petroleum use and population density
Graph showing the relationship between per capita petroleum use and urban population density for selected cities.
urban ecosystem
urban ecosystem, any ecological system located within a city or other densely settled area or, in a broader sense, the greater ecological system that makes up an entire metropolitan area. The largest urban ecosystems are currently concentrated in Europe, India, Japan, eastern China, South America, and the United States, primarily on coasts with harbours, along rivers, and at intersections of transportation routes. Large urban areas have been features of the industrialized countries of Europe and North America since the 19th century. Today, however, the greatest urban growth occurs in Africa, South and East Asia, and Latin America, and the majority ...(100 of 1300 words)