川西亚高山针叶林树种云杉和冷杉土壤酸碱性差异及其机制

比较了川西亚高山针叶林主要树种粗枝云杉(Picea asperata)和岷江冷杉(Abies faxoniana)样地各土层(0—5 cm、5—10cm、10—20 cm)土壤pH值差异,并从两树种养分吸收和养分归还相关累积H~+输入方面探究其差异原因。研究结果表明:云杉样地各土层土壤pH值均显著高于冷杉样地(P0.05);云杉样地地被物累积H~+输入显著低于冷杉样地(P0.05);云杉样地凋落物中P、Mg、N、C平均浓度显著低于冷杉(P0.05),而Ca、C/N、木质素/N、C/P显著高于冷杉样地(P0.05),两树种凋落物中木质素、K平均浓度无显著差异。云杉和冷杉凋落物化学特性主成分分析PC_1、PC_2方差贡献率分别为73.7%和15.6%,累积方差贡献率为89.4%,其中PC_1主要综合Ca、C/P、C/N、木质素/N、P、N、Mg的信息;PC_2主要综合木质素、K、C的信息。各土层土壤pH值均与地被物累积H~+输入显著负相关,与PC_1样本分数显著正相关。研究结论:云杉和冷杉样地土壤pH值存在显著树种差异,且云杉使土壤pH值变大,冷杉使土壤pH值变小,这主要与地被物形成以及凋落物化学特性有关,即与凋落物的量和凋落物分解速率、凋落物养分归还率密切相关。

Difference in soil pH values between Picea asperata and Abies faxoniana stands in subalpine regions and a preliminary study on its mechanism

Soil pH value is the most important soil property. It can not only directly affect the growth of crops, but is also involved in altering other soil properties. Our objective was to determine the difference in soil pH values between Picea asperata and Abies faxoniana stands and its mechanism. We used the seedlings of Picea asperata and Abies faxoniana, the widely distributed and important species in subalpine coniferous forests of Sichuan, China, as materials with which to conduct the experiment. We measured soil pH values of different soil layers, calculated the cumulative H⁺ input through nutrient uptake and storage in biomass, and forest floor accumulation, and analyzed the litter quality. The results showed that the pH value of A. faxoniana soil was greater than that of P. asperata. The soil pH value was significantly positively related to the calculated cumulative H⁺ input through forest floor accumulation, and negatively related to the first principal component scores of different plots. Thus, soil pH value was significantly positively related to the ratio of lignin/N, C/N, C/P, and total concentration of Ca, and negatively related to total concentrations of N and P in leaf litter. The results suggested that the difference in the soil pH values between P. asperata and A. faxoniana was related to the forest floor accumulation and the leaf litter quality, i.e., the mass, decomposition, and nutrient-restitution of leaf litter.