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    党毅, 王维, 张永娥, 王渝淞, 丁兵兵, 樊登星, 贾国栋, 余新晓, 董俊杰. 坝上高原不同植被类型覆盖下土壤水分含量对降雨的动态响应[J]. 北京林业大学学报, 2023, 45(5): 106-118. DOI: 10.12171/j.1000-1522.20220220
    引用本文: 党毅, 王维, 张永娥, 王渝淞, 丁兵兵, 樊登星, 贾国栋, 余新晓, 董俊杰. 坝上高原不同植被类型覆盖下土壤水分含量对降雨的动态响应[J]. 北京林业大学学报, 2023, 45(5): 106-118. DOI: 10.12171/j.1000-1522.20220220
    Dang Yi, Wang Wei, Zhang Yonge, Wang Yusong, Ding Bingbing, Fan Dengxing, Jia Guodong, Yu Xinxiao, Dong Junjie. Dynamic response of soil moisture content to rainfall under different vegetation cover types on the Bashang Plateau, northwestern Hebei Province of northern China[J]. Journal of Beijing Forestry University, 2023, 45(5): 106-118. DOI: 10.12171/j.1000-1522.20220220
    Citation: Dang Yi, Wang Wei, Zhang Yonge, Wang Yusong, Ding Bingbing, Fan Dengxing, Jia Guodong, Yu Xinxiao, Dong Junjie. Dynamic response of soil moisture content to rainfall under different vegetation cover types on the Bashang Plateau, northwestern Hebei Province of northern China[J]. Journal of Beijing Forestry University, 2023, 45(5): 106-118. DOI: 10.12171/j.1000-1522.20220220

    坝上高原不同植被类型覆盖下土壤水分含量对降雨的动态响应

    Dynamic response of soil moisture content to rainfall under different vegetation cover types on the Bashang Plateau, northwestern Hebei Province of northern China

    • 摘要:
        目的  土壤水是连接大气降水、地表水、地下水的关键因子,在地表径流、降雨入渗和植被蒸腾等生态水文过程中发挥重要作用。分析坝上高原地区不同雨量降雨事件中各植被类型覆盖下土壤水分含量动态响应过程及差异,将有助于深入探讨该区土壤水分含量的补给效应特性,对优化区域植被结构具有十分重要的理论及现实的意义。
        方法  选取河北省张北县草地、柠条灌木林、杨树乔木林为研究对象,通过监测2019年4—10月连续土壤水分含量和降雨数据,分析不同植被类型覆盖下土壤水分含量对大小降雨事件的动态响应过程及差异。
        结果  (1)研究区主要降雨事件由小雨和中雨构成,但主要降雨量由大雨提供。小雨和中雨发生次数占比为81.58%,其贡献的降雨量仅占年总降雨量42.66%;大雨发生次数占比仅为18.42%,却提供了年总降雨量的57.34%。(2)4—10月杨树乔木林土壤水分含量均值显著高于草地(P < 0.05),而柠条灌木林波动最为强烈。各植被类型覆盖下土壤水分含量均值分别为杨树乔木林(13.99 ± 2.04)% > 柠条灌木林(12.63 ± 0.93)% > 草地(10.67 ± 2.77)%,土壤水分含量变异系数均值呈柠条灌木林(26.22%) > 杨树乔木林(20.51%) > 草地(13.89%),均为中等强度变异。(3)草地20 ~ 40 cm土层的土壤水分含量显著高于0 ~ 20 cm及40 ~ 100 cm的4个土层(P < 0.05);柠条灌木林在20 ~ 40 cm和80 ~ 100 cm土层之间、0 ~ 20 cm和40 ~ 60 cm之间均不存在显著差异,且20 ~ 40 cm和80 ~ 100 cm土层土壤水分含量均显著高于其他3层(P < 0.05);杨树乔木林80 ~ 100 cm土层的土壤水分含量显著高于其他4个土层(P < 0.05)。(4)在不同雨量降雨作用下,除某些特殊情况外,柠条灌木林对降雨响应的各指标常与其他两种植被类型呈显著差异(P < 0.05)。各植被类型覆盖的土壤水分含量开始响应速度均值、补给量均值、补给速率均值为柠条灌木林最大而杨树乔木林最小。小雨、中雨只能使3种植被类型0 ~ 20 cm土层做出响应,补给较为有限;而大雨作用下草地响应土层为0 ~ 60 cm,乔、灌木均为0 ~ 80 cm。3种植被类型覆盖下土壤水分含量响应速度、达峰速度、补给量、补给速率均随着土壤深度增加而变弱,上层土壤对于降雨的响应总是快于且幅度大于下层土壤。
        结论  在当前降雨条件下,柠条灌木林对降雨响应最为敏感且响应效应最为强烈,而杨树乔木林响应速度最慢且响应效应最弱。此外,只有在大雨作用下,3种植被类型所覆被的中下层土壤水分含量才会得到明显的响应与补充。本研究结果为该地区未来营造防护林过程中改变重乔木轻灌木的传统观点,合理调整灌木比重,实现生态水文功能的整体提高等提供了一定的科学依据。

