The difference between above‐ and below‐ground self‐thinning lines in forest communities

Quantifying the self‐thinning process in various plant communities has been a long‐standing issue in both theoretical and empirical studies. Most studies on plant self‐thinning have centered only on aboveground parts, and rarely on belowground parts. There is still a general lack of comparison between above‐ and belowground self‐thinning processes, especially for forest communities. The fundamental mechanistic difference and the functional association between above‐ and belowground competition indicate that the self‐thinning process of belowground parts may be different from that of aboveground parts. We investigated the self‐thinning lines for above‐ground ( M A ), below‐ground ( M B ), and total biomass ( M T ), respectively, across forest communities in China. The results showed that neither the classical self‐thinning rule (−3/2 exponent) nor the universal scaling rule (−4/3 exponent) can apply to all the self‐thinning relationships across these forest communities and that the self‐thinning lines for belowground biomass were flatter and lower than those for aboveground biomass across most of these forest communities.