郑州都市圈不同等级城镇扩张对生态系统服务的影响研究

Impacts of urban expansion on ecosystem services in different size cities of Zhengzhou metropolitan area

我国进入快速城镇化阶段,建设用地无序扩张导致生态系统服务功能下降。本文以郑州都市圈为研究对象,基于夜间灯光数据构建城镇扩张模型表征城镇扩张时空特征,采用农产品供给、植被净初级生产力a(NPP)、地表径流、森林娱乐指数等指标量化生态系统服务,研究不同等级城镇扩张过程与生态系统服务的相关关系,探究郑州都市圈城镇扩张进程对生态系统服务的影响,研究结果表明:①郑州都市圈城镇扩张指数由2000年的1482.49增长至2015年的2590.91,增幅75.24%,地级市中心城区城镇扩张指数较高,而位于城市边缘区的县城城镇开发指数较小但有扩大趋势。②2000—2015年郑州都市圈年均NPP值由242.45 gC/m^(2)增长至2015年的303.43 gC/m^(2),增幅25.15%,但中心城区呈下降趋势;地表径流量呈递减趋势,年平均地表径流量变化范围为570.31~808.73 mm,年均径流量减少14.9 mm/a,而中心城区有所增加;农产品供给量呈上升趋势,但中心城区递减趋势明显;森林娱乐指数呈增长趋势,其分布西部高于东部,北部高于南部。③城镇扩张与农产品供给、NPP等服务呈负相关关系,与森林娱乐服务呈正相关关系;在中心城区城镇扩张与地表径流呈弱正相关关系。(特)大城市扩张对NPP、农产品供给服务影响大,中等城市扩张对森林娱乐服务影响显著,小城市扩张对生态系统服务的影响较小。研究成果可为中国都市圈绿色城镇化道路、生态保护政策制定提供支撑。

China is experiencing a rapid urbanization,and the disorderly expansion of construction land leads to the decline of ecosystem services.Taking Zhengzhou metropolitan area as the target area,we constructed an Urban Expansion Level(UEL)model based on nighttime light data to explore the spatio-temporal characteristics of urban expansion,and estimated ecosystem services by using agricultural production,net primary productivity(NPP),surface runoff,and forest recreation index(FRI).Furthermore,we calculated correlations between UEL and ecosystem services at different city levels,and revealed the impact of urbanization expansion process on ecosystem services.The results show that:(1)The UEL of Zhengzhou metropolitan area increased from 1482.49 in 2000 to 2590.91 in 2015,with an increase of 75.24%.The UEL of central urban areas was high,while that of counties located in urban fringe was low but with an increasing trend.(2)From 2000 to 2015,the average annual NPP value of Zhengzhou metropolitan area increased from 242.45 gC/(m^(2)·a)to 303.43 g C/(m^(2)·a)in 2015,an increase of 25.15%,but that of the central cities was on the decline.The surface runoff showed a decreasing trend,the annual average surface runoff varied from 570.31 mm to808.73 mm,and the average annual runoff decreased by 14.9 mm/a,but the surface runoff of the central cities increased.The agricultural production showed an upward trend,while the downward trend was obvious in the central cities.The FRI showed an increasing trend,and its value was higher in the west and north than that in the east and south.(3)UEL was negatively correlated with agricultural production and NPP,and positively correlated with forest recreation service.In the central urban area,urban expansion had a weak positive correlation with surface runoff.The expansion of large cities had a significant impact on NPP and agricultural production,the expansion of medium-sized cities had a significant impact on forest recreation service,and the expansion of small cities had a smaller impact on ecosystem services.The results may provide support for policy making of green urbanization and ecological protection in China’s metropolitan areas.