Effects of plant functional traits on grassland ecosystem function in the karst desertification control area

Plant functional traits, as a bridge between plant, environment and ecosystem function, play an important role in predicting the changes of ecosystem function during ecological restoration. However, the effects of plant functional traits on grassland ecosystem function under the background of ecological restoration remains unclear. Therefore, in this study, we selected 5 plant functional traits of plant height (H), specific leaf area (SLA), leaf dry matter content (LDMC), root length (RL) and root dry matter content (RDMC), used community-weighted mean (CWM) and functional trait diversity, and combined with 10 indexes related to ecosystem function to investigate the differences in plant functional traits and ecosystem functions of four ecological restoration models (<em>Dactylis glomerata</em> (DG), <em>Lolium perenne</em> (LP), <em>Lolium perenne</em> + <em>Trifolium repens</em> (LT) and natural grassland (NG) ). We found that: 1) Margalef index and Shannon-Wiener index of plant species in DG and LP were significantly lower than those in NG (<em>P</em> &lt;0.05), while Simpson index was significantly higher than that in NG (<em>P</em> &lt;0.05). 2) CWMH, CWMLDMC and CWMRDMC in DG, LP and LT were significantly higher than those in NG, but CWMSLA was significantly lower than that in NG (<em>P</em>&lt;0.05). Functional richness index (FRic) in DG and LP was significantly higher than that in NG and LT, but functional dispersion index (FDis) and Rao’s quadratic entropy index (RaoQ) were significantly lower than that in NG and LT (<em>P</em>&lt;0.05), but there was no significant difference between DG and LP, NG and LT (<em>P</em>&gt;0.05). 3) The system productivity, carbon storage, water conservation and soil conservation function in LT grassland ecosystem were the highest, and they were the lowest in NG grassland ecosystem. 4) CWMLDMC (F=56.7, P=0.024), CWMRL (F=28.7, P=0.024), and CWMH (F=4.5, P=0.048) were the main factor affecting ecosystem function. The results showed that the mixed pasture of perennial ryegrass and white clover was more beneficial to the restoration of ecosystem function, which provided scientific basis for vegetation construction, resource maximum utilization and sustainable development of karst degraded ecosystem.