Restoration priorities for Caatinga dry forests: landscape resilience, connectivity and biodiversity value.
Restoration actions can halt biodiversity loss and rescue its services. However, in order to be effective, priority areas for restoration should be chosen based on objective large-scale restoration planning. Here, a multicriteria graph theory framework was used to propose restoration priority areas for the Brazilian Caatinga, the largest seasonally dry tropical forest of the New World, based on landscape resilience, landscape connectivity and biodiversity conservation value, focusing on threatened endemic plant species. We applied this graph theory framework to 10,406 Caatinga catchment basins. Vegetation cover and within-catchment connectivity were used to select catchments of intermediate landscape resilience, which in principle offer more effective opportunities for restoration. Then, such catchments were independently classified into (a) three classes according their contribution for between-catchment connectivity and (b) three classes according their value for biodiversity conservation, estimated by the richness of threatened, endemic plant species. By the integration of landscape resilience, landscape connectivity and biodiversity conservation values, three priority classes for restoration were generated. The multicriteria framework generated several restoration priority cut-offs. Prioritization based on landscape resilience selected 36% of the Caatinga catchments as high priority for restoration. By independently adding landscape connectivity and biodiversity conservation value, only 12% and 3% of the catchments, respectively, were considered as high priority. By combining all three criteria, 9% of the catchments were selected as high priority and < 1% as top priority for restoration. Synthesis and applications. Restoration of drylands can contribute immensely to the conservation of its threatened biodiversity but large-scale planning is quintessential. Here, a multicriteria graph theory framework was applied to indicate priority areas for restoration, which maximizes the effectiveness of restoration actions, landscape connectivity for climate change adaptation and conservation of threatened species. The framework was applied to the Caatinga, the largest seasonally dry tropical forest of the new world, but it can be applied world-wide under different budged limitations and spatial scales, being useful for private, state and federal initiatives.