The latitudinal pattern of fine root intraspecific trait variation among species in plant communities.

Intraspecific trait variation (ITV) drives plant species performance in natural communities and can have substantial influences on multiple ecological processes. However, current studies on plant belowground (root) ITV are limited in trait coverage, spatial scale and biome type. Here, by conducting in-situ measurements of root traits in three forests from temperate to subtropics and compiling a large-scale dataset of root traits, we explore the latitudinal pattern of root ITV among species within natural plant community, its drivers and implications. Our results show that intraspecific variation constitute a substantial component of the total variation in root traits, and the physiological trait, root exudation, exhibit the highest ITV among traits. The extent of root ITV tends to increase with root diameter across species, with thick-root species having higher root ITV than thin-root species. We also find a significant latitudinal gradient for species' intraspecific root trait variation in natural communities, with increasing ITV towards the equator. These findings can simplify the incorporation of root ITV in trait-based ecology, and contribute to understanding of plant species performance and community assembly under environmental changes.