Density effect and self-thinning in Eucalyptus urophylla stands  

作　　者：Zhiyang Lie Li Xue 

机构地区：[1]College of Forestry and Landscape Architecture, South China Agricultural University

出　　处：《Journal of Forestry Research》2019年第2期529-535,共7页林业研究（英文版）

基　　金：partially supported by the Forestry Technology Popularization Demonstration Project of the Central Government of China(No.[2015]GDTK-07)

摘　　要：Density effects on the growth and self-thinning of Eucalyptus urophylla stands were examined for 7 years.The reciprocal equation of the competition-density(C–D)effect was used to describe the C–D effect in even-aged pure stands of E. urophylla during course of self-thinning and showed a good fit to the data. The time trajectories of mean stem volume-density nearly paralleled the y-axis during early growth stages of stands, and then began to curve left. Finally, the mean stem volume-density trajectories of the low-, middle-and high-density stands tended to follow the self-thinning lines with slopes of-2.01,-1.90 and-1.99, respectively. With increasing physical time t, the biological time s increased rapidly during early growth stages and became slow gradually during later growth stages. Realized density-initial density curves tended to become more or less flat with increasing initial density, indicating the existence of an asymptotic value for density at a given time. The coefficient e, the reciprocal of which represents the asymptotic density at a given time,increased with increasing biological time s, indicating that the asymptotic density decreased with increasing stand age.Final yield Y(t) increased gradually with increasing stand age.Density effects on the growth and self-thinning of Eucalyptus urophylla stands were examined for 7 years.The reciprocal equation of the competition-density(C–D)effect was used to describe the C–D effect in even-aged pure stands of E. urophylla during course of self-thinning and showed a good fit to the data. The time trajectories of mean stem volume-density nearly paralleled the y-axis during early growth stages of stands, and then began to curve left. Finally, the mean stem volume-density trajectories of the low-, middle-and high-density stands tended to follow the self-thinning lines with slopes of-2.01,-1.90 and-1.99, respectively. With increasing physical time t, the biological time s increased rapidly during early growth stages and became slow gradually during later growth stages. Realized density-initial density curves tended to become more or less flat with increasing initial density, indicating the existence of an asymptotic value for density at a given time. The coefficient e, the reciprocal of which represents the asymptotic density at a given time,increased with increasing biological time s, indicating that the asymptotic density decreased with increasing stand age.Final yield Y(t) increased gradually with increasing stand age.

关 键 词：C–D effect General LOGISTIC CURVE EUCALYPTUS urophylla Reciprocal EQUATION SELF-THINNING 

分 类 号：S[农业科学]