Most of us running the trails love nature. It's a large part of why we do what we do. It's hard to beat that feeling of working hard while climbing a mountain trail and hearing nothing but the wind through the trees and a hawk above the canyons.
It's no wonder, then, why so many trail runners help preserve the trails and preserve environmental health through volunteering and trail maintenance. Environmental stewardship is foundational to the trail running community. Large numbers of trail races require several hours of trail maintenance just to participate. And even the Pro Trail Runners Association touts environmental ethics as core to the sport.
Others who often run the same trails in their neighborhoods develop a sense of communal ownership over those trails and help to keep them in good condition. And in general, trail runners (and other outdoor enthusiasts) also tend to live a more environmentally friendly life, overall.
Does Trail Running Negatively Impact the Environment?
Running through nature is pure joy. And in general, it's a pretty low-impact activity. Most runners do a good job of sticking to the trail which keeps wear and tear of the forest floor to a minimum. We also do a good job of preventing litter. Most races are moving towards a "cup-less" format which requires you to bring your own cup or bottle for refilling hydration to eliminate the waste and litter of non-reusable cups.
But our impact isn't zero.
Running through wild spaces means running through the lands of countless other creatures who call it home. Our presence is never unnoticed. And while the changes to wildlife behavior that occur from trail runners and hikers isn't all bad, there can be some damaging consequences.
Trail Running's Impact on Wildlife
We've all encountered an animal on the trails. It's one of the joys of running through nature. In the San Gabriel mountains of LA county, I've personally come across bobcats, deer, snakes, coyote, bears, and a tarantula. And in the hills of northern California, once came across a mountain lion.
But as the number of trail users continues to rise, our presence can impact wildlife behavior.
Researchers from the University of Washington saw changes to wildlife behavior even at low levels of human activity. As the number of people using the trails in the backcountry increased, the numbers of animals in that area decreased, especially among wolves. And amazingly, at just around 40 daily users, the wildlife sightings from camera traps dropped to zero in many locations.
A PhD student from Colorado State University previously looked across the array of research articles looking at the impacts of people on wildlife. Across 274 papers, 93% of them reported at least one impact on wildlife, and 59% of the impacts were identified as negative.
Typically, wildlife tends to avoid human contact, staying away from the trails, hikers, and runners alike. This isn't true for all animals, but for those it applies to, it means they must change their behaviors that can cause problems with finding food, water, mates, or safety.
Trail Running's Impact on Native Plant Life
A variety of studies in various parts of the world, including the US, Chile, Sweden, Australia, Tasmania, and others all point to the same thing - increased foot-traffic can damage the local ecosystem. Non-natives can spread, often simply being carried accidentally on shoes and clothing.
Boot brushes, like the image above from trails in Hawaii, can help spread seeds, non-natives, and plant diseases if you clean your boots and shoes before hitting the trails. The boot brushes were installed in Hawaii in large part to help combat Rapid 'Ohi'a Death (ROD), an infectious disease killing the native 'Ohi'a tree.
These studies also show the impacts are very species-dependent. So good trail design and placement is important for land and recreation managers, and probably suggests you shouldn't be too quick to bushwhack your own trail if you're not familiar with the local ecosystem!
Leave no Trace, and Giving Back
So yes, trail runners do have an impact on the environment. But before you hang up your shoes, you shouldn't be too worried as long as you follow some basic rules and do you best to treat the environment with the respect it deserves.
Stick to the trail. Unless you know you're on lands that allow venturing off into the wild, be cautious about going off the trail. Not only can you upset local plant and animal species, but you can increase risk of more erosion. If others see a path getting started, they'll follow it.
Pack everything out. It's a common hiking and camping rule, but applies to trail runners, too. If you have trash, don't leave it behind. That should include things like banana peels!
Participate in trail maintenance and cleanups. Most trail networks have organizations, both formal and informal, that organize trail maintenance work and cleanups that are a great way to keep the trails in good shape. As active users of the trails, it is only fitting that you help keep them in order.
Leave wildlife alone. Seeing wildlife on the trails is one of the treasures of trail running. But don't try to interact with them, for their safety and for yours! Be safe, and do what's needed to keep yourself safe, but don't go starting trouble.
The trail running community is growing. That's great. More people are discovering the joys of running through nature.
But with increasing trail users comes a reality. Our wild spaces are getting used at a higher rate, and that threatens to degrade the essence of what it is we love. Fortunately, the trail running community has a deep love and respect for the environment that leads to good trail stewardship by and large. As new runners join the community, it's our duty to continue to foster that love for the wild and carry that tradition forward for generations to come.