城市生态背景值包括自然生态背景值与人文生态背景值。城市生态背景值越高,城市生态环境形象建设与管理的成本就越低。通过城市生态背景值的相关因素分析与量化分等,在选择分析的中国14个特大城市中,生态背景值相差甚远。按综合分值分等,第一等空缺,第二等和第三等分别只有广州市和上海市,第四等有7个城市,第五等有3个城市,得分最低的第六等有兰州市和乌鲁木齐市。按自然生态背景值分值划分,第一等空缺,得分最高的第二等只有广州市,最低的第九等是乌鲁木齐市。按人文生态背景值分值划分,第一等空缺,第二等是北京市,其余为第三等和第四等。文章以城市生态背景值为依据,较为详细地分析了广州市何以在较短的时间内由一个"不适合居住"的城市变为"国际花园城市"的原因。

Urban ecological background values include two aspects: nature ecological background values and human ecological background values. The higher urban ecological background values are, the lower cost of developments and management urban ecosystem environment image are. The degree of dryness , the temperature in the coldest month, plant productivity, precipitation, daily precipitation and topography are used to measure nature ecological background values. The usual 7 indexes of western society, namely, society moral consciousness, public awareness, choice tradition value, custom habits, knowledge distribution, time budget and, culture and art are used to measure human ecological background values.The paper analyzes the correlative factors of urban ecological background values and grades them. The analysis of fourteen super metropolis of China showes that their urban ecological background values are widely discrepant. According to synthesis score, none of the fourteen cities are measured up to the first grade, one (Guangzhou) to the second, one (Shanghai) to the third, seven(Nanjing,Kunming,Chongqing, Chengdu,Wuhan, Beijing and Xi'an) to the fourth, three(Tianjin, Harbin and Shenyang) to the fifth and two (Lanzhou and Urumqi) to the sixth. According to the natural ecological background value score, none of them are measured up to the first grade either, with only Guangzhou to the second and Shanghai to the third, five(Chongqing, Wuhan, Chengdu, Nanjing and Kunming)to the fourth, three(Xi'an, Shenyang and Tianjin) to the sixth, two (Harbin and Beijing) to the seventh, one (Lanzhou) to the eighth and one (Urumqi) to the ninth, and the fifth grade is vacant. According to the human ecological background value score, none is measured up to the first grade, with only Beijing city to the second, seven(Shanghai, Nanjing, Kunming, Xi'an, Harbin, Guangzhou and Tianjin) to the third and the other six(Chengdu, Shenyang,Lanzhou, Urumqi, Chongqing and Wuhan) to the fourth. On the basis of urban ecological background values, the paper analyses in detail why Guangzhou city that has ever been an "unlivable city" could win the title of "international garden city".