| As a significant kind of urban forest, urban recreational forest provide resident with the most convenient ecological recreation sites. In addition, urban recreational forest also plays a considerable role in such as beautify the urban landscape, air quality improvement, balance of the city ecological environment, promoting physical and mental health of residents. Therefore, it is of critical importance to investigate the function of the ecological healthcare of urban recreational forest and its variation. During the day time(5:00am~19:00pm) from the fall of 2011 to the summer of 2012, we investigated several air health indicators such as time variation of micro-climate and climate comfort, air VOCs, negative ions, particulate matters, air oxygen content in three urban forests, combining methods through the monitoring and sample analysis indoor. Three typical urban recreational forests include Cinnamomum camphora forest, Pinus elliotii forest and Quercus variabilis forest located in the Hui Mountain of Wuxi city, Jiangsu Province, southern China. The comparative monitors were taken at the road beside the forest edge and Helie Leisure Square in spring. The results showed that:1. Compared with the forest edge road and downtown square, three recreational forest exhibits obvious ecological health functions of regulating climate comfort, releasing more wholesome VOCs, reducing air particles, increasing the negative ions and oxygen concentration.2. There are several significant seasonal variations of the ecological health indicators of the three recreational forests in a year. ①The strongest light intensity was in spring, the highest temperature was in summer, the highest air humidity was in summer and autumn, wind speed seasonal variation was not significant. The best of forest climate comfort was in spring, and achieving ‘comfortable’ in other seasons. ②The numbers and concentrations of TVOCs in spring and summer were more thriving than in autumn and winter. The most plentiful kinds of wholesome VOCs were in summer, the higher total concentrations of VOCs appeared in summer and autumn. ③The best cleanliness of air particulate matter was in summer, on the contrary, it was relatively serious in autumn. ④The highest level of negative aero ion within forest was in summer, which reached healthy level, and secondly in autumn, lowest in winter. ⑤The highest air oxygen concentration in forests was in summer, and secondly in spring. ⑥Forest Air Health Index(FAHI) were in order of summer> autumn> winter> spring.3. In different seasons, the ecological healthcare indexes showed significant diurnal variation in three recreational forests of Hui Mountain, and the suitable times for recreation were different. ①The peak of light intensity and temperature appeared in 11:00-15:00, and which of humidity was in 5:00-7:00, whereas the diurnal variation of wind velocity were not obvious. The level of climate comfort in 11:00-17:00 was ‘very comfortable’ in spring, and time aheaded to 5:00-7:00 in summer. Most of the time were ‘comfortable’ in autumn, however the day time in winter were ‘uncomfortable’. ②The peaks of total numbers and concentrations of TVOCs focused in 5:00-9:00 and 17:00-19:00, and that of wholesome TVOCs were difference in different seasons. ③The peaks of air particulate matters appeared around 7:00, and the trough times were 13:00 and 17:00 in 4all years. ④Negative air ion concentrations reached peaks at about 13:00 in each season, but the trough times were different. ⑤The peaks of air oxygen concentrations were concentrated in 13:00 in each season. ⑥The peaks of FHAI in all year round appeared at noon or in the afternoon. Evaluating of FHAI indicated that the daytime in summer and autumn were suitable for recreating, and during 9:00 to 19:00 in spring, 9:00 to 17:00 in winter.4. The variations of seasonal and diurnal of each ecological healthcare indexes were not the same between different recreational forest. ①The microclimate indicators of Quercus variabilis forest were highest, and the comfort level of which was best. The comfort time of Cinnamomum camphora forest was longest in spring and summer, and was Quercus variabilis forest in winter. ②The highest concentration of TVOCs was in Cinnamomum camphora forest, and that of wholesome TVOCs was in Quercus variabilis forest. ③The highest concentration of TSP and PM10 were in Cinnamomum camphora forest, whereas the lowest concentration of PM2.5 was in Pinus elliotii forest, and the highest proportion of PM2.5 was in Quercus variabilis forest. ④The air negative ions level was highest in Cinnamomum camphora forest all the year, and were higher in Pinus elliotii forest in summer and winter, and of Quercus variabilis forest in summer. ⑤The highest oxygen content all the year was in Quercus variabilis forest, and of Cinnamomum camphora forest in spring, and of Pinus elliotii forest in summer. ⑥The highest FHAI was in spring, summer and winter within the Quercus variabilis forest and in summer within the Cinnamomum camphora forest.5. There were close relation ship between several ecological health factors within recreational forests in the Hui Mountain. The dominant factors that limiting negative aero ion concentration was PM10, whereas the stimulatives were cation and TSP. The promoting effect was obvious between TSP and PM10, or PM10 and PM2.5. Temperature was the dominant factor in promoting oxygen content. The small particals, negative aero ion and oxygen content could be enhanced by VOCs.Finally, this paper proposed the recreation routes of Hui Mountain in 4 seasons, which based on combination with evaluation results of ecological health indexes and FHAI. |
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