封育对黄河源头玛多高寒草原水源涵养的影响

Effects of Fencing on the Soil Water Conversation in Maduo Alpine Grassland-source of Yellow River

为探讨封育对高寒草地水源涵养能力的影响,以黄河源头玛多高寒草原封育和未封育的样地为研究对象,通过对降水、土壤湿度、渗漏量的观测,利用水平衡法计算草地的实际蒸散量,得到以下结果：植物生长期内的5月1日-9月28日,0-40cm土壤实际贮水量在16.89-98.16mm之间,封育与未封育条件下差异极小;5月1日-9月28日40cm深层处封育与未封育渗漏量分别为6.70mm和8.55mm,占同期降水量的3%和4%,依此推算年内约11mm的降水渗入地下。5月11日至9月下旬,封育与未封育植被蒸散量分别为272.95mm和299.36mm,自然放牧的植被蒸散量比围栏封育地高,考虑到冷季降水全部用于蒸发,可推算玛多高寒草原年实际蒸散量约为334.86mm,稍大于降水量（318.5mm）。围栏封育后,0-40cm整层平均容重降低6%,土壤毛管持水量和饱和持水量分别增大了16%和14%;近10a的封育不仅降低了土壤容重,而且使土壤毛管持水量和饱和持水量分别按每年1.95mm和1.77mm的速率增加,表明封育在一定程度上提高了土壤的水源涵养能力,对草场恢复有利。

Two types of grassland including grazing and fencing for 11 years belonging to Maduo meteorological administration were used to study the effects of fencing on the soil water conversation.Precipitation,soil water content and water percolation were observed and then evapotranspiration was calculated by water equilibrium analysis method.The results showed that soil water content in the layer of 0-40 cm was between 16.89 mm and 98.16 mm from May to October.There was little difference between grazing and fencing grassland.In the same time,water percolation in the 40 cm was 6.70 mm and 8.55 mm accounting for 3% and 4% of the rainfall in fencing and grazing grassland respectively,evapotranspiration in grazing grassland was a little higher than fencing grassland and was 272.95 mm and 299.36 mm respectively.Actual evapotranspiration was 334.86 mm and a little higher than rainfall which was 318.5 mm in Maduo alpine grassland.Soil bulk density decreased by 6%and capillary and maximum water holding capacity increased by16% and 14% after fencing.Results above indicated that fencing could increase the soil water holding capacity in some extent and it was favorable to grassland restoration.