Yang Yuting, Chen Zhifei, Xu Bingcheng, Wei Jiaqi, Zhu Xiaoxu, Yao Hongbin, Wen Zhongming
College of Grassland Agriculture, Northwest A&F University, Yangling 712100, China.
College of Life Sciences, Guizhou University, Guiyang 550025, China.
Plants (Basel). 2022 Aug 4;11(15):2045. doi: 10.3390/plants11152045.
Grassland is the dominant vegetation type in the Loess Plateau, and grassland productivity and processes are limited by nitrogen (N) and phosphorus (P). Studies have shown that productivity would change following fertilization in the grassland. The response of productivity to fertilization mainly depends on the dominant species traits. Trait-based methods provide a useful tool for explaining the variations in grassland productivity following fertilization. However, the relative contribution of plant functional traits to grassland productivity under N and P addition in the Loess Plateau is not clear. We measured aboveground biomass (AGB) and leaf N content (LN), leaf P content (LP), leaf N/P ratio (LN/P), specific leaf area (SLA), leaf tissue density (LTD), leaf dry matter content (LDMC), and maximum plant height (H) to study how these plant functional traits regulate the relative biomass of different species and grassland productivity following fertilization. Our results showed, that under different nutrient addition levels, the linkages between plant functional traits and the relative biomass of different species were different. Community AGB was positively related to community-weighted mean LN (CWM_LN), CWM_LN/P, CWM_SLA, and CWM_H, but negatively related to CWM_LTD and CWM_LDMC. Dominant species traits largely determined grassland productivity, in line with the mass ratio hypothesis. These findings further highlight the close linkages between community-level functional traits and grassland productivity. Our study contributes to the mechanisms underlying biodiversity-ecosystem function relationships and has significance for guiding semiarid grassland management.
草地是黄土高原的主要植被类型，草地生产力及其过程受氮（N）和磷（P）的限制。研究表明，施肥后草地生产力会发生变化。生产力对施肥的响应主要取决于优势物种的特性。基于性状的方法为解释施肥后草地生产力的变化提供了有用的工具。然而，在黄土高原地区，添加氮和磷条件下植物功能性状对草地生产力的相对贡献尚不清楚。我们测量了地上生物量（AGB）、叶片氮含量（LN）、叶片磷含量（LP）、叶片氮磷比（LN/P）、比叶面积（SLA）、叶片组织密度（LTD）、叶片干物质含量（LDMC）和植株最大高度（H），以研究这些植物功能性状如何调节施肥后不同物种的相对生物量和草地生产力。我们的结果表明，在不同养分添加水平下，植物功能性状与不同物种相对生物量之间的联系各不相同。群落AGB与群落加权平均LN（CWM_LN）、CWM_LN/P、CWM_SLA和CWM_H呈正相关，但与CWM_LTD和CWM_LDMC呈负相关。优势物种特性在很大程度上决定了草地生产力，这与质量比假说相符。这些发现进一步突出了群落水平功能性状与草地生产力之间的紧密联系。我们的研究有助于揭示生物多样性与生态系统功能关系的潜在机制，对指导半干旱草地管理具有重要意义。
