Abstract:

The paper adopted difference methods to build the polymorphic site index equations based on six theoretical growth equations such as Korf, further explored their polymorphic meaning, and analyzed their modeling qualities, finally got several main conclusions: (1) Based on theoretical growth equations, through difference methods the polymorphic dominant equations can be built and have good biological basis; (2) The inflection points of theoretical growth equations have very important effect on their modeling precision of dominant height; (3) Difference equations have better modeling effect on the big range of region; (4) The polymorphic dominant height equations, such as the two-parameter polymorphic forms of Korf, Richards, Weibull and three-parameter polymorphic form of Sloboda, showed higher precision, the polymorphic site index equations with good theoretical basis can be built when excellent polymorphic dominant height growth models are adopted.

Key words: Chinese Fir plantation, Dominant height, Polymorphic site index equations, Difference equation