喀斯特干热河谷植被类型和小生境对土壤活性有机碳和基础呼吸的影响

Effect of Vegetation Type and Micro-habitat on Soil Active Organic Carbon and Basal Respiration in Karst Dry and Hot Valley Region of Guizhou Province, China

以贵州西南部典型喀斯特干热河谷地区荒草地（I）、小灌丛（Ⅱ）、灌木疏林（III）、灌木林（IV）和乔木林（V）下一般土壤、石缝土壤和石沟土壤为研究对象，对比研究其土壤微生物生物量碳（MBC）、可溶性有机碳（DOC）、易氧化有机碳（EOC）和基础呼吸量（BR）的变化。结果表明：土壤MBC、DOC含量分别为123．2。616．8mgkg-1和76．6～258．6mgkg-1，EOC、BR含量分别为1．62～8．32gkg^-1和15．9～41．6CO2μlg^-1·h^-1。不同植被类型下，一般土壤、石缝土壤和石沟土壤MBC、DOC、EOC和BR含量均表现为：Ⅴ〉Ⅳ〉Ⅲ〉Ⅱ〉Ⅰ，差异显著，且土壤EOC与土壤总有机碳的比值总体也呈增加趋势。同一植被类型中，与一般土壤和石缝土壤相比，石沟土壤中EOC和DOC表现出了较高的含量水平。相关性分析表明，MBC、DOC和EOC可以作为喀斯特干热河谷地区土壤有机碳变化的敏感性指标。

Taking the normal soil, stone crevice soil, and stone gully soil under grass （ I ）, shrub-grass （Ⅱ）, Thin shrub （Ⅲ）, shrub （IV） , and forest （V） in typical Karst dry-hot valley region of southwest Guizhou Province as research objects,a comparative study was made on their soil microbial biomass C （MBC）, dissolved organic C （DOC）, soil easily oxidizable carbon （EOC）, and soil basal respiration （BR）. The pool sizes of MBC, DOC, EOC, and BR at test sites ranged in 123.2 - 616.8 mg kg-1, 76.6 - 258.6 mg kg-1, 1.62 - 8.32 g kg-1 , and 15.9 - 41.6 CO2 μl g-1 h-l, respectively. The MBC, DOC, and EOC which in normal and micro-habitat were significant differences under different vegetation types, and showed an obvious increasing trend in the order of Ⅴ〉Ⅳ〉Ⅲ〉Ⅱ〉Ⅰ , moreover, with the vegetation changes in the process of Ⅰ→Ⅱ→Ⅲ→Ⅳ→Ⅴ, the ratio of EOC and soil total organic carbon also showed an overall increasing trend. In same vegetation, the contents of EOC and DOC in stone gully soil showed higher level. In the in normal soil, stone crevice soil, and stone gully. Correlation analysis showed that MBC, DOC, EOC, and BR could sensitively indicate soil organic carbon dynamics in Karst dry-hot valley.