Abstract: We examined the response of soil N components in forests along an elevational gradient to the stoichiometric characteristics of soilplantlitter with four typical forests Quercus aliena var. acuteserrata (QVA), Quercus liaotungensis (QW), Betula albo sinensis (BA), Betula albo sinensisvar.septentrionalis (BAV) in the range of 1300-2600 m elevation in Taibai Mountain. We measured the contents of organic C, total N, total P in soil, leaves, litter and roots, and soil ammonium N, nitrateN and microbial biomass N. We analyzed the stoichiometric characteristics of soil, plants, and litter in different forests and their effects on soil N components. The results showed that: (1) The variation ranges of soil C, N and P in the four forests were 36.77-59.80, 2.91-4.76 and 0.13-0.80 g·kg^-1, respectively. The changes of soil C and N contents in different forests followed the same trend: BAV>BA>QW>QVA; the trend of change for soil P showed QW>BAV>BA>QVA. (2) The foliar N∶P ratio of QVA was lower than 14, indicating that plant growth in QVA was limited by N availability. Foliar N∶P ratio of QW, BA and BAV was above 16, indicating that plant growth in QW, BA and BAV were all limited by P. (3) Microbial biomass N varied significantly among different forests (P <0.05). There was no significant difference in ammoniumN content. The nitrateN content showed QVA (0.33 mg·kg^-1)>BAV (0.28 mg·kg^-1)>QW (0.27 mg·kg^-1)>BA (0.17 mg·kg^-1). (4) The results of redundancy analysis showed that the N∶P ratio of soilplantlitter was an important factor affecting microbial biomass N. Soil C∶N ratio was an important factor affecting ammonium N and nitrate N contents. Our results provide a basis for the rational management of major tree species and the study of nitrogen cycling in forest ecosystems of Taibai Mountain.

Key words: physiological characteristic., barnyardgrass, rice, nitrogen level, grain yield