Abstract: This paper dealt with the relationships and correlation models of the population density of 5.6 years old Eucalyptus urophylla plantation with its crown width,diamter at breast height(DBH),tree height,individual standing volume,stand volume,wood properties and survital rate.The results showed that the population density remarkably affected DBH,individual standing volume,crown width,live branch height,stand volume and wood fiber width;but not affect tree height,basic density of wood,and length of wood fibers.It had a positive relationship with stand volume,live branch height and wood fibers width,and a negative relationship with DBH,individual standing volume and crown width.In addition, E.urophylla had a wide range of reasonable density.For short-rotation puplwoods,the optimum planting density of E.urophylla is 2000 individuals per hectare.

Key words: Eucalyptus urophylla, Density, Functional rule, Correlation model, summer maize, increasing light, shading, chloroplast ultrastructure, grain yield