不同经营方式毛竹林氮流失年动态规律

为研究自然降雨条件下不同经营方式毛竹林径流养分流失的年动态变化规律及其差异,以浙江省杭州市临安区青山毛竹园为试验区,在粗放经营和集约经营区域,设置独立观察站。每次连续降雨后采集沉砂池水样,测定总氮（TN）、总磷（TP）、硝态氮（NO₃^--N）、铵态氮（NH₄⁺-N）、磷酸根离子（PO₄^3-）含量,同时在动态观测期中采集坡面土壤样品,测定pH、有机质及有效N、P含量。结果表明：（1）集约经营和粗放经营毛竹林年单位产流量分别为8086.52 m³/hm²、4850.95 m³/hm²。（2）毛竹林径流水氮流失以硝态氮为主。（3）毛竹林集约经营增加了氮磷流失风险,集约经营和粗放经营毛竹林TN年单位流失量分别为45.26 kg/hm²、25.05 kg/hm²,TP年单位流失量分别为0.31 kg/hm²、0.21 kg/hm²,与粗放经营相比,集约经营氮磷流失分别增加了80.68%、47.62%。（4）毛竹林径流水中TN浓度与土壤碱解氮含量成极显著负相关,径流水中TP浓度与土壤有效磷成极显著正相关。

Effect of management intensity on runoff losses of nitrogen and phosphorus in bamboo forests in Zhejiang province

To determine the effect of management intensity on runoff nutrient losses in bamboo forests under natural rainfall conditions, separate field observation stations were set up at the mouths of each field-sized catchment (micro-watershed) in extensively or intensively managed areas, at Qingshan Bamboo Orchard in Lin'an district, Hangzhou city, Zhejiang province. After every successive rainfall during the year, runoff volumes were measured, and water samples from the sand-settling tanks at the observation stations were collected and analyzed for total nitrogen (TN), total phosphorus (TP), nitrate nitrogen (NO₃^--N), ammonium nitrogen (NH₄⁺-N), and phosphate (PO₄^3-) contents. Simultaneously, soil samples were also collected and analyzed for pH, organic matter, effective nitrogen and available phosphorus contents. The results showed that: (1) Annual runoffs from intensively managed and extensively managed bamboo forests were 8086.52 m³/hm² and 4850.95 m³/hm², respectively; (2) Nitrogen loss in runoff from the bamboo forests was dominated by nitrate nitrogen; (3) Intensive management increased the risk of nutrient losses from the bamboo forests; the annual losses of nitrogen and phosphorus from intensively managed areas were 45.26 kg/hm² and 25.05 kg/hm², respectively; but they were only 0.31 kg/hm² and 0.21 kg/hm², respectively, from extensively managed area. Compared with losses from extensively managed area, the losses of nitrogen and phosphorus from intensively managed area increased by 80.68% and 47.62%, respectively; (4) The TN content in runoff water had a significant negative correlation with alkali-hydrolyzed nitrogen content of the soil, while the TP content in runoff water had a significant positive correlation with soil available phosphorus.