DataSheet_1_Perennial herb diversity contributes more than annual herb diversity to multifunctionality in dryland ecosystems of North-western China.docx

BackgroundConsiderable attention has been given to how different aspects of biodiversity sustain ecosystem functions. Herbs are a critical component of the plant community of dryland ecosystems, but the importance of different life form groups of herbs is often overlooked in experiments on biodiversity-ecosystem multifunctionality. Hence, little is known about how the multiple attributes of diversity of different life form groups of herbs affect changes to the multifunctionality of ecosystems.
MethodsWe investigated geographic patterns of herb diversity and ecosystem multifunctionality along a precipitation gradient of 2100 km in Northwest China, and assessed the taxonomic, phylogenetic and functional attributes of different life form groups of herbs on the multifunctionality.
ResultsWe found that subordinate (richness effect) species of annual herbs and dominant (mass ratio effect) species of perennial herbs were crucial for driving multifunctionality. Most importantly, the multiple attributes (taxonomic, phylogenetic and functional) of herb diversity enhanced the multifunctionality. The functional diversity of herbs provided greater explanatory power than did taxonomic and phylogenetic diversity. In addition, the multiple attribute diversity of perennial herbs contributed more than annual herbs to multifunctionality.
ConclusionsOur findings provide insights into previously neglected mechanisms by which the diversity of different life form groups of herbs affect ecosystem multifunctionality. These results provide a comprehensive understanding of the relationship between biodiversity and multifunctionality, and will ultimately contribute to multifunctional conservation and restoration programs in dryland ecosystems.

**背景**：生物多样性（biodiversity）的不同维度如何维持生态系统功能（ecosystem functions），一直是生态学领域广受关注的研究方向。草本植物是旱地生态系统（dryland ecosystems）植物群落的核心组成部分，但在生物多样性-生态系统多功能性（biodiversity-ecosystem multifunctionality）相关实验中，不同生活型群（life form groups）草本的功能重要性常被忽视。因此，目前对不同生活型群草本的多样性多维度属性如何影响生态系统多功能性（ecosystem multifunctionality）变化的认知仍较为匮乏。
**方法**：本研究沿中国西北2100公里的降水梯度，调查了草本植物多样性与生态系统多功能性的地理分布格局，并评估了不同生活型群草本的分类学（taxonomic）、系统发育（phylogenetic）及功能（functional）多样性属性对生态系统多功能性的影响。
**结果**：研究发现，一年生草本（annual herbs）的从属种（介导丰富度效应（richness effect））与多年生草本（perennial herbs）的优势种（介导质量比效应（mass ratio effect））是驱动生态系统多功能性的关键类群。最为重要的是，草本植物多样性的多维度属性（分类学、系统发育及功能维度）可显著提升生态系统多功能性；其中，草本功能多样性（functional diversity）对生态系统多功能性的解释力优于分类学多样性与系统发育多样性。此外，多年生草本的多维度多样性对生态系统多功能性的贡献度高于一年生草本。
**结论**：本研究揭示了此前被忽视的不同生活型群草本多样性影响生态系统多功能性的内在机制。研究结果深化了对生物多样性与多功能性关系的全面认知，可为旱地生态系统的多功能保护与修复工程提供理论支撑。