The importance of monsoon precipitation for foundation tree species across the semiarid Southwestern U.S.

Frontiers in Forests and Global Change

Forests and Global Change

Jessica S. Guo¹  Christopher Schwalm²  Drew M. P. Peltier³  George W. Koch³  Jeffrey M. Welker⁴  Marcy Litvak⁵  Yao Liu⁶  John D. Shaw⁷  William R. L. Anderegg⁸  Kimberly E. Samuels-Crow⁹  Kiona Ogle^1,10 

[1] Arizona Experiment Station, University of Arizona, Tucson, AZ, United States;Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, United States;Woodwell Climate Research Center, Falmouth, MA, United States;Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, United States;Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, United States;Department of Biological Sciences, University of Alaska, Anchorage, AK, United States;Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland;Ecology and Genetics Research Unit, University of the Arctic, Rovaniemi, Finland;Department of Biology, University of New Mexico, Albuquerque, NM, United States;Department of Geography and Environmental Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom;Rocky Mountain Research Station, USDA Forest Service, Logan, UT, United States;School of Biological Sciences, University of Utah, Salt Lake City, UT, United States;School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ, United States;School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ, United States;Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, United States;Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, United States;

关键词: semiarid ecosystems;    North American Monsoon;    Southwest U.S.;    water sources;    stable isotopes;    drought;   

DOI  :  10.3389/ffgc.2023.1116786

 received in 2022-12-05, accepted in 2023-03-06,  发布年份 2023

来源: Frontiers

【 摘 要 】

Forest dynamics in arid and semiarid regions are sensitive to water availability, which is becoming increasingly scarce as global climate changes. The timing and magnitude of precipitation in the semiarid southwestern U.S. (“Southwest”) has changed since the 21st century began. The region is projected to become hotter and drier as the century proceeds, with implications for carbon storage, pest outbreaks, and wildfire resilience. Our goal was to quantify the importance of summer monsoon precipitation for forested ecosystems across this region. We developed an isotope mixing model in a Bayesian framework to characterize summer (monsoon) precipitation soil water recharge and water use by three foundation tree species (Populus tremuloides [aspen], Pinus edulis [piñon], and Juniperus osteosperma [Utah juniper]). In 2016, soil depths recharged by monsoon precipitation and tree reliance on monsoon moisture varied across the Southwest with clear differences between species. Monsoon precipitation recharged soil at piñon-juniper (PJ) and aspen sites to depths of at least 60 cm. All trees in the study relied primarily on intermediate to deep (10-60 cm) moisture both before and after the onset of the monsoon. Though trees continued to primarily rely on intermediate to deep moisture after the monsoon, all species increased reliance on shallow soil moisture to varying degrees. Aspens increased reliance on shallow soil moisture by 13% to 20%. Utah junipers and co-dominant ñons increased their reliance on shallow soil moisture by about 6% to 12%. Nonetheless, approximately half of the post-monsoon moisture in sampled piñon (38-58%) and juniper (47-53%) stems could be attributed to the monsoon. The monsoon contributed lower amounts to aspen stem water (24-45%) across the study area with the largest impacts at sites with recent precipitation. Therefore, monsoon precipitation is a key driver of growing season moisture that semiarid forests rely on across the Southwest. This monsoon reliance is of critical importance now more than ever as higher global temperatures lead to an increasingly unpredictable and weaker North American Monsoon.

【 授权许可】

Unknown   
Copyright © 2023 Samuels-Crow, Peltier, Liu, Guo, Welker, Anderegg, Koch, Schwalm, Litvak, Shaw and Ogle.