缙云山不同土地利用方式土壤有机碳组分特征
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西南大学资源环境学院,西南大学资源环境学院,西南大学资源环境学院

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X144

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国家自然科学基金项目(41275160,41005069,40975095);中央高校基本科研业务费专项资金(XDJK2012A005,XDJK2013A009)


Distribution characteristics of soil organic carbon and its physical fractions under the different land uses in Jinyun Mountain
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College of Resources and Environment, Southwest University,,Southwest University

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    摘要:

    探讨了我国西南地区缙云山亚热带常绿阔叶林(以下简称林地)、果园、坡耕地以及撂荒地4种土地利用方式对土壤有机碳(SOC)组分含量及其分配比例的影响。采用物理分组技术,将SOC分为粗颗粒有机碳(cPOC)、细颗粒有机碳(fPOC)、微团聚体内颗粒有机碳(iPOC)、微团聚体内粉+黏颗粒(s+c_m)有机碳及粉+黏颗粒(s+c)有机碳。研究结果表明:在0-60 cm的土壤深度范围内,SOC、cPOC、fPOC、iPOC、s+c_m组分以及s+c组分有机碳平均含量均为林地(9.02、3.14、1.61、0.33、0.42、3.53 g/kg)显著高于果园(3.27、0.93、0.27、0.10、0.24、1.73 g/kg)和坡耕地(2.58、0.51、0.10、0.12、0.08、1.77 g/kg),说明林地开垦会导致SOC及各组分的流失;而撂荒地上述SOC及其各组分含量分别为14.90、5.17、2.36、0.42、0.59和6.36 g/kg,均显著高于坡耕地,表明耕地撂荒后SOC及其组分能得到有效的恢复和截存。在SOC的各物理组分中,iPOC的有机碳分配比例最低,4种土地利用方式下均为3%左右;cPOC和fPOC作为活性较强的非保护有机碳库,在林地和撂荒地中所占SOC分配比例最高,达到50%以上;而果园和坡耕地中<53 um的粉+黏颗粒有机碳组成的化学保护有机碳库分配比例最大,分别为65.9%和71.6%,表明林地和撂荒地土壤有机碳的活性远远大于坡耕地及果园,支持更高的土壤肥力。在SOC及其组分中,fPOC可作为评估土地利用变化对土壤有机碳库影响的良好指标。

    Abstract:

    The distribution characteristics of soil organic carbon (SOC) and its physical fractions under the different land uses in Jinyun Mountain were studied in this paper. Subtropical evergreen broad-leaved forest (forest for short), sloping farmland, orchard and abandoned land were selected and soils at the depths of 0-60 cm were sampled in the spring of 2011 to determine the contents of soil organic carbon fractions. Five soil organic carbon fractions, i.e., coarse particulate organic carbon (cPOC), fine particulate organic carbon (fPOC), intra-microaggregate particulate organic carbon (iPOC), silt and clay within microaggregates (s+c_m), silt and clay (s+c) were separated by physical fractionation technique. The results showed that the contents of SOC, cPOC, fPOC, iPOC, s+c_m and s+c in the whole soil depth from 0 to 60 cm were significantly higher in the forest (9.02, 3.14, 1.61, 0.33, 0.42, 3.53 g/kg) than those in the orchard (3.27, 0.93, 0.27, 0.10, 0.24, 1.73 g/kg) and in the sloping farmland (2.58, 0.51, 0.10, 0.12, 0.08, 1.77 g/kg), which indicated the reclamation of forest would result in the loss of SOC and its fractions. 14.90, 5.17, 2.36, 0.42, 0.59, 6.36 g/kg of SOC and its corresponding fractions in the abandoned land were remarkably higher than those in the sloping farmland, which indicated the abandon from farmland would lead to the effective recovery and sequestration of SOC and its fractions. Among the SOC physical fractions, the ratios of iPOC to SOC were the lowest and accounted for only 3% in each land use type. The cPOC and fPOC fractions were considered as unprotected carbon pool with higher liability. The ratios of cPOC and fPOC to SOC were highest in the soils of the forest and abandoned land, reached to more than 50%. The <53 μm fraction contains organic carbon which is stabilized both as a consequence of its complex chemical composition and by adsorption to silt and clay particles. The ratios of <53 μm fraction containing organic carbon to SOC were highest in the soils of the orchard and sloping farmland, 65.9 and 71.6%, respectively. The results showed that the liability of soil organic carbon in the soils of forest and abandoned land were higher than those in the orchard and sloping land, that is to say, there is stronger soil fertility in the soils of forest and abandoned land. Furthermore, we suggest that fPOC is a promising fraction for assessing the impact of land use change on SOC in Jinyun Mountain.

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李鉴霖,江长胜,郝庆菊.缙云山不同土地利用方式土壤有机碳组分特征.生态学报,2015,35(11):3733~3742

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