The expansion of urban areas into surrounding natural habitats has been widely criticized for its negative impacts on biodiversity. However, a growing body of evidence suggests that urban development, when planned thoughtfully, can actually benefit local ecosystems. Three key arguments support this view. First, urban green spaces, such as parks and gardens, provide new habitats for many species. Studies in cities like Berlin and Chicago have shown that urban parks host a greater diversity of bird species than adjacent agricultural lands, because these parks offer a variety of food sources and nesting sites that are often absent in monoculture farmlands. Second, urban environments can act as refuges for rare and endangered species. For example, the peregrine falcon, once on the brink of extinction, has successfully nested on skyscrapers and bridges in many cities, finding safety from natural predators and abundant prey such as pigeons. Third, urbanization often reduces the pressure on pristine wilderness areas by concentrating human populations. When people live in dense cities, they require less land for housing and infrastructure compared to sprawling suburban developments, thereby leaving more remote forests and grasslands untouched. Thus, with careful planning, cities can play a positive role in conservation.
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The professor challenges each of the reading's points. First, while it is true that urban parks may host more bird species than farmland, this does not mean urbanization benefits biodiversity overall. Urban parks are typically small, isolated patches surrounded by concrete and traffic. Species that thrive there, like pigeons and starlings, are common generalists, while native specialists, such as ground-nesting birds or large mammals, are often absent. The high diversity in parks is often due to introduced exotic species, which can disrupt local ecosystems. Second, the example of peregrine falcons is misleading. These birds are an exception, not the rule. They are large raptors that can adapt to vertical structures, but most endangered species, such as amphibians or small mammals, cannot survive in urban settings due to pollutants, noise, and lack of natural food. Moreover, urban refuges often lack sufficient genetic diversity, making populations vulnerable to diseases. Third, the claim that urbanization spares wilderness is not supported by evidence. In reality, cities expand into wild areas, and they generate high demand for resources like timber, food, and water, leading to habitat destruction elsewhere, often more severe than if populations were dispersed. For instance, urban growth in the Amazon has driven logging and farming in surrounding forests to supply city needs. Therefore, the reading's optimistic view is not justified.
📝 写作提示 Summarize the points made in the lecture, being sure to explain how they cast doubt on the specific points made in the reading passage.
