Dry forest decline is driven by both declining recruitment and increasing mortality in response to warm, dry conditions

Global Ecology and Biogeography
By: , and 



Aim: Anticipating when and where changes in species' demographic rates will lead to range shifts in response to changing climate remains a major challenge. Despite evidence of increasing mortality in dry forests across the globe in response to drought and warming temperatures, the overall impacts on the distribution of dry forests are largely unknown because we lack comparable large-scale data on tree recruitment rates. Here, our aim was to develop range-wide population models for dry forest tree species (pinyon pine and juniper), quantifying both mortality and recruitment, to better understand where and under what conditions species range contractions are occurring.

Location: Western United States.

Major taxa studied: Two pinyon pine (Pinus spp.) and three juniper (Juniperus spp.) species.

Methods: We developed range-wide demographic models for five species using forest inventory data from across the western United States and estimated population trends and climate vulnerability.

Results: We find that four of the five species are declining in parts of their range, with Pinus edulis having the largest proportion of populations declining (24%). Population vulnerability increases with aridity and temperature, with up to ~50% of populations declining in the warmest and driest conditions. Mortality and recruitment were both essential to explaining where populations are declining.

Main conclusions: Our results suggest that dry forest species are undergoing an active range shift driven by both changing recruitment and mortality, and that increasing temperatures and drought threaten the long-term viability of many of these species in their current range. While four of the five species examined were experiencing some declines, P. edulis is currently most vulnerable. Management actions such as reducing tree density may be able to mitigate some of these impacts. The framework we present to estimate range-wide demographic rates can be applied to other species to determine where range contractions are most likely.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Dry forest decline is driven by both declining recruitment and increasing mortality in response to warm, dry conditions
Series title Global Ecology and Biogeography
DOI 10.1111/geb.13582
Volume 31
Issue 11
Year Published 2022
Language English
Publisher Wiley
Contributing office(s) Southwest Biological Science Center
Description 11 p.
First page 2259
Last page 2269
Country United States
State Colorado, Idaho, Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, Utah, Washington, Wyoming
Other Geospatial Great Basin, Rocky Mountains
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