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测定了不同植被恢复类型[包括撂荒地、沙棘灌木林、华北落叶松人工林和混交林(主要由华北落叶松、白桦和山杨组成)]土壤有机碳、总氮、硝态氮、铵态氮及与氮代谢有关的土壤微生物数量(细菌、放线菌、真菌、固氮菌、硝化细菌和反硝化细菌)的季节动态。结果表明,不同植被类型土壤无机氮和微生物数量存在显著的季节波动,土壤有机碳、总氮、硝态氮、铵态氮和不同种类的微生物数量随土壤深度的加深而显著降低。沙棘灌木林、华北落叶松人工林和混交林3种植被类型的土壤有机碳氮、无机氮以及微生物数量均较撂荒地高,其中自然恢复的混交林提高幅度最大,土壤碳、氮和微生物数量分别提高了0.21%～2.05%和0.09%～19.25%,真菌最大提高幅度可达19.25%,无机氮含量增幅较小,为0.01%～0.49%。土壤有机碳、总氮、无机氮与微生物数量间呈显著线性正相关。总之,不同植被恢复后土壤肥力均会显著提高,但以次生混交林对土壤肥力提高效果最明显。
Soil organic carbon, total nitrogen, nitrate nitrogen, ammonium (NH4 +) -N and NH4 + -N were measured in different types of vegetation [including fallow land, seabuckthorn shrubs, Larix principis-rupprechtii plantations and mixed forests (mainly composed of Larix principis-rupprechtii, Betula platyphylla and Betula platyphylla) Nitrogen and Seasonal Dynamics of Soil Microorganisms (Bacteria, Actinomyces, Fungi, Azotobacter, Nitrobacteria and Denitrifying Bacteria) Related to Nitrogen Metabolism. The results showed that there was a significant seasonal fluctuation in soil inorganic N and microbial counts in different vegetation types. The contents of soil organic carbon, total nitrogen, nitrate nitrogen, ammonium nitrogen and different kinds of microbes decreased significantly with the deepening of soil depth. The contents of soil organic C, N and microbial biomass in the three vegetation types of seabuckthorn shrub forest, Larix principis-rupprechtii plantation and mixed forest were higher than those in fallow land, of which the natural recovery mixed forest had the highest increase rate and the soil carbon, nitrogen and microbial quantity Increased by 0.21% ~ 2.05% and 0.09% ~ 19.25%, the maximum increase of fungi was 19.25%, and the content of inorganic nitrogen increased slightly by 0.01% ~ 0.49%. There was a significant linear positive correlation between soil organic carbon, total nitrogen and inorganic nitrogen and microbial population. In short, the soil fertility of different vegetation restoration will be significantly increased, but the effect of secondary mixed forest on soil fertility is the most obvious.