四川盆地西缘4种人工林土壤团聚体碳氮磷生态化学计量学特征

Ecological stoichiometry of soil carbon, nitrogen, and phosphorus within soil aggregates of four plantations in the western edge of Sichuan Basin

采集四川盆地西缘都江堰灵岩山柳杉、含笑、桢楠和麻栎4种人工林两个层次（0-20 cm和20-40 cm）土壤样品,通过干筛法分离6个团聚体组分,分析各团聚体组分有机碳、全氮和全磷含量,并计算生态化学计量比值.结果显示,含笑林土壤平均碳、氮、磷含量为15.07、1.78和0.33 g/kg,总体低于其他3个森林类型;柳杉林0-20 cm土壤碳、氮、磷含量分别为20-40 cm土壤的2.38、1.72和1.51倍;而其他3种人工林土壤碳氮磷含量在两个土壤层次之间差异较小.团聚体粒径对土壤碳氮磷含量及化学计量比没有显著影响,但林型、土壤层次和团聚体之间的交互作用对土壤碳氮磷含量及其化学计量比影响显著;含笑林土壤碳氮磷化学计量比都显著低于其他3种人工林.本研究表明森林群落对土壤碳氮磷含量及其化学计量比有显著影响,而林型效应与土壤层次和团聚体粒径有关.

The soil samples f rom t wo layers— 0 –20 and 20 – 40 cm depth—were collected f rom the plantations of Cryptomeria fortunei, Michelia wilsonii, Phoebe zhennan, and Quercus acutissima in the Lingyan Mountain, Dujiangyan along the western edge of the Sichuan Basin. Six aggregate sizes were obtained by the dry sieve method. Soil organic carbon, nitrogen, and phosphorus contents were measured, and their stoichiometric ratios were calculated. The results showed that the soil carbon, nitrogen, and phosphorus contents in the M. wilsonii plantation were 15.07, 1.78, and 0.33 g/kg, respectively, which was lower than that in the other three forest types. Soil carbon, nitrogen, and phosphorus contents in the C. fortunei plantation was significantly higher in the top 0–20 cm layer of the soil when compared with those at a depth of 20–40 cm. However, there were no significant differences between the soil layers in the other three plantations. The aggregate size had no significant effect on soil carbon, nitrogen, and phosphorus contents, and their stoichiometric ratios. However, the interaction between forest type, soil layer, and aggregate size had significant effects on the indicators measured. The stoichiometric ratios of the soil in the M. wilsonii plantation were generally lower than those of the soil in the other three plantations. These results suggest that the effects of forest type on soil carbon, nitrogen, and phosphorus contents, and their stoichiometric ratios are dependent on the soil layer and aggregate size.