Life history characteristics and spatial distribution of Pinus tabulaeformis population in Songshan Nature Reserve of Beijing

This paper analyzes the life history characteristics and spatial distribution of Pinus tabulaeformis population in Songshan Nature Reserve through four aspects(life table characteristics,age stucture,survival curve,and spatial pattern of individuals in different ageclasses).Results showed that,1)there is a peak of mortality at the DBH of about 22.5 cm,which was caused by intraspecific competition for space and light resource.Then the population will enter a stable growth period,after which mortality increases gradually with ages until they die.2)The survival curve of P.tabulaeformis population generally matches the Deevey TypeⅢ,and the seedlings have a low survival rate due to high crown density.3)The spatial pattern of different ageclasses P.tabulaeformis and the spatial association among individuals depend on spatial scales.In small scales,individuals of all ageclasses P.tabulaeformis tend to clumping distribution,and the spatial association among individuals in different ageclasses P.tabulaeformis is considerably strong.By contrast,if the scales enlarge beyond these points,individuals of all ageclasses P.tabulaeformis disperse randomly,and their spatial association weakens.