塔里木河流域土地开发的生态响应研究

60 a来塔里木河流域耕地面积净增100×10⁴ hm²，在流域内部形成众多生态环境安全问题。通过选取水资源生态环境指数、社会生态环境指数和生态环境压力指数，运用ESDA空间分析方法和GWR模型对塔里木河流域35 a间土地开发与生态时空演变特征和空间响应关系进行研究，构建"土地开发-生态风险预警"模型，得出以下结论：1980-2015年克孜勒苏州和喀什地区生态等级正向转移比例较大，有84.86%的比例由较低等级（I）正向转移为低等级（Ⅱ）；和田地区的克里雅河流域，阿克苏北部区域以及塔里木河末端且末县等级退化严重，负向转移比例23.46%。和田、阿克苏、喀什地区每增加1.0×10⁴ hm²未利用地开垦规模，综合生态环境分值下降0.60到0.35，而克孜勒苏州则上升1.3~2.1；上游喀什与中游阿克苏两地区每1.0×10⁴ hm²生态退耕，每年将分别化解32.06×10⁴ t和15.60×10⁴ t化肥污染压力。阿克苏地区与巴音郭楞州土地开发生态风险达到环境资源承载力指数的75%以上，预警程度超过Ⅱ级，而克孜勒苏州土地开发处于生态安全范围。每1.0×10⁴ hm²未利用土地开发，全流域风险指数增长均值为0.003 4，下游巴音郭楞州在增加15×10⁴~20×10⁴ hm²耕地后，生态风险将逼近并超过环境预警界限，上游克孜勒苏州将在15 a之后进入中度警告阶段。

Ecological response to the land development in Tarim River Basin

Over the past 60 years,the cultivated land area of the Tarim River has increased by about one million hm²,resulting in many ecological and environmental security problems within the basin.Using ESDA spatial analysis method and GWR model,this paper selects the water resources ecological environment index,social ecological environment index and ecological environment pressure index to study the ecological response to the land development and its temporal spatial evolution in the Tarim River Basin in 35 years from 1980 to 2015.Then the model on the land development versus ecological risk early-warning was built and the conclusion was summarized as follows:from 1980 to 2015,the ecological level of Kizilsu Kirgiz Autonomous Prefecture and Kashi Prefecture had a big portion of positive transfer at 84.86% from the lower grade (I) to low level (Ⅱ).The ecological environment grades of the Keriya River Basin in Hotan Prefecture,northern Aksu and Qiemo County on the end of the Tarim River were seriously degraded with a negative transfer ratio at 23.46%.In Hotan,Aksu,and Kashi Prefectures,each increased of 10 thousand hm² of reclamation of unused land,the comprehensive ecological environment score was dropped from 0.60 to 0.35,while in the Kizilsu Kirgiz Autonomous Prefecture area it was increased by 1.30~2.1 points.De-farming one million hm² of cropland in Kashi and Aksu each year will amount to the alleviation of the pollution pressure of 0.32 million tons and 0.15 million tons of chemical fertilizer respectively.The ecological risk of land development in Aksu and Bayingolin Mongol Autonomous Prefecture reaches more than 75% of the environmental carrying capacity index,and the early warning level is more than Ⅱ.The land development in Kizilsu Kirghiz Autonomous Prefecture is in the ecological security range.With ten thousand hm² of unused land development,the average growth of risk index in the whole basin was 0.003 4.If Bayingolin Prefecture increases 0.15~0.20 million hm² of arable land,the ecological risk will be close to and even exceed the warning limit.Kizilsu Kirgiz Autonomous Prefecture will enter the stage of moderate warning after 15 years.