北方典型林地系统土壤水分动态和水量平衡随机模拟研究

Study on probabilistic modeling of soil moisture dynamics and water balance of typical forest land in northern China

以我国北方干旱半干旱地区3种典型林地植被元宝枫、油松、侧柏为研究对象,基于实测数据验证和构建土壤水分动态随机模型,量化区域土壤水分随机分布、水量平衡过程及其水分胁迫特征。结果显示:模型可较好地模拟3种林地的土壤水分动态分布特征,3种林地的土壤湿度概率密度分布区间接近,呈单峰状;大部分土壤水分通过蒸散发损耗且以胁迫蒸散发为主,土壤层深层渗漏量所占比例较小且几乎不产流,符合我国北方干旱半干旱山区林地水循环的实际特征;3种林地系统均受到一定程度的水分胁迫且水分胁迫特征值相近,表明土壤水分条件是影响区域生态系统的决定性因素。

Using the measured data to verify and construct the stochastic model of soil moisture dynamic,three typical forest ecosystems of maple, pine and cypress forest land were selected to quantify regional soil moisture stochastic distribution, water balance process and the water stress characteristics in the arid and semi-arid area of northern China. The results showed that the stochastic model can effectively simulate the characteristics of soil moisture dynamic distribution of three typical forest land. Meanwhile, it showed the distribution range of the probability density function for three forest is similar and the curves are one-humped. Most of moisture losses from the soil is evaporation and the main part is the evapotranspiration under stressed condition. On the other hand, the soil infiltration take a very small proportion, and the runoff hardly oceours which matching the real situation of the forest land in arid and semi-arid mountain areas. Three forest land is suffered a certain degree of water stress and the water stress for three forest turns out to be very similar, suggesting that soil moisture condition is the decisive factor which can influence regional ecological system.