Assessing conservation outcomes and maximizing habitat connectivity for multiple species in systematic conservation plans: a case study in Yolo County, California

Abstract

Context: Habitat connectivity is key when designing reserve networks for conservation of species at risk. Acquiring land over time to achieve connectivity for multiple species in a systematic conservation plan can pose a challenge because not all high priority parcels will be acquired, species occurrence data is often limited, and using multiple species models together is complex. Objectives: We evaluated four possible land acquisition strategies in a such a plan in their ability to meet each of three objectives. The strategies represent different combinations of what are termed ‘Priority 1’, ‘Priority 2’, and ‘Corridor’ lands in the plan. The objectives are to (1) meet conservation target acreages identified in the plan; these are distinct from connectivity goals, (2) maximize structural habitat connectivity, and (3) maximize connectivity for multiple focal species. Methods: For this case study in Yolo County, California, we compared the efficiency of strategies to meet conservation targets using MARXAN. We compared structural connectivity of MARXAN solutions for each strategy using FRAGSTATS and distance between patches using ArcGIS. We compared focal species connectivity by using ArcGIS to define species-specific least cost networks and then assessing each network’s conformity with MARXAN solutions. Results: ‘Priority 1’ parcels and ‘Corridor’ parcels together provide (1) the most efficient solution for attaining conservation targets, (2) the highest structural connectivity, and (3) high connectivity for the greatest number of focal species. Conclusions: Because land acquisition patterns are time sensitive and data may be limited, we recommend using spatial prioritization software often and employing several measures of connectivity in decision-making.