Are absorptive root traits good predictors of ecosystem functioning? A test in a natural temperate forest

Abstract

Trait-based approaches provide a useful framework to predict ecosystem functions under intensifying global change. However, our current understanding of trait-functioning relationships mainly relies on aboveground traits. Belowground traits (e.g. absorptive root traits) are rarely studied although these traits are related to important plant functions.We analyzed four pairs of analogous leaf and absorptive root traits of woody plants in a temperate forest and examined how these traits are coordinated at the community-level, and to what extent the trait covariation depends on local-scale environmental conditions. We then quantified the contributions of leaf and absorptive root traits and the environmental conditions in determining two important forest ecosystem functions, aboveground carbon storage, and woody biomass productivity.The results showed that both morphological trait pairs and chemical trait pairs exhibited positive correlations at the community level. Absorptive root traits show a strong response to environmental conditions compared to leaf traits. We also found that absorptive root traits were better predictors of the two forest ecosystem functions than leaf traits and environmental conditions.Our study confirms the important role of belowground traits in modulating ecosystem functions and deepens our understanding of belowground responses to changing environmental conditions.

Tree growth is better explained by absorptive fine root traits than by transport fine root traits

“…By contrast, Da et al (2023) found that the conservation gradient of absorptive root traits explained forest aboveground carbon storage and woody biomass productivity better than conservation gradients in leaves and absorptive root collaboration gradients. Although few existing studies have been restricted to absorptive fine root trait effects on tree growth, the simultaneous effects of absorptive and transport root traits have so far been unexplored.…”

“…Shen et al (2022) showed that acquisitive leaf traits had a higher explanatory power than fine root traits for relative growth rates for height across tree species, even though SRL and RTD were significantly correlated with the relative growth rates for height of individuals. By contrast, Da et al (2023) found that the conservation gradient of absorptive root traits explained forest aboveground carbon storage and woody biomass productivity better than conservation gradients in leaves and absorptive root collaboration gradients. Although few existing studies have been restricted to absorptive fine root trait effects on tree growth, the simultaneous effects of absorptive and transport root traits have so far been unexplored.…”

“…Consequently, there has been a lot of interest in identifying the relationship between leaf functional traits and forest functioning (Gibert et al, 2016; Paine et al, 2015; Poorter & Bongers, 2006). For instance, along with the leaf economic spectrum, tree annual growth was positively related to acquisitive traits, characterised by a high specific leaf area (SLA) and stomatal density in subtropical forests (Liu et al, 2015), and a high leaf nitrogen content and SLA in temperate forests (Da et al, 2023). In principle, such relationships have been attributed to higher photosynthetic capacity and a higher potential for a quick return on investment of resources in fast-growing species, leading to a higher growth rate (Reich, 2014; Wright et al, 2004).…”

“…However, our understanding of the relative importance of fine root traits for tree growth lags behind that of leaf traits, partly due to the difficulty of sampling and/or measuring root traits (Freschet, Roumet, et al, 2021). A few recent studies have examined the explanatory power of root traits—in combination with leaf traits—on tree growth, in which for fine roots they focused only on the first three root orders (Shen et al, 2022; Weemstra et al, 2021) or the first two root orders (Da et al, 2023). Shen et al (2022) showed that acquisitive leaf traits had a higher explanatory power than fine root traits for relative growth rates for height across tree species, even though SRL and RTD were significantly correlated with the relative growth rates for height of individuals.…”

Chronic anthropogenic disturbance mediates the biodiversity‐productivity relationship across stand ages in a large temperate forest region

“…Da et al. (2023) found that root traits emerged as more effective predictors of forest ecosystem functions compared to leaf traits. In addition, recent studies have indicated distinct responses of leaf and root traits to environmental conditions, underscoring their divergent strategies in coping with various and intricate environmental constraints (Isaac et al., 2017).…”