Abstract: According to the principles and methods in plant genecology,natural thinning process ofJapanese larch population is analysed.The natural differentiations of trees in man-made Japa-nese larch forest is most intensive before 16 years of age,with an annual withering mortality larger than 3.5%.There are four peaks of natural thinning in the natural developmentprocess during 6—26 years of age,appearing at 9,13,17,20 years respectively.The GrayGM(1,1)model was applied to fit the natural thinning process of Japanese larch population.Fitness results show a higher accuracy and can be used for the prediction of futurepopulation densities.

Key words: Wheat, Allelopathy, Allelochemicals