Research gaps in knowledge of the impact of urban growth on biodiversity

By 2030, an additional 1.2 billion people are forecast in urban areas globally. We review the scientific literature (n = 922 studies) to assess direct and indirect impacts of urban growth on habitat and biodiversity. Direct impacts are cumulatively substantial, with 290,000 km(2) of natural habitat forecast to be converted to urban land uses between 2000 and 2030. Studies of direct impact are disproportionately from high-income countries. Indirect urban impacts on biodiversity, such as food consumption, affect a greater area than direct impacts, but comparatively few studies (34%) have quantified urban indirect impacts on biodiversity. The world is urbanizing. This Review assesses impacts of urban growth on habitat and biodiversity, finding direct impacts more in high-income countries while indirect impacts affect more land but are lesser studied.