Concepts and Methods for Identifying Species Niche Edges, Potentially Truncated Edges, and Climate Risks and Opportunities

Aim Unmitigated climate change will subject species to environments unlike any experienced for millions of years, creating new risks and opportunities for species, especially where niches are truncated and novel climates open previously unavailable portions of the fundamental niche. Here we present a conceptual framework and explore methods for identifying niche edges, potentially truncated edges, and the risks and opportunities associated with changing climate prevalence. Innovation We provide conceptual and methodological frameworks to identify and quantify potentially truncated edges and associated risks and opportunities which can be incorporated into studies regarding conservation biology and novel ecosystems. This method uses multidimensional kernel density analysis to identify portions of the niche that are particularly susceptible to climate changes, the potentially truncated niche edges. Climate‐prevalence analysis then identifies which portions of the niche, including edges, may become more (opportunity edge) or less (risk edge) common in the future. Using three North American tree species, we test the sensitivity of this method to different representations of climate (via dimension reduction) and species‐specific available climates (via buffer distance), discuss the geographic and environmental distributions of potentially truncated edges and risk/opportunity edges, and recommend future implementations of this method in research and conservation. Main Conclusions Niche‐edge and climate‐prevalence analyses together help identify populations sensitive to changes in climate and assess climate risk or opportunity. Estimates of edge frequency and climate‐prevalence risk/opportunity are sensitive to climate dimensionality, with 4‐dimensional representations recommended over 2‐dimensional representations, and to buffer distance, with buffers > 100 km showing the best performance. This new method complements traditional approaches for assessing species‐level effects of climate change, such as species distribution models, and can help conservation planning by identifying populations that are particularly vulnerable to disappearing climates versus populations poised to leverage the opportunities associated with novel climates, with perhaps surprising effects.