Evaluation of ecological restoration effect of high-steep rocky slopes in dry-hot valley region.

To evaluate the actual effects of different ecological restoration technologies on high and steep rock slopes in the dry-hot valley area, we compared three typical slope ecological restoration techniques, vegetation concrete (VC), soilless spraying (SPF), and vegetation trough (VS) on the high and steep rock slope of Baihetan Hydropower Station. We conducted a one-year monitoring of soil physical and chemical indicators and vegetation characteristics from January to December 2022, and calculated the ecological restoration index (ERI) using the minimum dataset method, which were used to comprehensively evaluate the ecological restoration effects of each technique. The results showed that: 1) During the maintenance monitoring period, soil physical characteristics (bulk density, porosity, moisture content), soil organic matter, and nutrient (total nitrogen, total phosphorus, available phosphorus) contents of the three remediation techniques showed a fluctuating trend with seasons. Plant characteristics (plant height, plant diameter, vegetation coverage coefficient, aboveground biomass) increased from 3.6-9.3 cm, 0.98-2.16 mm, 0.12-0.61, and 42.80-163.56 g·m^-2 to 11.5-14.7 cm, 2.85-4.05 mm, 0.68-0.98, and 368.00-421.12 g·m^-2, respectively, while cation exchange capacity increased from 6.13-13.94 cmol·kg^-1 to 13.94-20.42 cmol·kg^-1. Soil pH decreased from 7.56-8.05 to 7.17-7.51. VC was generally superior to SPF and VS in enhancing soil structure and plant growth. 2) The minimum dataset consisted of plant height, available phosphorus, vegetation coverage, bulk density, and total nitrogen, which were significantly positively correlated with the entire dataset (<i>R</i>²=0.733) and could effectively replace the entire dataset for ecological restoration evaluation. 3) The restoration process of slopes presented a restoration path of "soil matrix construction plant growth and reproduction". The contribution rate of soil ERI of the three restoration techniques in spring was 66.3%-70.5%, that in summer was 43.7%-58.4%, with the contribution rate of vegetation to ERI being 41.6%-56.3%. The contribution rate of vegetation to ERI in autumn and winter exceeded that of soil, ranging from 54.7% to 64.1% and 55.6% to 61.0%, respectively. 4) The annual average ERI values of three typical slope ecological restoration techniques were ranked as VC (0.576)>SPF (0.549)>VS (0.452), and the final values showed the same trend (0.676>0.639>0.538), indicating that VC had the best ecological restoration effect.