林木氮素吸收偏好性及其形成机制研究进展

森林土壤中可被林木吸收利用的氮（N）素主要以铵态氮（NH₄+-N）和硝态氮（NO₃--N）的形态存在。受全球气候变暖、氮沉降和人类活动等因素的影响，NH₄+和NO₃-的分布存在很大的时间波动性和空间异质性，且NH₄+-N和NO₃--N亏缺已成为限制林地生产力的主要因素。在森林土壤N亏缺和N异质分布的逆境中，在林木长期进化过程中形成了对不同形态N素的吸收偏好，且这种吸收偏好会随生长环境条件而发生改变。特别是对于NH₄+和NO₃-这2种主要形态的偏好选择性已被证明是决定林木生产力、竞争、共存和生态演替的重要因素之一。对不同树种在N异质分布环境下的N吸收偏好和形成机制的研究，是揭示林木N素营养遗传特性和提高林地N素利用效率的关键。文中从森林土壤中N的主要形态及其分布特征、林木对不同形态N素的吸收偏好和形成机制、林木N吸收偏好的影响因素3个方面进行总结阐述，并对未来研究方向进行展望，以期为我国人工林培育中不同树种的造林配置和合理N素施肥技术提供理论依据和参考。

A Review of Nitrogen Uptake Preference of Trees and Its Formation Mechanism

NH₄⁺ and NO₃^- in forest soil are the main inorganic nitrogen (N) that can be absorbed and utilized by trees. Their distribution is subject to high temporal fluctuation spatial heterogeneity due to global warming, N deposition, and human activities. And NH₄⁺ and NO₃^- deficiency is one of the major factors limiting the productivity of forest plantations. Under N stress and N heterogeneous environments, different tree species have developed different N uptake preferences during their evolution, which have changed with different environment conditions. The N uptake preferences have been proven to be one of the significant determinants of plant productivity, competition, coexistence and ecological succession. Studying the N uptake preference of tree species under N stress and heterogeneous distribution environments and relate formation mechanism is the key to reveal the genetic characteristics of N nutrition in trees and improve the N use efficiency. This paper summarizes the existing research from the three aspects of the forms and distribution characteristics of N in forest soil, the N uptake preferences of trees and its formation mechanism, and influencing factors to N uptake preference, and prospects the future research direction. This study is aimed to provide the theoretical basis and references for the species configuration and composition of planted forests and the reasonable N use technology.