寒温带林区不同林型土壤中游离氨基酸的研究

为了解大兴安岭北部寒温带林区不同林型各层次土壤游离氨基酸种类和含量的变化,以及不同林型对土壤游离氨基酸含量的影响,应用柱前衍生高效液相色谱法采用梯度洗脱在254 nm波长处检测土壤中常见的17种游离氨基酸。结果表明:①不同林型下游离氨基酸态氮的平均含量分别为杜鹃-白桦林(33.86 μg/g)>杜鹃-落叶松林(31.44 μg/g)>杜香-落叶松林(28.76 μg/g)>偃松林(27.66 μg/g)。②同一林型不同土壤层次游离氨基酸态氮含量整体表现为凋落物层高于矿质土层,0～5 cm的矿质土层高于≥5～20 cm的矿质土层。③不同林型各土壤层次检测出的氨基酸种类和含量不同,种类上各林型均以凋落物层出来最多; 含量上大多表现为中性氨基酸所占的比例最大,酸性和碱性氨基酸次之,含硫氨基酸最少。研究结果在一定程度上说明不同森林类型由于林内气候环境、土壤条件和林下伴生树种等的差异,对土壤游离氨基酸含量和种类存在不同程度的影响。

A study on free amino acid in different forest types soil of cold-temperate forest region

In order to study the variation of the type and content of free amino acid in different soil layer, as well as the influence of different forest types on free amino acid content in the boreal forest of Greater Hinggan Mountains, a reverse-phase high performance liquid chromatographic method for simultaneous determination of 17 free amino acids in soil with gradient elution technique at 254 nm UV wavelengths was applied. It can not only determinate the concentration of the total amino acid content, but also the content of each amino acid component accurately. Furthermore, it has better derivative effect and high separation efficiency. The results showed that the average contents of free amino acids in the different forest were Rhododendron-Betula platyphylla forest(33.86 μg/g)>Rhododendron-Larix dahurica forest(31.44 μg/g)>Ledum palustre-Larix dahurica(28.76 μg/g)>Pinus pumila forest(27.66 μg/g). In the same forest, the size order of free amino acid nitrogen content of every soil layer was litter layer> mineral layer, and the 0-5 cm of mineral layer> the ≥5-20 cm of mineral layer. There is some difference of the types as well as the content of free amino acid in different forest types of soil layer, and the type of free amino acid was the most in litter layer. Neutral amino acid content was the highest, followed by alkaline and acidic amino acid, and sulfur-containing amino acid was lowest. This studie showed that different forest types have generated various effects on the content and type of soil free amino acid accounting for various stand climatic environment, edaphic conditions, and understory associated trees.