Biodiv Sci ›› 2022, Vol. 30 ›› Issue (2): 21419.  DOI: 10.17520/biods.2021419

• Original Papers: Plant Diversity • Previous Articles     Next Articles

Plant community assembly processes and key drivers in an arid inland river basin

Yin Wang1,2, Jianming Wang1,2, Mengjun Qu1,2, Jingwen Li1,2,*()   

  1. 1 School of Ecology and Nature Conservation, Beijing Forestry University, Beijing 100083
    2 Ejina Institute of Populus euphratica, Beijing Forestry University, Alxa, Inner Mongolia 735400
  • Received:2021-10-21 Accepted:2021-11-18 Online:2022-02-20 Published:2022-02-28
  • Contact: Jingwen Li
  • About author:*E-mail:


Aims One of the determinants of water availability in drylands, groundwater plays a fundamental role in regulating plant traits, phylogeny, and community assemblage. However, considerable uncertainties exist regarding how groundwater depth influences the relative importance of community assembly process in plant communities, as well as how the influence differs among the above- and belowground components.

Methods By using the leaf and root functional traits, in addition to associated environmental factors in 230 plant communities in the lower reaches of an arid inland river basin, we attempted to uncover how the pattern of the community assembly process varied along a depth gradient of groundwater and the key drivers of this variation.

Results (1) Across all study sites, we found that the standard effect size of Rao’s quadratic entropy (SES.RaoQ) of leaf and root functional diversity determined using the plant individual species, mean functional traits and phylogenetic information was significantly less than zero. Functional clustering was pervasive among plant communities (90% of the traits). (2) Groundwater depth and soil variables together explained 13%-39% and 14%-48% of the variation in SES.RaoQ determined using leaf and root traits, respectively, and groundwater depth individually explained 13%-22% and 14%-36% of the variation. (3) The SES.RaoQ determined using leaf and root traits decreased as mean groundwater depth decreased, but it increased with increased groundwater depth seasonality. Root traits showed a faster shift in SES.RaoQ along groundwater depth gradients than leaf traits.

Conclusion Plant communities in an arid inland river basin are primarily affected by deterministic processes, which supports the niche theory. Most plant communities exhibited functional clustering. Groundwater depth is the key factor determining the relative importance of the community assembly process of plant communities. With the decrease of groundwater depths, the functional structure changes from a pattern of mostly overdispersion to a pattern of clustering. The variation in aboveground functional structure along groundwater gradients is highly consistent with that of the belowground functional structure, but the belowground component of plant communities may be more sensitive to changes in groundwater depth.

Key words: community assembly, leaf, root, groundwater depth, arid inland river basin