湿润区红层劣地发育条件及其形成机制研究—— 以粤湘赣边区为例

Badlands are erosion landforms of criss-cross ravines developed from weak rock strata which are subjected to fluviation. Generally, there’s no mature soil, the vegetation degenerates or even disappears, the bed rock or weathered debris is exposed. Badlands are known as erosion hotspots on the earth, which can change the landscape on the scale of human’s life or even a few years of study time, thus has become a hot area of research in the field of landform and ecological envioronment changes. But Chinese scientists in the field of Geoscience have not paid enough attention to this important landform, let alone red beds badlands.. Recent research shows that red beds basin in border area of Guangdong-Hunan-Jiangxi is the important red beds area of China, where a large number of similar desert landscapes developed from red beds soft rocks which are called red beds badlands or red beds deserts are discovered. They are different from deserts in arid regions, red soil or red soil deserts, they are deep erosion landforms developed from red beds soft rocks which are subjected to fluviation. The red beds area in Guangdong-Hunan-Jiangxi is among the areas severely afflicted by water and soil loss in China, the process of water and soil loss and land degradation is basically the formation process of badlands. Therefore, according to the existing research basis, this project will comprehensively analyze the effects of lithology, climate, hydrology, soil, vegetation and human activities, mainly solve the problems of the developmental conditions and formation mechanism of red beds badlands in humid regions, with the process of fast weathering and eroding of red beds soft rocks at core.

劣地是软弱岩层在流水作用下发育的沟壑纵横的侵蚀地貌，一般无成熟土层，植被退化甚至消失，基岩或其风化碎屑裸露。劣地被认为是地球上的侵蚀热点，可在人的生命尺度甚至在几年的研究时间尺度内改变景观，而成为地貌与生态环境变化研究的热点。但是，中国地学界尚未对这一重要的类型给予足够的关注，红层劣地的研究更是空白。. 近年研究表明，粤湘赣边区各红层盆地是我国重要的红层分布区，发现了大量红层软岩发育的类似荒漠景观，被称为红层劣地或红层荒漠。它不同于干旱区荒漠，也不是红土或红壤荒漠，而是红层软岩在流水作用下发育的强侵蚀地貌。粤湘赣红层区是我国水土流失的重灾区之一，其水土流失和土地退化的过程实质也是劣地的形成过程。因此，本项目将在现有研究的基础上，以红层软岩快速风化和侵蚀过程为核心，综合分析岩性、气候、水文、土壤、植被和人类活动等因素的影响，重点解决湿润区红层劣地的发育条件及其形成机制问题。

通过系统性采样，并通过对软岩的矿物成分、元素成分、表面结构、颗粒结构、孔隙结构的测试，对研究区软岩岩石性质进行了系统性实验研究，并探究了不同岩性对劣地发育过程的影响。通过Image J 技术确定了风化过程中碎屑的尺寸、形态等参数的变化，从而实现定量软岩的物理崩解速率。通过设计实验室条件探究温湿度、酸雨对软岩风化过程的影响，通过野外监测探究了降雨和温度对软岩侵蚀过程的影响，从而揭示了湿润区典型红层劣地发育的外动力作用机制。通过对225个采样点的土壤各项物理化学指标的空间分析，确定了地形和人类活动对劣地发育的影响。建立了湿润区红层劣地分级评价模型，探讨了红层劣地区资源环境保护利用的途径与方法，建设和培育了3个典型红层劣地综合研究观察点和2个定点监测观察场和试验站。