岩溶石山地区土壤退化与恢复的成因和机理一直是近年来土壤学和生态学研究的热点。以贵州西南部贞丰一关岭岩溶石山区为对象,选择了区内退化地、农用地、恢复地等生态样块以及与未退化地为对照,采集了其中的表层和亚表层土壤,分别进行了土壤的养分库量、微生物活性与功能和土壤酶活性等化学分析。研究表明土壤养分库是土壤中微生物活性基础,微生物量碳随土壤养分库客的退化或恢复而相应变化,退化岩溶地植被恢复3~6年后,主要养分总库客得到明显恢复(恢复程度55%~65%),因而带动了微生物量碳的恢复(平均恢复程度60%以上),但养分的活性(有效磷)、微生物的功能(呼吸熵及土壤脲酶和磷酸酶活性)并没有得到相应程度的恢复(平均恢复程度仅在25%~40%)。这些结果提示,限制性养分活性和微生物功能的恢复是植被恢复下生态系统健康水平的重要指示。因此,在分析岩溶土壤和生态系统退化过程的本质以及评价生态恢复的效应时,不仅应将微生物量碳和总养分库指标作为岩溶土壤退化恢复的指标,更应将微生物区系的质量和功能指标纳入关键评价内容。
The process of soil degradation in mountainous karst regions has been the research focus of soil science and ecology in China for the last decade. Taking an example of karst soils from Guanling-Zhengfeng area, southwestern Guizhou, China, changes of soil total and available pool of major nutrients, microbial biomass carbon and Soil respiration, activities of major soil enzymes in a degradation-reclamation sequence were studied. The soils of surface 0 -5 cm and subsurface 5 -25 cm were collected from selected eco-tesseras of degraded abandon lands, corn cultivated lands, vegetation recovery lands and well-protected vegetation lands respectively. Total pool of soil major nutrients showed sensitive changes with vegetation cover, accompanying a similar change of soil microbial biomass carbon. Vegetation recovery resulted in a remarkable change of soil total nutrient pool and increased soil microbial biomass carbon. However, vegetation recovery for 3 -6 years long did not drive a significant change in available pool of the nutrients as well as the microbial respiration quotient and soil enzyme activities. The results implicated that the recovery of available nutrient pool and microbial functioning could be a reliable indicator for ecosystems health of the karst soils under different degrees of land degradation and vegetation recovery. It is suggested that not only total nutrient pool and microbial biomass carbon but also the microbial functioning indicators as microbial respiration quotient, activities of key soil enzymes should be taken into account while evaluating the intensity of land degradation and/or the effect of vegetation recover on soil quality and ecosystem functioning for the karst lands in Southwest China.