西藏色季拉山急尖长苞冷杉林下苔藓持水性能研究

西藏色季拉山为典型的高原山地原始暗针叶林，面积较大的急尖长苞冷杉林为原始暗针叶林的主体。其林分生长良好，林下植被丰富，特别是林下苔藓层发育很好。采用野外观测法和室内浸泡法对西藏色季拉山不同坡向不同海拔急尖长苞冷杉林下的苔藓进行种类鉴定并进行持水能力研究。结果表明:调查地内共有苔藓9科13属14种，其中羽藓科锦丝藓属锦丝种为优势种，各海拔段均有分布；色季拉山阴坡各海拔段苔藓厚度均要高于阳坡；无论是天然持水量还是最大持水量，阴坡均要高于阳坡，两个坡向的3 800 m海拔段持水量最大；苔藓在浸水后0.5～1 h内持水量迅速上升，1 h后慢慢增加并稳定。结果表明苔藓在降雨1 h内对降雨的吸持有重要作用；苔藓持水量与浸泡时间可用对数函数拟合。

Water Holding Capacity of Bryophyte in Understory of Mount Sejila in Tibet

Dark coniferous forest grows in the Plateau mountain region of Mountain Sejila in Tibet.This stand grows well. Undergrowth of vegetation is rich. The rather thick bryophyte grows on the surface of understory. Water holding capacity and species identification in different aspect altitude of mount Sejila in Tibet were studied by field survey and water immersion. The results showed that: there were 9 families, 13 genera and 14 species among these specimens, the predominant species was Thuidiaceae Actinothuidium hookeri, which distributes at every elevation. The thickness of moss on shady slope is higher than sunny slope of Mountain Sejila in Tibet. Whether the water holding capacity or the maximum water holding capacity on shady slope is higher than that on the sunny slope. The water holding capacity on two aspects with 3 800 m altitude is the biggest. The water holding capacity of moss increased rapidly after moss was soaked for 0.5～1 h. The water holding capacity increased slowly and stabilized 1 hour later. Therefore, the research showed that moss played important roles in the absorption of rainwater within 1 hour of rainfall. The relation between water holding capacity and the immersion time can be described by y=a+bln (t).