Root trait variation of seed plants from China and the primary drivers

Abstract

Aim Root traits play important roles in plant growth and ecosystem processes. Clarifying the primary drivers of variation in root traits is indispensable for understanding and predicting ecosystem responses to environmental changes. Location China. Taxon Seed plant species. Methods We compiled six key first‐order root traits of 437 seed plant species from different biomes, phylogenetic affiliations, plant growth forms and mycorrhizal types in China. The six root traits included root diameter (RD), root tissue density (RTD), specific root length (SRL), root C content (RCC), root N content (RNC) and root C:N ratio (RCN), which are highly relevant for plant growth rate and resource acquisition. The phylogenetic linear mixed model was employed to examine the effects of climate and soil variables on root traits and to quantify the relative contributions of environment, phylogeny, plant growth form and mycorrhizal type to root trait variation. Results Environment explained most of the variations in RTD and RCC (37.4% and 24.2%, respectively). Mean precipitation of the wettest quarter and mean diurnal temperature range were the main climate drivers of RTD and RCC, respectively. Phylogeny contributed the most to the variation in RD, RNC and RCN (27.0%–52.3%). SRL showed strong links to both environment and phylogeny (35.0% and 27.8%, respectively). However, plant growth form and mycorrhizal type had little effect on root trait variation (<6.0%). Main conclusions Our study revealed the primary drivers of variations in different root traits of seed plants in China. Climate variability and seasonality variables were more important factors driving root trait variation than the annual averages of temperature and precipitation. Incorporating the different responses of root traits to changing environments and phylogenetic affiliations observed in the present study into terrestrial ecosystem models will improve our ability to predict future vegetation distribution and ecosystem functions under global change.

Evidence of Differences in Covariation Among Root Traits Across Plant Growth Forms, Mycorrhizal Types, and Biomes

“…However, we observed that RNC was strongly associated with RCN, whereas RCC was not. This indicated that RNC, rather than RCC, was more important in the trade-offs between C investment and resource uptake in roots (An et al, 2021). Our results is not consistent with the global and regional studies (Kramer-Walter et al, 2016;Wang et al, 2018a;McCormack and Iversen, 2019;Bergmann et al, 2020), we found that the RES explained the most variation of root traits and the trade-off between RD and SRL loaded on the second axis in China, suggesting that root trait covariation may not be generalized from global-scale and other regional analyses.…”