不同土壤团聚体及其有机碳库的分布特征

通过野外调查与室内分析相结合的方法,对山西农业大学校园内的农田、灌木丛、针叶林、阁叶林和草地土壤团聚体及其有机碳库的分布特点进行了研究.结果表明：（1）不同土地利用方式下土壤团聚体的分布均以＞10 mm团聚体为主,总体随着团聚体粒径的减小呈先减小,后增加,再减小,然后增加,最后减小的变化.（2）0～20 cm土层中,不同土地利用方式的分形维数表现为：阔叶林＞针叶林＞农田＞灌木丛＞草地,草地的分形维数与灌木丛、阔叶林、农田、针叶林间差异极显著,在20～40 cm土层中,分形维数表现为：灌木丛＞草地＞阔叶林＞农田＞针叶林,针叶林的分形维数与灌木丛、草地、阔叶林、农田间差异极显著.（3）土壤团聚体有机碳含量随着粒径的减小呈先增加后降低的趋势.（4）不同土地利用方式下,随着土层深度的增加有机碳贮量降低,在0～20 cm、20～40 cm土层,有机碳贮量随着土壤粒径大小的变化趋势与不同粒级土壤团聚体质量百分比的变化趋势相同,主要以＞ 10 mm粒级团聚体最高,且与其余粒级间均呈极显著关系,＞10mm粒级的有机碳贮量表现为农田＞阔叶林＞灌木丛＞针叶林＞草地.

Distribution Characteristics of Different Soil Aggregate and Their Organic Carbon Pools

The effects of the soil aggregate and its organic carbon distribution in the farmland, thickets, coniferous for est, broad-leaved forest and grass land of Shanxi Agricultural University were studied by the method of field investiga- tion and laboratory analysis. The results showed that： （1） the major soil particle size with different land usage were all dominated by ones larger than 10 ram, and the sizes of soil aggregates were reduced first, then increased, decreased, increased, in the last decreased with the decreasing of particle size for all sizes of soil aggregates. （2） Within 0- 20 cm depth of soil layer, the fractal dimension （FD） of different /and was in the order of broad-leaved forest〉 coniferous forest〉 farmland〉 bushes 〉 grass; The FD of grass was significantly different from that of bushes, farmland, conif erous forest and broad-leaved forest with p value of 0.01, while, within the depth of 20-40 cm soil layer, the FD of different land was following the order as bushes〉 grass〉 broadqeaved forest〉 farmland 2〉coniferous forest. The FD of coniferous forest was significantly different from that of bushes, farmland, grass and broad-leaved forest. （3） The content of organic carbon were increased first then decreased with the decreasing of particle size for all types of soil ag- gregates. （4） The storage content of organic carbon was reduced with the increase of soil depth under different appliea tion methods within the depth of 0-20 cm and 20-40 cm soil layer. The variation trend of organic carbon storage con- tent with the change of soil particle size was consistent with the change of mass percentage of soil aggregate. The high est organic carbon storage content was found with the particle size larger than 10 mm which was significantly different from other particles, and the organic carbon storage content was in the order of farmland〉 broad leaved fores〉 bu- shes〉 coniferous forest〉 grass.