Abstract: In this paper, we analyzed soil inorganic nitrogen (NH₄⁺-N, NO₃^--N), pH, bulk density, organic carbon and total nitrogen in four waterconservation forests (e.g. Acer mono-Quercus mongolica forest, Populus davidiana forest, Betula platyphylla-P. davidiana forest, and Larix kaempferi plantation) in the mountain area of eastern Liaoning, to reveal the relationships of vegetation type with soil layer and soil inorganic nitrogen distribution. Results indicated that the concentrations of soil NH₄⁺-N and NO₃^--N were highest in the Oa horizon (0-5 cm) and decreased gradually in the mineral soil layers. Soil inorganic nitrogen concentration was in a sequence of L. kaempferi plantation (27.46 mg·kg^-1) > P davidiana forest (21.76 mg·kg^-1) > A. mono-Q. mongolica forest (19.09 mg·kg^-1) > B. platyphylla-P. davidiana forest (17.88 mg·kg^-1). NH₄+-N was the major form of soil inorganic nitrogen in the broadleaved forests, while NO₃^--N was dominant in L. kaempferi plantation soil. There was a highly significant positive correlation between soil inorganic nitrogen and organic carbon or soil moisture in the four forest types (P<0.01). Overall, vegetation type greatly affected the distribution of soil inorganic nitrogen. Our results can provide a reference for vegetation type selection and structural regulation of water conservation forests in the mountainous area of eastern Liaoning.

Key words: air temperature, solar radiation, indica rice, spikelet differentiation and degeneration, sowing date