Humans are not the only ones to cross over or under bridges, and local forest officials are taking that into consideration.

Shawnee National Forest is implementing a plan to replace five crossings of small streams by forest roads with improved crossing structures that would improve the passage of aquatic life and reduce fragmentation of stream habitats. Experts believe the inclusion of these crossings will create a healthier environment for aquatic life and alleviate the effects of human interaction with forest wildlife.

Improvement will take place at the Johnson Creek crossing on Forest Road 768, Grande Pierre Creek crossing on Dutton Chapel Road and three small stream crossings on Snake Road; all within 100 miles of Carbondale.

Matthew Lechnar, national resource program manager for Shawnee National Forest, said the crossings are older and are making an impact on the wildlife, even disrupting the movement of fish up or downstream.

“Some of those roads were put in a long time ago and are creating barriers to fish moving upstream or downstream,” he said. “So our goal was just to make it so the road system does not impact a natural, evolutionary force.”

Lechnar said the road system in the forest is constantly updated, but projects such as the crossing updates are not common. He said only a handful of projects are approved each fiscal year depending on how much money the park has to spend.

The beginning of the project will depend on how much grant money the park has available, Lechnar said.

“Construction is dependent on funding and right now we have some grant applications in for the (crossings),” he said. “If they get funded, then we will implement them. Some of them we will just implement with our own growth maintenance budget.”

One of the considerations before projects begin is conducting studies to assess if the construction will affect wildlife and asking the public about the condition of the area, Lechnar said. Projects such as these stream crossings can have a vast improvement on wildlife communities and will likely be funded soon, he said.

Marjorie Brooks, an assistant professor in zoology at SIU, said improving the quality of a bridge to help the wildlife is beneficial as bridges can be disruptive to nature.

“Just the noise and vibration can disrupt the aquatic communities right there,” she said. “Obviously, you’ve got exhaust, you’ve got higher (carbon dioxide) right there so you’re going to have more CO2 going into the water and then you actually get run-offs of heavy metals, specifically copper from the brake pads.”

Brooks said while copper is a good thing for aquatic life, too much of it can be deadly to any species. She said an abundance of copper would kill sensitive species first and lead to an imbalance of the food chain.

The migration and movement of some species might be affected, but it would depend on the species, Brooks said.

“As far as migration routes, it depends on the species, but sure (they can be affected),” she said. “Anything that could look like a barrier to them is going to discourage or make them change their habits from night time to day time, from day time to night time, and you can have that happen and get some indirect effects.”

A lot of different factors can go into how animals react to roads and bridges, such as how the natural environment worked before human intervention, Brooks said. She said it is even possible that a man-made crossing can improve the environment it is built around.

Matt Whiles, a professor of zoology at SIU, said that connectivity is the lifeblood of any stream and is crucial to maintain.

“Streams are longitudinal networks and the better the connectivity, the better it is for all aquatic life that live in streams,” he said.

Whiles said one such example of this importance is some small fishes migrate up headwaters to reproduce and if they cannot reach these areas, then it will impact these species and the food chains they belong to. He said a crossing could interfere with the nature of a stream such as disrupting the flow of organic materials downstream.

Human interaction can play a large part in how an environment develops over time, Whiles said.

“Human activities are certainly affecting everything in forests and streams,” he said. “We have a large impact on the planet and our national forests are not immune.”

The improved crossings can benefit the wildlife of Shawnee National Park if they are created properly, Whiles said.

“If they reduce human impact and they improve connectivity of the streams, then that is certainly a good thing,” he said.

Matt Daray can be reached at [email protected] 

or 536-3311 ext. 254.