红壤丘岗区林草生态系统土壤水分状况

Soil Water Status of Forest and Grass Ecosystems in Red Soil Hilly Region

在红壤丘岗区自然次生马尾松-草灌植被基础上,组建4种林草生态系统,长期观测结果表明,各生态系统地表径流量逐年减少,而入渗量和渗漏量逐年增加,径流量呈现阔叶林和混交林<马尾松林<自然草被,渗漏量则相反。阔叶林和混交林与马尾松林和自然草被比较,前者径流量年内分布在雨季更加集中,这正是不同林草生态系统涵养水源能力不同的体现。干旱季节4种林草系统土壤剖面水分分布有差别,阔叶林和混交林上下层土壤水吸力差别较小,而马尾松林和自然草被上下层土壤水吸力差别较大,前者土壤导水能力好而后者导水能力差是原因之一;阔叶林和混交林下层土壤水分含量比马尾松林和自然草被低。

Four forest and grass ecosystems were established under the natural secondary Massons pineshrubgrass land in red soil hilly region. Over a long period of field test and measurement in the four catchments, the results showed that the runoff increased and infiltration or leakage decreased year after year. The runoff observed in the broadleaved forest land (F1) and the mixed forest land  (F2)<the Massn pine land  (F3)<the natural grassland(G), but the leakages reversed. The comparison among the four ecosystems revealed that  F1 and F2 scattered higher percents of runoff in rainy season than  F3 and G did. And it just reflected the different water conservation abilities of the four kinds of forest and grass ecosystems. The water distribution pattern in the soil profile were also different among the four ecosystems especially in dry season. The soil water suction differences between upper and lower soil layers were smaller in  F1 and  F2 than in  F3) and G. The larger soil water conductivity in  F1 and  F2 and smaller in  F3 and G was one of the reasons. The lower layer soil water contents were lower in  F1 and  F2 than in  F3 and G.