Dynamic Evaluation of Land Ecological Security in Anhui Province Based on PSR Model

Based on PSR framework method, the land ecological security evaluation index system of 16 cities of Anhui Province was constructed. The land ecological security value of subsystem in Anhui Province from 2000 to 2011 was calculated using the index weight which was determined by the entropy weight method, and land ecological security trend from 2012 to 2017 was forecasted using GM （1,1） model. The results indicated that, the land ecological security index in Anhui Province from 2000 to 2017 was rising on the whole, with the average value increasing from 0.442 in 2000 to 0.450 in 2017, and there was a huge difference among cities; at the same time, the state index and response index of each subsystem of land ecological security also rose. GM （ 1, 1 ） model had high simulation precision and was able to predict the land ecological security level and the de- velopment trend of each subsystem of Anhui Province from 2012 to 2017. The main factors that influenced the land ecological security of Anhui Prov- ince included per capita farmland area, population density, natural growth rate of population, urbanization level, soil coordination degree, agricultur- al mechanization degree, and the area proportion of nature reserve, which are the focus of land ecological security regulation in the future.

1990—2014年印度城市扩张时空特征对比分析

印度是人口仅次于中国的发展中国家,也是"一带一路"倡议的重要节点。印度正处于城市化快速发展阶段,分析印度城市化特征具有重要意义,而中国国内关于印度城市化和城市扩张的研究和报道相对较少。论文选取10个人口超过100万的印度城市,获取1990、2000和2014年基于Landsat影像的土地利用数据和人口数据,采用圈层分析法将城市划分为等间距的同心圆圈层后统计各圈层内建设用地密度,选取增长率、密度、强度以及景观指数指标对印度城市扩张进行多维度对比分析。研究发现:①城市土地扩张快于人口增长,1990—2000、2000—2014年土地年均增长率分别是人口年均增长率的3.27和2.43倍。②建设用地密度随着与城市中心距离增加而衰减,且在一定距离内快速下降;同圈层内建设用地密度随时间逐渐增加;城市以分散的方式向外扩张,城市形态变得更加松散,特别是在第二阶段(2000—2014年)。③建设用地斑块破碎化程度与城市扩张强度的空间变化相吻合。城市扩张最活跃区域与景观破碎度最严重区域都随时间不断向外推进,城市扩张对景观格局产生显著影响。在全球城市扩张背景下,研究结果将为理解城市扩张时空特征而提供印度样本,也将为研究其他地区城市扩张提供分析方法和思路。