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流域内植被类型、地形地貌特征对土壤氮循环过程有重要的作用,是影响下游水体无机氮素来源以及富营养化的关键因子。通过比较小流域内4种植被类型(落叶松人工林、油松人工林、天然阔叶次生林和农田(玉米))对土壤NO3--N和NH4+-N含量空间变化的影响,揭示流域内不同立地条件下水源涵养林与土壤无机氮变化特征之间的关系。结果表明:4种植被类型土壤NO3--N和NH4+-N含量差异显著(P<0.05);由坡上到坡下土壤NO3--N和NH4+-N含量显著降低;在土壤表层NO3--N和NH4+-N含量最高,随着土层深度增加无机氮含量减少;与水源涵养林天然植被和人工林植被相比,农田土壤NO3--N含量最高(11.86mg·kg-1),有较高的氮流失风险。
The vegetation types and topography in the basin play an important role in the soil nitrogen cycle and are the key factors that affect the source and eutrophication of inorganic nitrogen in the downstream waters. By comparing the effects of four vegetation types (larch plantation, Pinus tabulaeformis plantation, natural broad-leaved secondary forest and farmland (maize)) on the spatial variation of soil NO3 - N and NH4 + -N contents in small watershed, Relationship between Water Conservation Forest and Inorganic Nitrogen Variation under Site Conditions. The results showed that the contents of NO3 - N and NH4 + -N in the soil of four vegetation types were significantly different (P <0.05); the content of NO3 - N and NH4 + -N in the soil from the slope to the slope were significantly decreased; N and NH4 + -N contents were the highest, with the soil depth increasing, the content of inorganic nitrogen decreased. Compared with the natural vegetation and plantation vegetation in the water conservation forest, the content of NO3 - N in the soil was the highest (11.86 mg · kg-1) Higher risk of nitrogen loss.