Abstract:

Urban lawn,as the main part of urban green land,plays very important role in regulating the carbon balance in city.The characteristics of CO2 emission flux over an urban lawn ecosystem in Shanghai were studied with the static closed chamber sampling technique and gas chromatograph analysis.The results showed that CO2 emission flux exhibited an obvious diurnal and seasonal variation.The daily maximum values appeared at about noon when the temperature was highest,while the daily minimum values appeared at night or dawn when the temperature was lowest.The maximum daily variation range was 1 1876 mg /(m2·h)(1st July),and the minimum one was 892 mg /(m²·h)(3rd Jan.). The seasonal variation of the flux showed the maximum value in summer and the minimum one in winter,which was caused by temperature and plant growth.During the observation period,the annual average value CO2 flux was 6194 mg /(m2·h).Temperature was the main factor influencing the CO2 flux in the studied lawn,while soil moisture seemed not a significant factor.The results provide the basic data of CO2 flux in urban lawn,which can contribute to the study and management of carbon cycle in the city.