J Plant Ecol ›› 2020, Vol. 13 ›› Issue (2): 157-164.DOI: 10.1093/jpe/rtz057

• Research Articles • Previous Articles     Next Articles

Species turnover drives grassland community to phylogenetic clustering over long-term grazing disturbance

Juntao Zhu1,2 , Yangjian Zhang1,3,4, *, Wenfeng Wang5 , Xian Yang2 , Ning Chen1 , Ruonan Shen1 , Li Wang6 and Lin Jiang2   

  1. 1 Lhasa Plateau Ecosystem Research Station, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China, 2 School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA, 3 CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China, 4 College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China, 5 Tibet Academy of Agricultural and Animal Husbandry Science, Lhasa 850032, China, 6 Shenzhen Graduate School, Peking University, Shenzhen 518000, China

    *Corresponding author. E-mail: zhangyj@igsnrr.ac.cn
  • Received:2019-09-04 Revised:2019-12-07 Accepted:2019-12-18 Online:2019-12-23 Published:2020-04-01

Abstract:

Aims

Grazing exerts profound effects on grassland ecosystem service and functions by regulating species composition and diversity, and structuring community assembly worldwide. However, adaptions of phylogenetic diversity and phylogenetic community structure to long-term grazing disturbance remain poorly studied, especially for ecosystems distributed in extreme environments.

Methods

Here, we conducted an experiment with multigrazing intensities to explore the impacts of grazing disturbance on plant phylogenetic diversity and community structure in an alpine grassland of the Tibetan Plateau.

Important Findings

Grazing disturbance enriched plant species richness (SR), and stimulated species turnover from regional species pool, consequently changing community species composition. Under low intensities, grazing exerted no obvious effects on phylogenetic diversity and community structure, whereas communities changed from overdispersion to clustering under high grazing intensity. High grazing intensity resulted in stronger environmental filtering, which consequently selected those species with high resilience to grazing disturbance. The observed clustering structure was associated with the colonizing species which were closely related to resident species, and locally extinct species, and distantly related to residents. At the plant functional trait level, high grazing intensity increased species colonization largely by altering the effect of root depth on species colonization compared to light grazing. Our results highlight that solely utilization of SR and diversity cannot fully represent grassland communities responses to grazing. The effects of species turnover on community phylogenetic diversity and structure are entailed to be explored in the future grazing studies.

Key words: alpine grassland, grazing, phylogenetic diversity, phylogenetic community structure, species richness

摘要:
放牧通过改变草地群落物种组成和生物多样性,进而影响草地群落结构,对草地生态系统服务和功能产生深远的影响。然而,有关系统发育多样性和系统发育群落结构对长期放牧干扰的响应和适应的研究仍然很少,尤其是对于分布在极端环境中的生态系统。我们在青藏高原高寒草地上开展了多放牧强度的试验,探讨放牧干扰对植物系统发育多样性和群落结构的影响。研究发现,放牧干扰增加了植物群落的物种丰富度,促进了群落物种周转,从而改变了群落物种组成。低强度放牧对系统发育多样性和群落结构没有显著影响,而高强度放牧促使群落结构由分散向聚集变化。高强度放牧通过强烈的环境过滤作用,选择了一些耐牧的草地植物物种。在高强度放牧条件下,草地群落的聚集结构由近缘种的入侵和远缘种的丢失共同驱动。在植物功能性状水平上,我们发现与低强度放牧相比,高强度放牧通过改变根系深度对物种入侵产生影响,在很大程度上提升了物种的入侵性。我们的研究强调,仅仅利用物种丰富度和多样性并不能全面反映放牧干扰对草地群落的影响,而且在以后的放牧生态学研究中应该更加关注物种周转对群落系统发育多样性和群落结构的影响。

关键词: 高山草原, 放牧, 系统发育多样性, 系统发育群落结构, 物种丰富度