| In this study,the function of cooling service,carbon fixation,oxygen release and canopy interception of urban forest were evaluated by using the method of remote sensing and field sampling,and the multi-functional index of urban forest ecological service was calculated.In addition,this study constructed the evenness index to evaluate the spatial distribution pattern of urban forest and also evaluated the equity of the ecological service functions and landscape multi-functional results based on the population distribution data and the equation of Gini coefficient.The main conclusions are as follows:(1)Urban forest of Changchun City is 106.66 km2 which is composed of attached forest(AF),road forest(RF),landscape forest(LF)and ecological and welfare forest(EF).The area of AF is the largest,accounting for 43% of the total area of urban forest.The fragmentation of urban forest in Changchun city is much serious,and most of the urban forest patches are small with regular shapes.At the request of "seeing green within 500 meters",there is shortage of urban forest in 55% of the area of Changchun City,reprensenting the unreasonable spatial pattern so that the spatial distribution of urban forest reaches an unfair state.(2)Urban forest plays an important role in improving the urban thermal environment.Cooling effect of different types of urban forest is different.The cooling intensity and cooling distance of urban forest in Changchun are LF(3.2 ?,125m),EF(0.2 ?,150m),AF(0.6 ?,5m).However,RF does not show the cooling effect.Cooling effect of urban forest benefites about 760,000 people,accounting for 29.85% of the total population of Changchun City.Among the eight administrative districts of Changchun City,the proportion of beneficiaries in Lvyuan District,Nanguan District and Jingkai District are 66.48%,34.76% and 29.85%,respectively,and the proportion of beneficiaries in the other districts is within 15-20%.The Gini coefficient of urban forest cooling effect based on the percentage of beneficiaries in Changchun is 0.2917,meaning the urban forest cooling function is fair.(3)The annual fixation of carbon content is 39.94×103 t and the annual release of oxygen content is 106.4×103 t in Changchun City.Among the four types of urban forest,the annual average carbon fixation of the AF is the highest,accounting for 41.2% of the total annual carbon fixation and oxygen release of urban forest,which is an important component of the urban forest carbon pool in Changchun.The annual carbon fixation capacity and oxygen release rate per capita of urban forest in Changchun City are obviously different among districts and the order is Gaoxin District(carbon fixation 535.44 t/million,oxygen release 1427.83 t/million),Jingkai District(carbon fixation 232.74 t/million,oxygen release 620.63 t/million),Xixin District(carbon fixation 212.74 t/million,oxygen release 567.31 t/million),Kuancheng District(carbon fixation 208.93 t/million,oxygen release 557.14 t/million),Lvyuan District(carbon fixation 135.18 t/million,oxygen release 361.48 t/million),Nanguan District(carbon fixation 113.48 t/million,oxygen release 302.62 t/million),Erdao(carbon fixation 83.94 t/million,oxygen release 223.85 t/million)and Chaoyang District(carbon fixation 77.28 t/million,oxygen release 206.09 t/million).Based on the per capita annual carbon fixation capacity of urban forest in Changchun City,the Gini coefficient is 0.3376,meaning the carbon fixation and oxygen release of urban forest is relatively fair.However,the indicator value is close to the "alert value",so urban forest construction in the future should focus on improving the ecological services of poor areas.(4)Among the 20 main tree species of Changchun City,Pinus koraiensis has the largest unit leaf area water holding capacity of 146.84 g·m-2,and apricot had the largest unit branch area water holding capacity of 704.75 g·m-2.For the same tree species,the water holding capacity of branch is greater than leaves.The order of per capita canopy water holding capacity is Gaoxin District(0.4517×103 m3/million),Lvyuan District(0.4394×103 m3/million),Xixin District(0.2281×103 m3/million),Nanguan District(0.2274×103 m3/million),Jingkai District(0.2152×103 m3/million),Chaoyang District(0.1609×103 m3/million),Kuancheng District(0.1404×103 m3/million)and Erdao District(0.0700×103 m3/million).The Gini coefficient of urban forest canopy interception based on per capita canopy water holding capacity was 0.2833,which means that the interception function of urban forest canopy is relatively fair.(5)The multifunctional value of urban forest ecological service in Changchun i s quite different among regions and the order is Gaoxin District(0.5131)> Lvyuan District(0.3081)> Jingkai District(0.1123)> Xixin District(0.0635)> Nanguan Distrcit(0.0565)> Kuancheng District(0.0360)> Chaoyang District(0.0004)> Erdao District(0.0001).The results carried out by radar map evaluation method show that the multi-function of urban forest landscape in Changchun can be divided into three types: single function prominent type and representative areas are Gaoxin District and Lvyuan District;weak equilibrium type and representative areas are Kuancheng District,Xixin District,Nanguan District and Kuancheng District;functional missing type and representative areas are Chaoyang District and Erdao District.Based on the multi-functional index of urban forest ecological services,the Gini coefficient is 0.6151,meaning the value of multifunctional service of urban forest in Changchun is extremely unfair.The types of leading function and effects of multi-function of urban forest ecological services are extremely different. |
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