【目的】探究自然降雨下不同坡面三七(Panax notoginseng)种植林地和自然林地的氮、磷流失特征。【方法】以云南省临沧市博尚镇小道河林场为研究区,在自然林地(CK)、2年生三七种植林地(BP)、3年生三七种植林地(KP)中,各布设5°、15°、20°共3个坡度水平的径流小区,于2022年雨季观测径流泥沙量和氮、磷流失量,探究影响氮、磷流失的因素。【结果】BP和KP小区年产流产沙量分别比CK高93.94%、185.07%和35.02%、112.06%;泥沙中的TN、TP、 ${\mathrm{NH}}_{4}^{+}-\mathrm{N}$发生富集, ${\mathrm{NO}}_{3}^{-}-\mathrm{N}$没有明显变化;BP和KP小区的年TN、TP、 ${\mathrm{NO}}_{3}^{-}-\mathrm{N}$、 ${\mathrm{NH}}_{4}^{+}-\mathrm{N}$流失量分别比CK高97.23%,141.92%,88.8%、88.14%和67.82%,137.39%,66.65%、48.06%;侵蚀泥沙是TN、TP流失的主要途径, ${\mathrm{NO}}_{3}^{-}-\mathrm{N}$和 ${\mathrm{NH}}_{4}^{+}-\mathrm{N}$主要随径流流失;降雨量和降雨侵蚀力对氮、磷流失影响最显著,与各流失量呈极显著幂函数关系(P < 0.01);氮、磷流失量与坡度呈指数函数关系,各试验处理、降雨量和坡度交互作用影响氮磷流失。【结论】林下三七种植导致产流产沙量及氮、磷流失量较自然林地显著增加,但随着三七种植年限的增加,产流产沙和氮、磷流失相对减少,这表明林下三七种植具有可行性,通过合理调整种植年限和种植方式,能实现林下三七种植的可持续发展。此外,应注意高强度降雨和陡坡对林下三七种植的影响,减少林下氮、磷流失风险。

【Objective】Understory cultivation of Panax notoginseng serves as a key agroforestry model for developing the forest-based economy. Investigating runoff, sediment yield, nitrogen (N), and phosphorus (P) loss patterns between P. notoginseng cultivation forestland and natural forestland under natural rainfall can provide critical scientific evidence for evaluating soil and nutrient loss in agroforestry systems, and optimizing understory medicinal plant cultivation. 【Method】This study took the Xiaodaohe Forest Farm in Boshang Town, Lincang City, Yunnan Province as the study area, using the in-situ observation experiment of field runoff plot to conduct fixed-point observations of runoff and sediment yield, as well as N and P losses of natural forestland (CK), 2-year-old P. notoginseng cultivation forestland (BP), and 3-year-old P. notoginseng cultivation forestland (KP) at different slope gradients (5°, 15°, 20°) in the rainy season of 2022. Then conducting significance tests for differences and correlation analyses on the amounts of runoff, sediment yield, N, and P losses under the various treatments. Building on these findings, this study further examined how slope gradient, rainfall characteristics, and their interaction influence N and P losses. 【Result】The annual runoff and sediment yields in plots BP and KP were 93.94%, 185.07% and 35.02%, 112.06% higher than those in plot CK, respectively. The total nitrogen (TN), total phosphorus (TP) and ammonium nitrogen (${\mathrm{NH}}_{4}^{+}-\mathrm{N}$) in the sediment were enriched, while there was no significant change in nitrate nitrogen (${\mathrm{NO}}_{3}^{-}-\mathrm{N}$). The annual losses of TN, TP, ${\mathrm{NO}}_{3}^{-}-\mathrm{N}$ and ${\mathrm{NH}}_{4}^{+}-\mathrm{N}$ in plots BP and KP were 97.23%, 141.92%, 88.8%, 88.14% and 67.82%, 137.39%, 66.65%, 48.06% higher than those in plot CK, respectively. Eroded sediment was the main pathway for TN and TP loss, while ${\mathrm{NO}}_{3}^{-}-\mathrm{N}$ and ${\mathrm{NH}}_{4}^{+}-\mathrm{N}$ were mainly lost with runoff. Rainfall amount and rainfall erosivity had the most significant impacts on N and P losses, showing extremely significant power function relationships with various loss amounts (P < 0.01). The nitrogen and phosphorus losses showed exponential function relationships with slope gradient, and the interaction of different experimental treatments, rainfall amount and slope gradient affected nitrogen and phosphorus losses.【Conclusion】Understory P. notoginseng cultivation significantly increased runoff, sediment yield, and N and P losses compared to natural forestlands. However, with the increase in the cultivation years of P. notoginseng, runoff, sediment yield, and N and P losses relatively decreased. This indicates that understory P. notoginseng cultivation is feasible, and the sustainable development of understory P. notoginseng cultivation can be achieved by reasonably adjusting the cultivation years and planting methods. In addition, attention should be paid to the impact of high-intensity rainfall and steep slopes on understory P. notoginseng cultivation to reduce the risk of N and P losses in the understory.