This paper presents recent studies on distribution, growth and decline, transformation and cycling of nitrogen in the Chinese fir plantation ecosystem. The results show that the total quantity of nitrogen in the ecosystem is 12287.6 kg/ha and the majority of the nitrogen of the system (about 97%) is found in the soil compartment as organically bound nitrogen, and only 2.5% is located in the vegetation. Nitrogen content in the branch at d leaf decreases with increasing time because of "dilution effect". Nitr...