Trombulak, S.C., and C.A. Frissell. 2000. Review of ecological effects of roads on terrestrial and aquatic communities. Conservation Biology 14: 18-30.

RELEVANT TO: ROADS/OFF-ROAD VEHICLES

INVASIVE SPECIES

VEGETATION AND WILDLIFE

MONITORING/ADAPTIVE MANAGEMENT

DESCRIPTION

This article reviews extensive scientific literature on the ecological effects of roads and documents the general conclusion that they are associated with negative effects on biotic integrity in both terrestrial and aquatic ecosystems.

MAJOR FINDINGS

Seven general effects of roads were noted:

  1. Mortality from road construction. Sessile and slow-moving organisms are killed, organisms adjacent to road are killed or injured, and the physical conditions beneath the road are altered.
  2. Mortality from collision with vehicles. Affects demography of many species, both vertebrates and invertebrates.
  3. Modification of animal behavior. Can cause changes in home ranges, movement, reproductive success, escape response and physiological states.
  4. Alteration of the physical environment. Roads change soil density, temperature, soil water content, light levels, dust, surface waters, patterns of runoff, and sedimentation.
  5. Alteration of the chemical environment. Roads add heavy metals (lead), salts, organic molecules, ozone and nutrients to roadside environments.
  6. Spread of exotic species. Altering habitats, stressing native species and providing movement corridors for exotic, invasive species..
  7. Increased use of areas by humans. Promotes more harassment of animals, reduces security of wildlife. and facilitates more landscape modifications. [I would not take on the hunting/fishing argument; those are legitimate uses of the forest. We need hunting and fishing groups supporting our alternative. The security issue gets to the negative aspect of hunting that roads facilitate.]

Not all species and ecosystems are affected equally, but overall presence of roads is highly correlated with changes in species composition, population size and hydrologic and geomorphic processes that shape aquatic and riparian systems.

More experimental research is needed to complement post-hoc correlative studies. This review underscores the importance to conservation of avoiding construction of new roads in roadless or sparsely roaded areas and of removal or restoration of existing roads to benefit both terrestrial and aquatic biota.

QUESTIONS RAISED FOR THE THREE FORESTS

  1. Do these Forests have any reason/evidence to believe that the findings relating to ecological effects of roads do not hold in these Forests?
  2. Do these Forests have any survey information regarding effects of the roads on nongame wildlife and/or invasive species?

RELEVANCE TO FOREST MANAGEMENT

Given that all roads involve adverse ecological impacts, the number, location, and necessity of roads should be carefully considered in which roads remain open.