[Experience model for self-thinning process of even-aged pure stands].
Based on the famous -3/2 power rule and generalized Schumacher growth equation, a mathematical model for the density change of even-aged pure stands with time during self-thinning process was presented, and the genetic algorithms was used to fit this nonlinear model. With the collected data from Populus tremula var. davidiana, Pinus yunnanensis and Cunninghamia lanceolata even-aged pure stands, the new model was verified and compared with other models. The results showed that the new model could fit observed data very well, and was very useful in practice. The surplus square, mean relative error, mean absolute error and surplus standard deviation of the new model were all smaller than those of other models, indicating its good qualification in describing stand density change during self-thinning process and its useness in studying forest self-thinning rules. The study also showed that genetic algorithms could give a better global convergence, and be used to estimate the parameters of nonlinear models in ecology, biology and forestry.
Wu
Chengzhen
C
Fujian Agriculture and Forestry University, Fuzhou 350002, China. fjwcz@126.com
Hong
Wei
W
Yan
Shujun
S
D000465:Algorithms; D032486:Cunninghamia; D017753:Ecosystem; D008962:Models, Theoretical; D028223:Pinus / Q000254:growth & development; D032107:Populus / Q000254:growth & development; D014197:Trees / Q000254:growth & development*