Abstract:

This study was carried out in a 15-year0old progeny test forest of open-pollinated families for Larix kaempferi in Jianshi County, Hubei Province. The growth variation of dominant height among Japanese larch families was analyzed, and height-age models were developed for each family. Aanalysis of variance revealed that height-age curves were polymorphism among families at a given location due to differences in asymptote and rate parameter but with same shape parameter. Therefore, it was necessary to develop separate height-age curves for each family. Dominant height (or site indices) would increase with the application of genetically improved materials. Results demonstrated that both logarithmic linear Schumacher equation and flexible non-linear Richards equation could be used to describe the dominant height-age curves of the juvenile Larix kaempferi families. The differences of dominant height among families were increased with age, and their growth rates were also various. Reasonable height-age relationships would be simulated by fitting to the progeny test data if the models selection and calculation were suitable. With combination of the general unimproved stand growth models of this species, the growth, yield and genetic gain of improvement stands could be predicted properly.

Key words: Larix kaempferi, family, growth variation, height_age relationship