川西亚高山不同彩叶林土壤水稳性团聚体特征

Characteristics of soil water stable aggregates in different colored-leaf forests in subalpine western Sichuan

彩叶林是川西亚高山地区重要的生态系统类型之一.以川西亚高山典型彩叶林为对象,研究彩叶林不同季节土壤有机层和矿质土壤层水稳性团聚体粒径组成和稳定性特征.结果表明:(1)彩叶林土壤水稳性团聚体各粒径占比总体呈现随团聚体粒径减小而降低的变化趋势,以>2 mm团聚体最高,0.053-0.25 mm团聚体最低,土壤有机层和矿质土壤层>2 mm团聚体分别占21.1%-54.3%和17.2%-60.0%.(2)土壤团聚体总量中大团聚体(>0.25 mm)百分比(R_(0.25))占60%以上,土壤有机层R_(0.25)、团聚体平均重量直径(MWD)和几何平均直径(GMD)以糙皮桦-岷江冷杉林(BAF)最高;矿质土壤层R_(0.25)以BAF最高,MWD和GMD以白桦-云杉-川滇长尾槭林(BPA)最高;两个土层的土壤粒径分形维数(D)以BAF最低.(3)彩叶林类型变化显著影响土壤水稳性团聚体粒径组成、R_(0.25)、MWD、GMD和D,但采样时期、土层及其交互作用未显著影响土壤R_(0.25)、GMD和D.上述结果表明川西亚高山森林土壤水稳性团聚体粒径组成和稳定性特征随彩叶林类型变化明显不同,BAF具有较好的土壤团粒结构和稳定性.

Colored-leaf forests are an important ecosystem type in the subalpine region of western Sichuan.In this study,typical colored-leaf forests in this region were taken as the object,and the particle size composition and stability characteristics of soil water stable aggregates in the soil organic layer and mineral soil layer were investigated at different sampling times in these forests.The results showed that the percentage of soil water stable aggregates generally decreased as particle size decreased,with>2 mm aggregates being the most prevalent and 0.053-0.25 mm aggregates being the least prevalent.Moreover,the>2 mm aggregates accounted for 21.1%-54.3%and 17.2%-60.0%of all aggregates in the soil organic layer and mineral soil layer,respectively.Large soil aggregates(R_(0.25))accounted for more than 60%of the total soil aggregates.For the soil organic layer,the R_(0.25),mean weight diameter(MWD),and geometric mean diameter(GMD)were the highest in the birch-fir forest(BAF).For the mineral soil layer,the R_(0.25)was highest in the BAF,and the MWD and GMD were highest in the birch-spruce-Acer palmatum forest.The fractal dimension(D)in both layers was the lowest in the BAF.Changes in the type of colored-leaf forests significantly affected the composition of soil water-stable aggregates,R_(0.25),MWD,GMD,and D,but the sampling time,soil layer,and their interaction did not significantly affect R_(0.25),GMD,and D.These results suggest that the particle size composition and stability characteristics of soil water-stable aggregates in the subalpine region of western Sichuan significantly vary with variations in colored-leaf forest types,and the BAF has good soil aggregate structure and stability.