西南岩溶地区植被喀斯特效应

Vegetation Karst Effects on the Karst Area of Southwest China

西南岩溶地区是我国主要岩溶带之一 ,也是世界岩溶研究重点地区。区内因人口众多 ,植被破坏严重 ,部分地区因人为作用已经产生一系列的环境问题。本文从岩溶地区植被演替规律出发 ,针对不同植被生态条件 ,通过对比不同表层岩溶泉的水化学特征和表层土壤空气CO2 (g) (表示CO2 以气相形式存在 )的含量 ,分析了植被在岩溶区 ,特别在表层岩溶带的喀斯特效应。由此 ,一方面可以推动岩溶研究的进一步发展 ;另一方面可以提高人们的岩溶环境保护意识 ,从而为西南地区生态恢复提供基础资料。

Southwest karst area is one of the main karst zones in China and also the research focus in the world. Large population and heavy environmental pressure have seriously destroyed the vegetation in the research region and even brought about a series of environmental problems due to human activities in some areas. In this paper, based on the vegetation succession principle in the karst area, the authors studied the different vegetation habitats and analyzed the karst effect of vegetation in the karst area, especially in the epikarst area, by comparing the hydrochemical characteristics in diverse epikarst springs and the content of CO 2 in surficial layer soil.Here are some conclusions drawn from the study: (1) In the Southwest karst area, different vegetation coverages result in different contents of CO 2 in surficial soil and different chemical powers. Thus the dissolubilities are different. The higher the vegetation coverage, the higher the carbon dioxide content and the stronger the dissolubility of soil solution to carbonate rock. (2) Soils of different vegetation coverages have different water retention capacities.In general, in areas with higher vegetation coverage the water retention and fertilizer-holding capacity is stronger due to the effect of root system and litter layer.As a result, physicochemical reaction occurs between soil solutions more completely for a longer time. For example, the average content of HCO - 3 in the epikarst spring in Yajicun (Guilin) covered mainly with bush is 5.56 mmol/L,whereas the average content of HCO - 3in epikarst spring in Meihuashan (Liupanshui) covered mainly with grass is only 3.25 mmol/L. (3) As presented in many references, vegetation can improve water and soil retention, which is important to the karst area with a fragile environment. On the one hand, barely poor soil can be kept to provide vegetation with necessary nutrient and water resource. On the other hand, improving dissolubility can enhance soil formation in the karst area. (4) From what is discussed above we know the effect of vegetation plays an important role in ecological recovery of the karst area,especially of bare or semi-bare karst areas. Therefore, we should forbid deforesting, mountain firing and overgrazing. If conditions are ripe,we should resort to a series of means to recover vegetation and ensure its positive succession to improve the ecological recovery in karst areas. The research into the karst effect of vegetation in karst area shows that the karst study can be promoted. In addition, we can increase the karst environmental protection consciousness in people's mind and provide basic material for ecological recovery in Southwest area.