基于不同样带的干旱区城市景观格局时空演变特征——以张掖市为例

景观格局的变化影响着区域生态安全及可持续发展，研究干旱区城市景观格局时空变化特征，对干旱区景观格局优化具有一定的指导意义。基于1987、1995、2000、2006、2011和2016年6期土地利用数据，利用景观格局指数计算方法，研究张掖市景观格局的时空演变特征。结果表明：(1)2016年张掖市景观类型主要为未利用地，最大斑块指数和斑块聚集度最高，草地和耕地次之，草地的斑块个数和密度最大。(2)张掖市景观格局呈现明显的地域分异特征，圈层梯度带上揭示了绿洲-荒漠用地变化，研究期内第1梯度带内破碎度先上升后下降，城市在2006—2016年扩张较快，其余梯度带破碎度逐年升高；空间演变上，居住地在圈层上的变化呈“L”型，未利用地呈“N”型，张掖市从中心城区到外围区域依次为绿洲城市区、绿洲农业区和自然景观区。(3)水平样带揭示了山地-绿洲-荒漠的用地变化，将张掖市分为4类区域，分别为绿洲城市区、绿洲农业区、荒漠区、山地区；西北-东南样带上景观破碎度年变化不规律，在空间上经过居民点波动变化；东北-西南样带研究期内景观水平指数经过居民点波动变化，其余范围内年变化较稳定，中心城区景观异质性较强。(4)...

Spatio-temporal evolution of urban landscape pattern in arid areas based on different zones: A case study of Zhangye City

The change of landscape pattern affects the regional ecological security and sustainable development. The study on the spatio-temporal change characteristics of urban landscape pattern has a certain guiding significance to the optimization of landscape pattern in arid areas. Based on the land use data of 1987, 1995, 2000, 2006, 2011 and 2016, the temporal and spatial evolution characteristics of landscape pattern in Zhangye City were studied by using landscape pattern index calculation method. The results showed that:(1) The unused land was the main landscape type in Zhangye City in 2016, and the maximum patch index and patch aggregation degree were the highest, followed by grassland and cultivated land, and the grassland patch number and density were the largest. (2) The landscape pattern of Zhangye City showed obviously regional differentiation characteristics, and the gradient zone of circle layer revealed the change of oasis-desert land. The fragmentation degree in the first gradient zone increased firstly and then decreased during the study period, and the Zhangye City expanded rapidly from 2006 to 2016, while the fragmentation degree in the rest gradient zones increased year by year. In terms of spatial evolution, the change of residential area on the circle layer is "L" shape, and the unused land is "N" shape. From the central area to the periphery area, Zhangye City was divided into oasis urban area, oasis agricultural area and natural landscape area successively. (3) The horizontal transect revealed the land use change of mountain, oasis and desert, and Zhangye City was divided into four regions:oasis urban area, oasis agricultural area, desert area and mountain area. The annual change of landscape fragmentation degree in northwest-southeast transect is irregular, and fluctuated through residential area in space. The landscape level index from the northeast to southwest transect fluctuated through residential areas during the study period, and the annual change was relatively stable in the remaining areas. The landscape heterogeneity of the central urban area was strong. (4) The river transect was divided into upper, middle and lower sections by human activities. The landscape index of the transect and the lower section remained stable, and the unused land was the main part, while the upper section had some woodland and grassland. The landscape index in the middle section fluctuated in space, and the landscape types were mainly unused land and cultivated land.