The CO2 concentrations and fluxes over an urban forest site （Namsan） and an urban residential region （Boramae） in Seoul, Korea, during the non-growing season （2 4 March 2011）, the growing season （10-12 June 201...The CO2 concentrations and fluxes over an urban forest site （Namsan） and an urban residential region （Boramae） in Seoul, Korea, during the non-growing season （2 4 March 2011）, the growing season （10-12 June 2011）, and the late-growing season （22-24 September 2011） were analyzed. The CO2 concentrations of two sites showed nearly the same diurnal variation, with a maximum value occurring during the night and a minimum value occurring during daytime, as well as the same seasonal variation, with a maximum value during the non-growing season （early spring） and a minimum value during the growing season （summer）. The CO2 flux over the urban forest did not show any typical diurnal variation during the non-growing season, but did show diurnal variation with a small positive value during the night and a large negative value during daytime in the growing and late-growing seasons due to photosynthesis in the urban forest. The CO2 flux over the urban residential region showed a positive daily mean value for all periods, with large values during the non-growing season and small values during the growing season, and it also showed diurnal variation with two maxima at 0600-1000 LST and 1800-2400 LST, and two minima at 0300-0600 LST and 1100-1500 LST, and was strongly correlated with the use of liquefied natural gas for cooking and heating by surrounding houses.展开更多
Atmospheric nitrogen （N） deposition may affect carbon （C） sequestration in terrestrial ecosystem. The main objective of this paper was to test the hypothesis that N addition would increase CO2 emission in the N li...Atmospheric nitrogen （N） deposition may affect carbon （C） sequestration in terrestrial ecosystem. The main objective of this paper was to test the hypothesis that N addition would increase CO2 emission in the N limited meadow steppe in Inner Mongolia, China. Response of CO2 fluxes to simulated N deposition was studied in the growing season of 2008 and 2009 by static chamber and gas chromatograph techniques. Parallel to the flux mea- surements, soil temperature, soil moisture, TOC, DOC, soil NH4~ and NO3- were measured at the same time. The results indicated that two-year N additions had no significant effect on NH4＋, but slightly increased NO3- in the later period. The HN treatment tended to increase CO2 fluxes in the two years, and LN treatment tended to decrease CO2 fluxes in 2008, and shifted to increase CO2 fluxes in later growing season of 2009. N addition significantly in- creased the aboveground biomass and root biomass. The correlation between CO2 fluxes and moisture or tempera- ture factors did not significantly change due to N addition, but N addition enhanced the moisture sensitivity of CO2 fluxes as well as the temperature sensitivity of CO2 fluxes. These results suggest that the increasing ammonium N deposition would be likely to stimulate CO2 fluxes in the meadow steppe of Inner Mongolia, China.展开更多
We report on the effects of forest management practices of understory removal and N-fixing species（Cassia alata） addition on soil CO2 fluxes in an Eucalyptus urophylla plantation（EUp）,Acacia crassicarpa plantation...We report on the effects of forest management practices of understory removal and N-fixing species（Cassia alata） addition on soil CO2 fluxes in an Eucalyptus urophylla plantation（EUp）,Acacia crassicarpa plantation（ACp）,10-species-mixed plantation（Tp）,and 30-species-mixed plantation（THp） using the static chamber method in southern China.Four forest management treatments,including（1） understory removal（UR）;（2） C.alata addition（CA）;（3） understory removal and replacement with C.alata（UR＋CA）;and（4） control without any disturbances（CK）,were applied in the above four forest plantations with three replications for each treatment.The results showed that soil CO2 fluxes rates remained at a high level during the rainy season（from April to September）,followed by a rapid decrease after October reaching a minimum in February.Soil CO2 fluxes were significantly higher（P 〈 0.01） in EUp（132.6 mg/（m2.hr）） and ACp（139.8 mg/（m2.hr）） than in Tp（94.0 mg/（m2.hr）） and THp（102.9 mg/（m2.hr））.Soil CO2 fluxes in UR and CA were significantly higher（P 〈 0.01） among the four treatments,with values of 105.7,120.4,133.6 and 112.2 mg/（m2.hr） for UR＋CA,UR,CA and CK,respectively.Soil CO2 fluxes were positively correlated with soil temperature（P 〈 0.01）,soil moisture（P 〈 0.01）,NO3？-N（P 〈 0.05）,and litterfall（P 〈 0.01）,indicating that all these factors might be important controlling variables for soil CO2 fluxes.This study sheds some light on our understanding of soil CO2 flux dynamics in forest plantations under various management practices.展开更多
