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弄清退耕还林工程实施后土壤团聚体粒径分布及其有机碳的变化,可为协调区域土地利用和土壤碳库管理提供科学依据.选取成都市退耕还林工程实施中主要造林树种巨桉和水杉人工林,以及马尾松天然次生林和临近坡耕地为研究对象,探讨了土地利用变化对0-20 cm、20-40 cm和40-60 cm不同土壤层次团聚体稳定性及其结合有机碳分配与储量的影响.结果显示:不同土地利用方式下土壤团聚体均以大团聚体(>0.25 mm)的含量在土壤团粒结构中占主导地位,且土壤团聚体中有机碳含量随团聚体粒径的增大而减小.农地转变为林地后,>0.25 mm粒径土壤团聚体含量、团聚体平均重量直径,以及各粒径团聚体有机碳含量均有所增加.其中,团聚体有机碳尤以在0-40cm土层>2mm粒径中的含量增加倍数为大.相比农耕地,马尾松天然次生林、巨桉和水杉人工林各土层土壤>2 mm团聚体有机碳储量占总有机碳储量比例增加了5.96%-47.57%,而<0.053 mm团聚体有机碳储量占总有机碳储量比例减少了0.95%-33.28%.0-60 cm土层土壤团聚体总有机碳储量以马尾松天然次生林最高,而农耕地为最低.研究结果表明该区退耕还巨桉和水杉林增加了土壤团聚体稳定性和有机碳储量,但与天然林次生林相比仍有一定差距.
Understanding the particle size distribution and the changes of organic carbon after the implementation of the conversion of cropland to forest project can provide a scientific basis for coordinating regional land use and soil carbon pool management.Considering the implementation of the project of returning farmland to forest in Chengdu, And Metasequoia fir plantations, and natural secondary forest and adjacent slope farmland of Pinus massoniana were studied. The effects of land use change on the stability of aggregates at 0-20 cm, 20-40 cm and 40-60 cm soil layers and their combination of organic carbon Distribution and storage of soil aggregates.The results showed that soil aggregates dominated the soil aggregate structure with large aggregates (> 0.25 mm) under different land use types, and the contents of soil organic carbon The soil aggregates> 0.25 mm in diameter, the average weight diameter of aggregates and the organic carbon content of aggregates in each size increased after the agricultural land was converted to woodland, in which, Carbon especially in 0-40cm soil layer> 2mm particle size of the fold increase is large.Compared with agricultural land, Pinus massoniana secondary forest, Eucalyptus grandis and Metasequoia plantation soil> 2mm soil aggregate organic carbon reserves total Organic carbon storage increased by 5.96% -47.57%, while <0.053 mm aggregate organic carbon storage accounted for 0.95% -33.28% of the total organic carbon storage. Total soil organic carbon storage in 0-60 cm soil layer The highest secondary natural forest and the lowest agricultural land were found in this study. The results showed that Eucalyptus grandis and Metasequoia glyptostroboides increased the stability of soil aggregates and organic carbon storage in the area, but there was still a gap compared with the natural forest secondary forest.