拉萨半干旱河谷宜林地土壤水分时空分布格局

土壤水分是植被恢复的主要限制因子之一。本文选择拉萨半干旱河谷宜林地7个典型立地类型0～20 cm,20～40 cm,40～60 cm深度的土壤为研究对象,研究其土壤水分的变化规律,探讨拉萨半干旱河谷地区土壤水分时空分布格局。研究结果表明:不同立地类型的土壤水分变化走势大致相同,呈单峰状分布,土壤最低含水量与最高含水量分别出现在1月和8月,其变化范围在2.43%～30.03%之间;土壤含水量由高到低排序为:河滩地高水位阴坡上部阴坡下部河滩地低水位阳坡上部阶地阳坡下部;土壤水分时间格局总体上分为土壤水分积累期(6—9月)、土壤水分消耗期(10月至翌年1月)、土壤水分稳定期(2—5月)3个时期,土壤水分空间分布分为土壤水分速变层(0～20 cm)、土壤水分活跃层(20～40 cm)及土壤水分相对稳定层(40～60 cm)3层。本研究对该区植被建设具有一定的指导意义。 

Distribution pattern of soil moisture space-time of forestland in semi-arid valley of Lhasa,southwestern China

Soil moisture is one of the main limiting factors of vegetation restoration. As the research objects of seven typical site types which belong to the layers of 0--20 cm, 20--40 cm, 40--60 cm depth soil, the paper studies the change and pattern of space-time distribution of soil moisture in semi-arid valley of Lhasa, southwestern China. The results showed that the soil moisture changing trends of different site types were roughly same and the shape was unimodal distribution. The minimum and maximum water content occurred in January and August respectively, and its range was between 2. 43%--30. 03%. The order of soil water content from high to low was as follows:high water level of flood land > upper part of shady slope>lower part of shady slope> low water level of flood land> upper part of sunny slope >terrace> lower part of sunny slope. The time spatial pattern of soil moisture could be divided into three periods, ie soil water accumulation period ( from June to September ) , soil water consumption period ( from October to the January of next year) and soil water stationary period( from February to May) . The space distribution of soil moisture could be divided into three layers, ie soil water comported layer (0--20 cm) , soil water active layer ( 20--40 cm ) and soil water relatively stable layer ( 40--60 cm ) . This conclusion has a certain guiding significance for the vegetation construction in this area.