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Urbanization alters the relative importance of local and landscape factors affecting plant communities in the Tokyo megacity
  • Yuki Iwachido,
  • Takehiro Sasaki,
  • Kei Uchida
Yuki Iwachido
Yokohama National University

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Takehiro Sasaki
Yokohama National University
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Kei Uchida
The University of Tokyo
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Abstract

Plant communities are impacted by local (related to environmental filtering) and landscape (related to dispersal limitation) factors. While previous studies have shown that the relative importance of these factors varies depending on different aspects (i.e., spatial-temporal scale), little is known about how they are altered by urbanization—a significant threat to biodiversity. This study evaluates the relative importance of local environmental (local factors), landscape, and spatial (landscape factors) variables that influence plant communities in 34 urban green spaces comprising two different habitats (forests and grasslands) along the urban–rural gradients in the Tokyo megacity, Japan. To continuously assess the relative importance of each factor along the urban–rural gradients, we extracted 1,000 landscapes within a certain range that contained several sites. Subsequently, the relative importance of each factor and urbanization rate (proportion of artificial built-up area) was estimated at each landscape. The relative importance of the local factor increases, while the landscape factor decreases with urbanization, and the local factor becomes a primary factor in highly urbanized areas in forest habitats. However, the relative importance of the local factor decreases, whereas the landscape factor increases with urbanization in grassland habitats for native species. Collectively, these findings suggest that city size and target habitat characteristics must be considered when predicting changes in plant communities caused by urbanization.