Abstract: Evaluation methods for soil N availability are important to assess forest N cycling and its related issues.This paper reviewed the soil N availability in situ evaluation methods,which included buried-bag incubation,PVC closed-top tube incubations,ion exchange resin bags,resin cores,¹⁵N methods and ecosystem N budgets.As a result of the challenges to the classical soil N cycling paradigm,N mineralization being the perceived center point of the soil N cycle,ecologists provided the new paradigm,depolymerization,plant-microbe competition and microsite processes being the three key problems to assess soil N availability.Thus,all methods above were limited,and new method needed to be provided and developed as an urgent task in the future.

Key words: forest soil, nitrogen availability, evaluation methodology