Effects of elevated CO2 concentration and nitrogen supply on biomass and
active carbon of freshwater marsh after two growing seasons
in Sanjiang Plain, Northeast China |
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Authors: | ZHAO Guangying LIU Jingshuang WANG Yang DOU Jingxin and DONG Xiaoyong |
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Institution: | 1. Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130012, China.
E-mail: zhaoguangying2004@126.com
2. School of Geographical Science, Harbin Normal University, Harbin 150080, China
3. Graduate School of Chinese Academy of Sciences, Beijing 100039, China,1. Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130012, China.,1. Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130012, China.,1. Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130012, China.
E-mail: zhaoguangying2004@126.com
3. Graduate School of Chinese Academy of Sciences, Beijing 100039, China and 4. Heilongjiang Academy of Forestry Science, Harbin 150040, China |
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Abstract: | An experiments were carried out with treatments di ering in nitrogen supply (0, 5 and 15 g N/m2) and CO2 levels (350 and 700
mol/mol) using OTC (open top chamber) equipment to investigate the biomass of Calamagrostis angustifolia and soil active carbon
contents after two years. The results showed that elevated CO2 concentration increased the biomass of C. angustifolia and the magnitude
of response varied with each growth period. Elevated CO2 concentration has increased aboveground biomass by 16.7% and 17.6%
during the jointing and heading periods and only 3.5% and 9.4% during dough and maturity periods. The increases in belowground
biomass due to CO2 elevation was 26.5%, 34.0% and 28.7% during the heading, dough and maturity periods, respectively. The responses
of biomass to enhanced CO2 concentrations are di ered in N levels. Both the increase of aboveground biomass and belowground
biomass were greater under high level of N supply (15 g N/m2). Elevated CO2 concentration also increased the allocation of biomass
and carbon in root. Under elevated CO2 concentration, the average values of active carbon tended to increase. The increases of soil active
soil contents followed the sequence of microbial biomass carbon (10.6%) > dissolved organic carbon (7.5%) > labile oxidable carbon
(6.6%) > carbohydrate carbon (4.1%). Stepwise regressions indicated there were significant correlations between the soil active carbon
contents and plant biomass. Particularly, microbial biomass carbon, labile oxidable carbon and carbohydrate carbon were found to be
correlated with belowground biomass, while dissolved organic carbon has correlation with aboveground biomass. Therefore, increased
biomass was regarded as the main driving force for the increase in soil active organic carbon under elevated CO2 concentration. |
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Keywords: | elevated CO2 concentration freshwater marsh biomass soil active carbon |
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