Vegetation structure and species composition variation of roadside slopes in the Sichuan Basin of China

Authors: HE, HUIQIN - Yibin University; Monaco, Thomas

Submitted to: Journal of Agricultural Science and Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/2/2018
Publication Date: 1/16/2018
Citation: He, H., Monaco, T.A. 2018. Vegetation structure and species composition variation of roadside slopes in the Sichuan Basin of China. Journal of Agricultural Science and Botany. 2:1-9.

Interpretive Summary: Sichuan Basin in southwestern China is a region of great conservation concern due to poor vegetation recovery on steep roadside slopes, yet little is known about the influence of edaphic factors on plant community dynamics of disturbed slopes. A greater understanding of vegetation patterns across variable substrates may provide useful indicators of edaphic conditions and assist practitioners in choosing appropriate restoration species to stabilize slopes and improve species diversity. In this study, we sought to identify differences in vegetation and species composition betwen sandstone and shale soils in Sichuan Basin. We sampled at 39 locations and recorded percentage coverage of each species as well as soil depth and soil texture. Data were using multivariate analysis. Our results found that fegetation structure did not differ between sandstone and shale substrates, but instead plant community composition and six indicator species were identified. The most notable indicator species included two perennial grasses; namely, Imperata cylindrica on sandstone substrate and Miscanthus sinensis on shale substrate. Both species were also the most dominant perennial grass species and we present evidence that they control species diversity on roadside slopes. In addition, our results indicate that a number of suitable species could be used for future restoration projects in the Sichuan Basin. However, future research is needed to determine how plant diversity of roadside slopes is limited by seed dispersal of potential colonizers and competitive displacement by dominant perennial grasses.

Technical Abstract: Sichuan Basin in southwestern China is a region of great conservation concern due to poor vegetation recovery on steep roadside slopes, yet little is known about the influence of edaphic factors on plant community dynamics of disturbed slopes. A greater understanding of vegetation patterns across variable substrates may provide useful indicators of edaphic conditions and assist practitioners in choosing appropriate restoration species to stabilize slopes and improve species diversity. In this study, we sought to identify differences in vegetation structure (i.e., tree, shrub, forb, and graminoid) and species composition between sandstone and shale substrates on roadside slopes in Sichuan Basin. Soil depth, soil texture, and species covering richness of plant communities were sampled at 39 locations that varied in elevation and slope degree. Differences in vegetation structure and plant community composition were assessed with non-parametric t-tests and multivariate analyses [i.e., Multiple Response Permutation Procedures (MRPP) and Indicator Species Analysis (ISA)], respectively. Vegetation structure did not differ between sandstone and shale substrates (P > 0.05), but plant community composition varied significantly (P = 0.0017) and six indicator species were identified. The most notable indicator species included two perennial grasses; namely, Imperata cylindrica for intermediate soil depths (20-30 cm) on sandstone substrate (P =0.016), Miscanthus sinensis for greater soil depths (> 30cm) on sandstone (P-0.012), as well as on intermediate soil depths (20-30 cm) on shale substrate (P = 0.0002). Imperata cylindrica and M. sinensis were also the most dominant perennial grass species on sandstone (15.6 plus or minius 5.3% cover) and shale (12.3 plus or minus 4.9% cover), respectively. These patterns provide insights into species interactions and successional dynamics of roadside slopes, and offer guidance when choosing suitable species for future restoration projects in the Sichuan Basin. Future research is needed to determine how plant diversity of roadside slopes is limited by seed dispersal of potential colonizers and competitive displacement by dominant perennial grasses.