Background With the rapid development of highway construction, the highway networks gradually develops from plain to mountainous area and from southeast to northwest of China. In process of highway construction, slope protection and vegetation restoration in the northwest region bring many difficulties to the builders. Masonry protection can remain slope stable, but it brings damage to the ecological environment. Reasonable use of slope protection can improve the effect of vegetation restoration better in the construction of highway.

Methods According to the characteristics of environment and geology and geomorphology in cold and dry areas, four methods such as planting grass in three-dimensional web, honeycomb cell, planting grass via sowing seeds and planting grass via ecological bag were selected to explore the influences of different protective forms on soil environment construction and plant life. Basic physical properties of soil, plant composition, root growth were used to compare the effects of different forms of protection on vegetation restoration in slope.

Results Four vegetation restoration methods had ensured plant growth on several levels, but the effects of vegetation restoration on soil environment and plant growth were different. Method of honeycomb cell and planting grass in three-dimensional web could improve the soil conditions and ensure the plant growth well, which remained soil moisture not less than 22% and vegetation coverage not less than 85%. Followed by planting grass via sowing seeds and planting grass via ecological bag, which remained soil moisture not less than 18% and vegetation coverage not less than 65%. Planting grass in three-dimensional web and planting grass via sowing seeds were beneficial to the growth of plant roots, which showed higher root growth depth (14.7 cm in average) than other methods. Honeycomb cell had the maximum root number of 179 and root area ratio of 0.023 2 within 5 cm soil depth.

Conclusions For the vegetation restoration of highway slope in cold and dry area, honeycomb cell was recommended for slope vegetation restoration. While method of planting grass via ecological bag could be adopted for the slope with stable demand when carried out slope protection.