川西低山区几种林(竹)-草复合经营模式水土保持能力对比研究

通过坡面人工径流小区的定位观测,对川西低山区2003年几种林(竹)-草复合经营模式与农耕地的产流产沙特征及养分流失情况分析与比较,结果表明:①植被类型及土地经营利用方式的不同对径流特征及产沙量有很大的影响,苦竹+牛鞭草模式在3年后所表现的生态效益优于其他模式;②由于川西低山区强降雨主要集中在7、8月份,此两月各模式与农耕地的产流产沙量均达各自全年总量的70%以上。在此两月保持林地覆盖物特别是林下的枯落物或地被物能显著减少水土流失;③坡地上的纯牧草地或林(竹)草模式林分郁闭度较低时,刈割牧草的时间对水土保持是至关重要的因素;④苦竹+牛鞭草模式的养分流失量最少。各模式内均以全K流失量最多,全N次之,全P最少。

Study on Capability of Soil and Water Conservation for Some Forest (Bamboo)-Grass Compound Management Patterns in the Western Hills of Sichuan Province

Based on the observation in runoff plots in the western hills of Sichuan Province in 2003, the feature of runoff, sediment yield and the nutrient losses in different patterns of forest (bamboo)-grass compound management were analyzed. The results are as follows: ①The feature of the surface flow and sediment yield are largely affected by the vegetations and the means of land utilization. It is the pattern Arundinaria amara+Hemarthria compressa that has the best effects on soil and water conversation. ②There is more than 70 percent of the surface flow and sediment yield of these patterns in July and August. In these two months, maintaining litter layer or ground cover contributes to lessening surface flow and sediment yield. ③When the field is covered by pure forage grass or the canopy density is low, it is vital to pay attention to the time of cutting grass. ④The pattern Arundinaria amara+Hemarthria compressa also has the least nutrient losses, with the result, TK>TP>TN.