Biblio Notes

As the human population grows, our wildlands face threats from increased access for recreation and resource extraction, subdivision for residential and commercial development, and movements to pave and improve many of our secondary and tertiary roads.  Road improvements include paving, widening, and/or other methods.  While paving may afford conveniences that satisfy commercial and residential demands, such improvements increase the detrimental ecological impacts of roads including direct effects such as fragmentation and loss of secure wildlife habitat (Forman & Alexander, 1998), increa

The U.S. northern Rocky Mountains cover a huge area of relatively pristine and undeveloped land, creating unique areas of core habitat for many important carnivore and ungulate species. However, many parts of this region also have a long history of resource extraction and road building. On Forest Service lands alone, there are more than 50,000 miles of roads. Today many areas in this region are being rapidly developed and critical wildlife habitats are increasingly being fragmented.

Editor’s Note: This review updates research since our last Bibliography Notes on this topic, in May/June 1998 (Vol. 3 #3, or visit: http://www.wildlandscpr.org/biblio-notes/roads-kill-grizzly-bears-and-ef...). Since that time, more research has addressed the effects of highways and railroads, rather than just low volume roads.

Editor’s Note: Bibliography Notes typically covers the ecological effects of roads or ORVs by reviewing scientific literature. However, assumptions about social behavior also influence the debate around the management of off-road vehicle use on public lands. This edition of Bibliography Notes explores one important social science issue that has been studied by researchers. Introduction

Scenes of Yellowstone Park Rangers wearing gas masks brought national attention to snowmobile pollution. In Yellowstone (YNP) where the cleanest air in the nation should be found, levels of pollution often exceeded those of downtown Los Angeles (Rodes et al. 1998). Studies were quickly initiated and two-stroke snowmobiles were banned from the Park. Elsewhere, millions of snowmobilers still rev up these engines each winter and head into the snow-covered wildlands.

The U.S. is home to 3,981,512 miles of public roads (US Dept. of Transportation 2004). Unfortunately, the number of these roads that are currently lighted or will be lighted is not recorded by either the Department of Transportation nor the Federal Highway Administration, and therefore is unknown. We can infer that the majority of these roads are at least illuminated over specific portions. Ritters and Wickham (2003) report that 20% of the coterminous United States lies within 127 m of a road. In addition, U.S.

Picture a restored road halfway overgrown with vegetation. Most of us involved in restoration would generally see this vegetative cover as a good thing. It is a sign that something is able to grow on the once disturbed and compacted soil. Erosion is held in check, minus some bare spots here and there. Wildlife are likely beginning to use some of the plants for cover and food. As for the plant community itself, we expect that successional processes will eventually result in a diverse array of desired plant species.

The negative impacts of wildland roads on wildlife have been well documented (e.g., Wisdom et al. 2000, Trombulak and Frissell 2000). In addition to road-kill, roads increase animals’ vulnerability to over-hunting, poaching, and the effects of degraded habitat. Despite this qualitative understanding, however, the actual road mileage that would significantly reduce wildlife populations is still under review. A common measure used to gauge the impact of roads on wildlife is road density, measured as kilometers of roads per square kilometer of land area.

Roads and the human activities associated with them have profound impacts on wildlife. Roads, however, are not the only human intrusion that cuts through natural landscapes. Many other linear barriers mar the natural landscape, including trails, electrical power lines, oil and gas pipelines, and railways. According to Lyon et al. (1985), the linear development itself typically does not cause a disturbance response; it’s the human presence on it that causes problems, therefore the level of use must be assessed and evaluated.

Sedimentation is widely acknowledged as a major cause of degradation of instream habitats (Wood et al. 2005). During rain storms and snowmelt, dirt and gravel roads bleed sediment into ditches that often drain into streams. These roads are a major source of stream sediment loads, especially harmful fine sediments, and roads contribute more sediment to streams than any other land management activity (USDA 2000). Sedimentation is directly related to a decrease in benthic macroinvertebrate density and a change in diversity according to a number of studies.