Analysis On The Distribution Pattern Of Blue And Green Space In Downtown Beijing And Its Influencing Factors

Urban blue and green space is an important object to evaluate the ecological environment quality of urban human settlements,and it is a key element supporting the normal operation of urban landscape ecosystems and guaranteeing and improving people's lives.In this paper,this article takes the area within Beijing's fifth ring road as a research area and 97.1k street view pictures of Beijing were captured by useing web crawler technology.Using the ICNet neural network model,the proportion of the urban blue sky and green vegetation area in the photos was extracted as the basic data,and the spatial distribution pattern and differentiation law of the typical urban blue and green space were attempted to be described.At different scales,a geographic weighted regression model was used to analyze the relationship between blue-green space and urban NDVI data,urban housing transaction data,and population density in the study area.The blue-green space extraction and analysis technology that was constructed by this research institute provides new data sources and new research ideas for urban landscape ecology study,and the results proposed here also provides decision support for government decision-makers to optimize urban ecological layouts.The results showed the following:(1)The spatial distribution of Beijing's blue-green space area proportion index showed a pattern of being higher in the west and lower in the middle and east.The high-value area of the blue-green space area in the downtown area of Beijing has a good spatial correspondence with the city's scenic spots,parks and green spaces,and the new era buildings(Especially since the 21st century).The low-value area of blue-green space area has a close spatial relationship with the historical and cultural buildings in the core area of the city,the building area during the early years of the founding of the People's Republic of China(1950-1970s),etc.(2)Correlation analysis between the satellite remote sensing NDVI and the proportion of green space area through two different mathematical models proves that there is a positive correlation between the two.Using geographic weighted regression analysis method,the correlation fitting analysis was carried out at different spatial scales at 500m,1000m and street scales,and it was found that the adjusted degree of fitting(R~2=0.73)was the largest at 500m pixel scale.Studies have shown that the fit of geospatial weighted regression will decrease as the analysis scale increases,but the areas with better spatial fitting effects are mainly concentrated in residential areas.(3)There were difference in the relationship between the housing prices in different regions and the proportion index of blue-green space.Areas within the third ring are positively correlated,and areas outside the third ring are negatively correlated.But the spatial fitting degree of the two increased with the increase of study scale.(4)The correlation coefficient between the proportion of urban blue-green space area and population density is-0.259**,proving that there is a negative correlation between the two;this shows that the greater the number of population in a unit area,the blue-green The lower the proportion of space area.It can be seen from the spatial distribution of population on the street scale:the low-population areas on the unit blue-green space are mainly distributed in the southern part of the city and on the edge of the city outside the third ring road;its Qianmen Street and Tiantan Street are the proportion of blue-green space per capita in the core area of Beijing The highest block.