Managing for the Conservation of Forest Landscape Connectivity Under Different Land Cover Change Scenarios

Landscape connectivity has become a key issue for the conservation of biodiversity to counteract the adverse effects of habitat fragmentation and to facilitate the accommodation of species to the shifts in their natural domains caused by climate change. It is actually being included into an increasing number of policies, programs and projects. However connectivity is a dynamic property affected by global and local changes (land use, climate, etc.), and landscape planning and conservation efforts should take into account the current and foreseen patterns of change in the landscape and habitat patterns. Here we compared the contribution of different forest habitat patches for maintaining connectivity across different land-use change scenarios, including (1) loss of forest patches through forest fires, conversion to agriculture, and urban development and (2) land use changes in the non-forest matrix that may cause a reduced connectivity in the forest landscape. We integrated each of these changes into a least-cost model, where the distance between forest patches is weighted by the effort (resistance) of a particular species to traverse the different landscape elements in the matrix (effective or least-cost paths). These effective distances were incorporated into the Probability of Connectivity index index (PC) (Pascual-Hortal and Saura 2006; 2007; Saura and Pascual-Hortal 2007), which is based on graphs and the habitat availability concept (Pascual-Hortal and Saura 2006; 2007). Through a new version of the Conefor Sensinode software developed specifically for these purposes, we analyzed the importance of each forest patch as a connecting element or stepping stone between the rest of the forest habitat, through the recently described PCconnector component of that index (Saura 2007). To illustrate this methodology we applied it to a forest-dwelling bird (Sitta europaea) in the region of Galicia (NW Spain), with an extent of 29574 km2. This bird, affected by forest fragmentation, has a median dispersal distance of 3 Km (Matthysen et al. 1995) and prefers wooded cover in its dispersal movements (Verboom et al. 1991), avoiding open areas (Bélisle et al. 2001). We model the population dispersal through the least-cost analysis, taking into account the intrinsic characteristics of each land cover type (increasing the resistance from wooded to open areas, according with the forest¿s natural succession schemes, and with maximum resistance on anthropogenic land uses) and the spatial context of each pixel (percentage of forest cover around each pixel), based on a recent model (Rodríguez Freire 2006; Rodríguez Freire and Crecente 2006; 2007) that was modified to incorporate the different analyzed land-cover changes. We illustrate how the different land-use change scenarios impact the connectivity of the forest landscape and how the conservation priorities in the landscape have to be adapted to minimize the consequences of land cover change. Finally, we discuss how the methodology can be applied to a wide range of forest landscape management applications in different countries, where both the conservation of the forest critical areas and an adequate management of the landscape matrix between them are of concern to achieve the sustainability of the ecological flows and ecosystem services in the forest landscapes.JRC.H.7-Land management and natural hazard