植物生态学报 ›› 2004, Vol. 28 ›› Issue (5): 657-664.DOI: 10.17521/cjpe.2004.0088

• 论文 • 上一篇    下一篇

六盘山林区几种土地利用方式下土壤活性有机碳的比较

吴建国1 张小全2 徐德应2   

  1. (1 国家环保总局气候变化影响研究中心, 北京100012)(2 中国林业科学研究院森林生态与环境研究所, 北京100091)
  • 收稿日期:2003-03-10 出版日期:2004-03-10 发布日期:2015-11-03
  • 通讯作者: 吴建国

CHANGES IN SOIL LABILE ORGANIC CARBON UNDER DIFFERENT LAND USE IN THE LIUPAN MOUNTAIN FOREST ZONE

WU Jian-Guo1ZHANG Xiao-Quan2 and XU De-Ying2   

  1. (1 Research Center of Impact of Climate Change of Chinese State Environmental Protection Administration, Beijing 100012, China) (2 Institute of Forest Ecology and Protection, Chinese Academy of Forestry Science, Beijing 100091, China)
  • Received:2003-03-10 Online:2004-03-10 Published:2015-11-03
  • Contact: WU Jian-Guo

摘要:

应用KMnO4氧化法测定分析了六盘山林区天然次生林(杂灌林、山杨(Populus davidanda)和辽东栎(Querces liaotungensis)林)、农田、草地和人工林(13、18和25年华北落叶松(Larix principis-rupprechtii))土壤活性有机碳含量及分配比例的差异。结果表明:农田和草地土壤活性有机碳含量比天然次生林分别低60%和36%,差异主要在0~70 cm土层;人工林比农田和草地分别高129%和29%,差异主要在0~50 cm土层。农田和草地土壤活性有机碳分配比例比天然次生林分别低11%和4%以上, 差异主要在0~20 cm与70~110 cm土层;人工林比农田和草地分别高13.3%和5.3%,差异主要在0~110 cm土层。土壤活性有机碳含量和分配比例随土层加深而递减,其中天然次生林和人工林土壤活性有机碳含量随土层加深而递减的幅度比农田和草地中大,农田土壤活性有机碳分配比例随土层加深而递减幅度较大。不同土地利用方式间土壤活性有机碳含量的差异比活性有机碳分配比例的差异大,土壤活性有机碳含量随土层加深而递减的幅度比分配比例随土层加深而递减的幅度大。这可能由土壤有机碳的输入、稳定性、质量和根系分布等差异所致。结果说明土壤活性有机碳含量和分配比例随天然次生林变成农田或草地而降低,随农田或草地中造林而增加,且土壤活性有机碳含量的变化幅度比分配比例大。另外,土壤活性有机碳含量和分配比例在土壤剖面的分布也随土地利用变化而改变,其中活性有机碳含量的变化幅度比分配比例大。

Abstract:

Soil carbon is a large component of the global carbon cycle, and the influence of land-use changes on soil carbon pools can significantly affect atmospheric CO2 concentrations. Labile soil organic carbon (LSC) is the fraction of soil organic matter that is most sensitive to changes in land-use. Over the last several centuries, extensive areas of native vegetation in the Liupan Mountain Forest Zone have been converted to croplands and rangelands and, in last several decades, some of these former croplands and rangelands have returned to forests. The impacts of these land-use changes on soil organic carbon (SOC) are unclear. In order to assess the impacts of land-use change on LSC, we compared the LSC concentrations in adjacent plots of secondary forest (i.e. dominated by Quercus liaotungensis, Populus davidiana, or brushwood), cropland, rangeland, and 13, 18, and 25-year old larch (Larix principis-rupprechtii) plantations that were planted on former croplands and rangelands. All plots were the same elevation, exposure and soil type. The LSC concentrations were determined using a KMnO4 (333 mmol•L-1) oxidation technique. It was found that the mean content of LSC in 0-110 cm deep soil layer was 60% lower under cropland (0.605 gC•kg-1) and 36% lower in rangeland (0.973 gC•kg-1) than under the secondary forest (1.612, 1.68 and 1.325 gC•kg-1 for the brushwood, Populus davidiana and Quercus liaotungensis forests, respectively). LSC was 129% and 29% higher under the plantations (1.127, 1.520 and 1.523 gC•kg-1 for the 13, 18 and 25-year old Larix principis-rupprechtii plantations, respectively) than under the cropland and rangeland respectively. The change of LSC content with soil depth was greater under the secondary forest and plantation than under the cropland or rangeland. The difference of LSC content between secondary forest and rangeland or cropland was greater in the 0-70 cm depth than in the 70-90 cm deep soil layer, whereas differences in LSC content between the plantations and rangeland or cropland was greater in the 0-50 cm than 50-110 cm soil layer. The mean fraction of LSC in the 0-110 cm soil layer was 11% lower under cropland (0.087) and 4% lower under rangeland (0.094) than under the secondary forest (0.098, 0.099 and 0.099 for brushwood, Populus davidiana and Quercus liaotungensis forests, respectively). The mean LSC fraction was 13.3% and 5.3% higher under the plantations (0.103%, 0.093% and 0.101% for the 13, 18 and 25-year old Larix principis-rupprechtii plantations, respectively) than under the cropland and rangeland, respectively. The change in the LSC fraction with soil depth under cropland was greater than for all other land use types. The difference in the LSC fraction between secondary forests and rangeland or cropland was greater in the 0-20 cm and 70-110 cm than the 20-70 cm soil layer, whereas the difference in the LSC fraction between the plantation and rangeland or cropland was greater in the 0-110 cm soil layer. In general, the differences in LSC among the different land use types and changes with depth were greater for the content of LSC than the LSC fraction. Differences in LSC among the different land use types are attributed to differences in the inputs, stabilization and quality of soil organic matter, and the distribution of roots among the different land uses. The results of this study indicate that the LSC content and fraction will decline if natural secondary forest are converted to cropland or rangeland but will increase with afforestation of croplands or rangelands. In addition, the distribution of the content or fraction of LSC within the soil profile will change with changes in land use, but the change in the LSC fraction is smaller than the chaoge of the LSC content.