Ecological Stoichiometric Changes and the Synergistic Restoration of Vegetation Concrete Restoration Systems under Different Precipitation Conditions

Abstract

Based on vegetation-soil nutrient monitoring data under different precipitation conditions, this study investigated the impact of precipitation changes on the ecological restoration process of disturbed slopes. Precipitation change, to a certain extent, changed the carbon (C), nitrogen (N) and phosphorus (P) content and the stoichiometric ratio of the soil–plant system. With the increase of the weekly precipitation from 10 to 20 mm, the C content of Cynodon and Indigofera Amblyantha Craib on each slope gradually increased, increased by 8.69% and 4.28%, respectively, compared with the initial recovery period, and the N/P of Cynodon increased from 3.81 to 4.94, and the N limit gradually decreased, while the limit of P increased continuously. The efficiency of the coordinated utilization of N and P of the Indigofera Amblyantha Craib increased, which had a certain adaptability to changes in precipitation. The C/N and C/P in the soil first increased and then decreased, and reached the peak at the slope of 15 mm precipitation, while the N/P fluctuated around 0.35 overall. N was an important element restricting the growth of grass, while P was an important influencing element limiting the growth of shrubs. This also showed that soil C, N and P had a good promoting effect on plant growth, and the self-regulating nutrient utilization strategies of different growth forms of plants under different precipitation conditions differed. There was a coupling effect in the contents of C, N, P and their stoichiometric ratio in the soil–plant system, and stoichiometry and elastic ecological interactions jointly controlled the supply and demand of elements in the plants, but there was no consistent temporal pattern of nutrient ecological stoichiometric ratio in the plant–soil system during the recovery process, thus requiring further research and evaluation.