Long-term vegetation restoration elevates soil and litter nutrient concentrations of Pinus massoniana plantations in southern China

Vegetation restoration (VR) is essential for degraded ecosystems by enhancing surface cover and improving soil properties, particularly soil nutrients and water retention in eroded and degraded land. However, long-term studies evaluating the interactive effects of VR on soil properties, plant-soil feedbacks, and nutrient cycling remain limited. This study examined how VR years (8, 11, 14, 17, and 20 years) influenced soil physical characteristics, water regulation, nutrient concentrations across soil depths (0–5, 5–20, 20–40, and 40–60 cm), litter yield and nutrient contents in eroded and degraded Pinus massoniana plantations (CK). Results showed that restoration treatment, restoration years (RY), and soil depth significantly affected soil physical properties, water regulation capacity (represented by soil porosity and soil water content), and nutrient availability. Compared to CK, VR reduced soil hardness (by 1.360–15.25 kg cm −2 ) and bulk density (by 0.118–0.800 g cm −3 ), but increased water content (by −6.126–25.18%), porosity (by 1.597–25.23%), organic carbon (by 0.910–21.70 g kg −1 ), total nitrogen (by 0.190–0.780 g kg −1 ), and total phosphorus (by −0.013–0.210 g kg −1 ), with these improvements intensifying over RY. These improvements of the 0–5 cm were more significant, evidenced by a higher R 2 value. Under VR treatment, RY significantly altered soil texture and litter dynamics, evidenced by decreased sand content but increased clay content and increased litter yield and nutrient concentrations ( P < 0.001). Strong correlations were observed between soil and litter properties, with RY driving increases in litter and soil nutrients through enhanced litter production and improved soil water regulation. Moreover, soil porosity and soil water content were the dominant drivers of soil organic carbon ( R 2 = 76.81%), total nitrogen ( R 2 = 86.19%), and total phosphorus ( R 2 = 92.12%). These findings elucidate the mechanisms by which VR influences soil-litter interactions and nutrient cycling in degraded Pinus massoniana forests, offering a scientific basis for sustainable forest management.