Climate-driven, but dynamic and complex? A reconciliation of competing hypotheses for species' distributions
Abstract
Estimates of the percentage of species “committed to extinction” by climate change range from 15% to 37%. The question is whether factors other than climate need to be included in models predicting species’ range change. We created demographic range models that include climate vs. climate-plus-competition, evaluating their influence on the geographic distribution of Pinus edulis, a pine endemic to the semiarid southwestern U.S. Analyses of data on 23,426 trees in 1941 forest inventory plots support the inclusion of competition in range models. However, climate and competition together only partially explain this species’ distribution. Instead, the evidence suggests that climate affects other range-limiting processes, including landscape-scale, spatial processes such as disturbances and antagonistic biotic interactions. Complex effects of climate on species distributions – through indirect effects, interactions, and feedbacks – are likely to cause sudden changes in abundance and distribution that are not predictable from a climate-only perspective.
What the paper shows and why it matters (AI-generated)
Estimates of species “committed to extinction” by climate change range from 15% to 37% depending on whether the underlying models include only climate or climate plus other factors. Testing this directly on a semiarid pine species using data from over 23,000 trees, the authors find that climate and competition together still leave much of its real distribution unexplained, pointing instead to disturbances and other indirect climate effects a climate-only model simply can't see — a caution against reading such range-model extinction percentages too literally.