Over the past century, the United States government’s policies have increased the development of land surrounding urban centers, a process known as urban sprawl. The point is not to say that urban sprawl has to be eradicated in order to preserve biodiversity. Instead, federal, state, and local governments, as well as residents, can be smarter about city planning, space usage, and sustainable urban lifestyles. Taking action to limit cities’ disruption of ecosystems will not only improve the lives of urban-dwelling fauna, but will also have economic and health benefits for residents.
Zoning
Urban sprawl does not always occur as a result of population growth—in fact, from 1972 to 1996, Massachusetts experienced a 6% population increase but a 95% increase in the area of developed land.[2] The sharp contrast between city centers with high population densities and the surrounding suburban areas with low population densities further underscores that the motivation for urban sprawl is not always related to population growth.
Suburban expansion is often the result of policies and procedures surrounding zoning, which stem from the 1924 State Standard Zoning Enabling Act.[3] In the US, state and local entities currently control zoning, and can issue single-use zoning policies, where all the land in a zone can be used only for one purpose.[4] They can also create legislation requiring suburbs to remain at low population densities, thus increasing land use.[5]
Zoning laws are important to managing the health of local communities and neighborhoods. Initially, zoning laws focused on separating industrial areas from living areas to reduce the risk of diseases and health problems. However, over time, studies show how current zoning practices do not focus on public health as the main concern.[6] This bias in the zoning process has led communities to have unequal development which is further detailed in the Impact section below.
Roadways
Large roads with multiple lanes of fast-moving traffic such as highways, expressways, freeways, and parkways, have a significant impact on the behavior, migrations, and health of animal populations.[7] Train tracks and other transportation-related infrastructure pose threats to fauna living in the area as well, but the traffic density of roadways can be especially dangerous to animals.
In the 1950s, the US federal government rolled out the National Interstate and Defense Highways Act. Also known as the Federal-Aid Highway Act, it authorized funding for 41,000 miles of interstate highways as a facet of the national defense program.[8] In addition to the increased affordability of cars, people were able to move to the suburbs while still reasonably commuting to more urban areas for work.
Such major roadways, however, isolate ecosystems and animal populations and cause habitat fragmentation, due to the fact that it is difficult for animals to cross. In fact, the US Department of Transportation estimates 300,000 wildlife-vehicle collisions per year.[10] Fragmentation reduces the number of members in a population, while also stopping interactions between separate populations. This in turn decreases the success and viability of those species near roadways.
Impact of Greenification
Increasing the natural parks, green spaces, and wildlife corridors within urban and suburban spaces is known as greenification. These improvements have a positive impact on the economic value of neighborhoods, pest control, and human health. Incorporating dedicated green spaces and natural parks into residential areas increases the value of homeowners’ properties by 5% or more for houses that are within 500 feet of these spaces.[11],[12] Furthermore, through leaving the food chain intact, biodiversity prevents insect and rodent populations from drastic and sudden increase, possibly eliminating the need for pest control and related repairs.[13] On average, this could save homeowners between $200 to $450 annually.[14]
As mentioned earlier, communities face unequal development, especially around access to natural areas like parks. The differences in development bring unforeseen consequences that directly affect the public health of communities. The lack of access to parks and green spaces leads to higher exposure to unhealthy environments. This higher exposure leads to health disparities in asthma, cancer, and diabetes. Additionally, there are higher obesity rates as a result of a lack of infrastructure that is catered towards physical activity.[15]
Be it the lack of facilities for physical activity or increased risk of disease, it is important for the health of these communities to have accessible green spaces in their area.