Low growth resilience to drought is related to future mortality risk in trees

Lucía Desoto ,Gabriel Sangüesa‐Barreda ,Frank J Sterck ,Maxime Cailleret ,Ricardo Villalba ,Laurel J Haavik ,Mariano M Amoroso ,Tom Levanič ,Christof Bigler ,J Julio Camarero ,Αλέξανδρος Παπαδόπουλος ,Dejan Stojanović ,Guillermo Gea‐Izquierdo ,Tamir Klein ,Juan Carlos Linares ,K Krämer ,Jeffrey M Kane ,В И Харук ,Katarina Čufar ,Ana‐Maria Hereș ,Steven Jansen ,Thomas Kitzberger ,Elisabeth M R Robert ,Brigitte Rohner ,Sten Gillner ,Walter Oberhuber ,Harri Mäkinen ,Tuomas Aakala ,María Laura Suárez ,Jordi Martínez‐Vilalta

doi:10.1038/s41467-020-14300-5

Abstract

Severe droughts have the potential to reduce forest productivity and trigger tree mortality. Most trees face several drought events during their life and therefore resilience to dry conditions may be crucial to long-term survival. We assessed how growth resilience to severe droughts, including its components resistance and recovery, is related to the ability to survive future droughts by using a tree-ring database of surviving and now-dead trees from 118 sites (22 species, >3,500 trees). We found that, across the variety of regions and species sampled, trees that died during water shortages were less resilient to previous non-lethal droughts, relative to coexisting surviving trees of the same species. In angiosperms, drought-related mortality risk is associated with lower resistance (low capacity to reduce impact of the initial drought), while it is related to reduced recovery (low capacity to attain pre-drought growth rates) in gymnosperms. The different resilience strategies in these two taxonomic groups open new avenues to improve our understanding and prediction of drought-induced mortality.

Highlights

Severe droughts have the potential to reduce forest productivity and trigger tree mortality
Our results show that trees that died because of drought were less resilient to previous droughts occurring decades before their death, relative to coexisting surviving trees of the same species (Fig. 2a)
This pattern is observed across the variety of regions we studied and for most of the species we sampled (Fig. 1 and Supplementary Fig. 4) and it is consistent for both gymnosperms and angiosperms (Table 1 and Supplementary Table 1)

Summary

Introduction

Severe droughts have the potential to reduce forest productivity and trigger tree mortality. We assessed how growth resilience to severe droughts, including its components resistance and recovery, is related to the ability to survive future droughts by using a tree-ring database of surviving and now-dead trees from 118 sites (22 species, >3,500 trees). Growth resilience can be defined as the capacity of a tree to reach growth rates similar to those prior to drought Defined this way, resilience encompasses the capacity to reduce the impact of the disturbance, i.e. resistance, and the ability to return to pre-disturbance growth levels after drought, i.e. recovery[32,33]. Resilience encompasses the capacity to reduce the impact of the disturbance, i.e. resistance, and the ability to return to pre-disturbance growth levels after drought, i.e. recovery[32,33] These two components of resilience may vary within taxonomic groups. Based on mixed-effect models, we analysed the relationships between these three resilience indices and future mortality risk, accounting for the effects of taxonomic group (angiosperms vs. gymnosperms) and several variables characterising environmental conditions and tree size (see “Methods”)

Methods

Results

Conclusion