PRELIMINARY STUDY OF CARBON DENSITY,NET PRODUCTION AND CARBON STOCK IN NATURAL SPRUCE FORESTS OF NORTHWEST SUBALPINE SICHUAN,CHINA

Aims Carbon density, net production and carbon stock were estimated using data from natural spruce forests of Northwest Subalpine Sichuan. Methods We harvested biomass, litter and soil carbon and calculated net production by dividing biomass by forest age. Important findings The mean biomass of spruce forest is 230.37×103 kg·hm-2, with the tree layer accounting for 212.77×103 kg·hm-2 (92.36%). The percentage of carbon density in tree organs are stem 57.85%, bark 47.12%, branch 51.22%, leaf 48.27%, and root 52.39%. The percentage of carbon density in different strata are shrub 49.91%, herb 46.34%, duff 43.21%, litter 39.44%, and soil 1.41%. Carbon density declines with increased soil depth. The carbon stock is 273.79×103 kg·hm-2, divided among the tree layer with 109.30×103 kg·hm-2 (39.92%), shrub 5.69×103 kg·hm-2 (2.08%), herb 1.26×103 kg·hm-2 (0.46%), duff 0.60×103 kg·hm-2 (0.22%), litter 0.83×103 kg·hm-2 (0.30%), and soil (0-100 cm) 156.11×103 kg·hm-2 (57.01%). Therefore, the carbon stocks are ordered: soil (0-100 cm) tree layer shrub herb litter duff. Mean net production is 6 838.5 kg·hm-2·a-1, with the tree layer accounting for 4 676 kg·hm-2·a-1 (68.38%). Mean annual carbon sequestration is 3 584.98 kg·hm-2·a-1, with the tree layer accounting for 2 552.99 kg·hm-2·a-1 (71.21%).