Vegetation Alteration in Response to Highway Construction in the Desertified Steppe Zone of the Tengger Desert, North China

Abstract

This study was conducted to determine if there are differences in the composition of plant communities between road verges and adjacent areas, and to what extent road and traffic influence the characteristics of vegetation in a desertified steppe area. Sixteen transects perpendicular to the road were set at the southeastern edge of the Tengger Desert, to survey the characteristics of vegetation at different distances from the road. The results indicate that cover and density of the shrubs were lower at the road verges than in the control plots, while no significant differences were observed for species composition. For herbaceous plants, cover, above-ground biomass, species richness and α-diversity were higher at 0–3 m from the road edge than at plots more than 5 m from the edge, while differences in the density between plots at different distances from road edge were not found. β-diversity indices demonstrated that the species turnover rate was low at 0–2 m from the road edge, and that it increased from 2 m to 10 m from the road, after which it was similar among plots. Road verge vegetation was primarily dominated by ruderal species and rhizome grass, and also contained many drought intolerant species. The soils in plots within 2 m of the road edge had higher soil moisture, greater levels of sand, soil organic carbon and total nitrogen, and lower silt content and pH than plots located greater than 10 m from the road edge, indicating that these are important factors influencing the pattern of road verge vegetation.