土壤呼吸和土壤团聚体对土壤肥力、质量和土壤的可持续利用等具有重要作用。通过湿筛法得到华北地区不同土地利用类型土壤大团聚体(>2 mm)、中间团聚体(0.25～2 mm)、微团聚体(53 μm～0.25 mm)以及粉+黏团聚体(人工林>灌木>农田>果园,其中,次生林和人工林显著高于其他土地利用类型(p0.05),果园显著低于其他土地利用类型(p人工林>灌木>农田>果园。次生林和人工林以>0.25 mm的大团聚体为主,占粒径总组成的20%以上; 灌木以中间团聚体和粉+黏团聚体为主; 而农田和果园则以粉+黏团聚体为主,约占粒径总组成的40%。林地的开垦会导致大团聚体的破碎化,灌木及农田>0.25 mm的大团聚体含量较林地低,土壤结构趋于恶化; 而农田闲置为果园后,则会促使粉+黏团聚体向粒径大的微团聚体及中间团聚体转化,使土壤结构趋于改善。灌木及农田土壤颗粒的MWD(平均质量直径)和GMD(几何平均直径)值均显著低于林地和灌木(p0.25 mm团聚体含量、MWD、GMD和土壤呼吸均与土壤TOC,SLOC和POC皆呈现显著正相关性(p0.25 mm团聚体含量、MWD、GMD和土壤呼吸与LFOC和POC之间的相关关系达到极显著水平(p<0.01),且相关系数较大,说明与土壤TOC相比,LFOC和POC对土壤水稳性团聚体和稳定性的贡献更大,并且LFOC和POC对土壤呼吸的贡献更大。
Soil aggregates and aggregates have the important effect on soil fertility, soil quality and the sustainable utilization of soil. In this paper, in order to study the effect of land use types on stability of soil aggregates and soil respiration in Northern China, we took soil samples from five land use types which are secondary forest, artificial forest, shrubland, farmland and orchard, then we got the proportion of large macroaggregates(>2 mm), small macroaggregates(0.25～2 mm), microaggregates(53 μm～0.25 mm)and silt+clay(artificial forest>shrubland>farmland>orchard, and there was no significant difference in soil respiration between farmland and orchard (p>0.05); soil total organic carbon(TOC), particulate organic carbon(POC)and light component organic carbon(SLOC)were significantly affected by different land use types, which decreased in the order: secondary forest>artificial forest>shrubland>farmland>orchard. Reclamation of woodland will lead to fragmentation of macroaggregates and deterioration of soil structure, respectively. Changing the sloping farmland to abandoned land, led to the conversion of soil fraction from silt +clay to large macroaggregates and small macroaggregates, and could improve the soil structure. We found the MWD and GWD in farmland were significantly lower than those in woodland (p0.25 mm WAS, MWD, GMD and soil respiration were significantly (p0.25 mm WAS, MWD and GMD with greater coefficients were founded, suggesting that soil particulate organic C plays a more important role in maintaining soil aggregate stability and soil respiration.
