Watch Your Step: Human Disturbances to Plant Assemblages

Human activities often cause disturbance to the environment, even when their activity is meant to conserve the environment. In order to manage environmentally protected areas, people usually look for ways to get around. When humans walk around, they risk stepping on vulnerable plants and animals. Furthermore, land managers often use all-terrain vehicles (ATVs) to transport heavy materials long distances. ATVs and foot traffic potentially cause stem breakage and fatalities to surrounding plant species. In addition to land management, humans often walk around or ride ATVs in preserved areas for recreation. Because of the great potential for humans’ well-intending activities to be harmful, we should study the extent of our disturbances on other species.

An experimental study looked into the effect of the land management practice of using all-terrain vehicles to apply mosquito treatments to wetlands. This study looked at the impact of two different types of ATVs at two different intensities on stem breakage and the canopy height of a San Francisco Bay wetland plant, pickleweed (Figure 1).

Figure 1. Salicornia virginica L., the variety of pickleweed featured in the wetland study. Picture from the Digital Atlas of Virginia Flora.

They found that heavier ATVs create more stem breakage and reduce the canopy height. Additionally, the researchers found that the more that ATV ran over a plot, the more time it took for that plot to return to the canopy and stem breakage level before the ATV disturbance. The researchers suggested that ATV usage should be eliminated or reduced and used on a different path each time to avoid damage in coastal marsh systems.

I am proposing to do a similar study at Conard Environmental Research Area, a restored prairie site in Kellog, Iowa. At this site, ATVs are used to spray poison on invasive species, among other reasons. Additionally, most management practices, environmental research, and recreational activities at CERA are done by foot (Figure 2).

Figure 2. Students conduct a research project while walking through the Conard Environmental Research Area. Photo from the Grinnell College website.

My proposal includes setting up experimental plots that will either be ran over by ATVs or walked over by students and local participants. I will be looking at the effect of foot traffic and ATV usage on diversity, stem breakage, and canopy height on the surrounding plant assemblages. Additionally, I will study how these disturbances affect the soil compaction and how long it takes for the plant assemblages and soil to recover to a pre-disturbance state, if at all. This study will intend to scale up research on ATVs that looks at only a single species and also fill in a research gap for the prairie setting. Additionally, this project will engage the public to educate others about the effects of human recreation and management on the environment.

References

Groom, J.D., L.B. McKinney, L.C. Ball, and C.S. Winchell. 2007. Quantifying off-highway vehicle impacts on density and survival of a threatened dune endemic plant. Biological Conservation 135: 119-134.

Hannaford, M.J. and V.H. Resh. 1999. Impact of all-terrain vehicles (ATVs) on pickleweed (Salicornia virginica L.) in a San Francisco Bay wetland. Wetlands Ecology and Management 7: 225-233.

Schlater, T., A., L. Thompson, and S. Price. 2007. Vehicles versus conservation of invertebrates on sandy beaches: Mortalities inflicted by off-road vehicles on ghost crabs. Marine Ecology 28: 354-367.