Permafrost instability negates the positive impact of warming temperatures on boreal radial growth

• 成果类型: Article
• 署名作者: Alfaro-Sanchez, Raquel; Richardson, Andrew D.; Smith, Sharon L.; Johnstone, Jill F.; Turetsky, Merritt R.; Cumming, Steven G.; Moine, James M. Le; Baltzer, Jennifer L.
• 署名单位: Natural Resources Canada; Canadian Forest Service; Wilfrid Laurier University; Northern Arizona University; Northern Arizona University; Natural Resources Canada; Lands & Minerals Sector - Natural Resources Canada; Geological Survey of Canada; Yukon University; University of Alaska System; University of Alaska Fairbanks; University of Colorado System; University of Colorado Boulder; Laval University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-15324
• DOI: 10.1073/pnas.2411721121
• 发表日期: 2024-12-10
• 关键词: nonstructural carbon; forest; DYNAMICS; thaw; plants; LIMITS; availability; mechanisms; storage; stress

摘要

Climate warming can alleviate temperature and nutrient constraints on tree growth in boreal regions, potentially enhancing boreal productivity. However, in permafrost environments, warming also disrupts the physical foundation on which trees grow, leading to leaning trees or drunken forests. Tree leaning might reduce radial growth, undermining potential benefits of warming. Here, we found widespread radial growth reductions in southern latitude boreal forests since the 1980s. At mid latitudes, radial growth increased from similar to 1980 to similar to 2000 but showed recent signs of decline afterward. Increased growth was evident since the 1980 s at higher latitudes, where radial growth appears to be temperature limited. However, recent changes in permafrost stability, and the associated increased frequency of tree leaning events, emerged as a significant stressor, leading to reduced radial growth in boreal trees at the highest latitudes, where permafrost is extensive. We showed that trees growing in unstable permafrost sites allocated more nonstructural carbohydrate reserves to offset leaning which compromised radial growth and potential carbon uptake benefits of warming. This higher allocation of resources in drunken trees is needed to build the high- density reaction wood, rich in lignin, that is required to maintain a vertical position. With continued climate warming, we anticipate widespread reductions in radial our understanding of how climate warming and indirect effects, such as ground instability caused by warming permafrost, will affect boreal forest productivity in the future.