林地生态系统土壤可溶性有机氮库及其生态功能研究进展

Research Progress on Soluble Organic Nitrogen Pool in Soil and Its Functions in Forestry Ecosystem

本文综述了国内外林地生态系统土壤可溶性有机氮(SON,Soluble Organic Nitrogen)库大小、组成及生态功能等领域的研究进展。林地土壤SON含量因土壤类型、森林种类、气候条件、分析方法等的不同而异,土壤矿质层中SON含量通常介于1～87mg.kg-1,有机层变化于23～448mg.kg-1,约占土壤可溶性总氮的16%～96%。土壤SON是不同结构含氮化合物组成的混合物,主要包括氨氮、氨基酸、氨糖等。森林植物可直接利用低分子量SON(如人为施入的氨基酸),但直接利用土壤本身具有的SON的证据至今仍十分缺乏。林地土壤SON是一个非常重要的氮源,并在森林生态系统氮循环中具有重要作用。林地土壤SON未来的研究重点应包括林地土壤SON化学和生物学性质、土壤中天然SON动力学特性及其在限制性氮林地生态系统中的营养学作用、SON生态功能评估、微生物在林地生态系统SON动力学以及森林植物直接吸收SON的作用等。

This paper reviews the recent research progress in China and abroad on the pool size,composition and eco-functions of the soluble organic nitrogen（SON） in soil in the forestry ecosystem.The SON content in forest soil varied with soils,forest types,climate conditions and analytical methods.The soil SON content in the mineral layer is generally between 1 mg·kg-1 and 87 mg·kg-1.It ranges from 23 mg·kg-1 to 448 mg·kg-1 in the organic layer.They account for 16%-96% of the total soluble nitrogen in the soil.Soil SON includes a mixture of nitrogenous compounds of different structure,including ammonia nitrogen,amino acids and ammonia sugar.Forest plants can utilize low molecular weight SON（such as artificial fertilization of amino acids）.However,no evidence has been shown that the plants could directly absorb the natural SON in soil.Forest soil SON is a very important nitrogen source.It plays a significant role in the nitrogen cycle in the forestry ecosystem.Future research on forest soil SON should focus on chemical and biological properties of SON,dynamic characteristics of soil natural SON,nutritional functions of the natural SON in N-limited forestry ecosystem,eco-function evaluation of SON,impact of microorganisms on SON kinetics in the forest ecosystem and direct uptake of SON by forest plants.