Indices Of Eco-Chemical Characteristicsin A Degradation-Reclamation-Action Sequence Of Soils In Mountainous Karst Area: A Case Study In Guanling-Zhenfeng Region, Guizhou, China

The process of soil degradation in mountainous karst regions has been one of research foci 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 0-5cm and subsurface 5-25cm 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.