基于根系解剖结构的金沙江干热河谷土壤侵蚀研究初探
文献类型：学位论文
| 作者 | 孙丽萍 |
| 学位类别 | 硕士 |
| 答辩日期 | 2011-05-27 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 王小丹 |
| 关键词 | 干热河谷 土壤侵蚀 赤桉 根系 解剖结构 |
| 其他题名 | Preliminary rearch of soil erosion based on anatomical structure of tree roots — A case study in the dry-hot valley of Jinsha River |
| 学位专业 | 自然地理学 |
| 中文摘要 | 土壤侵蚀是指在水力、风力、重力、冻融以及其它外营力作用下土壤、土壤母质及其它地面组成物质如岩屑、松散岩层等，被破坏、剥蚀、运转、沉积的过程。土壤侵蚀速率估算方法主要有：野外调查、径流小区、核素示踪和模型模拟等。植物作为地表下垫面组成的一种物质实体，不仅影响着地表景观和结构，而且其生理生态特征也记录着侵蚀过程对其生长环境稳定性和适宜性影响的相关信息，从植物解剖结构中反演土壤侵蚀信息的研究方法倍受关注。本研究基于侵蚀过程会导致树木生长环境变化，进而改变根系生长生理特征的基本研究思想，以金沙江干热河谷龙川江流域为典型区，从树根细胞解剖结构和组合特征的变异中提取土壤侵蚀信息，探索和发展基于树木生理生态的土壤侵蚀研究新方法与技术。主要研究结果与结论如下：（1）赤桉根系在土壤侵蚀中呈偏心生长。按照侵蚀后根系的暴露程度将样本分为：浅埋根样、局部暴露根样和完全暴露根样，平均偏心率分别为0.461（±0.133）、0.218（±0.096）、0.158（±0.121），大小顺序依次为：局部暴露根系＞浅埋根系＞完全暴露根系，且偏心率与根系以上土层厚度、暴露厚度存在显著性相关；不同暴露程度根系的年轮分布特征存在一定的差异性，且受干扰根系的轮宽与年降雨量、年均温的相关性减弱。（2）土壤侵蚀过程中受干扰根系的生理生态响应表现为晚材导管面积首先减小，由散孔结构变为环孔结构，年轮分界线清晰、晚材率增大；直至根系上表皮暴露于土层之外时，早材导管面积显著减小（减小百分比＞50%），并有大量伪轮或霜轮形成。因此，根系导管面积是反演侵蚀过程的敏感指标，早材导管面积的变异是确定根系暴露时间的重要依据之一，分辨率为1~2年。其中坡面侵蚀过程中暴露根系的解剖结构表现为渐变过程，而沟蚀过程暴露根系的解剖结构表现为突变。（3）研究区土壤流失厚度为1.04～3.61(mm/a)，平均土壤侵蚀模数为3110（±1043）t/km2•a（范围值1463～5106t/km2•a），根据土壤侵蚀分级分类标准属强度侵蚀。侵蚀模数的大小与采样点的坡度呈显著性（p﹤0.001，R2﹦0.75）正相关关系。本研究区域为水土保持治理区，侵蚀模数与果园地的（4000t/km2•a）相近，因此，人工赤桉林的水土保持效益并不理想。 |
| 英文摘要 | Soil erosion is defined as the course of destroying, denudating, moving and depositing of soil and other substances on the ground, under the actions of hydraulic forces, wind, gravity and freeze-thaw. The main tools for estimating soil erosion rates include field investigation, runoff plot, radionuclide tracing, model simulation, etc. As a material entity of earth surface, vegetation not only affects local landscape, but also records information related to soil erosion process. Many studies focused their attention on reconstructing soil erosion dynamics with anatomical features of tree rings. Based on physiological responses of tree growth to environmental changes, the paper developed a new method to extract information of soil erosion from tree-root anatomical structures and cell features. A case study has been carried out in the Longchuanjiang Watershed, Dry-hot Valley of Jinsha River. The study results showed： 1) The root of Eucalyptus is eccentric growth in soil erosion. The sample is divided into roots exposed partially,roots buried shallowly, roots exposed absolutely, based on the erosion degrees. The eccentricity ratio of tree ring is 0.461（±0.133）、0.218（±0.096）、0.158（±0.121）and the order is roots exposed partially > roots buried shallowly > roots exposed absolutely. There are some significant correlations bewteen the eccentricity and soil depth, the width of tree rings is inconsistent due to difference of erosion intensity. 2) Results of ongoing analyses show that the varying anatomical changes due to the type of process that caused root exposure. First, the area of vessel decreases in latewood, whereas there is no significant change in earlywood, fiber wall thickness increases (decrease of fiber volume), The border of growth rings is clearly visible. Abrupt reductions (above 50%) of vessel area in earlywood until the root exposed, additionally wedging rings appear very often.Vessel area was a sensitive indicator for reconstructing soil erosion process, and abrupt variations of earlywood vessels size was one of the important evidences to date the first year of exposure at 1~2 years resolution. 3) The soil loss thickness is 1.04~3.61(mm/a), and the average erosion modulus is about 3310(±1043)t/km2•a in Longchuanjiang Watershed. It is serious erosion based on the Standards for classification and gradtion of soil erosion. The erosion modulus is positively correlated with slope angle(p﹤0.001，R2﹦0.75). |
| 语种 | 中文 |
| 公开日期 | 2013-01-25 |
| 源URL | [http://192.168.143.20:8080/handle/131551/4842]  |
| 专题 | 成都山地灾害与环境研究所_山地表生过程与生态调控重点实验室 |
| 推荐引用方式 GB/T 7714 | 孙丽萍. 基于根系解剖结构的金沙江干热河谷土壤侵蚀研究初探[D]. 北京. 中国科学院研究生院. 2011. |
入库方式： OAI收割
来源：成都山地灾害与环境研究所
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