兰州大学机构库 >资源环境学院
黄土高原地鼠挖掘活动对土壤侵蚀的影响机制研究
Alternative TitleStudy on the mechanism of soil erosion on the Loess Plateau induced by zokor excavation activities
刘茹
Subtype硕士
Thesis Advisor耿豪鹏
2023-05-29
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name理学硕士
Degree Discipline第四纪地质学
Keyword地鼠挖掘活动 zokor excavation activities 侵蚀计算定律 geomorphic transport law 土壤侵蚀 soil erosion 生物地貌 Biogeomorphology 黄土高原 Loess Plateau
Abstract

生物侵蚀的定量化研究是生物地貌学领域的热点问题,不同环境中动物活动对侵蚀过程的影响机制是其中的关键环节。黄土高原土壤侵蚀问题严重,实施了退耕还林还草等一系列生态恢复措施,取得了显著成效,但也引起了部分区域的鼠害问题。地鼠挖掘活动可以直接或间接地促进土壤侵蚀。因此亟需量化黄土高原土壤侵蚀中地鼠挖掘活动的作用,为控制黄土高原土壤侵蚀及生态恢复措施的可持续发展提供科学依据。通过单点重复监测获取经验公式是较为常规并可行的方案,但是此类方法往往缺乏物理过程信息,阻碍了研究结果在更大时空尺度上的推广。构建基于侵蚀过程的计算定律(geomorphic transport law)不仅能够解决尺度问题,相关成果还能服务于地貌演化数值模型的计算,是目前过程地貌学研究领域的主攻方向。
本研究基于野外调查并利用高精度无人机航拍技术,对位于黄土高原西部永登县的典型坡面(2942.34m2)进行了一年连续的定点重复监测,追踪了地鼠挖掘活动的空间分布与时间动态,量化了研究坡面内挖掘活动所产生的土壤侵蚀量,并探讨了环境因素和地形条件对挖掘活动时空分布动态以及挖掘活动侵蚀过程的影响,从而建立了地鼠挖掘活动的侵蚀计算定律。主要结论如下:
(1)野外观测结果表明,研究区内约有34只地鼠,地鼠的密度约为116ha-1。地鼠挖掘活动的时空动态呈现出一定的规律。在时间上,采食活动全年都在进行,而掘穴活动数量变化呈现出明显的双峰特征,分别出现在春末夏初和秋季。采食活动和掘穴活动全年最繁盛时期均出现在4、5月份,而全年最低谷时期均出现在1、2月份。在空间上,地鼠挖掘活动在坡面尺度上呈现出一定的季节性迁移规律,自春季到冬季依次从上坡迁移至中坡再至下坡。
(2)通过连续的土丘体积及洞道测量,我们大致估算了地鼠一年的挖掘体积为0.33m3,所折算的土壤侵蚀速率约0.11mm1y-1,对应的侵蚀通量约为0.83cm3cm-1y-1,土壤侵蚀模数约为135.71t1km-2y-1。如果假设挖掘的土壤均匀覆盖在地表,我们可以大致推算地鼠的挖掘活动可在62年内重塑地表。鉴于地鼠挖掘活动是一种典型的扩散侵蚀过程,综合考虑研究坡面的平均坡度和土壤容重,我们进一步计算得到地鼠挖掘活动所引起的扩散系数为1.10cm2y-1,符合半干旱区已有的全球统计认识。
(3)环境因素和地形条件对地鼠挖掘活动的时空动态具有一定影响。采食活动数量随时间的变化与降水量和土壤湿度密切关联。采食活动密度在坡面尺度内的空间变化与植被覆盖度密切关联。采食活动和掘穴活动均偏好于分布在坡度稍陡、汇水面积较小、流水分散区和凸形坡区域内。此外,地形条件对地鼠挖掘活动侵蚀过程具有显著的影响。掘穴活动地下搬运距离和地表搬运距离与坡度之间存在函数关系,采食活动地下搬运距离和地表搬运距离与坡度之间存在几何关系。基于地鼠挖掘活动过程并综合考虑环境因素和地形条件对挖掘活动的影响,我们最终提出了可推广的地鼠挖掘活动侵蚀计算定律:q_s (〖cm〗^3⁄(cm∙y))=2×10^5 N_i (cos⁡θ-2 tan⁡θ+4)。
综上,本研究量化了黄土高原土壤侵蚀中地鼠挖掘活动的作用,为控制黄土高原土壤侵蚀及生态恢复措施的可持续发展提供了一定的科学依据。提出了可推广的地鼠挖掘活动侵蚀计算定律,为地貌演化数值模型的计算提供了数据支持,为过程地貌学的发展融入了更多的生物地貌过程认识。
 

