摘要 [目的]研究干旱河谷區土地利用变化对土壤有机碳及碳库质量的影响。[方法]选取岷江上游干旱河谷区8种典型土地利用类型，即人工纯林、退耕荒坡、农用地、经济作物林、灌木林、人工混交林、次生林和天然林地，对其0～100 cm土层土壤有机碳、碳库质量及其分配特征进行分析。[结果]土壤有机碳及密度均随土层增加而递减，但因植被类型的差异和人类干扰活动的影响，递减程度有所不同。总体而言，土壤有机碳及其密度退耕荒地、农用地和经济作物林地均显著低于其他土地利用类型，而退耕荒地、农用地和经济作物林之间无显著差异，各土地利用类型土壤有机碳密度均值在1.35～303 kg/m2，平均以经济作物林最低（1.35 kg/m2），以灌木林最高（303 kg/m2） ；从有机碳密度及其变异系数看，表层土壤变异程度最高，10～40 cm各层间变异程度相对表层较低但变异波动大，40～100 cm土层变异程度又有所上升，表明碳密度差异主要取决于土壤厚度；从碳库质量看，非保护性碳库表现出与有机碳及其密度一致递减规律，但在0～40 cm土层各土地利用类型非保护碳库均呈快速下降趋势，尤其在0～20 cm土层，除农用地呈小幅上升外，其他土地利用类型土壤轻组有机碳在该层均大幅度降低，变化幅度最大的是人工纯林（78.45%），最小为经济作物林（7.28%）。在60 cm土层以下，轻组有机碳含量差异很小，灌木林地则在整个剖面中碳库质量最低。[结论]该研究为我国干旱河谷区科学调整土地利用方式、增强土壤碳吸存能力提供参考。
关键词 干旱河谷；土地利用；有机碳；轻组有机碳；碳库质量
中图分类号 S158 文献标识码
A 文章编号 0517-6611（2018）27-0137-06
Soil Organic Carbon and Quality Distribution Characteristics in Arid River Valley
JIANG Guangzheng1，GONG Yuanbo2
（1.Hainan Environmental Technology and Economic Development Company，Haikou，Hainan 571126；2.Key Laboratory of Forestry Ecological Engineering in Sichuan Province of the Upper ChangJiang River，Wenjiang，Sichuan 625014）
Abstract [Objective] To study effects of land use change on soil organic carbon and carbon pool quality in arid river valley.[Method]By selecting eight typical landuse types in dry valley of the upper Minjiang River，that was，artificial pure forest，abandoned wasteland，farmland，cash crop forest，brushwood，artificial mixed forest，natural secondary forest，natural forest，soil organic carbon，carbon quality and its distribution characteristics in 0-110 cm depth of soil for these landuse types were investigated.[Result]Soil organic carbon and its density decreased with increasing soil，but the degrees of diminishing were various due to the different vegetation types and the impact of human disturbances.Generally，soil organic carbon and its density significantly were lower in abandoned wasteland，farmland and cash crop forest than other landuse types，however，the differences among abandoned wasteland，farmland and cash crop forest were not significant.For the whole landuse types，the carbon density was between 1.35-3.03 kg/m2.The lowest carbon density value occurred in cash crops forest（1.35 kg/m2），and the highest occurred in brushwood（3.03 kg/m2）；From density and variation of soil organic carbon，the highest degree of variation occurred in surface soil.Compared with surface soil，the degree of variation was lower in 10-40 cm depth of soil，however，the fluctuation of variation was large.The degree of variation rised again in 40-100 cm depth of soil，showed that the difference of soil carbon density depended on soil thickness；From carbon quality，the same to soil organic carbon and its density，unprotected soil organic carbon pool also decreased with increasing soil.For the whole landuse types，it decreased rapidly in 0-40 cm depth of soil，especially in 0-20 cm，all the landuse types showed a significant reduction excepted a slight increase in farmland，the largest change was artificial pure forest（78.45%），and the minimum was cash crop forest（7.28%）.Below 60 cm depth of soil，the differences of lightfraction organic matter（LFOM） were very small，but the carbon quality of brushwood was lowest in the whole depths of soil.[Conclusion]The study provides a reference for the scientific adjustment of land use patterns and enhancement of soil carbon storage capacity in arid river valley areas in China.