       

      Abstract:
        Objective  Soil moisture is a key factor linking atmospheric precipitation, surface water and groundwater, and plays an important role in eco-hydrological processes such as surface runoff, rainfall infiltration and vegetation transpiration. The analysis of dynamic response process and differences in soil moisture content of various covers under rainfall events in Bashang Plateau of northwestern Hebei Province of northern China will be helpful to explore the characteristics of replenishment effects of soil moisture content in this region, which is of great theoretical and practical significance to optimizing regional vegetation structure.
        Method  The grassland, Caragana korshinskii shrub land and poplar forest land in Zhangbei County, Hebei Province were selected as research objects. The dynamic response process and differences of soil moisture to different types of rainfall under various vegetation cover types were analyzed by monitoring continuous soil moisture content data and rainfall data from April to October, 2019.
        Result  (1) The main rainfall events in the study area were light rain and moderate rain, but the main amount of water was provided by heavy rain. The percentage of light rain and moderate rain occurrences was 81.58%, but they only contributed 42.66% to the total annual rainfall. The percentage of occurrences of heavy rain was only 18.42%, but it provided 57.34% of the total annual rainfall. (2) From April to October, the mean value of soil moisture in poplar forest land was significantly higher than that in grassland, and the fluctuation of soil moisture in Caragana korshinskii shrub land was the strongest. The mean soil moisture values under each vegetation cover types were poplar forest land (13.99 ± 2.04)% > Caragana korshinskii shrub land (12.63 ± 0.93)% > grassland (10.67 ± 2.77)%, and the mean soil moisture coefficient of variation was Caragana korshinskii shrub land (26.22%) > poplar forest land (20.51%) > grassland (13.89%). The coefficient of variation at each layer was at a moderate variation level. (3) The soil moisture content in 20−40 cm soil layer of the grassland was significantly higher than that in the other four soil layers (P < 0.05). There was no significant difference in soil moisture content between the 20−40 cm and 80−100 cm soil layers, as well as between the 0−20 cm and 40−60 cm soil layers in the Caragana korshinskii forest, and the soil moisture content in the 20−40 cm and 80−100 cm soil layers was significantly higher than that in the other three layers (P<0.05); the soil moisture content of the 80−100 cm soil layer in the poplar tree forest was significantly higher than that of the other four soil layers (P<0.05). (4) Under the effect of different rainfall amounts, the indicators of soil response to rainfall in shrublands were often significantly different from those of the other two vegetation types, except for some special cases. Among all types of rainfall, the mean values of soil moisture content response rate, recharge amount and recharge rate for each vegetation type cover were the greatest in Caragana korshinskii shrub land but the smallest in poplar forest land. Light and moderate rain can only respond to the 0−20 cm soil layer of the three vegetation types, with limited supply. Under heavy rain, the response of grassland to soil layer was 0−60 cm, while that of trees and shrubs was 0−80 cm. The response speed, peak reaching speed, replenishment amount, and replenishment rate of soil moisture content under three types of vegetation cover weakened with the increase of soil depth, and the response of upper soil to rainfall was always faster and greater than that of lower soil. Conclusion Under current rainfall conditions, the Caragana korshinskii shrub land responded the fastest and strongest to rainfall, but the poplar forest land responded the slowest and weakest. In addition, the deeper soil moisture under the three vegetation covers only responds significantly during heavy rain and allows the soil moisture to be replenished. The results of this study provide a scientific basis for changing the traditional view of emphasizing arboreal forest land but neglecting shrubs in the process of creating protective forests in the region in the future, and then reasonably adjusting the proportion of shrubs to achieve the overall improvement of eco-hydrological functions.

       

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