Lindsay Rosa, Mark G Anderson, Brooke L Bateman, R Travis Belote, Julia L Michalak, Mindy B Rice

Deciding where to implement actions for biodiversity conservation remains challenging for many reasons, including the increase in maps aimed at prioritizing locations for conservation efforts. Although a growing numbers of maps can create the perception of uncertainty and competing science, a shared set of principles underlie many mapping initiatives. We overlaid the priority areas identified by a subset of maps to assess the extent to which they agree. The comparison suggests that when maps are used without understanding their origin, confusion seems justified: The union of all maps covers 73% of the contiguous United States, whereas the intersection of all maps is at least 3.5%. Our findings support the need to place a strong focus on the principles and premises underpinning the maps and the end users’ intentions. We recommend developing a science-based guidance to aid scientists, policymakers, and managers in selecting and applying maps for supporting on-the-ground decisions addressing biodiversity loss and its interconnected crises.

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Map of the contiguous United States showing four smaller inset maps (Belote 2021, Dreiss 2022, Taylor 2022, Anderson 2023) of top-priority biodiversity areas, overlaid into one composite map with a color-coded legend and Venn diagram showing where one, two, three, or all four methods agree on high-priority pixels.
Areas of agreement among biodiversity representation maps. The top-ranked 30% of pixels from four different mapping approaches (Belote et al. 2021, Dreiss et al. 2022, Taylor et al. 2022, Anderson et al. 2023) were overlaid to quantify the extent of overlap between them. We first reclassified the maps to identify the top-ranked 30% of pixels for each. The smaller maps show the top 30% of pixels for each method separately. We then overlaid these maps to show where one, two, three, and all four methods placed a pixel into the top 30% of priorities. The percentage of the contiguous United States covered by each overlay combination is included in the Venn diagram in the legend. The areas in white were not in the top-ranked 30% of pixels for any map. Combinations not shown in the legend are the coincidence between TNC and NAS (6.2%), the coincidence between DOW and TWS (4.2%), and the percentage of the contiguous United States that is not prioritized by any method (26.9%).