Chin J Plant Ecol ›› 2019, Vol. 43 ›› Issue (1): 16-26.DOI: 10.17521/cjpe.2018.0119

• Research Articles • Previous Articles     Next Articles

Variation and correlation of plant functional traits in the riparian zone of the Lijiang River, Guilin, Southwest China

LIANG Shi-Chu,LIU Run-Hong,RONG Chun-Yan,CHANG Bin,JIANG Yong()   

  1. Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection, Ministry of Education, Guangxi Normal University/College of Life Science, Guangxi Normal University, Guilin, Guangxi 541006, China
  • Received:2018-05-20 Accepted:2018-12-08 Online:2019-01-20 Published:2019-04-25
  • Contact: JIANG Yong
  • Supported by:
    Supported by the National Science and Technology Pillary Program during the Twelfth Five-year Plan Period of China(2012BAC16B03);the National Natural Science Foundation of China(31860124)

Abstract:

Aims Patterns of variation in plant functional traits and the correlation among them are important for understanding species coexistence and the maintenance of biodiversity. Our objectives in this study were to understand how variation and correlation of plant functional traits, at both the species and community levels, influence 1) plants adaptation to changing environments, and 2) the mechanisms of community assembly.
Methods We investigated species composition of riparian plant communities in 36 plots along the longitudinal gradient (represented by upstream, midstream, downstream) of the Lijiang River, Guilin, Southwest China. We measured three functional traits for 42 woody plant species: leaf area (LA), specific leaf area (SLA), and wood density (WD). For each plant community, we calculated 1) species abundance-weighted mean community trait values, and 2) species-level mean trait values. For each of these calculations, we used trait-gradient analysis to partition the three traits into alpha and beta components. We then conducted Pearson correlations to analyze the relationships among the three traits along the longitudinal gradient. Finally we tested the strength of environmental filtering using a null model that generates randomly assembled communities with species richness given by observed values.
Important findings The species abundance-weighted mean community value of LA was lowest in the midstream communities, which was significantly different from that in the downstream communities. The mean community value of WD for midstream and upstream communities was significantly higher than that for downstream communities. Mean community value of SLA was significantly different among the three reaches. The beta components of the three functional traits significantly differed among the three reaches and had observed values that are, on average, lower than simulated values. However, alpha components for all three traits were not significantly different among the three reaches and had consistently lower variation than beta components. This implies that the variation in the mean community trait value across plots was greater than trait variation between species within plots. The observed and simulated values of the alpha components for both LA and SLA were weakly correlated with each other within and among communities, which suggests that there are independent axes of differentiation among coexisting species. On the other hand, comparisons between observed and simulated values indicated that significantly negative correlations between SLA and WD were largely the result of strong environmental filters. Finally, these results imply that variation of plant functional traits is greater among communities than within communities.

Key words: Lijiang River, riparian zone, functional traits, scale variation, trait-gradient analysis, RDA ordination, correlation, null model