拉萨市城关区近50年城市扩展过程对自然生境质量的综合影响

Comprehensive impacts of urban expansion on natural habitat quality in Chengguan District of Lhasa City in recent 50 years

拉萨市城关区建设用地紧邻拉鲁湿地国家级自然保护区,导致城市发展与自然生境保护间的矛盾十分突出。全面揭示该地区城市扩展过程对自然生境质量的影响对于优化城市景观格局、保护生物多样性具有重要意义。为此,定量评价了该地区1968—2019年城市扩展过程对自然生境质量的综合影响。基于锁眼卫星遥感数据、Landsat系列遥感影像和Google Earth遥感数据获取了该地区土地利用/覆盖变化信息。结合空间叠加和模型模拟量化了城市扩展过程对自然生境质量的影响。结果表明,拉萨市城关区近50年城市扩展过程不断加快,城镇建设用地面积从9.78 km^(2)增加到67.67 km^(2),增加了近6倍。城市扩展过程导致自然生境质量加速下降,近50年下降了12.69%。自然生境质量同时受到城市扩展过程的直接影响和间接影响。在各类自然生境中,林地和湿地的生境质量下降尤为明显,分别下降了96.59%和49.21%。其中,林地主要被城镇建设用地直接占用,湿地则主要受城市扩展过程的间接影响。因此,需要同时关注城市扩展过程对自然生境的直接占用和间接影响,采取有效措施协调城市建设与生物多样性保护,促进区域可持续发展。

The urban land in Chengguan District of Lhasa City is close to Lalu Wetland National Nature Reserve, which leads to the contradiction between urban development and natural habitat protection. Assessing the impacts of urban expansion on natural habitat quality(NHQ) is significant to optimize urban landscape patterns and protect biodiversity in this region. Thus, this study quantitatively evaluated the comprehensive impacts of urban expansion on the NHQ in Chengguan District of Lhasa City from 1968 to 2019. Firstly, land use/cover change information in this region was obtained based on Keyhole satellite remote sensing data, Landsat remote sensing data, and Google Earth remote sensing data. Next, the effects of urban expansion on NHQ were quantified by combining spatial overlay analysis and simulation. The results showed that the urban expansion in Chengguan District of Lhasa City has been accelerating in the past 50 years. The urban area increased from 9.78 km^(2)to 67.67 km^(2), which increased by nearly 6 times. The urban expansion led to an accelerated decline in NHQ, which decreased by 12.69% in the last 50 years. The urban expansion had both direct and indirect effects on NHQ. Among different kinds of natural habitats, forest and wetland had obvious decline of NHQ, which decreased by 96.59% and 49.21%, respectively. Forest is mainly occupied directly by urban areas, while wetland is mainly affected indirectly by urban expansion. Therefore, it is necessary to pay attention to both the direct and indirect impacts of urban expansion on NHQ, and take effective measures to coordinate urban development and biodiversity conservation, to promote regional sustainable development.