COS 6-4 - CANCELLED - Are we underestimating the risk of extinction posed by climate change? Tree-ring data reject the leading edge-trailing edge paradigm for species range change

Monday, August 15, 2022

2:15 PM – 2:30 PM EDT

Location: 513E

Presenting Author(s)

ME

Margaret Evans

University of Arizona, Arizona, United States

Coauthor(s)

SD

Sharmila Dey

Harvard University
Tucson, AZ, United States
KH

Kelly Heilman

University of Arizona
Tucson, Arizona, United States
ES

Emily Schultz

University of Nevada Reno, United States
JS

John Shaw

US Forest Service, Utah, United States
JD

Justin DeRose

University of Utah, United States
SK

Stefan Klesse

Swiss Federal Institute for Forest, Snow, and Landscape Research WSL, Sweden
JT

John R. Tipton

University of Arkansas, United States

Background/Question/Methods

Climate change poses an existential threat to biodiversity, given our understanding of the importance of climate in shaping species’ geographic distributions. Climate envelope or species distribution models are commonly used to predict how species will respond to climate change. In doing so, it is assumed that individual- and population-level climatic tolerances match species-level climatic tolerances. This gives rise to the leading edge-trailing edge paradigm for range change: populations at the cool edge of a species’ distribution are expected to benefit from warming, whereas populations at the warm edge are expected to decline. We challenged this paradigm with a spatial network of 1,633 growth-ring time series sampled from an aridland pine (Pinus edulis, common or two-needle pinon), collected in 937 forest inventory plots encompassing this species’ entire geographic distribution.

Results/Conclusions

A Bayesian multiple regression analysis of ring widths showed that growth of P. edulis increases with temperature variation across space (warmer sites have higher growth rates, especially at relatively wet, warm sites) but that trees everywhere grow less in warmer-than-average years. This ubiquitous negative response to interannual temperature variability implies that instead of expecting leading edge populations to benefit from warming, we should expect all populations to experience decreased performance (and fitness). Thus we question the assumption underlying the use of climate envelope models that global (species-wide) climatic tolerances can be translated directly into projections of range change, ignoring individual-level plasticity and local adaptation. Our results imply that climate envelope (species distribution) models underestimate the risk of extinction posed by climate change. We conclude that range projections should be informed with a combination of longitudinal (time series) and spatial data.