东北黑土区水土保持林降雨截留特征分析

为了解林冠截留对东北黑土区水土保持林水分循环、分配及利用率的影响,以落叶松和落叶松-蒙古栎混交林为研究对象,在吉林省东辽县杏木小流域布设野外观测试验,对两种不同林分降雨截留特征进行分析。在15次降雨观测中,落叶松与落叶松-蒙古栎混交林的林下穿透雨分别占总降雨量的72.02%和67.42%,树干流占2.62%和2.74%,截留量占25.32%和29.80%,两种林分林冠截留率为8.93%~73.50%,落叶松-蒙古栎混交林对降雨的截留作用较佳。落叶松与落叶松-蒙古栎混交林产生地表径流各8次,共计产流3.52和3.40 mm。不同林分林下穿透雨和截留量随月份变化表现为8月7月6月5月9月,树干流为7月8月6月5月9月,9月截留率最高,分别为44.49%和49.02%,7月份截留率最低,分别为20.40%和25.17%。不同林种林下穿透雨、树干流及截留量均与降雨量呈显著线性相关(P0.05),且当降雨量30 mm时,树干流增幅较小,降雨量30 mm时,树干流迅速增加并逐渐趋于平稳。截留率随着降雨量的增加则逐渐降低,当降雨量较小时(30 mm),林冠截留率由73.50%降低到21.90%,随着降雨量的增大,截留率变化幅度较小,并趋于稳定。两林分林下穿透雨与降雨强度呈显著线性相关(P0.05),树干流与降雨强度以对数拟合较好(P0.05),降雨强度与林冠截留量和截留率相关性不显著。当降雨强度≤2.65 mm/h时,两林分林冠截留率均大于50%。

Characteristics of precipitation interception in soil and water conservation forests of the Northeast black soil areas of China

A study of forests for soil and water conservation has been undertaken to learn the effect of canopy interception on water circle,allocation and utilization in the Northeast black soil areas of China.Field monito-ring data was used to investigate precipitation interception in two forest types Larix gmelinii (LG)and Quer-cus mongolica-Larix gmelinii (QM-LG)]in the Xingmu small watershed of Dongliao County,Jilin Province. During the 15 rainfalls from May to September 2013,throughfall accounted for 72.0% and 67.4% of LG andQM-LG total precipitation respectively.Stemflow made up 2.6% and 2.7% of total rainfall and 25.3% and 29.8% of interception respectively.Interception percentages in the two forests varied from 8.9% to 73.5%. Compared with LG,QM-LG had higher interception efficiency.8 rainfall events generated surface runoff for LG at 3.52 mm and QM-LG at 3.40 mm.Monthly throughfall and interception in the two forests ranked as August>July>June>May>September,and stemflow as July>August>June>May>September.Monthly interception percentages in the two forests were the highest in September (44.5% and 49.0%)and the lowest in July (20.4% and 25.2%).Throughfall,stemflow and interception had significant linear associations with total rainfall.Stemflow increased slightly with light rain and more significantly when rainfall was above 30 mm.Interception percentages gradually decreased with increases in precipitation.Throughfall in LG and QM-LG was significantly positively correlated with rainfall intensity.Stemflow and rainfall intensity could be fitted with logarithmic curve.However,the relationship between rainfall intensity and interception or interception percentage was not significant.The interception percentage of the two forests was more than 50% when rain-fall intensity was equal to or less than 2.65 mm/h.