To help slow the unprecedented global loss of biodiversity, we need tools that quickly and effectively evaluate species at risk and the threats facing them. Threat maps can be a crucial component of informed conservation actions when employed in a structured decision-making process that considers the specific impact of threats on species of interest.
The Categories and Criteria of the IUCN Red List process, based on extinction risk theory, is used to assess a species comprehensively and systematically. The methods have been rigorously developed and are the most widely used and accepted measure of global threat at the species level. To complete IUCN Red List species assessments, extensive species-specific data are collected in consultation with species experts, available literature and other sources. Of the biodiversity assessment data fields, identifying threats is one of the most important, yet difficult, areas to complete. Because threats often occur at a regional level, a threats mapping approach has often been employed.
The Sonoran Desert ecoregion spans more than 320,000 km2 across the USA and Mexico, hosting a high diversity of habitats and endemic species. This is one of the most rapidly urbanizing regions in North America, with accompanying habitat loss and fragmentation, invasive species and other anthropogenic impacts. Because of the immediate threats and its high species richness, we chose the Sonoran Desert as a target system to create a downloadable threat map to assist in evaluating spatially explicit threats to plant species for use in Red List assessments and conservation planning. Our goals were to create a map in which threats could be evaluated for individual species, and to develop protocols for using the map in the Red List assessment process.
In May 2024, the completed Sonoran Desert threats map with associated documentation and help guides became publicly available (github.com/mereclay/North-America-Threats-Map). Documentation includes methods, instructions for installing and using the map in QGIS, and guidelines for applying the map results to IUCN Red List criteria. The map was developed from existing, high quality data layers. The threats not included in the map are either not relevant to the region or require data that is not fully known or mapped. This threats map provides, for the first time, a spatial tool to assess the threat of habitat loss, fragmentation and land degradation to a plant species, and is a powerful tool for assisting with assessments of extinction risk.
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