CARBON STORAGE AND FLUX IN URBAN RESIDENTIAL GREENSPACE

There is increasing concern about the predicted negative effects of the future doubling of carbon dioxide on the earth. This concern has evoked interest in the potential for urban greenspace to help reduce the levels of atmospheric carbon. This study quantifies greenspace-related carbon storage and annual carbon fluxes for urban residential landscapes. For detailed quantification, the scale of this study was limited to two residential blocks in northwest Chicago which had a significant difference in vegetation cover. Differences between the two blocks in the size of greenspace area and vegetation cover resulted in considerable differences in total carbon storage and annual carbon uptake. Total carbon storage in greenspace was about 26.15 kg/m(2) of greenspace in study block 1, and 23.20 k/m(2) of greenspace in block 2. Of the total, soil carbon accounted for approximately 78.7% in block 1 and 88.7% in block 2. Trees and shrubs in block 1 and block 2 accounted for 20.8% and 10.6%, respectively. The carbon storage in grass and other herbaceous plants was approximately 0.5-0.7% in both blocks. Total net annual carbon input to the study blocks by all the greenspace components was in the region of 0.49 kg/m(2) of greenspace in block 1 and 0.32 kg/m(2) of greenspace in block 2. The principal net carbon release from greenspaces of the two residential landscapes was from grass maintenance. Greenspace planning and management strategies were explored to minimize carbon release and maximize carbon uptake. (C) 1995 Academic Press Limited