托木尔峰自然保护区台兰河上游不同植被类型的水源涵养功能

Water Conservation Function of Different Vegetation Types in the Upper Tailan River in Mount Tumor Nature Reserve

为了研究托木尔峰自然保护区生态系统的水源涵养功能,选择台兰河上游为研究区域,采用野外观察与室内试验相结合的方法,分别对该区域具有代表性的雪岭云杉林、灌木林、草地植被,从林冠层、枯枝落叶层和土壤层3个层次及综合性的水源涵养能力进行了定量分析。结果表明:研究区云杉林林冠截留能力优于灌木林,穿透降雨量及林冠截留量平均值均大于灌木林。除草地外,各样地枯枝落叶未分解层平均厚度均大于半分解层,云杉林枯枝落叶层的厚度和蓄积量明显大于灌木林,不同植被类型枯枝落叶半分解层的自然持水率、最大持水率均高于未分解层,云杉林枯枝落叶层自然持水率、最大持水率均高于灌木林,灌木林和云杉林的枯枝落叶未分解层有效拦蓄量均高于半分解层。不同植被类型平均土壤容重大小表现为草地>灌木林>云杉林,土壤孔隙度的平均值大小则与之相反;不同植被类型的土壤自然含水率、饱和含水量及非毛管持水量均表现为云杉林>灌木林>草地,而不同植被类型30cm深土层的蓄水能力变化则存在差异。研究区不同植被类型的水源涵养能力在181.06~237.63mm,综合、有效水源涵养能力均表现为云杉林>灌木林>草地,其中土壤层的涵养贡献率最大,总有效蓄水量远小于总持水量。综上所述,台兰河上游云杉林和灌木林具有较好的涵养水源能力,放牧强度和人为干扰是影响研究区不同植被类型尤其是生境脆弱的草地植被水源涵养功能的重要因素。

To evaluate the water conservation function of ecological system in Mount Tumor Nature Reserve, we selected the upstream of the Tailan River as the study area to quantitatively analyze the water conserva- tion capacities of typical Picea schrenkiana forest, shrub woodland and grassland by using the combined method of field observation and laboratory experiments. The water conservation capacities in three layers including the forest canopy, litter layer and the soil layer, as well as the comprehensive capacity were analyzed. The result showed that the canopy interception capacity of Picea schrenkiana forest was greater than that of the shrub woodland in the study area, and the average throughfall and canopy interception were both greater than those of the shrub woodland. The average thickness of undecomposed layer was higher than that of semi decomposed layer in all kinds of vegetation, and the thickness and volume of litter layer in Picea schrenkiana forest were significantly greater than those in the shrug woodland. In all three types of vegetation, the natural and maximum water holding capacities of the semi decomposed layers were all higher than those of the undecomposed layers, and the natural and maximum water holding capacities of litter layer in Picea schrenkiana forest were both higher than those in the shrub woodland. The modified interception amounts of undecomposed layer were higher than those of semi decomposed layer in Picea schrenkiana forest and the shrub woodland. The average soil bulk density of different vegetation types followed the order of grassland 〉 shrub woodland 〉 Picea schrenkiana forest, while the order of soil porosity mean value was op posite; the natural moisture content, saturated water content and non-capillary water holding capacity of dif-ferent vegetation types followed the order of Picea schrenkiana forest 〉 shrub woodland 〉 grassland, but the water storage capacity of soil layer deeper than 30 cm varied among different vegetation types. The water conservation capacities of different vegetation types were 181.06 ~ 237.63 mm, and the comprehensive and effective water conservation capacities both listed in the order of Picea schrenkiana forest 〉 shrub 〉 grass- land. The soil layer contributed greatest in water conservation, and the total effective storage capacity was far less than the total water. In summary, Picea schrenkiana forest and shrub woodland in the study area had better water conservation ability. Grazing intensity and human disturbance were the important factors that affected the water conservation function of different vegetation types in the study area, especially for vulnerable grassland.