次降雨对马尾松低效林改造初期坡面产流产沙的影响

森林更新或改造是林地极易发生水土流失的关键时期。通过对四川省宜宾市高县马尾松低效林不同改造模式的5个人工径流小区不同降雨量条件下产流产沙数据分析,探索改造初期(3a)降雨与产流、产沙特征的关系及随植被恢复的演变规律。结果表明:2014年Ⅰ~Ⅴ号径流小区因不同降雨量条件下导致的产流总量较2012年同期分别降低-6.44%,-10.51%,20.95%,13.28%,12.73%;产沙总量降低58.4%,56.38%,77.72%,78.16%,79.68%。产流量与产沙量随降雨量增加呈指数增长趋势,但产沙量在森林改造当年增长幅度更大。不同改造模式径流小区产沙量第2年和第3年显著低于第1年,而第2年、第3年差异不显著,不同改造模式与产流、产沙量无显著相关性,改造模式不同并不是导致水土流失加剧的主要因素。改造时间与产流量、产沙量存在显著差异性。皆伐径流小区在改造初期恢复效果更佳,但随着林木生长及森林环境的形成后不同改造模式与产流、产沙量的关系可能会出现差异。

Effects of Single Rainfall on Slope Runoff and Sediment Yield of Low- efficiency Pinus massoniana Lamb. Forest in the Initial Stage of Reconstruction

Forest regeneration or transformation is a critical period for forest land to be prone to soil erosion.In this paper,through the analysis of single rainfall and runoff and sediment yield data of five artificial runoff plots in different transformation models of low-efficiency Pinus massoniana Lamb.forest in Yibin City,Sichuan Province,the relationship between rainfall,runoff and sediment characteristics was explored.The results showed that,with the vegetation evolution,the total runoff of I-Ⅴ in 2014 decreased by-6.44％,-10.51％,20.95％,13.28％,and 12.73％,respectively,compared with that in the same period of 2012;the total sediment yield decreased by 58.4％,56.38％,77.72％,78.16％,and 79.68％,respectively.The runoff and sediment yield increased exponentially with the increase of rainfall,but the amount of sediment yield increased more.The sediment yield of runoff plots in the second and third year was significantly lower than that in the first year,but the difference between the second and third year was not significant,and there was no significant correlation between the runoff and sediment yield.The different patterns were not the main factors leading to the aggravation of soil erosion.There were significant differences between the time of reconstruction and the runoff and sediment yield.The results showed that the restoration effect of the clear cutting plot was better at the early stage of the reconstruction,but with the growth of the forest and the formation of the forest environment,the relationship between the transformation model and the runoff and sediment yield might be different.