Guide To Road Ecology

The earliest roads were simply trails or pathways and traveled on foot. The ancient Romans first conceived a modernized system of road building as a means to transport military personnel and expand their territory. Unfortunately, when the Roman Empire fell, their 50 thousand mile road system also fell into disrepair. In America, early colonists followed the footpaths used by Native Americans and later developed these paths into trade routes. These routes were traveled on horseback but still far from the convenience, we expect of a roadway today. The Boston Trail Road built in 1673 as a mail route between Boston and New York was 250 miles long and took a rider on horseback four weeks to make the trip! As technology expanded, so did the roadways across the nation. Only in recent years have we begun to understand the impact these roadways have on the ecology.

The focus of road ecology is to understand the relationship road systems have on the surrounding environment. While the main principles of road ecology came from our understanding of landscape ecology, it also incorporates conservation methods and practices to minimize the impact on plants, fish, and wildlife. The earliest focus of road ecology was and remains on the impact on wildlife. Early naturalist voiced concern over wildlife killed on the roadways but it was not until the later part of the 20th century that ecologist began understanding that roads created fragmented habitats restricting natural migration of animals. Since that that time, the goal of road ecology is to document the effects roadways have on the movement of wildlife, water, sand, and sediment as well as vegetation.

The earliest understanding of the way roads impact ecology appeared in the article, The Toll of the Automobile, published in 1925. This article was published in the journal, Science and addressed concerns that the number of animal killed by automobiles was may become a problem to the survival of some species. Recent understanding of road ecology has shown that in addition to the ongoing concern over the number of animals killed in vehicle-animal collisions each day, the fragmentation of habitats further impacts healthy wildlife populations by interfering with natural migration patterns, decreasing feeding and breeding grounds and isolating certain species. Habitat fragmentation decreases the healthy growth of vegetation some wildlife depend upon for food or shelter in addition to the impact road way pollutants have on the growth of healthy vegetation along roadways. As habitats become fragmented, water movement is also affected.

Roadways have a huge impact on water movement. Most roadways are made of nonporous materials that cause water to run in sheets causing flooding, or diverting water to areas at risk for erosion. The unnatural movement of water from roadways also increases the risk of sediment movement and road pollutants such as lead and chloride during winter that then washes into streams or seeps into underground waterways affecting fish spawning and migration patterns. When roads are built elevated above the surrounding landscape, they act as dams and may contribute to flooding in some areas while preventing water to reach other areas and causing the death of vegetation or the drying of areas that were once wetlands. Future advances in road ecology will aid in finding solutions to managing roadside water problems as well as other concerns influencing the balance of the ecosystem surrounding roadways.

Future studies of road ecology can address the impact roads have on the ecosystem by educating the public in the importance of considering ecological impacts of roads in the early phase of planning and design. Designing and constructing barriers, overpasses, or underpasses that allow for safe wildlife migration can decrease wildlife mortality. Public or mass transportation within State and National Parks can limit the number of vehicles on the roads reducing vehicle pollutants and decreasing traffic that disrupts and endangers wildlife within regions designated as wilderness areas. Improving roadway design and materials to manage the runoff of storm waters and prevent the diverting of natural waterways are just a few steps that may decrease the impact roadways have on the surrounding environment. Road Ecology is a new and developing field working towards a green environment and preservation of habitats and resources.

For more information concerning the history of roads and road ecology, consult the following links.