Mountain biking is a popular sport that is considered to be close to nature. But anyone who practices it should know that it also influences nature around the cycle paths – and not just at the moment of passing. For example, according to a recent analysis, mountain biking hardens the soil, leads to changed plant communities along the way and affects the day-night rhythm of some animals. However, not all changes necessarily have to be negative for nature.
Almost four million people in Germany regularly get on their mountain bikes, according to a survey by the Allensbach Institute for Public Opinion. Cycling through fields, forests and meadows is one of the most popular leisure activities in this country. But for the nature that you cross, the sport sometimes has ecological consequences. It affects animals, plants and soil, among other things.
Soils consolidate and erode
Researchers led by Lukas Kuwaczka from the University of Bayreuth have now carried out a meta-analysis to find out exactly how mountain biking affects the nature around the cycle paths. To do this, they brought together various studies that have already dealt with the environmental consequences of this cycling sport and evaluated their findings as a bundle. It was shown that the effects of mountain biking can already begin before even a single cyclist has swung into the saddle, namely as soon as new paths are opened up. According to Kuwaczka’s team, this first major intervention in nature leads to particularly serious changes.
But already existing, busy routes also have an impact on nature. These concern three areas: soils, vegetation and wildlife. As for soils, they tend to compact quickly when subjected to the weight of multiple tires each day. According to one of the studies evaluated, this effect is significantly more pronounced on mountain bike routes than on hiking trails. Because the cycle paths are exposed to wind and weather, their soils also erode faster, as Kuwaczka and his colleagues have determined. Steep stretches are particularly affected.
Animals change their day-night rhythm
The flora is also influenced by mountain bike trails. For example, the research team reports that the vegetation along the wayside thins out over time and in some cases consists of fewer or different plants than before. In addition, plant seeds can get caught on the tires of the bikes, which the mountain bikers then unknowingly distribute on their tours. This can help the plants in their reproduction and spread. But instead of seeds, plant pathogens can just as easily get caught in the tires. According to one of the studies, this also includes the fungus Phytophthora ramorum, which triggers the disease of “sudden oak death”.
In animals, mountain biking primarily influences their behavior, as Kuwaczka’s team reports. The animals not only avoid busy routes, but also adapt their daily routines to the cycling visitors. For example, two studies in areas with busy routes show that mule deer, coyotes, and bobcats have shifted their activity into the night, while striped skunks suddenly become active early in the morning. In addition, for elk deer, disturbance of their habitat has resulted in reduced rest periods. The Gold-cheeked Warbler was even less successful at breeding due to the mountain bike trails. One study found that the small songbirds were three times more likely to abandon their nests in busy areas than in areas without bike lanes.
E-bikes could exacerbate problems
Kuwaczka’s team estimates that the ecological consequences of mountain biking will probably become more pronounced the more bikes are powered by electricity. “The increasing use of e-mountain bikes will lead to a larger number and spatial coverage by bikers and thus to an increasing number of routes,” say the scientists. More paths mean more disturbances of nature. In addition, with the help of the electric drive, more remote and steeper slopes, which previously had to bear only a few cycling consequences, will probably also be traveled more frequently.
However, Kuwaczka and his colleagues point out that, based on the knowledge gained so far, no long-term consequences for the ecosystems can be identified for both conventional and electric mountain bikes. Accordingly, it is not yet possible to say with certainty which of the previously determined consequences of mountain biking are negative for nature in the long term. This assessment would also depend on whether protected or rare species suffer particularly from them, but the data on this is still sparse.
However, according to Kuwaczka’s team, outdoor sports such as mountain biking could also have clear positive effects: they sensitize people to the beauty and importance of nature and therefore have the potential to promote a mindful use of it.
Source: University of Bayreuth; Specialist article: Global Ecology and Conservation, doi: 10.1016/j.gecco.2023.e02475