If a road runs through a forest, does it hurt the forest resources? The impacts of forest roads have been haunting natural resource managers for decades. What are the impacts when an old logging road winds through a national forest?
The Negative Effects of Roads on Forests
Roads have negative impacts on forests and their surrounding ecosystems. Unfortunately, those planning new roads overlook the forest impacts. Here are some of the most common issues associated with roads and forests:
Loss of Habitat for Species that Depend on Forests
Roads can severely limit the ability of species to access certain habitats. Roads cause habitat fragmentation: they create boundaries that limit movement. While it’s easy for humans to cross roads, roads are a lot bigger to small animals. Salamanders, frogs, and even insects can all have challenges with new forest roads.
Every time a road is built, species populations are split in half. They cannot find food, shelter, or mates in their natural environment. There’s not enough suitable space, and that leads to a decrease in their population.
Roads don’t just disrupt wildlife. Some plants only reproduce asexually – by rhizome or root. This is in contrast to seeds and berries transported by squirrels. So every time we build new forest roads, we fragment and destroy plant populations.
Scientists have found that:
- The impacts of roads on plants can extend pretty far past the road/forest boundary.
- Constructed roads change the soil composition of nearby natural areas.
- Roads can even impact forest butterfly populations.
Increased Fragmentation of Forests Leads To Invasive Species
Splitting a forest up via forest roads is known as disturbance. In a forest, there are “edge” habitats and “interior” habitats. Sort of like a puzzle. If you add more forest roads, you create more edges.
Forest edge habitats tend to be weedier. Road construction can cause a lot of damage, including:
- soil compaction
- water pollution
- noise that disrupts wildlife
- transfer of contaminants
- introduction of invasive species
What are invasive species?
An “invasion” of exotic plant species can occur after road construction. Invasive species that like roads include:
- garlic mustard
- purple loosestrife
- many others
Equipment accidentally brings rogue seeds into an area. Ultimately, they grow in the nearby ditches and edge habitats. Roads and vehicles are one of the most common ways that invasive species get spread.
People may not realize the impacts of a single forest road. But road clearings have direct and indirect impacts on wildlife and habitat quality.
Forest Roads Impact Water, Soil, Nutrients, and More
- disturbs natural vegetation
- changes the local hydrology (water systems)
- changes soil nutrient cycles
- alters microclimate conditions
All of these can lead to changes. Species composition may change, and so can ecosystem structure. Scientists are still learning about the impacts of forest roads on ecosystems. Their research shows that:
- Road construction crews need to reduce disturbances to minimize pollution and runoff.
- Best Management Practices (BMPs) can reduce impacts during construction. But, additional steps need to be taken during road maintenance.
- Even short or narrow roads can impact reptiles, amphibians, and other small animals.
Increased Potential for Pollution from Forest Road Traffic
Road traffic has been linked to increased air pollution levels. These can affect the health of nearby habitats and humans. Road debris (like plastic bags or containers) can find their way into waterways. In water, animals may eat that road debris. This pollution can even cause physical damage to aquatic habitats like mangrove forests.
These impacts can happen on normal roads, too. But a forest road (e.g., through national forests) should have the lowest possible impact. Scientists have found that:
- Vegetative barriers can help lower air pollution on high-impact roads (like highways).
- Forest resources can undergo a “creeping degradation” from things like air pollution.
- Littering in forests is a big issue. We need to do deeper studies on the impacts of littering and prevention techniques.
Considerations for Degradation to Areas Around Forest Roads
Constructing roads also introduces noise pollution. Human noise can disturb critters during mating season or nesting times. It can also cause behavioral changes. Loud noises may feel like a threat to animals. Light pollution from street lights also has similar effects. Some nocturnal species can’t hunt when artificial lights are on at night.
Challenges to Wildlife Migration Routes Across Forest Road Barriers
Roads that cross through wild areas create barriers. This can limit animal movement from one area to another. It can even disrupt migration routes. That can lead to population decline. Road barriers are difficult for animals who need wide open spaces to migrate. Scientists have found:
- Different amphibian species use differently sized culverts.
- We need to build safe road crossings to keep amphibians, reptiles, and mammals safe.
Solutions to the Negative Impacts of Forest Roads
Planning Forest Roads
One of the big negatives of forest roads is the lack of safe passage for wildlife. Keeping natural connectivity can help wildlife around new roads.
When thinking about placing a new forest road, we need to consider connectivity. There could be big impacts on the natural landscape. Governments and agencies should plan accordingly.
For example, planners should look at ways to place bridges or underpasses for animals. These are known as wildlife crossings or ecoducts. Planners can keep traffic slow (a “traffic diet”) in areas of high wildlife activity.
Reviewing things like topographic maps, wildlife camera captures, and other data sources can also help with forest road planning.
Planting Native Vegetation Along Forest Roads Helps Pollinators
Planting native vegetation along roads can help. Native plants reduce the negative impacts of forest roads:
- Plants can be a filter that remove pollutants from runoff.
- Native plants provide food and habitat for local species.
- Plantings restore biodiversity. They preserve ecosystems that are disturbed by new roads.
- Natural buffers are a physical barrier between vehicles and nearby forested landscapes.
- Planted buffers can reduce the noise pollution and dust particles from traffic.
Restricting Vehicle Speeds On Forest Roads
Reducing vehicle speeds on forest roads is an important measure. It helps protect against many of the issues with roads in forests. Lower speed limits discourage drivers from driving recklessly. It also reduces air pollution from exhaust fumes. It also decreases noise disturbances that could harm nearby organisms. Finally, slower speeds reduce the likelihood of collisions with animals. This means less in insurance bills for deer, moose, and other large animal collisions.
Final Thoughts on Forest Roads
Roads have a negative impact on forests and on the environment in general. While there are some benefits to roads, they also come with a great cost.
Roads can lead to deforestation, fragmentation of habitats, and increased pollution. Fortunately, there are many ways that we can reduce the harm of a forest road. Careful planning is important when constructing new roads. Protecting existing forests from road expansion is also important.
It’s our jobs to be good stewards of the land. There’s a limit to natural resources, and these forests do so much for us.
Will you take the next step and become a Forest Defender? Your monthly gift sustains the movement for forests, climate, and justice.