Do phylogenetic and environmental factors drive the altitudinal variation in absorptive root traits at the species and community levels?

AimsAlthough the variation in absorptive root traits at the species level and driving factors has received a lot of attention, it is still unknown how community-level root traits vary along the environmental gradients.MethodsIn this study, absorptive fine roots of 69 woody plants from four forest vegetation on the northern slope of Taibai Mountain were collected, and four root traits (including morphological and chemical traits) were measured.ResultsAt the species level, absorptive root traits, except root nitrogen concentration (RNC), did not change along altitudinal gradients. A large proportion of variation in root diameter (RD), specific root length (SRL) and root tissue density (RTD) was attributed to phylogenetic taxonomy (clade, 39.47-60.72%). Differently, community-level absorptive roots at birch forest exhibited thinner RDc and lesser RNCc but longer SRLc and greater RTDc than other altitudes, which were mainly influenced by the climatic (aridity index) and soil factors (soil available P and nitrate concentration). Moreover, unlike root economic space, community-level root traits were divided into the morphological (including RDc, SRLc and RTDc) and chemical (including RNCc) dimensions.ConclusionsOur results indicate that the response of community-level root traits to climatic and soil factors is more significant compared to species-level root traits. Future studies should incorporate community-level root traits into global vegetation distribution models.