A preliminary research of plant biomass and production of natural middle-age stand of Picea purpurea at elevation 3200–3350m in Songpan County of Sichuan Province is presented here. Spruce tree, spruce sapling, undergrowth, living plant cover and dead branches and leaves were observed by “average standard tree” and “divided-storeys” method. The following regression equations were derived from the standing crop of the destructive trees:
Ws= 3.1660 (D2H) 0.4567, WBk =0.8657 (D2H)0.4109,
WB= 12.4382(D2H)0.1928 WF=2.9259(D2H)0.3129,
WR= 14.8482 (D2H)0.1960
The estimated total biomass of P. purpurea forest community is 158.78 t/ha, net production 3.415 t/(ha.·r.). Total aboveground biomass of spruce is 134.407 t/ha, net-production 2.890 t/(ha·yr.), in which the percentages of stem, bark, branch, leaf and root are 44.6%, 5.9%, 19.5%, 10.6% and 19.4% respectively. The biomass percentages of spruce tree, spruce sapling, undergrowth and living plant cover and dead branch and leaf are 84%, 2%,9% and 5% respectively. The close relationship between leaf area index (LAI) and the production of spruce tree was further proved. Within a certain limit the stand of LAI of 4.34 would increase by 47.2% in comparison with the stand of LAI of 3.32, and that of close crown is higher than that of thin crown.