Effects of Different Management Measures of Cultivation Panax notoginseng Under Forest on Runoff and Sediment Yield and Soil Characteristics on Slope

[Objective] Revealing the effects of different management measures on runoff and sediment yield and soil characteristics of [Panax notoginseng (Burkill) F. H. Chen] forest land, can provide a theoretical basis for scientific prevention and control of soil erosion in understory P. notoginseng cultivation. [Methods] The in-situ observation experiment of field runoff plot was used to quantify the sediment yield of natural forest land (CK), forest prepared land (SP), no canopy P. notoginseng forest land (NC), and canopy P. notoginseng forest land (HC) at different slopes (5°,10°,15°) in the rainy season of 2022. to explore the effects of different management measures on the runoff and sediment yield and soil characteristics of P. notoginseng forest land slope. [Results] (1) The total rainfall in Xundian County in 2022 was 1031.70 mm, which belonged to a flat year. The cumulative erosive rainfall outside and inside the forest was 845.40 and 565.60 mm, Canopy interception rates ranged from 9.97% to 67.38%. (2) There were extremely significant (p<0.01) differences in runoff and sediment yield of P. notoginseng forest land under different management measures. Compared with CK, the average total runoff of SP, NC, and HC increased by 272.23%, 171.19%, and 106.89%, respectively, and the average total sediment yield increased by 385.15%, 248.82%, and 138.84%, respectively. With the increase of slope, the loss increased more significantly. The canopy in P. notoginseng forest has a good effect on sediment reduction. (3) Soil characteristics of CK and SP were significantly different from those of other management measures; There were significant differences in the mean geometric diameter and soil anti-scour coefficient between NC and HC (p<0.05), but no significant differences in other soil characteristics. Principal component analysis showed that soil saturated water conductivity, litter storage, soil bulk density and K value of cultivation P. notoginseng forest had great effects on sediment yield. (4) There was a significant power function relationship between event runoff and sediment yield in the P. notoginseng forest land and rainfall or rainfall erosivity and rainfall intensity (p<0.05); total runoff and sediment yield showed a significant positive exponential relationship with slope (p<0.01), R2>0.90. With the increase of slope, the loss of sediment increased more. [Conclusion] Forest land preparation and P. notoginseng cultivation led to a significant increase in soil erosion, but the maximum soil loss [34.53 t/(km2·a)] was far lower than the allowable soil loss in karst area of southwest China. It is recommended to cultivation P. notoginseng in gentle slope forest land, and hydraulic erosion can be alleviated by building canopy and improving soil characteristics.