Research On Urban Forest Mapping Using Landscape Ecological Index Model

Urban forests are an important type of ecosystem to achieve the “dual carbon” goal,but there is currently a lack of urban forest data that can be used in continuous national urban physical examination assessments.In response to this problem,this paper explores a universal method to obtain urban forests to serve the urban physical examination and evaluation,in order to promote the realization of the “dual carbon” goal.First,based on high-precision geographic monitoring data,this paper takes three characteristics of vegetation type,canopy cover or canopy coverage,and patch size as important basis for urban forest mapping.Based on this,the optimal aggregation distance between urban forest patches was explored using the aggregation method in cartographic synthesis and the landscape ecological index model,and the urban forest mapping results of 36 key cities across the country were obtained.Secondly,analyze the urban forest mapping results,mainly compare the urban forest mapping results with the initial land cover data and park green space that conform to the urban forest vegetation type,and use the comparative analysis method to verify the rationality of the urban forest mapping results.Finally,the obtained urban forest mapping results of 36 key cities in the country are applied to the calculation and analysis of the“forest coverage rate” index within the urban area in the continuous national urban physical examination assessment.The main results of the paper are as follows:(1)The urban forest mapping results obtained by the aggregation method and the landscape ecological index model in cartographic synthesis have the characteristics of high precision and completeness,and the method is universal and can meet the needs of continuous national urban physical examination evaluation work.It is of great significance to apply it to the continuous national urban physical examination and evaluation work and to grasp the spatial distribution of urban forests to accelerate the realization of the “dual carbon” goal.(2)The experimental results show that the optimal aggregation distance between urban forest patches in 10 cities is in the range of 30-34 m,and the optimal aggregation distance between urban forest patches in 13 cities is in the range of 35-39 m,indicating the original urban forest in more than half of the cities has a relatively large degree of fragmentation,and it is of certain value to obtain urban forests with high precision and integrity;The optimal aggregation distance between urban forest patches of different cities in the same geographic region may be within a certain range above and below the median or average value of the aggregation distance in the geographic region.Based on geographic divisions,it can provide a certain reference for predicting the optimal aggregation distance between urban forest patches in cities other than the 36 key cities across the country.(3)The top three urban forest coverage rates of 36 key cities in the country are Xiamen(33.06 %),Chongqing(31.50 %),and Beijing(27.62 %),and Lhasa(3.56 %)has the lowest urban forest coverage rate;according to the analysis of the seven geographical divisions,the urban forest coverage rate is greatly affected by geographical divisions.The average urban forest coverage rate of cities in South China is the highest,about 21.29 %,and the average urban forest coverage rate of cities in Northwest China is the lowest,about 11.66 %;according to the north-south boundary,the average urban forest coverage rate of southern cities(19.99 %)is higher than that of northern cities(13.34 %),and the urban forest construction of northern cities needs to be improved.The paper has 29 diagrams,4 tables and 58 references.