Shifting targets: spatial priorities for ex situ plant conservation depend on interactions between current threats, climate change, and uncertainty

Few strategies for conservation seed banking consider current and climate threats simultaneously and few-if any-represent uncertainty inherent in the assessment process. Here we evaluate the vulnerability of 5148 populations of 71 rare plant species in the North American Central Highlands to current threat, threat from climate change, and their combination. We calculated priorities based on current threat using existing conservation status and protection, and priorities based on climate threat using ecological niche models and species-level traits related to reproduction and dispersal. Current- and climate-based priorities were integrated using a weighted average of rank priority. We managed uncertainty using either a precautionary strategy that avoids any extinctions or a resource-conservative strategy that directs attention to species known to be vulnerable with high certainty. Priorities based on current threats highlighted presently rare species while priorities based on climate threat emphasized presently common species. The location of geographic "hotspots" providing opportunities for efficient seed banking depended strongly on the weight of the climate module relative to the current module, the strategy used to handle uncertainty, and emissions scenario. Integrating threats highlighted some hotspots that were not identified using just current or climate threat, indicating the importance of considering current and climate threats simultaneously. Only the Central Basin of Tennessee, a known center of endemism, was consistently emphasized. We urge (1) integrating current and climate threats when designing seed-banking strategies; and (2) reporting of uncertainty in a manner that allows decision-makers to choose actions based on available resources and tolerable risk.