A new well-behaved diameter distribution function for unthinned Chinese fir (Cunninghamia lanceolata) plantations in southern China

The objective of this study was to introduce a new high-performance diameter distribution function. The long-term repeated measurement data sets, consisted of 150 diameter frequency distributions from Chinese fir (Cunninghamia lanceolata) plantations in the southern China, were used. R distribution had presented a more accurate simulation than three-parametric Weibull function. The parameters p, q and r of R distribution proved to be its scale, location and shape parameters, and have the deep relationship with stand-level variables, which means that the parameters of R distribution have the good biological interpretation. The main distribution range of inflection points for the cumulative diameter distribution of Chinese fir plantations was 0.4~0.6.