Copyright © National Academy of Sciences. All rights reserved.
This executive summary plus thousands more available at http://www.nap.edu
Assessing and Managing the Ecological Impacts of Paved Roads
http://books.nap.edu/catalog/11535.html
8
Assessing and Managing the Impacts of Paved Roads
Ecological effects of roads at local scales (within a few kilometers
of the roads) have been widely studied, documented, and understood,
while effects at large scales are less documented and understood. More
is known about the effects of bridges, overpasses, and culverts on flows
of materials and organisms than about the effects of roads on larger patterns and processes, such as watersheds or migratory pathways. The lack
of information at large scales is related to many factors, such as (1) legal
and policy directives that guide what components of ecosystems must be
considered; (2) planning and assessment practices that restrict scales; (3)
limitations of data, indicators, and methods at broad scales; and (4) limited financial and technical support for ecological investigations at large
scales.
CONCLUSIONS AND RECOMMENDATIONS
CONCLUSION: Most road projects today involve modifications
to existing roadways, and the planning, operation, and maintenance of
such projects often are opportunities for improving ecological conditions.
A growing body of information describes such practices for improving
aquatic and terrestrial habitats.
Recommendation: The many opportunities that arise for mitigating or reducing adverse environmental impacts in modifications and repairs to existing roads should not be overlooked. Environmental considerations should be included when plans are made to repair or modify
existing roads, as well as when plans are made to build new roads.
CONCLUSION: Planning boundaries for roads and assessing associated environmental effects are often based on socioeconomic considerations, resulting in a mismatch between planning scales and spatial
scales at which ecological systems operate. In part, this mismatch results
because there are few legal incentives or disincentives to consider environmental effects beyond political jurisdictions, and thus decision making remains primarily local. The ecological effects of roads are typically
much larger than the road itself, and they often extend beyond regional
planning domains.
Scientific literature on ecological effects of roads generally addresses local-to-intermediate scales, and many of those effects are well
documented. However, there are few integrative or large-scale studies.
Sometimes the appropriate spatial scale for ecological research is not
This executive summary plus thousands more available at http://www.nap.edu
Assessing and Managing the Ecological Impacts of Paved Roads
http://books.nap.edu/catalog/11535.html
8
Assessing and Managing the Impacts of Paved Roads
Ecological effects of roads at local scales (within a few kilometers
of the roads) have been widely studied, documented, and understood,
while effects at large scales are less documented and understood. More
is known about the effects of bridges, overpasses, and culverts on flows
of materials and organisms than about the effects of roads on larger patterns and processes, such as watersheds or migratory pathways. The lack
of information at large scales is related to many factors, such as (1) legal
and policy directives that guide what components of ecosystems must be
considered; (2) planning and assessment practices that restrict scales; (3)
limitations of data, indicators, and methods at broad scales; and (4) limited financial and technical support for ecological investigations at large
scales.
CONCLUSIONS AND RECOMMENDATIONS
CONCLUSION: Most road projects today involve modifications
to existing roadways, and the planning, operation, and maintenance of
such projects often are opportunities for improving ecological conditions.
A growing body of information describes such practices for improving
aquatic and terrestrial habitats.
Recommendation: The many opportunities that arise for mitigating or reducing adverse environmental impacts in modifications and repairs to existing roads should not be overlooked. Environmental considerations should be included when plans are made to repair or modify
existing roads, as well as when plans are made to build new roads.
CONCLUSION: Planning boundaries for roads and assessing associated environmental effects are often based on socioeconomic considerations, resulting in a mismatch between planning scales and spatial
scales at which ecological systems operate. In part, this mismatch results
because there are few legal incentives or disincentives to consider environmental effects beyond political jurisdictions, and thus decision making remains primarily local. The ecological effects of roads are typically
much larger than the road itself, and they often extend beyond regional
planning domains.
Scientific literature on ecological effects of roads generally addresses local-to-intermediate scales, and many of those effects are well
documented. However, there are few integrative or large-scale studies.
Sometimes the appropriate spatial scale for ecological research is not