Two dimensions define the variation of fine root traits across plant communities under the joint influence of ecological succession and annual mowing

International audience1.Quantifying the variation in community-level fine root (40 year old plots) and possessed opposite trait values. Root nitrogen concentration (RNC) did not vary across communities along the succession. The trait values at community-level were not affected by mowing, except for a reduction in root mass density.4.We found covariation of fine root traits across communities along two dimensions: the first dimension (60% of total variation) represented changes in root foraging capacity (related to SRL) and resource conservation (related to RDMC, RCC, mean root diameter) whereas the second dimension (17 to 20% of the variation) represented variations in RNC, potentially related to root respiration and metabolism.5.SRL and SLA (specific leaf area) were correlated regardless of the mowing regime, but there was no analogous relationship between LDMC (leaf dry matter content) and RDMC in mown communities, showing a decoupling in the investment in tissue density above and belowground.6.Synthesis. Our study demonstrates coordinated variations of community-level fine root traits along a succession gradient and provides evidence that fine root traits covaried along two-dimensions, regardless of mowing regime. The relationship between LDMC and RDMC observed in unmown communities was modified by mowing, reflecting an uncoupled response to mowing