The ecological function optimization strategy of vegetation directly affects the self-stability and engineering sustainability of the vegetation concrete ecological restoration system, which is the key to the successful restoration of an ecosystem. To clarify the survival strategies of slope protection plants and their response mechanisms to the soil environment in the process of vegetation concrete ecological restoration, the resource allocation strategies and soil driving factors of typical slope protection plants, such as Cynodon dactylon (Linn.) Pers. and Indigofera amblyantha, in a co-operation environment mode, were investigated by controlled simulation experiments. The results showed that (1) the co-operating environmental model had a significant effect on the biomass (leaf, stem and root) and root shoot ratio of slope protection vegetation; (2) the sensitivity of plant biomass in the co-operating environmental model was leaf biomass ratio > root biomass ratio > stem biomass ratio, and the most sensitive organ was the leaf; (3) a common allometric growth index for the plants of all slopes existed, the root and leaf grew at the same rate, and the plant roots and stems showed allometric growth with the synergistic effect of rainfall and slope; (4) the total nitrogen content of soil had a significant correlation with the vegetation R/S (root shoot ratio) (p < 0.05) due to the synergistic effect of vegetation type and slope, while the total phosphorus content of the P3 slope had a significant negative correlation with the vegetation R/S (p < 0.05). The co-operating environmental model significantly affected the spatial distribution of vegetation biomass and had the greatest impact on leaf biomass. The contents of soil nitrogen and phosphorus were the key soil driving factors that affected the distribution pattern of plant biomass. The resource allocation characteristics of different vegetation and its response to soil factors had species specificity.

Using wheat and corn as the selected crops, this study aims to explore the effects of different ways to return biomass, on soil and crop yield with wheat and corn straw, and the biochar made by them as the material. The results exhibited that the different ways of returning biomass could significantly improve the soil cation exchange capacity (CEC) and the content of organic matter after the harvesting of two annual crops. The soil nutrient content showed a rising trend in general, and the effect was most significant when the biochar consumption was the most. The soil total nitrogen content in wheat and corn season significantly increased by 100% and 16.2% respectively compared with the control. The soil mineral nitrogen content and available P content in wheat season significantly increased by 0.9% and 217% respectively compared with the control. And the soil mineral nitrogen content, available P content and available K content in corn season significantly increased by 21.2%, 30% and 90% respectively compared with the control. The effects of direct straw application to soil was a bit poor, and it had no significant effect on crops yield, but it can promote plants to absorb nutrients, and the effect increased with the increase of biomass usage. The effect of sole biochar application is better than that of direct straw application.