六盘山华北落叶松林和红桦林枯落物持水特征及其截持降雨过程

在六盘山南坡野外调查了华北落叶松(Larix principis-rupprechtii)和红桦(Betula albo-sinensis)两个林分的枯落物数量特征,其厚度分别是3.6cm和4.0cm,储量为16.83 t/hm2和9.04 t/hm2.浸泡测定了单位重量(1.0kg/m2)枯落物的持水能力,华北落叶松林和红桦林的最大持水深分别是1.8 mm和2.7 mm.在六盘山地区自然雨强范围内(<30 mm/h),利用模拟降雨研究了枯落物的截持降雨过程,表明枯落物持水能力随雨强增大而提高;在雨强为30 mm/h时,华北落叶松林和红桦林枯落物(1.0kg/m2)的最大截持雨量为1.5mm和2.6mm,分别是浸泡测定持水能力的83.3%和96.2%,两种实验吸持水分的过程基本一致.分析表明,枯落物截持过程的吸水速率受其本身含水量大小的影响,同时构建了具有较好截持机制的枯落物截持降雨过程模型,并基于枯落物浸泡实验和模拟降雨截持实验的数据拟合了模型参数.

The water-holding capacity of litter layers in the forests of Larix principis- rupprechtii and Betula albo-sinensis in Liupan Mountain and their rainfall interception process

The quantitative characters of litter layer were investigated in the south side of Liupan Mountains of Northwest China for a larch (Larix principis-rupprechtii) and birch (Betula albo-sinensis) stand. The thickness of litter layer of the larch and birch forest was 3.6 cm and 4.0 cm, and their corresponding weight was 16.83 t/hm2 and 9.04 t/hm2 respectively. The water-holding capacity of unit weight of litter (1.0 kg/m2) measured by a soaking method was 1.8 mm for larch and 2.7 mm for birch. The rainfall interception process was studied under simulated rainfall within the normal rainfall intensity range of this region (< 30 mm/h). It showed that the interception capacity of litter increased with rainfall intensity. The maximum depth of interception of unit weight of litter (1.0 kg/m2) under the rainfall intensity of 30 mm/h was 1.5 mm for larch and 2.6 mm for birch, accounting for only 83.3% and 96.2% of the water-holding capacity determined by soaking method. However, the water soak-up processes in the two different experiments were essentially consistent with each other. The water absorption rate of litter was influenced by its moisture condition. A mechanism based model for describing the rainfall interception process of litter of the two tree species was developed, and the model parameters were fitted based on the measured data both from the soaking experiment and simulated rainfall interception experiments.