| 摘要: |
| 【目的】探究天然降雨条件下不同坡度三七种植林地和自然林地的水土及碳氮流失特征，为林下种植模式的水土及碳、氮流失评估和控制提供理论依据和数据支撑。【方法】采用野外径流小区原位观测试验，以云南省寻甸县三七(Panax notoginseng (Burkill) F. H. Chen)种植林地为研究对象，对2020和2021年天然降雨条件下不同坡度（5°，10°，15°）三七种植林地和自然林地的水土及碳、氮流失特征进行对比分析，并在此基础上对水土及碳、氮流失量与降雨特征和坡度的关系进行探究。【结果】（1）三七种植林地平均总径流量、总土壤流失量分别为17.35 mm/a和14.91 t/（km2·a），比自然林地分别增加了173.79%和249.43%，其中以15°坡面水土流失量最大，分别为24.10 mm/a和24.32 kg/（km2·a）。（2）三七种植林地平均有机碳、全氮（TN）、氨氮（NH+4-N）、硝态氮（NO-3-N）流失量分别为740.62，75.97，9.55和7.26 kg/（km2·a），比自然林地分别显著增加了251.44%，203.15%，220.47%和224.11%，其径流中TN和NH+4-N平均含量分别为0.77和0.33 mg/L。三七种植林地中，以侵蚀泥沙形式流失的有机碳和TN分别占各自总流失量的93.50%和82.01%，以地表径流流失的NH+4-N、NO-3-N分别占各自总流失量的62.09%和87.47%。（3）降雨量、降雨历时、5 min最大降雨强度（I5）、10 min最大降雨强度（I10）、30 min最大降雨强度（I30）均与径流量、土壤流失量及碳、氮流失量呈显著或极显著正相关关系。坡度与水土和碳、氮流失量呈极显著正相关（P＜0.01），可用二次函数拟合二者之间的关系（R2＞0.93）。【结论】三七种植林地土壤侵蚀强度属于微度侵蚀，最大土壤流失量远低于西南土石山区容许土壤流失量，且径流中TN、NH+4-N平均质量浓度分别低于Ⅲ、Ⅱ类地表水环境质量标准限值。三七种植林地水土及碳、氮流失量较自然林地显著增加，且随着坡度的增大急剧增大。建议在缓坡地段种植三七，以减少水土与养分流失。 |
| 关键词: 林下种植 三七种植林；水土流失；碳氮流失；面源污染 |
| DOI：10.13207/j.cnki.jnwafu.2024.09.013 |
| 分类号: |
| 基金项目:昆明市科技“揭榜挂帅制”项目（2021 J H-002-02）；云南省科技重大专项计划项目（202102AE090042-03）；云南省“兴滇英才支持计划”青年人才专项（XDYC-QNRC-2022-0205）；云南省科技特派团创新引导与科技型企业培育计划项目（202204BI090003）；国家自然科学基金项目（32060345） |
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| Effects of Panax notoginseng cultivation in forest land on runoff,soil,carbon and nitrogen losses from slope surfaces |
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ZHOU Yun1, HE Xiahong2, LI Jianqiang1, CHEN Qibo1, GAO Lang1, LI Jinghao1
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1.College of Ecology and Environment,Southwest Forestry University, Kunming,Yunnan 650224,China;2.Key Laboratory of Forest Resources Conservation and Utilization in the Southwest Mountains of China Ministry of Education,Southwest Forestry University, Kunming,Yunnan 650224,China
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| Abstract: |
| 【Objective】This study explored the characteristics of runoff, soil, carbon and nitrogen losses in natural and Panax notoginseng forests at different slopes under nature rainfall conditions to provide theoretical basis and data support for impact assessment and control of runoff,soil,carbon and nitrogen losses.【Method】The runoff,soil,carbon and nitrogen losses of rainfalls in 2020 and 2021 from the runoff plot in the Panax notoginseng (Burkill) cultivation land with 5°，10° and 15° slop and a natural forest land in Xundian County,Kunming,Yunnan were collected and analyzed.The relationships between losses,slope gradients and rainfalls were also were analyzed.【Result】(1) The average total runoff and soil loss of P. notoginseng cultivation forest land were 17.35 mm/a and 14.91 t/(km2·a),which were increased by 173.79% and 249.43% compared with natural forest land,respectively.The maximum soil and water losses of 24.10 mm/a and 24.32 t/(km2·a) were observed at 15° slope. (2) The average organic carbon,total nitrogen (TN),ammonia nitrogen (NH+4-N) and nitrate nitrogen (NO-3-N) losses in P. notoginseng cultivation forest land were 740.62,75.97,9.55 and 7.26 kg/(km2·a),respectively,which were 251.44%,203.15%,220.47% and 224.11% higher than those of natural forest land.The average concentrations of TN and NH+4-N in runoffs from P. notoginseng cultivation forest land were 0.77 and 0.33 mg/L.Carbon and TN losses by erosion sediments accounted for 93.50% and 82.01% of total losses,respectively,and NH+4N and NO-3-N losses by runoffs contributed 62.09% and 87.47% to total losses,respectively. (3) Runoff and losses of soil,carbon and nitrogen had very significant or significant correlations with rainfall indexes,including rainfall amount,duration,maximum 5 minutes intensity (I5),maximum 10 minutes intensity (I10) and maximum 30 minutes intensity (I30).Slope gradients had extremely significantly positive correlations with runoff,soil,carbon and nitrogen losses (P<0.01),which could be described using quadratic functions (R2>0.93).【Conclusion】The soil erosion intensity of P. notoginseng cultivated forest land was in micro-degree level,the maximum soil loss was significantly lower than the soil loss tolerance in southwest China,and average concentrations of TN and NH+4-N in runoffs were lower than the limits of the Ⅲ and Ⅱ standards of surface water environmental quality.Soil,water,carbon and nitrogen losses of P. notoginseng cultivated forest land increased significantly compared with those of natural forest land,and they increased sharply with the increase of slope.This study recommended cultivation of P. notoginseng in gentle slope forest land for reducing losses of water,soil and nutrients. |
| Key words: planting under forest Panax notoginseng cultivated forest water and soil losses carbon and nitrogen losses non-point source pollution |
