Assessing and Managing the Ecological Impacts of Paved Roads (2005) / Chapter Skim
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Appendix B: Spatial Scale of Road Effects on Ecological Conditions:
Appendix B: Spatial Scale of Road Effects on Ecological Conditions:
Pages 255-292
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The biotic consequences category is further divided into three subcategories, genetic consequences, plant and wildlife population consequences and ecosystem consequences. Within each subcategory the effects of roads on structure, function and composition are included.
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For example, the effect of several roads on one lake, range expansion by using roads as a dispersal corridor, or genetic isolation of a population surrounded by more than one road would be classified as intermediate. The boundary of a region is either politically (e.g., state of Florida, national park)
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The temporary addition of waterflows from the road network affects flooding, groundwater supplies and channel morphology of stream networks. For logging roads specifically, precipitation and vehicular use results in sediment production.
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Single segment · Inventories of almost 500 km of forest roads in several catchments indicate that untreated roads produced 1500 to 4700 m3 of sediment per kilometer of road length (Madej 2001)
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1981) · A study of a forest road network in the western Cascade Range, Oregon found that debris slides from mobilized road fills were the dominant process of sediment production from roads.
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, 22% come from sanding and de-icing agents, 17% from roadbed and road surface wear, and 13% from herbicide and pesticide use. These figures do not include heavy metals and other chemicals that leach from bridges into streams and other water bodies (Federal Highway Administration 1996, Kobringer 1984)
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. · Combustion gases may cause reductions in species richness in arthropods, some groups flourished in the environment polluted by combustion gases.
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on an unpaved forest road inhibited crossing of the road by salamanders. (Demaynadier and Hunter 1995)
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c. National · No citations Natural Disturbance Summary of Ecological Effects Logging and mountain roads are susceptible for creating landslides due to unstable soil, steep slopes and high road densities (Havlick 2002)
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The result is isolated and smaller populations. Genetic consequences for larger species with smaller population sizes or for endangered species with low dispersal abilities are thought to be greater (Gerlach and Musolf 2000)
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National · No citations Composition Summary of Ecological Effects Roads have a filtering effect, in that different species or segments of a population may interact distinctively in relation to roads. This can result in natural selection of specific genes.
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. · Road mortality is indicated in a shift in age structure toward younger age classes for painted turtles (Chrysemys picta)
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The benefits provided by roads must however, be weighed against the increased probability of those species incurring vehicular collisions or hunting. On the other hand, roadsides and adjacent land have a reduced habitat quality for many species due to disturbance from traffic presence and noise.
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. · Species richness and abundance of habitat-sensitive butterflies increased on roadsides restored to native prairie vegetation compared to grassy and weedy roadsides (Ries et al.
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. · Dutch studies of four bird species in open grasslands found the traffic disturbance effect on population density extended a further distance next to a busy highway compared to a rural road (van der Zande et al.
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exhibited longitudinal movements along a roadside and reduced crossing rates for paved and gravel roads (Mader 1990, Vermeulen 1994)
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on rainforest roads, but only during breeding season (Goosem 2001)
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density is inversely related to road density.
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. · Grizzly bears in the Swan Mountains of Montana used habitats with lower total road density and avoided buffer areas surrounding roads having >10 vehicles per day (Mace et al.
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c. National · No citations Composition Summary of Ecological Effects Plant species richness in roadsides depends on roadside management (mowing, planting, amount of disturbance and pollution)
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. Although a subsequent study found herptile, vascular plants, and bird species richness in wetlands was more accurately described by road density 30 to 40 years ago (Findlay and Bourdages 2000)
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b. Intermediate -- -political/ecological · The number of roads and road density was the strongest determinant in the decline of badgers in the Netherlands (Meles meles)
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. · Total traffic volume (dependent on road density)
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Intermediate -- -political/ecological · Fragmentation was quantified due to roads in 30 areas of a 213-ha section of Medicine Bow-Route National Forest in southeastern Wyoming. Average road density was 2.52 km/km2.
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c. National · No citations Function Summary of Ecological Effects Pollutants from roads and vehicles can alter ecological processes by weakening defense mechanisms in plants, increasing available nutrients and bio-accumulating in the food chain.
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National · No citations Composition Summary of Ecological Effects Environmental characteristics such as soil moisture, air temperature, soil compaction and composition, and light differ markedly on roads compared to adjacent surfaces. Dust from road surfaces that is carried onto adjacent surfaces extends the environmental effect of roads.
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Journal of Applied Ecology 20:403-15. Adams, L
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Biological Conservation 109:37-45. Braun, S., and W
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Biological Conservation 74: 177-82. Federal Highway Administration.
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2000. Effects of Tropical Rainforest Roads on Small Mammals: Edge Changes in Community Composition.
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2001. Effects of Tropical Rainforest Roads on Small Mammals: Inhibition of Crossing Movements.
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Biological Conservation 74:65-67. Kobringer, N
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Biological Conservation 29:81-96. Mader, H
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Biological Conservation 101:351-60. Ortega, Y
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Biological Conservation 54:239-49. Reijnen, R., and R
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De cline in the Netherlands. Biological Conservation 61:17-22.
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1998. Effects of Habitat Fragmentation and Road Density on the Distribution Pattern of the Moor Frog Rana Arvalis.
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Earth Surface Processes and Landforms 26:235-50.
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