Analysis Of Landscape Pattern And Ecological Benefit Of Urban Forest In Zhengzhou Based On TM Images And I-Tree Model

With the development of economy and further city urbanization, it increasingly becomes a basic requirement that people pursue a good living environment. There are so many questions in the process of development in Zhengzhou, such as air pollution, water resources problem, noise pollution and the contradiction between people and land. This paper analyzed landscape pattern, urban forest and the street side tree in Zhengzhou City, Henan Province based on TM images and i-Tree model. The results are as follows:(1) At the landscape level, landscape fragmentation changes complex from 2004 to 2013 in Zhengzhou under the main driving force of human factor. The Shannon-Wiener diversity index and evenness index increased first and then decreased. The number of landscape patches increased and the landscape was varied and more diverse. All kinds of construction land area increased year by year, while the arable land continued declining. The fragmentation of water body was increased, and obviously the city forest was non-balanced developed.(2)Analyst the survey for the urban forest, we got several results with i-Tree Eco. There are approximately 15 151 857 tree individuals in Zhengzhou, and 149 trees per hectare. The percent of diameter less than 23 cm at breast height(DBH) is about 95%. The carbon storage is 356 685 t and the carbon density 10.25 t/hm2. 1.224 t carbon was absorbed per hectare every year. It can remove CO 0.2 t、NO2 0.866 t、O3 0.062 t、PM10 1 306.013 t、PM2.5 2.462 t、SO2 1.701 t respectively.(3)There are 23 352 tree individuals in the street side, belonging to 14 families, 20 genera and 22 species. Among them, 80% of DBH is in 10-30 cm, and 90% species is more than good health. With the analysis of i-Tree Streets, it is showed that the street trees totally intercept rainfall about 25 219 m3 per year, and the CO2 net reduction is 1 760.307 t, total carbon storage was 6 399.081 t. 3 840.2 GJ energy was saved. NO2, PM10, VOC, SO2 was absorbed 336.9 kg, 320.8 kg, 2 316 kg, and 2193.4 kg per year, respectively. The total economical benefit was up to 2 987 183 yuan RMB.(4)A number of city centers could be set up to solve the contradiction between people and land. To keep the balanced development of urban forest, increase the green corridor will be the effective measures to build the urban forest. If the city green patches and streets trees form a continuous coverage, there will be more economical benefit.