title: [Effects of human disturbance on soil aggregates content and their organic C stability in Karst regions].
abstract: Taking the primary forest land (PF), natural restoration land (NR), grazing grassland burned annually in winter (GB), and maize-sweet potato cropland (MS) in Karst regions of Northwest Guangxi as test objects, this paper studied the soil aggregates content and their organic C stability in the four ecosystems under different human disturbance patterns. The soil water-stable aggregates (>0.25 mm) content in PF, NR, and GB accounted for more than 70%, while that in MS was only 37%. The destruction rate of soil aggregates structure in the four ecosystems decreased in the sequence of MS (54.9%) > GB (23.2%) > NR (9.8%) and PF (9.6%), with significant differences among them (P<0.05). With increasing incubation time, the mineralization rate of soil aggregate organic C decreased after an initial increase and kept stable after 20 days, and increased with decreasing aggregate size. In the same size aggregates, the mineralization rate of organic C in the four ecosystems increased in the sequence of MS < GB and NR < PF. In PF, the mineralization ratio of soil organic C was 1.7% - 3.8%, being significantly higher than that in NR, GB, and MS. The cumulative mineralization amount of soil organic C had the same change trend with the mineralization rate. The contents of soil organic C and aggregate organic C were significantly positively correlated with the mineralization rate and cumulative mineralization amount of organic C, respectively, and significantly negatively correlated with the mineralization ratio of organic C.
authors.affiliation: Key Laboratory for Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China. 2000wyw@163.com
authors.forename: Ya-wei
authors.initials: YW
authors.lastname: Wei
authors.forename: Yi-rong
authors.initials: YR
authors.lastname: Su
authors.forename: Xiang-bi
authors.initials: XB
authors.lastname: Chen
authors.forename: Xun-yang
authors.initials: XY
authors.lastname: He
authors.forename: Wen-geng
authors.initials: WG
authors.lastname: Qin
authors.forename: Guo-fu
authors.initials: GF
authors.lastname: Wei
mesh_terms: D000383:Agriculture / Q000379:methods; D002244:Carbon / Q000032:analysis*; D002681:China; D018556:Crops, Agricultural / Q000254:growth & development*; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods; D006802:Human Activities; D027723:Ipomoea batatas / Q000254:growth & development; D009930:Organic Chemicals / Q000032:analysis; D006109:Poaceae / Q000254:growth & development; D012987:Soil / Q000032:analysis / Q000737:chemistry*; D014197:Trees / Q000254:growth & development*; D003313:Zea mays / Q000254:growth & development
chemical_list: D009930:Organic Chemicals; D012987:Soil; D002244:Carbon