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贵州喀斯特山区土地利用对土壤有机碳及其周转速率的影响

张文娟1,2,廖洪凯1,龙健1**,李娟2,刘灵飞1   

  1. 1贵州师范大学山地环境重点实验室, 贵阳 550001; 2贵州师范大学地理与环境科学学院, 贵阳 550001)
  • 出版日期:2014-05-10 发布日期:2014-05-10

Effects of land use on soil organic carbon and its turnover rate in Karst mountain areas of Guizhou Province.

ZHANG Wen-juan1,2, LIAO Hong-kai1, LONG Jian1**, LI Juan2, LIU Ling-fei1   

  1. (1Guizhou Key Laboratory of Mountain Environment, Guizhou Normal University, Guiyang 550001, China; 2Department of Geography and Environmental Science, Guizhou Normal University, Guiyang 550001, China)
  • Online:2014-05-10 Published:2014-05-10

摘要:

以贵州西南部典型石漠化治理示范区的灌丛、水田、旱地、退耕3年草丛和退耕15年草丛为研究对象,分析了不同层次(0~10、10~20和20~30 cm)土壤有机碳含量及其矿化速率,探讨了喀斯特山区土地利用对土壤有机碳周转速率的影响。结果表明:5种土地利用类型土壤有机碳平均含量分别为30.37、31.24、21.86、17.49和22.50 g·kg-1,灌丛和水田的土壤有机碳含量均显著高于旱地、退耕3年草丛和退耕15年草丛(P<0.05);土壤有机碳的矿化规律表现为培养前期矿化速度快,培养中后期逐渐变缓。不同土地利用类型土壤有机碳的矿化速度存在差异,退耕3年草丛和退耕15年草丛的矿化速度较快,旱地的矿化速度快于水田;0~10和10~20 cm土层,灌丛土壤有机碳半衰期最长,分别为722和639 d,水田土壤有机碳含量及半衰期在各层次均高于旱地及其退耕草地,表明水田可以作为喀斯特山区长期固碳的优势土地利用类型。总之,土地利用,特别是退耕,是影响喀斯特地区土壤有机碳周转速率的重要因素。
 

关键词: 极值模型, 径级根长分布, 氮添加, 土壤增温

Abstract: To clarify the effects of landuse types on the turnover of soil organic carbon in Karst mountain areas, soil organic carbon content and its mineralization rates were measured in three soil layers (0-10, 10-20, and 20-30 cm) under shrub (SR), paddy (PD), dry land (DL), 3-year-old grassland converted from cropland (GCC-3), and 15-year-old grassland converted from cropland (GCC-15) in a typical demonstration area of desertification control experiment in southwestern Guizhou. The results showed that the contents of soil organic carbon in SR, PD, DL, GCC-3 and GCC-15 were 30.37, 31.24, 21.86, 17.49 and 22.50 g·kg-1, respectively. The contents of soil organic carbon in SR and PD were significantly higher than in DL, GCC-3, and GCC-15 (P<0.05). The mineralization rate of soil organic carbon was higher at the early stage, and lowered at the later stage. There were differences in the mineralization rate of soil organic carbon among the different land-use types. The mineralization rates of soil organic carbon in GCC-3 and GCC-15 were higher than under the other land-use types, and the mineralization rate of soil organic carbon in DL was higher than in PD. In the 0-10 and 10-20 cm layers, the longest halflife time of soil organic carbon was all found in SR, being 722 and 639 days in the corresponding layers, respectively. The content and half-life time of soil organic carbon in each of the three soil layers were greater in PD than in DL, GCC-3, and GCC-15, suggesting that PD could be one of the best land uses for long-term carbon sequestration in Karst mountain areas. In short, land use, especially returning cropland to grassland, was an important factor influencing soil organic carbon and its turnover rate in Karst mountain areas.

Key words: diameter class length distribution, soil warming, nitrogen addition, extreme value model.