Institutional Repository of Xishuangbanna Tropical Botanical Garden
| 云南喀斯特地区露石的汇水作用及其生态水文效应研究 | |
| Alternative Title | The Funnel Effect of Rock Outcrops and Its Eco-hydrological Effects in Karst Areas in Yunnan Province, Southwest China |
| 赵志猛 | |
| Thesis Advisor | 沈有信 |
| 2020 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 中国科学院西双版纳热带植物园 |
| Degree Name | 理学博士 |
| Degree Discipline | 生态学 |
| Keyword | 喀斯特水文，露石，土壤水分，岩溶作用 |
| Abstract | 喀斯特景观是一种受地质背景制约的生态环境，暴露的岩石（以下简称露石）与浅薄土层相互镶嵌，既塑造了复杂多变的地形地貌和水文地质结构，也使得植物生境呈现出高度的空间异质性。水是喀斯特植物生长、生存的基础，也是喀斯特发育与演化的动力，但关于露石对降水-径流过程的影响及其衍生的水文生态学功能的研究仍然不足。深入研究露石的生态水文学作用对于喀斯特地区植被恢复来说具有重大的理论与现实意义。本论文选取喀斯特地区多露石生境下的森林、灌木地和草地为研究样地，利用水样定期收集、染色模拟示踪、土壤水分定位监测和水文化学分析等方法，判定了露石对于降雨再分配、土壤水分入渗模式、土壤水分空间格局以及降雨引发的岩溶作用等一系列水文生态过程的影响，得到以下结果：（1）露石改变了喀斯特地区的降雨分配模式。喀斯特露石在截留雨水的同时，也通过露石径流将雨水再分配给邻近的土壤斑块，我们发现实验样地的“降雨-露石径流”转换系数约为35%。（2）露石改变了喀斯特地区地表土壤水分的入渗模式。染色灌溉实验显示，在多露石样地，地表土壤水分在露石-土壤界面（以下简称“岩土界面”）发生了很明显的优先流现象，优先流指数约为38.1%，与无露石样地均匀的水分入渗模式形成了鲜明的对比。染色喷洒实验显示，岩土界面是露石径流最主要的入渗路径，聚集在露石附近的根系通道和土壤动物洞穴也参与了这一过程。除此之外，露石也提高了土壤斑块的土壤含水量、孔隙率和渗透率等，并且露石周围的植物高度和地上/地下生物量显著高于远离露石的植物。（3）露石改变了喀斯特地区地表土壤水分的空间格局。通过对多露石生境下的森林、灌木和草地土壤水分的3 年监测，发现喀斯特地表土壤水分格局存在较高的空间异质性（最高可达62.8%），而这种空间格局同时存在较高的时间稳定性。随土壤深度的增加，土壤水分格局的均匀性和时间稳定性均呈现出增加的趋势。雨季的土壤水分格局具有非常强的均匀性和稳定性，但植物的根系会加强土壤水分格局的空间异质性并使其发生季节性变化。（4）露石是喀斯特基岩差异性溶蚀的产物。水文化学监测数据显示，降雨和露石径流的钙浓度没有达到饱和，仍具有较高的溶蚀潜力，为此我们提出了“土壤沉陷”假设模型来解释喀斯特露石的演变机制。即在一定的喀斯特演化阶段内，如果地表露石与土下基岩二者的风化残余物填充空间小于土下基岩释放的溶蚀空间时，石间的土壤将会持续下沉，露石高度则不断“增加”、数量不断“增多”。研究发现，露石溶蚀速率（在林地和无林地分别为：4.63 × 10-3 mm a-1 和4.97 × 10-3mm a-1）小于土下基岩溶蚀速率（在林地和无林地分别为：0.144 mm a-1 和0.127mm a-1）以及土壤沉陷速率（在林地和无林地分别为：0.126 mm a-1 和0.111 mma-1），这或许是喀斯特地貌演化和发育的根本原因之一；此外，林内地上与地下的岩溶速率存在相对较大的差值，林内露石溶蚀速率低于林外，而林内土下基岩溶蚀速率和土壤沉陷速率均高于林外，由此我们推测森林可能加速了喀斯特地貌的演化过程。以上研究结果证明，露石在喀斯特环境的生态水文过程中发挥着重要作用，其改变了降雨的分配格局，对周围生境起到了较强的水分补给作用，影响了地表土壤水分入渗模式和空间格局，改善了周围的土壤条件和植物生境，这些发现对于加深喀斯特生态系统地表水文过程、植物水文生境和植树造林项目的认识具有实际的指导意义。“土壤沉陷-基岩暴露”模型可以作为喀斯特地貌演变机理的新的补充，同时，森林与岩溶过程的联系为喀斯特地区森林管理提供了重要的科学依据。 |
| Other Abstract | Karst landscape is an ecological system intensively restricted by its geological background. Exposed rocks (hereinafter referred to as “rock outcrops”) are inlaid with shallow soil, not only shaping the complex and varied topography and hydrogeological structure, but also producing the high spatial heterogeneity of plant habitats. Water is the substance base of exist and development of karst plants, and is also a main driving factors of karst development and evolution. However, there is still a lack of research on the influences of outcrops on the rainfall-runoff processes and the hydro-ecological functions derived from it. To further study the ecological roles of outcrops in karst areas will have great theoretical value and practical significance. In this study, forest, shrubland, and grassland in karst area were selected as the study sites. Through water sample collection, dye tracer experiments, in-situ monitoring of soil water content and hydrochemical analysis data, this study attempted to reveal the influences of rock outcrops on the rainfall redistribution, soil water infiltration, soil water spatial pattern and rain-induced karstification. The results show:(1) Rock outcrops changed the distribution pattern of rainfall. The outcrops in karst areas can intercept part of the rainwater during the rainfall process to produce outcrops runoff, and the conversion coefficient of “rainfall-outcrops runoff” in the experimental sites was about 35%. (2) Rock outcrops changed the infiltration pattern of soil water in karst area. Dye irrigating experiment showed that in the rock outcrops plot, obvious preferential flow of soil water occurred at the interface between rock outcrops and soil (hereinafter referred to as “the soil-rock interface”) with fraction of preferential flow reaching 38.1%, in contrast to the uniform infiltration pattern in the non-rock outcrops plot. Dye sprinkling experiment