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.

植物功能性状作为连接植物、环境与生态系统功能的桥梁，在预测生态修复过程中生态系统功能的变化方面发挥着重要作用。然而，生态修复背景下植物功能性状对草原生态系统功能的影响仍不明确。因此，本研究选取株高（plant height, H）、比叶面积（specific leaf area, SLA）、叶干物质含量（leaf dry matter content, LDMC）、根长（root length, RL）及根干物质含量（root dry matter content, RDMC）共5种植物功能性状，采用群落加权均值（community-weighted mean, CWM）与功能性状多样性分析方法，结合10项与生态系统功能相关的指标，探究了4种生态修复模式下的植物功能性状与生态系统功能差异，这4种模式分别为鸭茅（*Dactylis glomerata*，DG）、多年生黑麦草（*Lolium perenne*，LP）、多年生黑麦草+白三叶（*Lolium perenne* + *Trifolium repens*，LT）以及天然草原（natural grassland, NG）。本研究结果如下：1）鸭茅与多年生黑麦草样地的植物物种Margalef丰富度指数、Shannon-Wiener多样性指数均显著低于天然草原（*P*<0.05），而Simpson优势度指数则显著高于天然草原（*P*<0.05）。2）鸭茅、多年生黑麦草及混播样地的CWM株高、CWM叶干物质含量与CWM根干物质含量均显著高于天然草原，而CWM比叶面积则显著低于天然草原（*P*<0.05）；鸭茅与多年生黑麦草样地的功能丰富度指数（FRic）显著高于天然草原与混播样地，但功能分散度指数（FDis）与Rao二次熵指数（RaoQ）则显著低于天然草原与混播样地（*P*<0.05），但鸭茅与多年生黑麦草之间、天然草原与混播样地之间均无显著差异（*P*>0.05）。3）多年生黑麦草+白三叶混播草原（LT）生态系统的生产力、碳储量、水源涵养与水土保持功能均为最高，而天然草原（NG）生态系统的上述功能则最低。4）CWM叶干物质含量（*F*=56.7，*P*=0.024）、CWM根长（*F*=28.7，*P*=0.024）及CWM株高（*F*=4.5，*P*=0.048）是影响生态系统功能的主要调控因子。研究表明，多年生黑麦草与白三叶的混播草地更利于生态系统功能的修复，可为喀斯特退化生态系统的植被构建、资源高效利用与可持续发展提供科学依据。