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通过野外调查与室内分析相结合的方法,对峡谷型喀斯特水田(ST)、旱地(HD)、草地(CD)、灌丛(GC)、人工林(RGL)、次生林(CSL)6种生态系统的土壤团聚体及其有机碳的分布特点进行了研究.结果表明:干筛处理下(除HD外)均以>8 mm的土壤团聚体含量最高,总体上不同粒径土壤团聚体含量呈现随粒径减小先降低后增加再降低的趋势;湿筛处理下(除HD外)均以>5 mm的土壤团聚体含量最高,总体上不同粒径土壤团聚体含量随粒径减少而降低.干筛处理土壤团聚体的平均质量直径(MMD)为ST>CD>RGL>CSL>GC>HD;几何平均直径(GMD)为ST>CD>RGL>CSL>HD>GC;湿筛处理的MMD为RGL>CSL>GC>CD>ST>HD,GMD为CSL>RGL>GC>CD>ST>HD,用湿筛的MMD特别是GMD评价喀斯特石灰土土壤团聚体质量性状比干筛指标更准确.团聚体机械稳定性的分形维数D表现为CD>HD>ST>RGL>CSL>GC,水稳定性表现为GC>CSL>RGL>HD>CD>ST.土壤SOC含量越高,D、MMD和GMD值越大,土壤结构越合理.不同生态系统下各粒径团聚体SOC含量均以0.053~0.25 mm粒径最高,部分>5 mm粒径含量最低,但以>5 mm团聚体对土壤SOC的贡献率最高,且贡献率随着粒径的减小逐渐降低.
Through the combination of field investigation and laboratory analysis, this paper analyzed the effects of the six types of gully karst paddy field (ST), dryland (HD), grassland (CD), shrub (GC), plantation (RGL) and secondary forest Soil aggregates and their organic carbon were studied.The results showed that the content of soil aggregates> 8 mm under dry sieving (excluding HD) was the highest, and the aggregate aggregates with different particle sizes were The particle size decreased firstly and then increased then decreased again. The content of soil aggregates> 5 mm in wet sieving (excluding HD) was the highest, and the aggregate aggregates with different particle sizes decreased with the decrease of particle size. The mean mass diameter (MMD) of soil aggregates under dry-sieving treatment was ST> CD> RGL> CSL> GC> HD. The geometric mean diameter (GMD) was ST> CD> RGL> The quality traits of soil aggregates in karst lime soil were more accurately evaluated by dry sieving MMD, especially GMD, than that of dry sieving with RGL> CSL> GC> CD> ST> HD and GMD CSL> RGL> GC> CD> The fractal dimension D of mechanical stability of aggregates showed CD> HD> ST> RGL> CSL> GC and the water stability was GC> CSL> RGL> HD> CD> The greater the MMD and GMD values, the dirt The more reasonable the soil structure, the SOC content of aggregates with different particle size was the highest in 0.053-0.25 mm and the lowest in> 5 mm, while the aggregates with> 5 mm had the highest contribution to soil SOC, The contribution rate decreases gradually with the decrease of particle size.