Diameter structure and spatial distribution pattern of Platycladus orientalis plantation in Beijing mountain area.

Four indexes(diameter structure,spatial distribution pattern,mingling,and neighborhood comparison) were used to analyze the spatial structure and spatial distribution pattern of the Platycladus orientalis plantation in Ming Tombs Forest Farm.The results showed that: 1) Diameter distribution of the P.orientalis plantation revealed truncated normal distribution.The quantity of grade I and II was about 82.6% of the total plants.2) The P.orientalis population of the community revealed highly clumped pattern.The aggregation degree was decreasing with the diameter increasing.3) The average mingling value of the whole stand was 0.15,which was at a low level.The P.orientalis population had the lower mingling value then other populations.The mingling values of the associated tree species presented almost moderate,intensity and high intensity.4) The value of neighborhood comparison of the population of P.orientalis and most of the associated tree species presented almost inferiority and absolutely inferiority.