基金funded by the Korea Meteorological Administration Research and Development Program (Grant No. CATER 2012-7010)the Korea National Long-Term Ecological Research (KNL-TER) project for their data distributions
文摘The CO2 concentrations and fluxes over an urban forest site （Namsan） and an urban residential region （Boramae） in Seoul, Korea, during the non-growing season （2 4 March 2011）, the growing season （10-12 June 2011）, and the late-growing season （22-24 September 2011） were analyzed. The CO2 concentrations of two sites showed nearly the same diurnal variation, with a maximum value occurring during the night and a minimum value occurring during daytime, as well as the same seasonal variation, with a maximum value during the non-growing season （early spring） and a minimum value during the growing season （summer）. The CO2 flux over the urban forest did not show any typical diurnal variation during the non-growing season, but did show diurnal variation with a small positive value during the night and a large negative value during daytime in the growing and late-growing seasons due to photosynthesis in the urban forest. The CO2 flux over the urban residential region showed a positive daily mean value for all periods, with large values during the non-growing season and small values during the growing season, and it also showed diurnal variation with two maxima at 0600-1000 LST and 1800-2400 LST, and two minima at 0300-0600 LST and 1100-1500 LST, and was strongly correlated with the use of liquefied natural gas for cooking and heating by surrounding houses.
基金the National Natural Science Foundation of China(Grant No.31130009,31300375)the National Key Project of Scientific and Technical Supporting Program(Grant No.2013BAC03B03)
文摘Atmospheric nitrogen （N） deposition may affect carbon （C） sequestration in terrestrial ecosystem. The main objective of this paper was to test the hypothesis that N addition would increase CO2 emission in the N limited meadow steppe in Inner Mongolia, China. Response of CO2 fluxes to simulated N deposition was studied in the growing season of 2008 and 2009 by static chamber and gas chromatograph techniques. Parallel to the flux mea- surements, soil temperature, soil moisture, TOC, DOC, soil NH4~ and NO3- were measured at the same time. The results indicated that two-year N additions had no significant effect on NH4＋, but slightly increased NO3- in the later period. The HN treatment tended to increase CO2 fluxes in the two years, and LN treatment tended to decrease CO2 fluxes in 2008, and shifted to increase CO2 fluxes in later growing season of 2009. N addition significantly in- creased the aboveground biomass and root biomass. The correlation between CO2 fluxes and moisture or tempera- ture factors did not significantly change due to N addition, but N addition enhanced the moisture sensitivity of CO2 fluxes as well as the temperature sensitivity of CO2 fluxes. These results suggest that the increasing ammonium N deposition would be likely to stimulate CO2 fluxes in the meadow steppe of Inner Mongolia, China.
基金supported by the National Natural Science Foundation of China (No. 30630015,30771704)
文摘We report on the effects of forest management practices of understory removal and N-fixing species（Cassia alata） addition on soil CO2 fluxes in an Eucalyptus urophylla plantation（EUp）,Acacia crassicarpa plantation（ACp）,10-species-mixed plantation（Tp）,and 30-species-mixed plantation（THp） using the static chamber method in southern China.Four forest management treatments,including（1） understory removal（UR）;（2） C.alata addition（CA）;（3） understory removal and replacement with C.alata（UR＋CA）;and（4） control without any disturbances（CK）,were applied in the above four forest plantations with three replications for each treatment.The results showed that soil CO2 fluxes rates remained at a high level during the rainy season（from April to September）,followed by a rapid decrease after October reaching a minimum in February.Soil CO2 fluxes were significantly higher（P 〈 0.01） in EUp（132.6 mg/（m2.hr）） and ACp（139.8 mg/（m2.hr）） than in Tp（94.0 mg/（m2.hr）） and THp（102.9 mg/（m2.hr））.Soil CO2 fluxes in UR and CA were significantly higher（P 〈 0.01） among the four treatments,with values of 105.7,120.4,133.6 and 112.2 mg/（m2.hr） for UR＋CA,UR,CA and CK,respectively.Soil CO2 fluxes were positively correlated with soil temperature（P 〈 0.01）,soil moisture（P 〈 0.01）,NO3？-N（P 〈 0.05）,and litterfall（P 〈 0.01）,indicating that all these factors might be important controlling variables for soil CO2 fluxes.This study sheds some light on our understanding of soil CO2 flux dynamics in forest plantations under various management practices.
