The process of plant nitrogen（N） uptake from soil and its multidimensional strategies significantly influence the biodiversity and carbon sequestration functions of ecosystems. This paper systematically reviewed the development of N nutrition theories in plants， introducing mineral nutrition theory and mineral-organic nutrition theory. It focused on the multidimensional strategies that plants use to absorb soil N， covering four main aspects： （1）multiform N absorption， which includes both inorganic N（e.g. ammonium and nitrate） and a range of low molecular weight organic N forms such as amino acids， amino sugars， and oligopeptides； （2）seasonal variation in N absorption， in which plants exhibit significant seasonal variations in both the magnitude and patterns of uptake of various forms of soil N， and different species may display distinct differences in uptake patterns； （3） stratified soil layer absorption， in which the root system configuration and the variation of available soil N across soil vertical profiles influence plant absorption of N amounts and N forms at different soil depths； （4）symbiotic absorption differentiation， in which nitrogen-fixing bacteria， mycorrhizal fungi， and dark-septate endophytic fungi promote N uptake by plants and， to some extent， affect the plant’s acquisition of different N forms. It was concluded that the multidimensional strategies of plant N uptake provide a basis for plant coexistence and niche differentiation in ecosystems， playing a key role in mitigating inter-plant competition， reducing N loss， and improving N use efficiency in ecosystems. However， research on plant N uptake strategies remains insufficient， with several key scientific issues yet to be resolved， such as the in-situ availability and dynamics of soil N， the turnover differences of various available N forms in soil， the molecular biological mechanisms of plant N uptake strategies， and the contributions of different available N forms to plant N nutrition.
