| phyllostachys edulis is one of the most important forest species in South China. Based on standing biomass inventory, soil section, chemical analysis and otherwise in type forestland, the study has researched the cabon banlance in phyllostachys edulis plantation ecosystem in Dagangshan in Jiangxi province. It has evaluated the ability of carbon sequestration as well as the characteristics of cabon banlance in phyllostachys edulis plantation ecosystem, which would provide essential data bases for the research on carbon source/sink in forest in Jiangxi province even in the country. The results showed:(1) The average carbon content in all phyllostachys edulis organs were 0.4630g/g～0.4917g/g. The value for branch, stem, rhizome root, rhizome and leaf were 0.4917g/g, 0.4818g/g, 0.4693g/g, 0.4636g/g and 0.4630 g/g. The average carbon content in phyllostachys edulis organs were not correlated to their age. The vegetation carbon content in phyllostachys edulis were 0.4260g/g～0.4917g/g, which order was branch, stem, sheath, rhizome root, sheath root, rhizome ,leaf, understory and litter. Carbon content of soil layers in phyllostachys edulis was 0.0024g/g～0.0274g/g, differing significantly among different soil layers. Carbon content of soil was highest in surface layer (0～20cm). There were three main phases in the whole , which were 0～60cm layer, 60～160cm layer and 160～300cm layer. In the layer 0～60cm, the carbon content decreased rapidly, while decreased slowly in the layer of 60～160cm and 160～300cm.(2) The carbon storage of phyllostachys edulis vegatation was 38.851tC·hm-2, which of arbor layer was 31.056tC·hm-2,understory layer and litter layer were 1.414tC·hm-2and 6.381tC·hm-2. Carbon storage of stem took up 34.31%, which was the most part of arbor layer in vegetation.The following were sheath, sheath root, branch, leaf, rhizome and rhizome root . The value was 23.31%, 8.22%, 5.47%, 3.10%, 2.77%and 2.76%.(3) Carbon storage in soil was 204.365tC·hm-2, where the 0～60cm layer took up 58.21%and 0～160cm layer took up 89.57%. It showed that carbon storage of soil was mostly in 0～160cm layer.(4) The total carbon storage of phyllostachys edulis ecosystem was 243.216tC·hm-2, where carbon storage of soil was 204.365tC·hm-2, taking up 84.03%. Then the following was arbor layer ,litter layer and understory layer, which the value was 31.056tC·hm-2, 6.381tC·hm-2 and 1.414tC·hm-2,taking up 12.77%, 2.62% and 0.58% of the whole phyllostachys edulis ecosystem.(5) Decomposition phases of litter in phyllostachys edulis ecosystem were the month from January to March, April to September and October to December, respectively. In the first phase, litter decomposed rapidly. Then in the second, it decomposed with steady steps. And in the last decomposition kept steady which showed the decomposition ability of litter was poor. The condition such as temperature and moisture affected the decoposition of litter prominently. Carbon content of litter decreased with the decomposition process. The release rate of carbon was bigger on the days 90,180 and 270, when the carbon content declined 9.41%, 8.15% and 24.88%.(6) The annual amount of litter fall was 1.609t·hm-2. It only took up 9.4% and 9.63% for the liiter fall in the months from January to March and June to August. And in the fourth, fifth and ninth month, it took up 18.6%, 16.1% and 8.53%. In the months from October to December, the monthly amount of litter fall took up 12.18%, 12.9% and 12.67% of the annual amount. The annunal amount of carbon release was 0.068t·hm-2·a-1. It was the most in April, which was 0.024t·hm-2·a-1. And in May , September, October, November and December were more than that in other months. The annual carbon fixation in litter of phyllostachys edulis ecosystem was 0.600t·hm-2·a-1.(7) The annual average root-free soil respiration rate was 2.315μmol·m-2·s-1, with the most value of 3.905μmol·m-2·s-1 in June and the least value of 0.753μmol·m-2·s-1 in January. The reasonal dynamic variation of root-free soil respiration rate in phyllostachys edulis ecosystem was single peak curve shaped. In the months from January to July, it took on rising trend which was the most in July. In the months from August to November, it appeared falling trend. And in November and December it was steady. The variation of amount of root-free soil respiration was similar to the rate. The amount of root-free soil respiration was more in July and June than others, which the value was 4.602tCO2·hm-2·a-1 and 4.225tCO2·hm-2·a-1,taking up 14.27% and 13.1%. While it was the least in January and February with value of 0.887tCO2·hm-2·a-1 and 1.072tCO2·hm-2·a-1, taking up 2.75% and 3.32%. The annual amount of root-free soil respiration was 32.261tCO2·hm-2·a-1 or 8.798tC·hm-2·a-1.(8) The total annual carbon fixation in phyllostachys edulis ecosystem was 10.949tC·hm-2·a-1, corresponding to 40.144 tCO2·hm-2·a-1. The annual carbon fixation of vegetation was 10.949tC·hm-2·a-1, which was more than the average level of that in our country. The annual carbon fixation of arbor layer, litter and understory was 8.487tC·hm-2·a-1, 0.600tC·hm-2·a-1 and 1.069tC·hm-2·a-1, corresponding to 31.120tCO2·hm-2·a-1, 2.198tCO2·hm-2·a-1 and 3.920tCO2·hm-2·a-1. The annual carbon fixation of soil was 0.793tC·hm-2·a-1, corresponding to 2.906tCO2·hm-2·a-1.(9) The output of phyllostachys edulis ecosystem was 32.261t CO2·hm-2·a-1 or 8.798tC·hm-2·a-1. Therfore, the balance value of phyllostachys edulis ecosystem was 40.144t CO2·hm-2·a-1 or 10.949tC·hm-2·a-1.
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