天然林和人工林对土壤团聚体组成和稳定性及有机碳分布特征的影响.doc

PAGE PAGE 23 天然林和人工林对土壤团聚体组成和稳定性及有机碳分布特征的影响 摘要 应用干筛法和湿筛法，对大兴安岭地区天然林和西伯利亚红松人工林的土壤团聚体及大团聚体含量、粒级分布、稳定性及其有机碳的分布特征进行了研究，以此来比较两种林型土壤结构的稳定性和含碳量差异及其随坡位的变化趋势。具体结果如下:1. 经过干筛和湿筛处理后，经过统计可知两种林型土壤团聚体组成均以大团聚体为主，所占比例达到68％以上。且均以2～1mm团聚体含量最多，＞2mm团聚体含量最少。天然林水稳性团聚体含量由坡上到坡下逐渐增多，人工林变化趋势相反。两种林型随着土层的加深，土壤团聚体的含量逐渐降低。同土层天然林大团聚体含量要普遍高于人工林。2. 经过团聚体稳定性分析表明，天然林由坡上到坡下土壤团聚体稳定性呈现逐渐增强的变化趋势，人工林则随坡位降低，团聚体稳定性逐渐减弱。同土层天然林土壤团聚体稳定性明显高于人工林，二者之间稳定性差异随坡位降低逐渐增大。随着土壤深度的增加，两种林型土壤团聚体稳定性均逐渐降低。3. 两种林型团聚体有机碳含量与水稳性团聚体含量呈现出相同的变化趋势。有机碳贡献率以2～1mm团聚体最高。两林型有机碳储量上层明显大于下层，天然林坡上到坡下有机碳储量逐渐增加，人工林则逐渐减小，说明人工林与天然林相比有机碳流失较为严重，不能更有效的保留有机碳。同土层天然林有机碳储量更高，说明天然林比人工林更有利于有机碳储量的增加。综上所述，天然林比人工林更有利于保留有机碳，从而形成大团聚体，使得土壤结构更加稳定。人工林土壤结构较差，导致土壤养分和大团聚体的破碎更严重。坡位降低有利于天然林稳定性和有机碳含量的提高。而人工林随坡位降低，土壤结构破坏更严重。 关键词人工林；天然林；团聚体；稳定性；有机碳 Natural forest and plantation on soil aggregate composition, and stability and the effect of organic carbon distribution characteristics Abstract Through the combination of field investigation and indoor analysis, the application of dry sieving method and wet sieving method,, of natural forest in Daxinganling region and Siberian pine plantation soil aggregate and aggregate content, particle size distribution, stability and organic carbon distribution characteristics were studied in order to a comparison of the two types of forest soil structure stability and containing carbon content difference and its change trend with slope position. Specific results are as follows: 1. after the dry sieve and wet sieve treatment, after statistics, the composition of the two types of soil aggregate were mainly composed of large aggregate, the proportion reached more than 68%. And all of the 2 - 1cm aggregate content is the most, is greater than the least 2cm content. The content of water stable aggregate in natural forest was gradually increased from the slope to the slope, and the change trend of the plantation was opposite. The contents of soil aggregate decreased gradually with the soil depth of the two types of forest. The content of ma