作　　者： (刘璐）; (陈浩）; (李德军）; (梁士楚）;

机构地区： 广西师范大学生命科学学院,桂林541004

出　　处： 《环境科学学报》 2017年第9期3528-3534,共7页

摘　　要： 土地利用方式的改变,如农田退耕是影响土壤有机碳固持的重要因素.喀斯特地区正开展大规模的生态系统恢复工程,然而生态系统恢复过程中土壤有机碳的固持机制依然不甚清楚.土壤有机碳的分解是土壤碳循环的一个关键过程.不同组分有机碳的分解受不同酶的活性控制,因此,在西南喀斯特山区不同植被恢复阶段下开展土壤酶活性特征研究,有助于了解该地区土壤有机碳固持机制并为该地区的生态恢复实践提供理论支撑.本研究在广西河池市环江县典型喀斯特区域的农田、草地、灌丛、次生林4种不同植被恢复阶段下采集0~10 cm深度的土壤样品,采用荧光光度法和紫外分光光度法测定3种土壤水解酶(即β-葡糖苷酶、α-纤维素酶和β-木糖苷酶)和1种氧化酶(过氧化物酶)的活性及相关土壤理化属性指标,研究植被恢复过程中土壤水解酶(参与活性碳库的分解)和氧化酶活性(参与惰性碳库的分解)的响应.结果显示,随着植被恢复土壤水解酶活性不断增加(次生林>灌丛>草地>农田),而土壤氧化酶无明显变化.导致该结果的原因可能是由于喀斯特地区土壤有机碳极高的稳定性导致微生物趋向于利用活性有机碳库,而对于惰性有机碳库的分解并无显著差别.本研究间接说明喀斯特地区农田退耕后将有利于土壤惰性有机碳的累积. Land use change such as the agricultural abandonment is an important factor affecting soil organic carbon （C） sink. China＇ s karst regions are undergoing large-scale ecosystem restoration. However, the mechanisms regarding how soil C pool changes with ecosystem restoration are still largely unknown. Soil organic C decomposition is a crucial process of soil C cycling, and the decompositions of different soil C fractions are controlled by various soil extracellular enzymes. Thus, studying soil enzyme activity under different vegetation restoration stages in China＇ s karst area is crucial for understanding the mechanism of soil C sink in this region and can provide useful application for the ecological restoration. In this study, the activities of soil hydrolase （ responsible for labile C decomposition） and oxidase （ responsible for passive C decomposition） under the process of vegetation restoration were studied in a karst area in Guangxi, southwest China. The 0 - 10 cm depth of soil was sampled in four ecosystems which represent four vegetation restoration stages after agricultural abandonment （i.e. cropland, grassland, shrublad, and secondary tbrest）. The activities of three hydrolase （i.e. β- Glucosidase, a-D-1, 4-Cellobiosidase, and β-1, 4-Xylosidase） and one oxidase （i.e. Peroxidase） and the relevant soil properties were measured. Our results showed that the activities of three hydrolases increased with the agricultural abandonment （secondary forest 〉 shrubland 〉 grassland 〉 cropland）, but the oxidase activity had no significant change. The reasons for different responses may be the preferential utilization of labile C by microbe, i.e. after agricultural abandonment microbe tended to use the labile C and thus did not increase the input of oxidase for decomposing passive C because of the high soil C stabilization in karst area. Our results suggested that agricuhural abandonment may increase the accumulation of passive C pool in the karst area.

关 键 词： 植被恢复 土壤酶活性 水解酶 氧化酶 喀斯特山区