Identification and prioritization of stepping stones for biodiversity conservation in forest ecosystems

Habitat degradation and fragmentation are two of the main drivers for biodiversity loss. To mitigate the negative impact of fragmentation in forests, conservation targets are increasingly addressing connectivity to facilitate the independent movement of species between habitat fragments to ensure genetic diversity and adaptation to climate change. In this article, we present a novel approach to identifying and prioritizing stepping stones for preserving connectivity based on national and regional biodiversity data for Austrian forest ecosystems. Our study identified forest areas where conservation measures should be taken to ensure future habitat connectivity by combining four indicator values with different requirements of a stepping stone habitat into a prioritization value. The four compounded indicators are: (i) the Protect Value, which includes distances to patches of protected areas with restricted management for the undisturbed development of retention areas, (ii) the Connect Value, which combines datasets of designated habitat corridors and connectivity areas in Austria based on landscape models and expert validation, (iii) the Species Value identifying species-rich areas, and (iv) the Habitat Value identifying biotopes of high ecological value, key biodiversity areas, and sites of favorable protection status. Nonparametric tests revealed significant differences in prioritization value among the ecoregions of Austria and therefore encourage the consideration of stepping stone prioritization at local and regional context. Building upon the insights from this case study on Austrian forest ecosystems, we developed a robust framework derived from our methodology. This framework is designed to facilitate future implementations in diverse study regions, accounting for factors beyond connectivity crucial for identifying high value stepping stone habitats. We encourage adaptation of this framework to local data availability, species requirements, and local conditions. The compiled framework provides decision support for managers and conservationists for prioritizing areas to conserve and improve connectivity of forest habitats. However, it does not substitute on-the-ground field assessments of habitat quality and measures of functional connectivity.