| With global warming, more attention have been paid to carbon source or sink. As the largest terrestrial ecosystem organic carbon pool, a great impact would be exerted on atmospheric CO2 concentration by any change of carbon storage of forest ecosystem. Forest ecosystem has great significance for increasing carbon sinks, offsetting CO2 emissions, and mitigating greenhouse effect.In this paper, Pinus massoniana in forest farm on different growth stages and with different density were selected to study. The studies were focused on biomass and carbon content of tree layer, shrub layer, herb layer and litter, and the carbon content in the soil, building regression model of tree-layer biomass. Biomass and carbon density distributing characteristics of Pinus massoniana. were studied. The aim was to understand the carbon sink function of Pinus massoniana., in the hope of supplying data and laying basis for researches on carbon sink functions and carbon circle of the regional forest ecosystem in China. Main findings are as followed:1. Regression models of biomass of different organs of Pinus massoniana tree layer were established based on the regression model W= aDb. The results showed that:the total biomass of Pinus massoniana is 141.99t/hm2. Tree layer biomass was the largest about 140.09 t/hm2,taking up to 98.67% of the whole. Trunk biomass was the main part of tree layer, accounting for 65.31%. The distributing sequence of the biomass of Pinus massoniana is:Tree layer>litter>shrub layer>herb layer. The biomass of tree layer increased with the increase of age whereas the biomass of shrub layer and herb layer decreases with the increase of shade density. The individual number of the community with DBH within the limits of 8-12cm accounted for 27.77% whereas the biomass of it only accounted for 8.97%. The biomass of the community with DBH within the limits of 12-28cm accounted for 78.36%.2. The carbon content differentiated in the organs of the tree layer, the difference was significant. The sequence of carbon content of organs was:needle>branch>trunk>bark>root. The mean carbon content were 37.77%,36.69% and 40.38%, respectively of shrub layer, herb layer and litter. The carbon content varied with ages in tree layer, shrub layer, herb layer and litter. The carbon content in tree layer increased with the increase of age. The carbon content of shrub layer, herb layer and litter didn't vary uniformly with the age change. The carbon content sequence of under storey in different age was:litter layer>shrub layer>herb layer. The carbon content of large root was the largest about 47.90%.The mean carbon content were 41.61%,43.21%, repectively of fine root and root stake. The carbon content sequence was:large root>root stake>fine root. Soil carbon content in different was between 0.32% and 3.50%,the difference is significant. The mean carbon content were 2.06%,0.99%,0.57%,repectively of A layer, B layer and C layer. The soil carbon content decreased with the increase of depth and increased with the increase of age.3. Carbon density of forest ecosystem was 130.55 t/hm2,Tree layer carbon density was 70.07 t/hm2,taking up to 53.67% of the ecosystem. The proportion increase with the increase of age. The mean soil carbon density was 53.38 t/hm2,accounting for 40.89%. The mean carbon density were 20.78 t/hm2,17.24 t/hm2,and 15.36 t/hm2, respectively of A layer, B layer and C layer. Soil carbon density generally increased with the increase of forest age. Tree layer and soil are two main carbon pools of forest ecosystem. The mean carbon density were 1.16 t/hm2 and 0.29t/hm2,repectively of shrub layer and herb layer.Litter carbon density was 5.65 t/hm2,accounting for more than 79% of under storey. It was a major carbon pool of under storey. The proportion of tree layer carbon density to the ecosystem decreased with the increase of forest density whereas the proportion of soil and litter carbon density increased. |
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