• 关键词：土壤团聚体  活性有机碳  人工刺槐林  黄土高原

• 基金项目：国家重点研发计划（No.2017YFC0504601，2016YFC0501707）

• 梁彩群
• 西北农林科技大学水土保持研究所, 杨陵 712100

• 刘国彬
• 1. 西北农林科技大学水土保持研究所, 杨陵 712100;2. 中国科学院水利部水土保持研究所, 杨陵 712100

• 王国梁
• 1. 西北农林科技大学水土保持研究所, 杨陵 712100;2. 中国科学院水利部水土保持研究所, 杨陵 712100

• 孟敏
• 西北农林科技大学水土保持研究所, 杨陵 712100

• 魏芙蓉
• 西北农林科技大学水土保持研究所, 杨陵 712100

• 摘要：不同粒径团聚体中的不同活性有机碳对人工林土壤质量改善及碳库动态平衡有重要的作用.本研究在黄土高原地区，从南向北沿着降雨和温度降低梯度选择淳化、安塞、绥德和神木共4个地区，比较研究了人工刺槐林土壤团聚体不同的活性有机碳含量变化及其影响因素.通过湿筛法将土壤团聚体分级为粉黏粒（<0.053 mm）、微团聚体（0.25~0.053 mm）和大团聚体（>0.25 mm），用Leffory法测定3种粒径土壤团聚体低、中、高活性有机碳含量.结果表明：①4个样区大团聚体（>0.25 mm）含量由南至北呈先降低后增加趋势，微团聚体（0.25~0.053 mm）含量逐渐增加，粉黏粒（<0.053 mm）含量则先增后减.②4个样区中土壤团聚体3种活性有机碳含量大小顺序为低活性 > 中活性 > 高活性，其中，粉黏粒（<0.053 mm）低活性有机碳含量为1.02~1.52 g·kg^-1，中活性有机碳含量为0.53~0.91 g·kg^-1，高活性有机碳含量为0.28~0.43 g·kg^-1；而微团聚体（0.25~0.053 mm）低活性有机碳含量为1.02~2.02 g·kg^-1，中活性有机碳含量为0.46~1.20 g·kg^-1，高活性有机碳含量为0.31~0.85 g·kg^-1；大团聚体（>0.25 mm）低活性有机碳含量为1.08~3.07 g·kg^-1，中活性有机碳含量为0.70~1.96 g·kg^-1，高活性有机碳含量为0.48~1.24 g·kg^-1.③黄土高原人工刺槐林3种粒径团聚体的低、中、高活性有机碳含量主要与年均气温（MAT）、年均降雨量（MAP）、土壤SOC、TN和含水率显著相关（p<0.05），且在同一活性下，活性有机碳含量与MAT、MAP、土壤TN、SOC、含水率的相关性随着土壤团聚体粒径的增大而越显著.研究结果对理解黄土高原土壤团聚体活性有机碳含量在空间尺度上的变化特征和影响因素具有重要意义.

• Abstract：Different labile organic carbon of different particle sizes in aggregates play an important role in improving forest soil quality and dynamic balance of carbon pool. In this study, Chunhua, Ansai, Suide, Shenmu, four regions were selected along with increasing gradient of rainfall and temperature from south to north in the Loss Plateau, and the changes of the different labile organic carbon content of soil aggregates of different particle sizes in Robinia pseudoacacia plantation and their influencing factors were studied systematically. In this study, three aggregate size fractions:silt and clay size particles(<0.053 mm), microaggregates(0.25~0.053 mm) and macroaggregates(>0.25 mm) were separated by wet sieving and the content of lowly, medium and highly labile organic carbon were measured by Leffory method. The result shows that ① the content of macroaggregates (>0.25 mm) in the four areas decreased first and then increased from south to north, and the content of microaggregates (0.25~0.053 mm) gradually increased, and the content of clay and silty (<0.053 mm) is increased first and then decreased. ②Among the three labile organic carbons, and the order is lowly labile > medium labile > highly labile. Among the four simple areas, the lowly labile organic carbon content of clay and silty (<0.053 mm) ranged from 1.02 to 1.52 g·kg^-1, and the content of the medium labile organic carbon is 0.53~0.91 g·kg^-1 and the highly labile organic carbon content is 0.28~0.43 g·kg^-1; while the lowly labile organic carbon in microaggregates (0.25~0.053 mm) is 1.02~2.02 g·kg^-1; the content of the medium labile organic crabon is 0.46~1.20 g·kg^-1; and the content of highly labile organic carbon in microaggregates is 0.31~0.85 g·kg^-1; the content of lowly labile organic carbon in macroaggregates (>0.25 mm) is 1.08~3.07 g·kg^-1 and the content of medium labile is 0.70~1.96 g·kg^-1; the content of highly labile organic carbon in microaggregates is 0.48~1.24 g·kg^-1. ③The content of lowly, medium and highly labile organic in the three kinds of aggregates of Robinia pseudoacacia plantation on the Loess Plateau was significantly related with mean annual temperature(MAT), mean annual precipitation (MAP), soil SOC, TN and water content. There is a significant correlation, and under the same labile, the correlation between the content of the labile organic carbon and the MAT, MAP, soil TN, SOC and water content increases with the increase of the soil aggregate size. The result of the study have important implications for understanding the spatial characteristics of the organic carbon content of soil aggregates in the Loess Plateau, China.

• Key words：soil aggregate  labile organic carbon  Robinia pseudoacacia plantation  Loss Plateau

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