In the last few posts, I have been reporting on land use/land cover (LULC) trends in Missouri. LULC trends have important environmental consequences. A recent report by the EPA, Our Built and Natural Environments: A Technical Review of the Interactions Among Land Use, Transportation, and Environmental Quality, Second Edition, explores and documents them.
The report finds that natural ecosystems provide certain ecological services that are essential to support life. Developing land (building on it) may enable the land to provide other services (to provide shelter, for instance, or to provide a route for transportation), but it degrades the lands ability to provide ecological services. The environment is directly affected:
For example, natural ecosystems maintain healthy air quality, regulate temperature and precipitation, prevent flooding, provide clean water for drinking and industrial use, maintain healthy and productive soil, pollinate wild plants and crops, maintain biological and genetic diversity, provide renewable natural resources, treat organic waste, control pests and diseases, and provide recreation areas. Land development often replaces natural areas and damages or destroys many of these ecosystem functions and services. (p. 2)
How we build on the land also affects the environment indirectly. For instance, the sprawl we have been discussing in previous posts influences how far people must travel to meet their daily needs. Their travel decisions affect air pollution and greenhouse gas emissions, how much time they must devote to travel each day, and even their vulnerability to traffic accidents. It also determines how much infrastructure must be built to supply essential services to the people. The infrastructure consumes resources in its creation, and it can degrade the environment (for instance, the building of roads and parking lots creates impermeable dark surfaces that worsen flooding during heavy precipitation, and which increase the ambient temperature on hot, sunny days – the heat island effect). And so forth.
The EPA report concludes that it is not so much that we will affect the environment if we continue building will-nilly on the land, but rather that we have done so already:
…we have developed land that serves important ecological functions at a significant cost to the environment. Development has destroyed, degraded, and fragmented habitat. Water quality has declined. Air quality in many areas of the country is still adversely affecting human health. The heat island effect and global climate change illustrate just how complex and far-reaching the impacts of our built environment are. Community design can make it difficult for people to get adequate physical activity, engage with neighbors, and participate in community events. It can also increase the risk of injury or death from a vehicle crash. (Executive Summary, p. i)
In following these trends, an important question arises: are the environmental effects of land development different depending whether it is rural, exurban, suburban, or urban? I will report some data on this question in future posts.
Our Built and Natural Environments: A Technical Review of the Interactions Among Land Use, Transportation, and Environmental Quality, Second Edition, Environmental Protection Agency, http://www.epa.gov/smartgrowth/built.htm.