Other Abstract

The quantitative study of bioerosion is a hot issue in the field of biomorphology, and the mechanism of animal activities in different environments on the erosion process is one of the key aspects. Soil erosion is a serious problem on the Loess Plateau, and a series of ecological restoration measures such as Grain for Green Project have been implemented, which have achieved remarkable results, but also caused rodent infestation problems in some areas. Zokor excavation activities can directly or indirectly promote soil erosion. Therefore, there is an urgent need to quantify the role of zokor excavation activities in soil erosion on the Loess Plateau, and provide a scientific basis for the sustainable development of soil erosion control and ecological restoration measures on the Loess Plateau. Repeated monitoring at a single site to obtain empirical equations is a conventional and feasible solution, but such methods often lack information on physical processes, which hinders the generalization of research results to larger spatial and temporal scales. The construction of a geomorphic transport law based on erosion processes can not only solve the scale problem, but also serve for the calculation of numerical models of geomorphic evolution, which is the main direction of research in the field of process geomorphology.
In this study, based on field surveys and high-precision UAV aerial photography technology, a typical slope (2942.34 m2 ) in Yongdeng County, western Loess Plateau, was continuously and repeatedly monitored for one year to track the spatial distribution and temporal dynamics of zokor excavation activities, quantify the amount of soil erosion generated by excavation activities on the study slope, and explore the effects of environmental factors and topographic conditions on the spatial and temporal distribution of excavation activities. We also explored the influence of environmental factors and topographic conditions on the spatial and temporal distribution of excavation activities and the erosion process of excavation activities, and thus established the geomorphic transport law of zokor excavation activities. The main conclusions are as follows:
(1) Field observations showed that there were about 34 zokors in the study area, and the density of zokors was about 116 ha-1. The spatial and temporal dynamics of zokor excavation activities showed a certain pattern. In terms of time, foraging activities were carried out throughout the year, while changes in the number of burrowing activities showed obvious bimodal characteristics, occurring in late spring and early summer and autumn, respectively. Both foraging and burrowing activities were at their peak in April and May, while the lowest period of the year occurred in January and February. Spatially, the excavation activity of zokors showed a certain seasonal migration pattern on the slope scale, from spring to winter, from the upper slope to the middle slope to the lower slope in turn.
(2) From continuous mound volume and burrow channel measurements, we roughly estimated that the zokor excavation volume for one year is 0.33 m3, the converted soil erosion rate is about 0.11 mm1y-1, the corresponding erosion flux is about 0.83 cm3cm-1y-1, and the soil erosion modulus is about 135.71 t1km-2y-1. If we assume that the excavated soil covers the ground surface uniformly, we can roughly project that zokor excavation activities can reshape the ground surface within 62 years. Given that zokor excavation activity is a typical diffuse erosion process, and considering the average slope and soil capacity of the study slope, we further calculated that the diffusion coefficient caused by zokor excavation activity is 1.10 cm2y-1, which is consistent with the existing global statistical understanding of semi-arid areas.
(3) Environmental factors and topographic conditions have an influence on the spatial and temporal dynamics of zokor excavation activities. The variation of the number of foraging activities over time was closely related to precipitation and soil moisture. The spatial variation of foraging activity density within the slope scale was closely related to the vegetation cover. Both foraging and burrowing activities preferred to be distributed in areas with slightly steeper slopes, smaller water catchment areas, divergent flow areas and convex slopes. In addition, topographic conditions had a significant effect on the zokor excavation activities erosion process. There is a functional relationship between subsurface transport distance and surface transport distance and slope for burrowing activities, and there is a geometric relationship between subsurface transport distance and surface transport distance and slope for foraging activities. Based on the process of zokor excavation activities and considering the influence of environmental factors and topographic conditions on excavation activities, we finally proposed a generalizable law for calculating the erosion of gopher digging activities: q_s (〖cm〗^3⁄(cm∙y))=2×10^5 N_i (cos⁡θ-2 tan⁡θ+4).
In summary, this study quantifies the role of zokor excavation activities in soil erosion on the Loess Plateau, and provides some scientific basis for controlling soil erosion and sustainable development of ecological restoration measures on the Loess Plateau. A generalizable geomorphic transport law of zokor excavation erosion is proposed, which provides data support for the calculation of numerical models of geomorphic evolution and incorporates more understanding of biomorphic processes for the development of process geomorphology.
 

Subject Area生物地貌过程
MOST Discipline Catalogue理学 - 地质学 - 第四纪地质学
URL查看原文
Language中文
Other Code262010_220200944800
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/535763
Collection资源环境学院
Affiliation
兰州大学资源环境学院
Recommended Citation
GB/T 7714
刘茹. 黄土高原地鼠挖掘活动对土壤侵蚀的影响机制研究[D]. 兰州. 兰州大学,2023.
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