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

Sichuan Basin in southwestern China is a region of great conservation concern, yet little is known about the influence of edaphic factors on plant community dynamics of disturbed areas. We used multivariate analyses to identify differences in vegetation structure (i.e., tree, shrub, forb, and graminoid) and species composition between sandstone and shale substrates across 13 successional forest plant communities that varied in soil depth and soil texture. Vegetation structure did not differ between substrates (P >0.05), but plant community composition varied significantly (P = 0.0017). In addition, six indicator species were identified, including two native perennial grasses; namely, Imperata cylindrica for intermediate soil depths (20-30 cm) on sandstone substrate (P = 0.016) and Miscanthus sinensis for greater soil depths ( > 30 cm) 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 ± 5.3% cover) and shale (12.3 ± 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.