Abstract: The biomass experimental plantation of poplar clones was established at Hangyun Forestry Farm,Jiangsu Province in 1992.Experimental treatments applied in a split plot design included four spacings and three poplar clones with three exact replications.Height and Breast Height Diameter(DBH)were measured annually,and sample trees were cut each year for biomass production measurement.There were significant differences among biomass production of the clones and also the spacings(α=0.05).Always the narrowest spacings gave the biggest amount of biomass at every clone until age six,except clone NL 80351.The asymptotic Baule Mitscherlich function was found to fit well on biomass data of single tree at every clone,although its asymptotic value changed in time.The Champman Richards function was found to be suitable for computing asymptotic values in Baule Mitscherich function.In this way,a two independent variable three diamensional function model,as a 3D response surface,was developed for modeling biomass production of single tree for clone NL 80351 and I 69 in pulpwood plantations.The single tree response surface multiplied by frequency or distribution of tree by growing space and age is a new basis for computing stand biomass production.