昆明石灰岩及玄武岩风化壳微形态对上覆植被生长的影响

The Micromorphology of Limestone and Basalt Regolith Affects the Growth of Overlying Vegetation in Kunming

以昆明地区同一气候带内上覆植被生长情况差异很大的石灰岩和玄武岩风化壳为研究对象,利用显微观察与图像分析处理技术开展微形态特征对比分析研究。结果发现:石灰岩、玄武岩风化壳与各自基岩存在明显继承性,主要表现在玄武岩风化壳各层中骨骼颗粒都含大量斜长石,而石灰岩风化壳各层中骨骼颗粒仅有石英,表明石灰岩风化壳与玄武岩风化壳不是同一类物质。石灰岩风化壳A层(表土层)呈现开裂状微结构,总孔隙度在15.85%,孔隙主要类型为通气孔隙,B层(心土层)呈整块状微结构,孔隙度仅占6.48%,主要孔隙类型为无效孔隙;玄武岩风化壳A层(表土层)呈现海绵状微结构,总孔隙度高达28.29%,其中通气孔隙居多,B层(心土层)呈孔洞、孔道复合微结构,孔隙度在9.53%,主要孔隙类型为毛管孔隙。石灰岩、玄武岩风化壳的有效含水量与毛管孔隙、通气孔隙存在正相关关系,而与无效孔隙负相关。本研究为基岩控制上覆植被生产量的理论研究勾勒出了一个新途径,即基岩可以通过控制风化壳的微结构来影响其有效含水量,从而导致即使在相同的气候条件下,不同基岩区上覆植被生产量也可能存在较大差异的现象出现。

In this paper,the regolith of limestone rock and basalt with different vegetation growth in the same climate zone of Kunming area is taken as the research object,and the micro-morphological characteristics are compared and analyzed by using microscopic observation and image analysis processing technology.The results show that there is obvious inheritance between limestone and basalt regolith and their respective bedrock,which is mainly manifested in that the skeleton particles in each layer of basalt regolith contain a large amount of plagioclase,while the skeleton particles in each layer of limestone regolith only contain quartz,indicating that the limestone regolith and basalt regolith are not the same kind of matter.Layer A(topsoil layer)of limestone regolith presents cracked microstructure,with a total porosity of 15.85%,and the main type of pores is aeration pores.Layer B(core soil layer)presents block microstructure,with a porosity of only 6.48%,and the main type of pores is ineffective pores.Layer A(topsoil layer)of basalt regolith presents spongy microstructure with a total porosity of 28.29%,most of which are aeration pores,and layer B(core soil layer)presents composite microstructure of pores and channels with a porosity of 9.53%,mainly capillary pores.The effective water content of limestone regolith and basalt regolith has a positive correlation with capillary pores and aeration pores,and a negative correlation with ineffective pores.These studies have outlined a new way for the theoretical study of bedrock controlling the production of overlying vegetation,that is,bedrock can affect its effective water content by controlling the microstructure of regolith,thus leading to the phenomenon that even under the same climatic conditions,the production of overlying vegetation in different bedrock areas may have a large difference.