黄土高原北部河北杨林的土壤水分特征

A Study on the Soil Water Characteristics of Populus Hebeinsis Plantation on Northern Loess Plateau

以河北杨林为研究对象 ,在对其土壤水分进行 7a定位观测的基础上 ,对其特点进行全面分析。结果表明 :河北杨林土壤水分动态的周年变化规律主要受降水及其分配特点和生长期初土壤水分含量的影响。 0cm～ 30 0cm深度内 ,生长期土层内土壤水分的年平均值多数年在 6 4g kg左右 ;特旱年仅 5 0g kg;特涝年也只有 76g kg ;土壤水分条件较差 ;多数年份土壤水分基本平衡 ;特旱、特涝年份土壤水分大量亏缺、积累 ,其值均达 15 0mm以上。 0cm～ 30 0cm深度内土壤水分剖面的垂直分布自上而下分为活跃层、过渡层和稳定层 ,但各层的厚度变化受年降水量的影响较大 ;土壤含水量的平均值随深度增加而减少 ,从 72g kg～ 5 7g kg。除特涝年份的生长季中后期外 ,生长期内的土壤有效水分含量较少 ,河北杨处于轻胁迫状态 ;5月下旬到 7月上旬河北杨有近一半时间处于中胁迫状态。但河北杨有较大的贮水库容 。

Based on the data of seven year field measurement, the paper deals with the characteristics of soil moisture of Populus hopeiensis plantation. The results showed that the annual changing regularity of soil moisture of P. hopeiensis plantation depended mainly on both annual precipitation and its distribution as well as soil moisture storage amount in the beginning of growing season. The cycle level of soil moisture from extra dry year to extra wet year was from 50 g/kg to 76 g/kg, and the mean value was about 64 g/kg. The soil water content was in balance in most of the years, but was in a greatly deficit in extra dry year and a considerably surplus in extra wet year reaching as much as 150mm. According to the vertical profile of soil water, the distribution of soil moisture were divided from surface to bottom into three layers: active layer, transitive layer and stable layer. The thickness of the each layer changed greatly from year to year. The available water storage amount in the plantation was lower in the whole growing season. The plantation suffered from water stress slightly in most of the year, and suffered from water stress moderately about a half period of time from May to July, and had a high capacity for raining water storage. But this kind of situation provided with a favorable condition for soil water regularity between years.