showed the soil-rock interface was the main flow path of the runoff from outcrops, and the root channels and soil animal burrows near the outcrops also participated in this process. In addition, rock outcrops increased the soil moisture, porosity and permeability of nearby soil patches, and the height, aboveground and underground biomass of herbs around the outcrops were significantly higher than those away from the outcrops. (3) Rock outcrops changed the soil moisture spatial pattern (SMSP) in karst area. Through a three-year monitoring of soil moisture in forests, shrubs and grasslands under rocky habitats, we found there existed high spatial heterogeneity (as high as 62.8%) as well as high temporal stability in the SMSP in the earth's surface of karst area. With the increase of soil depth, the uniformity and temporal stability of SMSP increased. During the rainy season, the SMSP became very homogeneous and stable, but plant roots can enhance the spatial heterogeneity of SMSP and make it change seasonally. (4) The appearance of rock outcrops is related to the differential weathering and dissolution process of underground bedrock. Hydrochemical analysis data showed that rainfall and runoff from outcrops might have great corrosion potential due to their unsaturated calcium concentration. We therefore proposed a “soil subsidence” model to explain the evolution mechanism of karst rock outcrops, namely, in a certain stage of karst evolution, if the space filled by the weathering residues of exposed rocks and subsoil rock is smaller than the dissolution space released by subsoil rocks, the soil between rocks will sink, and the exposed rock will appear to grow in height and number. We found that the dissolution rate of the exposed rock (4.63 × 10-3 mm a-1 and 4.97 × 10-3 mm a-1 for the forested and cleared area) was always lower than that of the subsoil rock (0.144 mm a-1 and 0.127 mm a-1 for the forested and cleared area) and the rate of soil sinking (0.126 mm a-1 and 0.111 mm a-1 for the forested and cleared area), which might be one of the reasons for the evolution and development of karst landform. In addition, there is a relatively larger difference between the aboveground and underground dissolution rates of limestone in forest. The dissolution rate of exposed limestone in forest is lower than that outside forest, whilst the opposite was true for the dissolution rate of subsoil limestone and soil sinking rate. Thus, we speculated that forest might accelerate the evolution process of karst landform. In conclusion, rock outcrops play important roles in the eco-hydrological processes in karst areas. Rock outcrops change the distribution pattern of rainfall to supply water to the surrounding, and affect the infiltration pattern and spatial pattern of soil water to benefit the growth of nearby plants. These findings have practical implications for the understanding of the hydrological processes, plant habitats, and afforestation projects for karst ecosystems. The rock dissolution-based “soil sinking and bedrock exposuring” model can be a new interpretation of the evolution mechanism of karst landform, and the relationship between forest and karst process provides important scientific basis for forest management in karst areas. Key words: Karst Hydrology, Rock Outcrops, Soil Water, Weathering Dissolution |
| Pages | 139 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | https://ir.xtbg.ac.cn/handle/353005/11707 |
| Collection | 西双版纳热带植物园毕业生学位论文 |
| Affiliation | 1.中国科学院大学; 2.中国科学院西双版纳热带植物园 |
| Recommended Citation GB/T 7714 | 赵志猛. 云南喀斯特地区露石的汇水作用及其生态水文效应研究[D]. 中国科学院西双版纳热带植物园. 中国科学院大学,2020. |
| Files in This Item: | ||||||
| File Name/Size | DocType | Version | Access | License | ||
| 赵志猛.pdf（7023KB） | 学位论文 | 开放获取 | CC BY-NC-SA | Application Full Text | ||
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