Abstract: Using the modeling data of 240 sample trees of Chinese fir(Cunninghamia lanceolata)in southern China,single tree volume and aboveground biomass equations based on one-variable and two-variable respectively were constructed,and the fitting results of weighted regression with special weight function,general weight function,and four expanded weight functions were compared.The results indicated that the weighted regression with special weight function would be a good choice for certain modeling data;the weighted regression with general weight function might have different performance on eliminating heteroscedasticity for different data.To expand the adaptability of general weight function,it is recommended that the function expression 1/f(x)² be revised to 1/f(x)ⁿ.

Key words: weighted regression, weight function, heteroscedasticity, volume model, biomass model