occurring only in small, isolated herds, and whose survival will depend on establishing larger, well-connected populations. Our goal here was to assess habitat connectivity of European bison in the Carpathians. We used an existing bison habitat suitability map and data on dispersal barriers to derive cost surfaces, representing the ability of bison to move across the landscape, and to delineate potential connections (as least-cost paths) between currently occupied and potential habitat patches. Graph theory tools were then employed to evaluate the connectivity of all potential habitat patches and their relative importance in the network. Our analysis showed that existing bison herds in Ukraine are isolated. However, we identified several groups of well-connected habitat patches in the Carpathians which could host a large population of European bison. Our analysis also located important dispersal corridors connecting existing herds, and several promising locations for future reintroductions (especially in the Eastern Carpathians) that should have a high priority for conservation efforts. In general, our approach indicates the most important elements within a landscape mosaic for providing and maintaining the overall connectivity of different habitat networks and thus offers a robust and powerful tool for conservation planning.
description: Large mammals play an important role in ecosystem functioning but today often occur in fragmented populations. A prominent example of a species occurring only in small, isolated herds is the European bison (Bison bonasus), whose survival will depend on establishing larger, well-connected metapopulations. The aim of this study was to estimate the potential connectivity of the European bison population in the Carpathians. We used two types of bison occurrence data: (1) the range maps of five Carpathian free-ranging bison herds and (2) the habitat suitability index (HSI) map for the Lowland-Caucasian line of European bison species in the Carpathians (Kuemmerle et al., 2010). Potential bison habitat patches were delineated as areas with HSI&gt;0.6 and larger than 200km2. Based on HSI map and data on dispersal barriers we derived cost surfaces, representing the ability of bison to move across the landscape. Cost analysis allowed to delineate potential corridors for bison movements between existing and potential bison habitat patches in the study area. Here we present some intermediate results of our study: existing and potential bison habitat patches with potential connections delineated between them based on two cost surfaces. The first cost surface (CS0) defining the landscape facilitating / hindering effects on the bison movement process, was derived by inverting and linearly scaling the original HSI values from 1 (no matrix resistance) to 11 (highest matrix resistance). In the second cost surface (CS100), cost assigned to grid cells that included a total barrier was 100 000, and cost assigned to grid cells with partial barrier was 100.Cost surfaces are provided as raster files (IMG format), while existing and potential bison habitat patches, and connections between them as shapefiles (SHP format). All data are in UTM coordinate system (zone 34N).The detailed description of habitat suitability map for European bison in the Carpathians is published in Kuemmerle, et al. (2010).The habitat suitability map is available from the authors upon request.
description: Supplement to: Ziolkowska, Elzbieta; Ostapowicz, Katarzyna; Kuemmerle, Tobias; Perzanowski, Kajetan; Radeloff, Volker C; Kozak, J (2012): Potential habitat connectivity of European bison (Bison bonasus) in the Carpathians. Biological Conservation, 146(1), 188-196