Differences in erosion resistance of degraded Mollisols restored with herbaceous plants across degradation gradients

Abstract：BackgroundThe black soil region of Northeast China is experiencing varying degrees of land degradation. Restoring degraded soils through herbaceous vegetation and improving its resistance to erosion are effective approaches to control soil and water loss, ensure food security, and promote the sustainable utilization of black soil resources. However, systematic studies on the differences in restoration effects of herbaceous vegetation across degradation stages are still limited. MethodsIn this study, lightly, moderately, and severely degraded black soils were simulatedunder field conditions, with bare soil as a control. Based on measurements and analyses of soil physicochemical properties, aggregate characteristics, and soil resistance to erosion and scouring, the mean square deviation decision method was employed to evaluate the integrated effects of three herbaceous species and their mixture—Bromus inermis, Festuca elata, Lolium perenne, and their combination (Bromus inermis–Festuca elata–Lolium perenne)—on improving soil erosion resistance. Results Results showed that herbaceous vegetation significantly enhanced the soils resistance to erosion, though the restoration performance varied with both degradation degree and plant species. Under light degradation condition, the effectiveness of herbaceous planting on soil erosion resistance followed the order: mixture > F. elata >B. inermis >L. perenne, with F. elata achieving the most significant improvement in soil slaking resistance (97% higher than bare soil). Under moderate degradation condition, the order of restoration effectiveness was L. perenne > mixture > F. elata > B. inermis, with L. perenne being most effective in increasing MWD(58.2%) and reducing PAD_0.25 (37.4%), while also producing the largest improvement in slaking resistance (98% increase). Under severe degradation, the order was F. elata > B. inermis > mixture > L.perenne, where F. elata increased MWD by 105%, reduced PAD_0.25 by 33%, and improved the disintegration rate and separability by 86% and 95%, respectively. ConclusionsOverall, herbaceous vegetation restoration significantly improved erosion and scouring resistance, with restoration effectiveness decreasing in the order light > moderate > severe degradation. These findings reveal the constraint of degradation degree on plant restoration effectiveness and provide theoretical support and practical references for optimizing vegetation restoration strategies and species selection in degraded black soils.