| Air anion was approved to be beneficial to human body according to many previous studies, in which vegetations were also found to be capable of increasing its content. Therefore, air anion concentration has become an important indicator to measure green space ecological service value. However, there were few reports whether this concentration could be affected by the urbanization gradients. Thus, fifteen parks from different urbanization gradient regions in Shanghai were chosen in the study, with Sheshan Forest Park (East Sheshan Hill) as control group. After one-year's fixed point observation from March,2009 to February,2010 in monthly, the spatial-temporal pattern of air anion in the parks from different urbanization gradient regions was focused analyzed in this paper, together with the influence other factors have upon the air anion concentration such as temperature and humidity, wind speed, total suspended particles(TSP) and surrounding population flow when measuring. Therefore conclusions were drawn as follows:(1) The air anion concentration in parks from different urbanization gradient regions in Shanghai was significantly higher than that in semi-natural ecosystem of East Sheshan (p>0.05); The concentration in those parks in forest was higher than that in open spaces, without significant variance between forests, of which the annual average was 489±24 Ions/cm3～578±31 Ions/cm3; there was certain variance in open spaces in medium-inner ring significantly lower than that of external ring (p>0.05); Whether plant communities exist or not made more effects than the urbanization gradients.(2) No significant variances of air anion concentration were found in the morning, afternoon and evening of one day in this study; an obvious regulation of seasonal variation that the air anion concentration in summer was higher than that in spring and autumn but lowest in winter was showed no matter in forests, open spaces or benefits (differentials between inner forests and open spaces), with mean value in forests and open spaces respectively being 990±33 Ions/cm3 and 712±36 Ions/cm3 in the maximum month(September).(3) After partial correlation analysis, the air anion concentration was found to be related with meteorology, environment and human activities. The concentration was positive correlated with temperature (0～40℃) and humidity (<85%) (p>0.05) but negative correlated with daily range of temperature; significantly restrictive by total suspended particles (TSP) (p>0.05); negative correlated with population flows in surrounding radius of 3m and 5m from measure points, but positive correlated with distance from measure points to traffic arteries (p>0.05) According to above conclusions, proposals were raised as follows:(1) Establish of park green space was emphasized suggested in low air anion concentration region of medium-inner ring, therefore to make up for the lack of air anion and further improve the ecological benefits in park green space in the region.(2) Try to steer clear of main roads or set vacancy areas designing for tourists activities far away from main roads rather than close to gates of parks near roads when newly built or reconstruct; increase the vegetation quantity around tourists'activities squares to improve the air anion concentration, therefore to enhance ecological service functions; or set footpaths and activity areas in arbor forests to improve the air anion concentration with application of plant communities for guide visitors.(3) Taking account of the effects whether plant communities exist or not may make higher than urbanization gradients may make, future study was more suggested to emphasize on the influence plants may have upon the air anion concentration.
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