渭北黄土高原刺槐林—草地景观界面土壤水分影响域及其动态变化规律研究

Depth of Edge Influence and Spatial Heterogeneity of Soil Moisture at Forestlnand-Grassland Landscape Boundary in Weibei Loess Plateau

对渭北黄土高原刺槐林—草地景观界面土壤水分影响域及其时空动态变化规律进行了研究。采用移动窗口法分析得出刺槐林—草地景观界面土壤水分影响域为林内4 m到林外12 m之间,宽度16 m,为渐变型界面,由此可将刺槐林—草地景观划分为3个区域：草地区、界面区和刺槐林区。经典统计分析表明,历经3个区域,不同层次的土壤水分在水平方向上随着水平距离梯度的变化表现出不同的上升或下降的趋势,在界面区域土壤含水量变化最为显著。基于标准差和变异系数两个指标,可将草地和林地区域土壤剖面水分垂直变化划分为4层,界面区域划分为3层。3个区域土壤含水量的季节变化表现为基本一致的“高-低-高”规律,可以划分为3个时期,4～5月中旬为土壤水分贮存期,6～7月中旬为土壤水分消耗期,8～10月中旬土壤水分恢复期。水分在时间和空间上的这种变化主要受植被类型、根系分布、降水资源再分配的影响。

The depth of edge influenee, the temporal and spatial variation of soil moisture in different soil layer in Weibei loess plateau were diseussed. By using moving split-window method, it was obtained that the depth of edge influenee was 16 m from 4 m inside forestland to 12 m outside forestland, the eetone between forestland and grassland was gradual type. The forestland-grassland landseape eould be divided into 3 parts; grassland area, eeotone area and forestland area. By traditional analysis methods,it was obtained that soil water in different layers absent or deseent with the ehange of horizontal distanee,and that the ehange of soil water on eeotone area were most signifieant. The vertieal ehange of soil water in the profile eould be divided into four layers in grassland and forestland, and three layers in eeotone area. Based on the seasonal variation of soil moisture,it ean be divided into three phase：the soil moisture stoeking phase from April to May,the lose phase from June to July,the refill phase from August to October. The temporal and spatial variation of soil moisture is mainly affected by the difference of vege- tation, soil mechanical composition.