| The Urban Ecological Forest plays an important role in maintaining the balance of urban ecosystem, protecting biodiversity and improving living environment of mankind. The value of an objective and accurate assessment of urban ecological forest will be conducive for ecological forest to reflect intuitively the ecological service functions the ecological forest plays.Zhenhai District, which is an important industrial area in China, located in the city of Ningbo in Zhejiang Province, owns masses of large-scale energy enterprises such as China Petrochemical. The construction of ecological forest plays a unneglectable role in the improvement of environmental quality. In this study, four ecological forests in Zhenhai District were taken as examples to analyze their ecological service functions and to assess their value as well.The four forest belts are Haitian forest belt, Zhenluo forest belt, Xiongzhen forest belt and Qingfeng forest belt. Three sides of the concentration of large-scale chemical enterprises in the district are semi-surrounded by the Haitian, Zhenluo and Xiongzhen forest belts and the other side faces the sea whereas the Qingfeng forest belt runs through the other three forest belts which finally constitute a network structure of the Ecological Forest. After the pre-prepared information research and literature reading, nine sample observation points were established in the four forest belts in this study. Besides, the field survey and sample collection were carried out in September and October of 2007, March and July of 2008. On the respect of the habitat provision in the forest belt to preserve resource and biodiversity maintenance, birds and insects were selected as representative to investigate. As to environment improvement, field determination including microbial content (including bacterial, actinomycetes and fungus), temperature and humidity, Negative Oxygen Ion, noise, wind velocity and Leaf Area Index (LAI) were also carried on in this study. The results showed that the forest belt plays significant roles in the killing of fungus, regulating of temperature and humidity, producing of Negative Oxygen Ion, noise reduction and wind velocity decrease. Meanwhile, healthy and complete leaves on the chosen grow-well wood samples were collected and transported to the Environmental Science Laboratory in East China Normal University. In view of the special environmental conditions in Zhenhai District, Sulfur, Chlorine, Fluorine, Lead, Zinc, Copper, Chromium and Ferrous were taken as pollutant indexes to analyze the amount of dust absorption and the Concentration of air pollutants. Among these elements, Lead and Chromium were detected whereas Copper in only a proportion of samples could be detected. In addition, nitrogen and phosphorus contents were determined to estimate the value of the conservation of fertility. As a result of the research carried out, capitalization accounting won't be showed in this paper.According to the analysis, among the ecological service functions of the Ecological Forests, the value of Carbon Fixation and Oxygen Release is RMB 176, 744,400 yuan; the value of regulating is 15, 016, 700 yuan; the value of pollutant degradation is 22,100 yuan; the value of conserving soil and water is 1, 994, 800 yuan; the value of blocking dust fall is 5, 140, 700 yuan; the value of noise reduction is 851, 300 yuan; the value of killing air fungi is 3, 403, 100 yuan; the value of increasing Negative Oxygen Ion is 113, 322, 000 yuan; the value of providing habitat is 2, 935, 000 yuan. The total value is 319, 425, 400 yuan.In this study, through the above evaluation, the value of the Zhenhai ecological forest belt to reduce pollutants is obviously on the low side, which is inconsistent with the common sense. We believe that there are two possible reasons. One may be that the accounting results are right whereas there is something wrong in common sense. Then, the Zhenhai ecological forest actually didn't have a greater efficiency. The other one may be that the assessment method is inappropriate due to not accurately and objectively enough to account the ecological service functions. In order to confirm the truth, in accordance with the general vies, one hypothesis was put forward that if the Zhenhai ecological forest belt has obvious purification abilities on the atmospheric pollutants, the pollutant contents of the leaves in forest belts near pollution source will be somewhat higher than the ones that are far away from pollution source, but not vice versa. The t test of different pollutant contents in different forest belts was done with SPSS. The results indicate that there are significant differences among the forest belts in different distances from the pollution source. Therefore, it can be considered that the Zhenhai forest belts have remarkable effects on the degradation of air pollutants. The air pollutants are greatly harmful to human body, but the value we accounted was somewhat lower which is contrary to the common sense. Therefore, we conclude that it is our impertinent accounting that made the accounting result lower. The method we adopted to study the degradation of air pollutants is the only case in our country. We suggest that a new assessment method should be explored to value the ecological service functions of the urban ecological forest's degradation of air pollutants in order to reflect its ecological service functions objectively.The results show that different plants will have different degradation abilities on different air pollutants. The departed research focused on purification abilities different plants have on one certain air pollutant. However, the complexity of urban air pollution drives us urgently to look for plants that have high purification abilities on variety of air pollutants. With the application of grey correlation with DPS, the comprehensive ability for the eight common tree species in forest belts to purify air was calculated in this study. The calculation result was as follows: poplar> Taxodium ascendens > viburnum > hibiscus > Ligustrum lucidum > Cinnamomum camphora > Elaeocarpus sylvestris > Osmanthus fragrans. Rational allocation will make the construction of Urban Ecological Forest full play its ecological service functions.In the last place, five factors that influence the performing and valuation of the ecological service functions of the Urban Ecological Forest were raised in this paper. The first one is the size of the evaluation objects; the second one is the choice of evaluation method; the third one is the assurance of service function project; the fourth one is the consideration of selective value and existential value and the fifth one is the diversity of plant furnishing.
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