Root structure and function could be affected by both climate and mycorrhizal type. However, how these two aspects jointly mediate the root structure-function relationships at the global scale remains unknown. Here we compiled a dataset of 145 species to unravel the effects of climate and mycorrhizas on fine root structure-function relationships.
Results/Conclusions
Our results showed that fine root respiration (FRR) was positively correlated with specific root length (SRL) and root tissue nitrogen content (RNC), but negatively with root diameter and root tissue density (RTD) for both arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) plants. The effects of climate (mean annual temperature and precipitation) on FRR and RNC were inconsistent between AM and EM, while those on SRL, root diameter and RTD were similar between the two mycorrhizal types. Interestingly, EM species had higher RNC and RTD than AM ones, largely owing to a larger proportional and more recalcitrant tissue, which made the EM species consume 2.45, 2.14 and 1.83 times more carbon for constructing RNC, SRL and RTD than AM ones did. Among these variables, RNC, RTD and mycorrhizal type were the most important factors explaining the variance in FRR. Results based on structural equation modeling also confirmed that climate and mycorrhizal types could jointly mediate the fine root traits-function relationships. These results highlighted that the mycorrhizal type is important to fine root function and should be integrated into global carbon cycles models for improving the prediction of future carbon dynamics.