作 者 ：俞月凤1,2,3,卢凌霄1,2,杜 虎1,2,3,彭晚霞1,2,曾馥平1,2,宋同清1,2*
期 刊 ：西北植物学报 2013年 5期 页码：1011~1019
Keywords:organic carbon, aggregate, calcareous soil, forest types, karst,
摘 要 ：选取中国西南喀斯特石灰土人工林、次生林、原生林3个主要森林类型的6个代表性群落,建立18个20 m×20 m的样方,按梅花型5点法采集各样方的原状土壤,基于团聚体的干湿筛2种分组方法,研究不同类型森林石灰土机械性、水稳性团聚体组成及全土、各粒级团聚体的有机碳分布特征。结果显示:（1） 3类森林石灰土干湿筛团聚体均以>2 mm粒径为主,分别为67.93%~81.24%和30.49%~76.81%,1~10 mm粒径的干湿筛优势团聚体分别高达78.18%~88.67%和43.41%~84.00%。（2）团聚体的整体稳定性很好,干湿筛平均重量直径（MWD）为4.82~5.77和0.75~2.13,平均几何直径（GMD）为2.87~4.17和1.45~2.85;>0.25 mm和>2 mm粒径的团聚体破坏率（PAD）分别仅为6.15~20.91和2.04~52.79。（3）石灰土的有机碳含量很高,全土和干、湿筛团聚体的有机碳含量分别为17.28~58.85、19.12~91.47、17.16~78.86 g/kg,其中干筛以<2 mm粒径团聚体的有机碳含量较高,湿筛反之,但干湿筛均以>2 mm粒径团聚体的有机碳贮量最高。研究表明,中国西南喀斯特石灰土林区土壤沿人工林、次生林、原生林土壤扰动递减梯度,石灰土的团聚化作用越来越强,稳定性越来越好,有机碳含量也越来越丰富。
Abstract:Three main forest types,manmade forest,secondary forest,and primary forest,were chosen to study sites in karst calcareous soil of southwest of China.Eighteen sample plots of 20 m×20 m were established based on six representative communities.Soil aggregation samples were collected as different particle sizes and separated by dry sieving and wet sieving.Then,composition of machinery-stable aggregation and water-stable aggregation,distribution of total organic carbon,and organic carbon in aggregation were analyzed.The results showed that:(1)Soil machinery-stable aggregations and water-stable aggregations of three type forests were dominated by >2 mm particle size,and the proportion were 67.93%~81.24% and 30.49%~76.81%,respectively.The proportion of 1~10 mm size in machinery-stable aggregation and water-stable aggregation were 78.18%~88.67% and 43.41%~84.00% respectively.(2)The stability of all particle size aggregates were perfectly.The mean weight diameter (MWD) and the mean geometric diameter (GMD) of machinery-stable aggregations were 4.82~5.77 and 2.87~4.17,respectively;the MWD and GMD of water-stable aggregations were 0.75~2.13and 1.45~2.85.Percentage of aggregation destruction (PAD) of >0.25 mm and >2 mm particle size aggregations were 6.15~20.91 and 2.04~52.79,respectively.(3)There is high organic carbon content in the calcareous soil.The content of total organic carbon,organic carbon contents of machinery-stable aggregation and water-stable aggregation were 17.28~58.85 g/kg,19.12~91.47 g/kg and 17.16~78.86 g/kg,respectively.The content of organic carbon in machinery-stable aggregation were dominated by <2 mm particle size,while these of water-stable aggregates reverse.Organic carbon storage in >2 mm aggregations were the highest in all size fractions of machinery-stable and water-stable aggregation.Therefore,with soil disturbance decreasing along the manmade forest,secondary forest and primary forest,soil aggregation and stability and organic carbon content in calcareous soil showed an upward trend.