土地利用和覆被变化对岩溶区土壤CO2浓度的影响

摘要

通过选择3个具有不同地质背景、气候条件等环境特征的山西汾阳马跑一郭庄岩溶泉域、湖南湘西大龙洞地下河流域、广西桂江流域,对流域内具有代表性的不同土地利用方式和覆被类型下垫面土壤20～50 cm深处CO2浓度进行检测.结果显示,土地利用方式和覆被变化对3个流域岩溶土壤中20 cm、30 cm、40cm和50 cm深处CO2浓度具有明显的影响作用:湖南湘西大龙洞地下河流域多数样地土壤CO2表现为随土层的加深先增加后降低的双向梯度；山西马跑-郭庄泉域玉米地的土壤CO2浓度比种植马铃薯的高,且随着覆被条件由草地→灌丛→林地的改善,土壤的扰动性变小,CO2浓度差趋于减少,变幅趋于稳定.各个流域相同覆被类型,群落结构和优势种变化越小,土壤CO2浓度变幅越小.%Three watersheds, the Mapao-Guozhuang Spring Catchment in Fenyang, Shanxi Province, the Da-longdong Underground River Watershed in Xiangxi, Hunan Province and the Guijiang Watershed in Guangxi Province, with different geologic and climatic conditions are selected as the study areas. Those three watersheds represents different typical land use type and vegetation cover. Their soil CO2 concentrations at 20~50 cm depth under the ground are tested. The results prove that the change of land use and vegetation cover affects intensely on soil CO2 concentration from 20 cm to 50 cm depth. Many plots in the Dalongdong Underground River Watershed show the character of Bidirectional gradient, which means that along with dep.th, CO2 concentration rises at first, but begins to reduce from 40cm deep downwards. In the Mapao-guozhuang Spring Catchment, soil CO2 concentration in the corn fields is higher than that in the potato fields. With vegetation condition improving from grass to shrub and to forest, soil disturbance gets less, the distinctions of CO2 concentration become smaller and the variation scope tends to stable. In every study watersheds, between the same vegetation cover patterns, the less the change in community structure and dominant species, the less variation scope of soil CO2 concentration.