长白山暗针叶林苔藓枯落物层的降雨截留过程

对长白山北坡暗针叶林地面苔藓枯落物层 (苔藓植物和枯落叶交织而成的层状结构 )持水能力、截留降雨过程及动态变化进行了研究。结果表明苔藓枯落物层持水能力很强 ,最大持水量相当于 4 .8mm的降雨量 ,这个结果大于将苔藓与枯落物分开来测定的结果之和 ,说明成层结构能够提高持水能力。在一次降雨过程中对降雨截留过程的观测发现 :持水量刚开始随降雨增加而增加 ,到一定量时 ,降雨再增加 ,持水量反而缓慢下降。对持水动态变化一个月的观测 ,表明苔藓枯落物层水分蒸发较快 ,当长时间无雨时 ,持水量显著下降 ,当降雨再次发生时 ,持水量迅速回升 ,这种动态过程伴随着降雨的发生而不断往复。此外 ,在夜间苔藓枯落物层有吸收空气中水气的特点 ,吸收量受空气湿度的影响

Studies on rainfall holding process of the bryophyte and litter layer in coniferous forest of Changbai Mountain

The ability of the bryophyte and litter layer(bryophytes interlace with litter)to hold water in dark coniferous forests is studied, and the dynamic process of holding water is observed for one month. The results show that the holding water ability of the bryophyte and litter layer is very strong. The maximal content of holding water is 48.15t/hm~2, and the maximal rate of holding water is 773.13%. Then the bryophyte and litter layers are separated and measured respectively for holding water ability. The content of holding water of bryophyte is 27.42 t/hm~2 and the content of holding water of litter is 2.30 t/hm~2. The sum is 29.72 t/hm~2 less than the content of holding water of bryophyte and litter layer. This shows that keeping layer structure is very important when observing bryophyte hydrologic function. In the process of one rainfall the bryophyte and litter layer can completely absorb about 3mm of rain. When rainfall exceeds 3mm the bryophyte and litter layer begins infiltrating water, but content of infiltrating water is very little when rainfall is under 4.5mm. With rainfall continually increasing the infiltrating water speed becomes fast, but content of holding water still continually increases. Content of holding water gets to the maximal value at 7mm of rainfall, and then begins descending. At last content of holding water sustains at 4.5mm. In studying the dynamic process of holding water we find that if there is no rain for a long time, content of holding water of the bryophyte and litter layer decreases too much. When rainfall occurs the bryophyte and litter layer can rapidly absorb water. The dynamic process to and fro occurs with raining. On the other hand, we find the bryophyte and litter layer can absorb water from the air at night and evaporate very much at fine daylight. In summary the bryophyte and litter layer has very important functions in rainfall distribution of dark coniferous forests.