Research On Composite Evaluation Index Of Urban Forest Health Effects

As green infrastructure and an important part of urban systems, urban forest has a positive role in the protection and promotion of the health of urban residents. Urban forest construction and urban environment improvement is an important guarantee of urban sustainable development. Scientific evaluation of the health effects of urban forests can contribute to the policy development, effective monitoring and management of urban forest, also is of great significance to the promotion of urban forests to serve the public better.Based on the analysis of the connotation of urban forest health effects, the basic theory and method of urban forest health effects evaluation have been systematic discussed, the urban forest health effects evaluation index was established, and then the empirical research were carried out in Beigong National Forest Park to analyze the law and characteristics of the generation of urban forest health effects.. The main purpose is to provide an evaluation method of urban forest health effects and fully understand the status and laws of urban forest health effects.Based on the definition of urban forest health effects clearly defined, the main research content, research scales and research methods of the urban forest health effects evaluation at home and abroad were generally summarized. Main existence problems and some suggestions as well as development directions for the further research of urban forest health effects evaluation were put forward. The mechanism of urban forest health effects was analyzed, and the main urban forest health effects served to urban residents reflected in three aspects such as pollutants removal, beneficial compounds release and comfortable environment supply. Specific including cooling and humidification, carbon sequestration and oxygen releasing, anion concentration improvement, particulate matter concentration reduction, other air pollutants reduction, reduction of airborne microbes, noise reduction and leisure functions supplied by urban forest. The ecological indicators should be the basis for comprehensive evaluation of multiple indicators in the study of urban forest health effects evaluation. Based on the summarize of the existing basic research methods of urban forest health effects evaluation and the definitude of the purpose and guiding ideology of urban forest health effects evaluation and monitoring system construction, according to the scientific, systematic, independent, comparability and usability principles, the human comfort index, air oxygen index and air cleanliness index was combined, and the comprehensive evaluation index of urban forest health effects (UFHI) was established. The weight of human comfort index, air oxygen index and air cleanliness index are 0.5, 0.42 and 0.08. Five grades is included in the comprehensive evaluation index, the critical values are 1, 0.8, 0.6, 0.4, 0.2 and 0.Based on the field survey of Beigong National Forest Park, the comprehensive evaluation index method was used to evaluate its urban forest health effects. In the aspect of Human comfort index, the Human comfort index seasonal change trend of Beigong National Forest Park have obvious differentiation. The time of human body feeling comfortable is the longest in autumn; the second is in summer, the time of human body feeling comfortable in spring is the worst. Human body feel comfortable within one day of specific time made by microclimate in various attractions have differences for seasonal change, each observation reflects the similar changing trend in spring, the highest comfort time appear at 14:00-15:00, consistent with the highest temperature appear time one day; The highest human comfort index in the summer day is before 10:00 in the morning, the human comfort index number showed a strong consistency with the magnitude of air temperature change in the summer; the human comfort values change trend of each observation became complicated in autumn, the overall trend appears "W" shape. In the aspect of air oxygen index, the average concentration of oxygen in Beigong National Forest Park is 21.068 percent and is 0.118 percent more than the average air oxygen concentrations, oxygen concentrations spatial distribution of each observation shows a strong negative correlation with the altitude. Due to the high quality forest in the valley, the benefit of oxygen concentrations is much better and the increase effect of oxygen concentration is obvious in the valley observation points. In the aspect of air cleanliness index, the annual average air anion concentrations are 3422 per cubic centimeter, far above the indoor and Beijing downtown, also significantly higher than the urban parks and suburbs average distribution values. The air anion concentrations has significant difference with other district especially in the summer, it's proved that Beigong National Forest Park has obvious tourist environmental advantage in summer. Air quality rating of each key scenic spots was conducted according to Abe rating method; the air quality is good in Beigong National Forest Park and achieved the cleanest level. The diurnal change of the air anion concentration of Beigong National Forest Park has a larger change extent in summer, compared small change extent in spring and autumn day. Air anion concentrations are significantly higher in summer than in spring and autumn. Some of the seasonal difference of air anion concentrations was showed between the mountain and valley areas, and the overall situation present that mountain higher than valley. On the whole, the urban forest health effects index (UFHI) is highest in summer, next in spring, the lowest is in autumn, there is no obvious difference between the urban forest health effects index (UFHI) value of spring and autumn.The innovation in this paper is the construction of urban forest health effects evaluation index (UFHI) by combining three indicators such as the human comfort index, air-oxygen index and air cleanliness index based on the comprehensive understanding of the concept of urban forest health effects and its mechanism, so the basic theory and methods of urban forest health effects evaluation and monitoring was provided. Finally, this paper puts forward some suggestions and development directions for the further research of urban forest health effects evaluation. Further perfecting the urban forest health effects assessment and monitoring index, to in-depth study the relationship of various health effects and perfecting the comprehensive index of urban forest effects; Carry out more direct test research on human body, only a handful studies were through the questionnaire survey to reflected people's subjective psychological feelings currently, and Is almost no study that directly test human body and mind index with instruments, therefore more direct test research on human body sense is need to develop the health effects scope of urban forest in the future; The urban forest health effects evaluation needs develop to guide practice from only theoretical research, it's also should adopt the practice of air quality index forecast to the public through various media by the American environmental protection bureau, based on the construction of urban forest health effects monitoring system to targeted forecast the urban forest effects evaluation results.