By Josh Woods ~

Try this: Search google for “environmental impact.” In the results, you’ll quickly see that almost everything humans do affects the environment, and that many of these impacts have been carefully studied by scientists.

Research on disc golf’s influence on the environment is still developing, but there are at least two studies, published in peer-reviewed academic journals, that examine a little-known problem that is right beneath our feet.

Assessing soil compaction, erosion and vegetation loss

In one study, Trendafilova and Waller (2011) looked at three related aspects of ecological degradation on disc golf courses, including soil compaction, soil erosion and vegetation loss. As illustrated below, soil compaction occurs when the density of the soil increases and its porosity decreases. Erosion involves soil and rock moving from one place to another. Vegetation loss is a decrease in grass and green cover due to trampling.

Trendafilova and Waller (2011) measured these variables at three courses in Austin, Texas: Pease Park, Zilker Park, and Mary Moore Searight Park. Their analysis focused on two areas on each course: off the course path and around the baskets. The different samples allowed them to compare the soil and vegetation conditions in areas with high and low foot traffic.

Measuring soil compaction, erosion and vegetation cover is not new, and Trendafilova and Waller followed standard scientific measurement procedures.

Though it may not surprise many disc golfers, Trendafilova and Waller (2011) found that soil compaction, erosion and depletion of vegetation are more severe in areas near baskets compared to areas farther out.

Leung and colleagues (2013) carried out a similar analysis on courses in North Carolina (Valley Springs, Cornwallis, Cedar Hills and Kentwood). Their study revealed, once again, that areas with high foot traffic are more likely to have vegetation loss, bare soil, root exposure and soil compaction than areas with less traffic.

Limitations

The studies reviewed above have two limitations. First, Trendafilova and Waller (2011) looked at courses in Austin, Texas, a hot bed for disc golf in one of the state’s biggest cities. In fact, their study included the most popular course in Texas (Zilker Park), per a recent article in Release Point. Though the researchers sidestepped this issue, their results may only be representative of conditions at courses with high use rates.

Leung and colleagues (2013, 283) addressed this limitation. They noted that “use data were unavailable” for the courses they studied and suggested a way to overcome this limitation with an enhanced sampling procedure in a future study.

Second, while both studies identified vegetation loss and soil compaction as significant environmental problems, neither study clarified how, exactly, these problems affect the ecological surroundings.

People walk on grass all the time, right? Sometimes the grass turns into hard, brown dance floors, which, by the way, are great for skip shots. What’s the big deal?

Why Care About Dirt?

Soil compaction is probably not the first thing disc golfers think about when they’re staring down a 25-foot putt. Yet, there are at least two reasons to think about soil when you’re inside “the circle.”

The first reason is obvious. Whether soil compaction near baskets is a severe environmental problem or not, if park officials perceive it as one, your favorite course could be closed. As noted above, Pease Park, one of the courses studied by Trendafilova and Waller (2011), was later shut down due to environmental degradation concerns. The Pease Park case is not a unique story. Several courses have been shuttered or were never built because of perceived dangers to the environment.

The second reason is more complicated, but no less important. In the long term, those smooth, brown dance floors around baskets can harm what disc golfers love most about wooded courses: healthy, upright trees. Changes in soil structure, brought on by constant trampling, can hamper the growth and shorten the life of woody plants and trees. It affects the organic material in soil, increases runoff and erosion, and in some cases weakens trees, making them more susceptible to pests and disease.

So, does soil compaction pose a major threat to wooded courses? Maybe, maybe not.

According to Jeff Homburg, a PDGA Hall of Famer with a PhD in soil science, the effects of soil compaction on trees “depends on the context.” Homburg told Parked that compaction is less of a problem in sandy soils than it is in clayey soils.” Other factors include the degree of slope around baskets and the type of tree species in the area. Compaction on disc golf courses is never a good thing, but it does not pose the same level of danger to trees in all situations.

How to Remedy Compaction

Fixing soil compaction is not easy. Professor Susan Day, a leading expert on below-ground systems of urban forests at the University of British Columbia, told Parked, “In general, a solution is really not just a question of what treatment to apply, but a design/systems problem. So, it probably takes an expert.”

Day has published several articles on the topic, including an excellent review of research on “the effects of soil compaction and amelioration treatments on landscape trees” (read it here). Although some experts have suggested that breaking up compacted soil or aerating it is the best way to go, Day (1994, 15) argued that “as long as drainage is adequate, aeration is most likely not the primary restricting factor resulting from soil compaction.”

Homburg offered a similar view, saying that “simply breaking up the soil, such as in a plowed field, can exacerbate the problem in the long run.”

In short, if severe soil compaction seems to be harming trees and plants on your course, it may be time to bring in an expert to check it out.

The Best Solution is Prevention

None of the scientists I consulted advocated for eliminating the sport altogether. Homburg and Day, as well as the two articles reviewed above, suggested that prevention is the key. After all, the traditional golf industry has been successfully managing this issue for decades.

Effective preventive measures include:

Apply six inches of wood-chip mulch in areas with soil compaction. (See Lance’s comment below, which suggests putting down gravel prior to mulching around baskets).

Minimize the impact of foot traffic and trampling by installing concrete tees and defining pathways down the fairway as well as between holes.

Rotate basket placements every few months.

Stay off exposed root zones when the soil is very wet.

If you see a tree declining quickly, consider if any of its roots have been severed. “That’s a more common cause of visible decline of previously healthy trees than compaction,” Day noted.

Supply information to disc golfers about the impact of the sport on the environment.

Ultimately, the sustainability of the sport rests largely on disc golfers themselves. If you have recommendations for handling any of the problems discussed in this article, please comment below.

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Parked is made possible in part by a grant from the Professional Disc Golf Association.

References

Day, Susan, and Nina Bassuk. 1994. A Review of the Effects of Soil Compaction and Amelioration Techniques on Landscape Trees. Journal of Arboriculture, 20(1): 9-17.

Leung, Yu-Fai, Walden-Schreiner, Chelsey, Matisoff, Craig, Naber, Michael, and Jessica Robinson. 2013. A Two-Pronged Approach to Evaluating Environmental Concerns of Disc Golf as Emerging Recreation in Urban Natural Areas. Managing Leisure, 18, 273-285.

Trendafilova, Sylvia, and Steven Waller. 2011. Assessing the Ecological Impact Due to Disc Golf. International Journal of Sport Management, Recreation and Tourism, 8, 35-64.