Objective This study aimed to investigate the effects of vegetation restoration and reconstruction on soil organic carbon (SOC) and soil nutrients, as well as the recovery efficacy of different tree species configuration patterns.

Method Four tree species configuration modes were designed: A control mode (CK) planting two species of Liquidambar formosana and Schima superba, a multi-species selection mode (Configuration I), a valuable species intercropping mode (Configuration II), and a conifer-broadleaf mixed mode (Configuration III). Permanent sample plots were established, and plants, SOC, and soil nutrients were continuously surveyed in 2012 (pre-planting), 2014 (2 years post-planting), 2016 (4 years post-planting), and 2024 (12 years post-planting).

Result A total of 63 tree species were planted in 2012. By 2024, 35 species remained, with Pinus massoniana (high-fat variety) showing the best growth performance, with an average diameter at breast height (DBH) of 17.22 cm and an average tree height of 8.65 m. After afforestation, SOC content showed a trend of decrease followed by an increase, averaging 19.88 g·kg⁻¹ after 12 years, close to the pre-planting level. In the 0−20 cm soil layer, SOC reached 20.33 g·kg⁻¹, with an increase of 38.21% compared to pre-planting. After 12 years, the CK configuration mode had the lowest SOC content at 8.45 g·kg⁻¹. There were no significant differences in SOC contents among Configurations I, II, and III. The SOC content in Configuration III was the lowest (9.34 g·kg⁻¹) before planting, but became the highest among all configurations after 12 years (13.25 g·kg⁻¹). After afforestation, soil total nitrogen (TN), total phosphorus (TP), total potassium (TK), alkali-hydrolyzable nitrogen (AN), and available phosphorus (AP) contents showed a trend of decrease-increase-decrease, while available potassium (AK) content showed a trend of decrease followed by an increase. Compared to pre-planting, all soil nutrient contents decreased after 12 years, with no significant difference among the configurations. However, the CK configuration mode had lower nutrient contents compared with Configurations I, II, and III for all nutrients, except for TP content in CK, which was slightly higher than that in Configuration III. The average TP content in this experiment was 0.21 g·kg⁻¹, far below the national average (0.56 g·kg⁻¹).

Conclusion During the vegetation restoration process on nearly barren mountains, the conifer-broadleaf mixed mode (Configuration III) has better recovery effects, and the multi-species mixed configurations are more effective than the two-species mixed mode.