Research On The Influencing Factors Of Xi’an Green Space Carbon Sink Benefit

At the UN General Assembly,China has vowed to peak its carbon dioxide emissions by 2030 and strive to be "carbon neutral" by 2060.Since then,the Central Economic Conference has listed "carbon peak" as one of the eight priorities for 2021.As an important natural carbon sink in cities,green space has been widely concerned.However,the current research on carbon sink mainly focuses on the spatial-temporal variation characteristics of carbon sink and the estimation of carbon sink,but there is little research on how to adjust green space to exert greater carbon sink benefits.At the level of green space system,in addition to the change of green space area,the continuity,balance and morphological characteristics of green space are the main factors affecting the benefits of green space carbon sink.Therefore,from these three perspectives,this paper uses landscape index to quantify the spatial layout structure and morphological characteristics of green space in urban areas.This paper studies the influence of the spatial layout structure and morphological characteristics of green space on the carbon sink,hoping to find out the main influencing factors on the urban carbon sink benefit.Firstly,this paper interprets the overall urban planning of Xi ’an,summarizes and sorts out the indicators of green space in the overall planning,and analyzes the existing problems.Secondly,on the one hand,the CASA model and remote sensing data were used to calculate the carbon sink of forest land,cultivated land and urban green space in Xi ’an during the 10 years since the last master plan of Xi ’an.On the other hand,the spatial distribution structure and morphological characteristics of forest land,cultivated land and urban green space were quantified by landscape index.Combined with the comparison of the two aspects,the influencing factors and the influencing mechanism of the carbon sink benefits of forest land,cultivated land and green land were analyzed respectively.The results are as follows:(1)the monthly average carbon sink in xi ’an decreases from south to north,among which the forest carbon sink is the highest,followed by the urban green space,and the cultivated land carbon sink is the lowest.(2)the forestland area decreased slowly from 2005 to 2010,and increased rapidly from 2010 to 2017,increasing by 35,449 hectares in the whole planning period,with an average annual growth rate of 0.27%;The urban green space area has been growing steadily since 2005,with an increase area of 17096 hectares,with an average annual growth rate of 0.13%.The cultivated land area continued to decline during the planning period,and 76,629 hectares of cultivated land had been cleared up by 2017.(3)the main influencing factors of green space carbon sink are green space aggregation degree,fragmentation degree,evenness and patch shape.The more complete the patches of green land and cultivated land are,the more concentrated and uniform the distribution is,and the more complex the patch shape is,the higher the carbon sequestration efficiency is.The more fragmented the patches are,the more dispersed and uneven the distribution is,and the more complex the shape is,the higher the carbon sequestration efficiency is.