Abstract
Extreme drought events have increased in frequency during the 20th century triggered by global change. Thus, understanding tree-growth resilience across different terrestrial biomes has become a key goal in forest ecology. Here, we evaluate the tree-growth resilience to severe drought in the only Mediterranean-type Ecosystems of South America, using five isolated populations ofNothofagus macrocarpa. For each tree, in each sampling site, we obtained wood cores and fresh leaves for dendrochronological and population genetic analysis, respectively. An evaluation was conducted on growth resilience components in response to the most extreme drought of the 20th century in central Chile (i.e., 1968, with ∼80% of rainfall deficit), and the influence of genetic variability, biogeography, and tree size. We hypothesize that even though current remnant populations ofN. macrocarpaare small and isolated, they have locally withstood changes in climate, and that they will be genetically diverse and have a high resilience to extreme droughts. We used nuclear microsatellite markers to estimate tree genetic variability inN. macrocarpaand investigate its correlation with phenotypic traits. We found a higher resistance in the two southernmost populations (mesic sites) than in the three northern populations (xeric sites), however those three xeric populations showed a higher recovery. In addition, a significant clear positive linear correlation between precipitation and resistance, and a negative recovery and relative resilience of tree growth to the extreme drought event of 1968 can be seen. High diversity for simple sequence repeats (SSR) markers was observed, although no population structure was inferred. Southern populations had a higher number of private alleles, which may be an indication of their long-lasting persistence under mesic conditions. Therefore, differences in resilience components are mainly explained by tree size and sites influences, but not genetic diversity. We concluded that observed differences in tree-growth resilience among sites can be explained by a great deal of phenotypic plasticity, fostered by genetically diverse gene pools. We advocate for a genome-wide analysis (i.e., SNP) so as to identify genomic regions correlated with phenotypic traits in order to improve the understanding of the evolutionary processes that shaped this forest resilience over time.
Highlights
IntroductionRecent global warming has favored droughts (i.e., belowaverage precipitations and increased atmospheric evaporation) and desertification in most Mediterranean and temperate biome (Ahmed et al, 2013; Tsakiris, 2017; McDowell et al, 2020), but precipitation has increased in other regions, such as central Asia (Chen et al, 2021)
Recent global warming has favored droughts and desertification in most Mediterranean and temperate biome (Ahmed et al, 2013; Tsakiris, 2017; McDowell et al, 2020), but precipitation has increased in other regions, such as central Asia (Chen et al, 2021)
Based on basal area increment (BAI), we considered four resilience components (“resistance”-Rt, “recovery”-Rc, “resilience”-Rs, and “relative resilience”-RRs) to assess the extent to which tree growth can return to their pre-disturbance equilibrium, i.e., engineering resilience (Nikinmaa et al, 2020)
Summary
Recent global warming has favored droughts (i.e., belowaverage precipitations and increased atmospheric evaporation) and desertification in most Mediterranean and temperate biome (Ahmed et al, 2013; Tsakiris, 2017; McDowell et al, 2020), but precipitation has increased in other regions, such as central Asia (Chen et al, 2021). Understanding how it influences tree growth and forest productivity across different terrestrial biomes has become a major aim of forest ecology research (Anderegg et al, 2015; Gazol et al, 2017a). There is still no agreement on the relationship between individual genetic diversity and tree growth, with positive relationships (e.g., Rodríguez-Quilón et al, 2015; Neophytou et al, 2016; González-Díaz et al, 2020) or no associations (Babushkina et al, 2016; Johnson et al, 2017)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
