Nanjing Urban Green Space Of Different Vegetation Types Of Soil Respiration

Soil respiration is an important process in soil ecosystem, and it is the major approach by which the carbon in the soil fluxes into the atmosphere, and thus it is connected with global change. Urban green space is an integral part of the earth's vegetation and an important pool of the carbon cycle. In order to examine the dynamics of soil respiration of different urban vegetation types and its influence to urban climate , we measured soil respiration rate their regulating factors in Nanjing Zhongshan botanical garden from Oct 2007 to Sep 2008 .The results were as follows:(1) The seasonal fluctuations of soil respiration rates were apparent, the maximum values of near-natural forest,open woodland,lawn appeared in summer ,were 3.2817μmol·m^-2·s^-1,4.0652μmol·m^-2·s^-1 and 7.5826μmol·m^-2·s^-1. and the minimum values were in winter 0.8197μmol·m^-2·s^-1,0.9942μmol·m^-2·s^-1 and 1.4239μmol·m^-2·s^-1.(2) The annual mean soil respiration rates among different urban vegetation types (P<0.05) were significantly different. The order of the annual mean soil respiration rate along elevation was: near-natural forest>open woodland>lawn.(3) Soil temperature was the most important regulating factor to the seasonal variation of soil respiration. In near-natural forest, soil temperature could explain 83⁸6%of soil respiration; In open woodland, soil temperature could explain 80⁸2% of soil respiration; In lawn, soil temperature could explain 877⁸0%of soil respiration.(4) Q10 value increased along soil depth. There was a certain degree of difference of different urban vegetation types.Our results indicate that soil respiration shows significantly variations in temporal and spatial, and the rapid development of lawn might increase the CO2 emission from soil apparently.