多因素作用下黑土区农田防护林带对小流域侵蚀产沙的影响研究

The black soil region is regarded as one of the major commodity grain bases. As the major component of the black soil region, farmland shelterbelt system continuously plays an important role in influencing natural processes and human activities since its construction in the 1950s. In this study, some small catchments as well as the constructed shelterbelts will be selected to quantitatively study the effect of farmland shelterbelt on catchment soil erosion and sediment yield using 137Cs technique and soil erosion model. From both spatial and temporal viewpoints, the impacts of the constructed shelterbelts on soil erosion and deposition characteristics within the catchment and on the sediment yield at the catchment outlet will be analyzed when multiple factors are considered, and the varying characteristics of the sediment trap efficiency (STE) by shelterbelt will be discussed since land use, soil and water conservation measures, and precipitation can be changed during the past decades. Based on the extraction and quantification of the factors, a STE model composed of landforms, soils, precipitation, land use and soil and water conservation measures is to be constructed in the end. Then, the major factors influencing STE as well as their contribution to STE will be clearly disclosed. This study will deepen influencing mechanism of shelterbelts on soil erosion and sediment yield. The research will be of theoretical and practical significance to guide farmland shelterbelt’s construction and soil conservation plan that will reduce or control black soil loss and guarantee our country’s food security.

东北黑土区是我国重要的商品粮基地，作为该区重要组成部分的农田防护林体系，自其建设以来持续对各种自然过程及人为活动产生重要影响。本项目采用核素（137Cs）示踪和模型模拟相结合的方法，以黑土区多个小流域及流域内农田防护林带为研究对象，从时间和空间两个角度，开展以下工作：深入研究多因素作用下农田防护林带建设对小流域侵蚀沉积特征、流域出口产沙的影响；探讨不同年代农田防护林带减沙效益随流域土地利用、水土保持措施和降水变化的响应特征；在提取、量化农田防护林带减沙效益诸多影响因素的基础上，构建基于地形、土壤、降水、土地利用和水土保持措施等多因素作用下的林带减沙效益模型，明晰影响林带减沙效益的主要影响因素及其贡献，深入揭示农田防护林带对小流域侵蚀产沙的影响机制。该研究为今后黑土区农田防护林带建设与水土保持合理规划、减缓或抑制黑土流失和维护我国粮食安全，均具有重要的理论与实践意义。

东北黑土区是我国重要的商品粮基地，作为该区重要组成部分的农田防护林体系，自其建设以来持续对各种自然过程及人为活动产生重要影响。本项目利用水库的淤积信息，结合核素示踪技术，研究得到了农田防护林带对小流域侵产沙时空特征的影响。在一个有两条林带的小流域，研究发现，近50年来平均每年沉积在两条林带前后60m范围内的泥沙占小流域总泥沙沉积量的18.8%；在100年时间尺度上，每年沉积在林带前后的泥沙占流域年泥沙总沉积量的7%。以多个小流域为研究对象，利用模型情景模拟的方法，构建了多因素作用下林带减沙效益模型，揭示了小流域平均坡度和流域形状以及林带分布密度对减沙的贡献。此外，研究发现，1954年至今土地利用变化和塘坝建设对小流域减沙贡献分别为80%和20%，而林带的减沙效益随着时间在减小。在本基金的支持下，发表了论文10篇，其中SCI论文5篇，完成了基金的研究内容和成果目标；培养硕士研究生2名。该基金资助成果可在深化黑土区小流域侵蚀产沙机理研究的同时，也为黑土区小流域农田防护林带建设和水土保持措施的合理实施提供科学依据。