| 1 | Diurnal and monthly variations of carbon dioxide flux in an alpine shrub on the Qinghai-Tibet Plateau显示文摘Continuous CO2 flux observation with eddy covariance method conducted in the alpine shrub on the Qinghai-Tibet Plateau indicates that there are distinct diur- nal and monthly variations for CO2 fluxes in the alpine shrub on the plateau. As for diurnal variation, with net CO2 influx from 08:00 to 19:00 and net CO2 efflux from 20:00 to 07:00, peak CO2 flux during warm season (July) appears around 12:00 (?1.19 g CO2·m?2·h?1); there is no obvious horary fluctuation for CO2 flux during cold season (January), and horary CO2 flux during most hours in a day is close to zero except for a small amount of net efflux (about 0.11 g CO2·m?2·h?1) from 11:00—17:00. As for monthly varia- tion, with net CO2 influx from June to September and net CO2 efflux from January to May and October to December, the peak monthly CO2 influx and CO2 efflux appear in Au- gust and April, respectively. The total net CO2 influx from June to September and total net CO2 efflux from February to May and October to December in the alpine shrub on the Qinghai-Tibet Plateau are estimated to be 673 and 446 g CO2·m?2. Results show that the alpine shrub on the Qing- hai-Tibet Plateau is remarkable carbon dioxide sink under no grazing conditions and the total yearly CO2 influx is esti- mated to be 227 g CO2·m?2. | XUShixiao ZHAOXinquan LIYingnian ZHAOLiang YUGuirui SUNXiaomin CAOGuangmin | 2005 | Chinese Science Bulletin2005，50，6： | 11 |
| 2 | Comparative study on CO_2 emissions from different types of alpine meadows during grass exuberance period显示文摘Potentilla fruticosascrub, Kobresia humilismeadow and Kobresia tibeticameadow are widely distributed on the Qinghai-Tibet Plateau. During the grass exuberance period from 3 July to 4 September, based on close chamber-GC method, a study on CO 2 emissions from different treatments was conducted in these meadows at Haibei research station, CAS. Results indicated that mean CO 2 emission rates from various treatments were 672.09±152.37 mgm -2 h -1 for FC (grass treatment); 425.41±191.99 mgm -2 h -1 for FJ (grass exclusion treatment); 280.36±174.83 mgm -2 h -1 for FL (grass and roots exclusion treatment); 838.95±237.02 mgm -2 h -1 for GG (scrub+grass treatment); 528.48±205.67 mgm -2 h -1 for GC (grass treatment); 268.97±99.72 mgm -2 h -1 for GL (grass and roots exclusion treatment); and 659.20±94.83 mgm -2 h -1 for LC (grass treatment), respectively (FC, FJ, FL, GG, GC, GL, LC were the Chinese abbreviation for various treatments). Furthermore, Kobresia humilismeadow, Potentilla fruticosascrub meadow and Kobresia tibeticameadow differed greatly in average CO 2 emission rate of soil-plant system, in the order of GG>FC>LC>GC. Moreover, in Kobresia humilismeadow, heterotrophic and autotrophic respiration accounted for 42% and 58% of the total respiration of soil-plant system respectively, whereas, in Potentilla fruticosascrub meadow, heterotrophic and autotrophic respiration accounted for 32% and 68% of total system respiration from GG; 49% and 51% from GC. In addition, root respiration from Kobresia humilismeadow approximated 145 mgCO 2 m -2 h -1 , contributed 34% to soil respiration. During the experiment period, Kobresia humilismeadow and Potentilla fruticosascrub meadow had a net carbon fixation of 111.11 gm -2 and 243.89 gm -2 , respectively. Results also showed that soil temperature was the main factor which influenced CO 2 emission from alpine meadow ecosystem, significant correlations were found between soil temperature at 5 cm depth and CO 2 emission from GG, GC, FC and FJ treatments. In addition, soil moisture may be the inhibitory factor of CO 2 emission from Kobresia tibeticameadow, and more detailed analyses should be done in further research. | HUQiwu CAOGuangmin WUQin LIDong WANGYuesi | 2004 | Journal of Geographical Sciences2004，14，2： | 8 |
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