## 3 Results Analysis  
### Influence Analysis of Soil Physico-Chemical Properties  
After investigation, the physical properties of the soil under different ecological forest restoration modes are shown in Table 1. Compared to abandoned land, the water content of all restoration modes has increased. Among them, the water content of the AR, AM, and AR&AM&MS treatments increased significantly. This means that the increase in soil water content is mainly related to the forest structure, such as involves trees. In terms of bulk density, except for the MS treatment, the bulk densities of the other restoration modes were significantly lower than those of AL (\(p<0.05\)). This is consistent with the results of soil moisture content. A lower bulk density leads to more developed soil pores and therefore a higher soil moisture content. Additionally, soil porosity is highly correlated with this phenomenon. It can be seen from Table 1 that the porosity of the AR, AM, and AR&AM&MS treatments is significantly higher than that of the AL treatment and the MS restoration mode. Therefore, it can be inferred that AR&AM&MS is the best forest restoration mode, followed by AR and AM. In contrast, the pure alfalfa restoration mode has lower moisture content and porosity than AL, which shows that the alfalfa restoration mode is the worst. Of course, this is also related to the mechanical composition and texture of the soil. It can also be seen from the physical properties in Table 1 that the AR&AM&MS treatment has a higher content of silt and clay and a lower content of sand, and the soil texture is silty loam, which has a good effect on holding soil moisture. However, a similar phenomenon was also observed in the MS treatment, which may be related to the rhizosphere effect of the soil [30]. Additionally, the soil chemistry and nutrient properties under different forest restoration modes are shown in Table 2 and Figure 2. It can be seen from Table 2 that the pH of all soil samples is alkaline. Compared to CK, the pH of the soil in the AR, AM, and AR&AM&MS treatments decreased slightly, especially in the AR&AM&MS restoration mode. The total salt content of the AR&AM&MS treatment increased slightly compared to the other treatments, while the total salt content of the MS treatment decreased, indicating that different forest land soil restoration modes have a significant impact on soil chemical properties. A similar phenomenon was also observed for alkalinity. The AR, AM, and AR&AM&MS treatments all showed a significant decrease in content, while the MS treatment showed an increase in content compared to the AL treatment, but the difference was not significant. Moreover, forest soil is the substrate that maintains the healthy growth of trees, and its fertility characteristics affect and control the growth and health of plants and trees. Forest degradation is closely related to declining soil fertility [2]. Compared with AL, the total phosphorus, available phosphorus, total potassium, and available potassium contents of AM, MS, and AR&AM&MS treatments increased significantly (Table 2); however, the total potassium and available potassium contents of AR decreased, which may be due to interference from other factors, such as the sampling area and soil rhizosphere allelopathy [11; 25].