不同生态系统对湘西洛塔降雨量及岩溶效应的影响

采用雨量器、滤膜法、CO2气体监测管法、标准试片对湘西洛塔不同生态系统降雨量、泥沙量、土壤CO2浓度、溶蚀速度进行了研究。结果表明:森林生态系统降雨量高于灌丛生态系统,观测第一年高6.84mm,第二年高218.08mm,且时间趋向均匀;灌丛生态系统水土流失严重,其泥沙含量是森林生态系统的1.53倍,土壤侵蚀为强度,而森林生态系统为微度;不同深度土壤CO2浓度在森林和灌丛生态系统中具有相同的变化趋势,在春季、秋季、冬季随土层加深而增大,在夏季,随土层加深先减少后增大,但季节变化动态略有差异,森林生态系统不同深度、不同季节土壤CO2浓度均大于灌丛生态系统;从全年土壤CO2浓度对比来看,10、20、40cm处,森林生态系统分别是灌丛生态系统的1.66、1.59和1.90倍;不同深度上,溶蚀速度在森林和灌丛生态系统具有相同的变化趋势,15cm处均大于地面,从同一深度来看,森林生态系统溶蚀速度均大于灌丛生态系统,地面、15cm处溶蚀速度分别是灌丛生态系统的1.11倍、2.57倍,说明森林生态系统具有较好的岩溶效应。

Influence of different ecosystems on the rainfall and karst effect in Luota, west Hunan Province of China

By using rain gauge, membrane filter, CO2 monitoring tube, and standard corrosion tablet, this paper measured the rainfall, suspended sediment content, soil CO2 concentration, and soil corrosion rate in forest ecosystem and shrub ecosystem in Luota of west Hunan Province. The rainfall in forest ecosystem was larger than that in shrub ecosystem, being 6.84 mm higher in the first observation year and 218.08 mm higher in the second year. There was a serious soil and water loss in shrub ecosystem, and the sediment content in the ecosystem was 1.53 times of that in forest ecosystem. The soil erosion was intensive in shrub ecosystem but slight in forest ecosystem. The CO2 concentration in different soil layers in forest ecosystem and shrub ecosystem had the same change trend, i.e., increased with the deepening of the soil layer in spring, autumn, and winter while increased after an initial decrease in summer. In forest ecosystem, the soil CO2 concentration in different layers and in different seasons was larger than that in shrub ecosystem. According to the comparison throughout the year, the soil CO2 concentration at the depths 10, 20, and 40 cm in forest ecosystem was 1.66, 1.59, and 1.90 times of that in shrub ecosystem, respectively. In different soil layers, the corrosion rate in forest ecosystem and shrub ecosystem had the same change trend, being larger at the depth 15 cm than on the soil surface. In the same soil layers, the corrosion rate was faster in forest ecosystem, being 1.11 and 2.57 times of that on the soil surface and at the depth 15 cm in shrub ecosystem, respectively. Our results suggested that there existed better karst effect in the forest ecosystem.