京津冀地区城市化对植被覆盖度及景观格局的影响

定量研究了2000—2010年,京津冀地区植被覆盖度及其景观格局的动态变化,揭示了城市化进程对植被景观的干扰过程及生态质量的影响。结果表明:(1)2000—2010年,城市化进程显著是京津冀城市群土地变化的一大特点,人工表面面积从2000年的1.79×10~4km~2增加至2.16×10~4km~2,增幅高达21.16%;(2)京津冀平均植被覆盖度呈增加趋势但不显著(P=0.46),存在明显的时空动态差异。在覆盖度结构上形成了以中低和中植被覆盖度为主导的格局;(3)从景观空间格局变化来看,中低、高覆盖度区域植被景观更加破碎,而低、中等覆盖度区域的植被面积增加,景观破碎度减小;尤其是低植被覆盖度为主的城市区域,景观格局变化幅度大,表现为绿地面积有所增加,景观破碎化程度降低,生态质量有所改善;(4)在整个研究区范围,城市化对区域植被覆盖度存在负面影响,表现为城市化程度与区域平均植被覆盖度存在负相关(P=0.08);但是在低植被覆盖度的区域(主要为城市区域),城市化程度与植被覆盖面积呈显著正相关(P0.001),表明城市区域在城市化进程中植被覆盖面积有所提高,生态质量有所改善,与城市化过程中,日益重视城市绿地的建设有关。

Spatiotemporal pattern of vegetation cover and its relationship with urbanization in Beijing-Tianjin-Hebei megaregion from 2000 to 2010

Accelerated urbanization and socio-economic development can cause a series of environmental problems, such as decreased ecological quality. Accurately and efficiently quantifying the effects of urbanization on vegetation is critical for understanding regional ecological conservation and achieving sustainable development. Previous studies have primarily focused on the spatiotemporal patterns of vegetation cover and its relationship with climatic factors. Here, we quantified the spatiotemporal patterns of vegetation cover from 2000 to 2010 in the Beijing-Tianjin-Hebei megaregion. We then analyzed the effects of urbanization on vegetation cover dynamics. We used MODIS data and Landsat TM data. We found that (1) during the study period, urban land expanded very rapidly in this megaregion. The area of built-up lands increased from 1.79×10⁴ km² in 2000 to 2.16×10⁴ km² in 2010, which is an increase of 21.16%. (2) There was a slight but insignificant (P= 0.45) increasing trend in vegetation coverage from 2000 to 2010. The region was dominated by low-medium and medium coverage vegetation. (3) There were similarities and differences in the spatiotemporal patterns among different types of vegetation with varied levels of vegetation density. For vegetation types with low to medium and high vegetation density, fragmentation of vegetation increased from 2000 to 2010. In contrast, for vegetation types with low and medium vegetation density, the landscape pattern became more aggregated rather than fragmented in regions covered with these types of vegetation. (4) The proportional cover of developed land and vegetation coverage showed negative correlations (P= 0.08). However, the proportional cover of developed land showed a significantly positive relationship with the proportion of area covered by vegetation types with low vegetation density (P < 0.001).