Vital Rates of Forest Dynamics Driven by Traits and Performance of Trees

Schematic representation of the impact of climate-driven environmental changes on plant traits and thus on vital rates which in turn determine the composition of forest communities. Such impacts can be different on the various biomes also due to the interaction with other drivers including genetics, tree-size, and ontogeny whose weight is variable and needs further research at multiscale levels.

Editorial

04 January 2023

Editorial: Vital rates of forest dynamics driven by traits and performance of trees

Veronica De Micco

and

Hans Beeckman

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Editors

Hans Beeckman

Royal Museum for Central Africa

Veronica De Micco

University of Naples Federico II

Impact

(A) Study area of five studied N. macrocarpa population (red is Santiago city). (B) BAI series of N. macrocarpa and annual total precipitation series by five sites for period 1950–2014. (C) Mean (bars) and SEM (segments) for the resilience components at each study site; Rt: Resistance, Rc: recovery, Rs: resilience, RRs: relative resilience. Different letters indicate significant difference between sites at 95% confidence level, while “ns” is not significative. (D) Relationship between precipitation and resilient components of N. macrocarpa five sites.

Original Research

28 February 2022

Tree-Ring Analysis and Genetic Associations Help to Understand Drought Sensitivity in the Chilean Endemic Forest of Nothofagus macrocarpa

Alejandro Venegas-González

, 4 more and

Pablo Fresia

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 of Nothofagus 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 of N. macrocarpa are 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 in N. macrocarpa and 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.

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12 citations

Original Research

14 January 2022

Montane Temperate-Boreal Forests Retain the Leaf Economic Spectrum Despite Intraspecific Variability

Matthew J. Hecking

, 3 more and

Julia I. Burton

Ordination of functional traits in relation to different taxonomic and structural groupings. (A) Ordination of individual trees by community type with functional traits overlaid. (B) Canopy openness for individual trees is highlighted using circle size, with species identified by color. (C) Life stage of individual trees is highlighted using circle size, with species identified by color. Sample size within the ordination is shown in the legend next the scientific name of the species. Trait acronyms; Specific leaf area (SLA), leaf area (LA), leaf dry matter content (LDMC), leaf nitrogen concentration (LNC), leaf phosphorous concentration (LPC), leaf nitrogen per unit area (Narea), stem specific density (SSD), leaf nitrogen to phosphorus ratio (N:P).

Trait-based analyses provide powerful tools for developing a generalizable, physiologically grounded understanding of how forest communities are responding to ongoing environmental changes. Key challenges lie in (1) selecting traits that best characterize the ecological performance of species in the community and (2) determining the degree and importance of intraspecific variability in those traits. Recent studies suggest that globally evident trait correlations (trait dimensions), such as the leaf economic spectrum, may be weak or absent at local scales. Moreover, trait-based analyses that utilize a mean value to represent a species may be misleading. Mean trait values are particularly problematic if species trait value rankings change along environmental gradients, resulting in species trait crossover. To assess how plant traits (1) covary at local spatial scales, (2) vary across the dominant environmental gradients, and (3) can be partitioned within and across taxa, we collected data on 9 traits for 13 tree species spanning the montane temperate—boreal forest ecotones of New York and northern New England. The primary dimension of the trait ordination was the leaf economic spectrum, with trait variability among species largely driven by differences between deciduous angiosperms and evergreen gymnosperms. A second dimension was related to variability in nitrogen to phosphorous levels and stem specific density. Levels of intraspecific trait variability differed considerably among traits, and was related to variation in light, climate, and tree developmental stage. However, trait rankings across species were generally conserved across these gradients and there was little evidence of species crossover. The persistence of the leaf economics spectrum in both temperate and high-elevation conifer forests suggests that ecological strategies of tree species are associated with trade-offs between resource acquisition and tolerance, and may be quantified with relatively few traits. Furthermore, the assumption that species may be represented with a single trait value may be warranted for some trait-based analyses provided traits were measured under similar light levels and climate conditions.

2,904 views

7 citations