South African grasslands are beautiful places to visit, often because those that remain occur in mountainous areas with beautiful views but also because of the wonderful array of interesting plants to be seen. They are not just a pretty face either, but provide valuable services including carbon storage, grazing, water provision and moderation of water flow. The plants themselves are valuable horticulturally, pharmaceutically and aesthetically. So it is understandable that we like to spend time in these special areas and those around Haenertsburg are no exception.
You may wonder then, why there are stern signs prohibiting vehicles from driving on the grasslands.
Unfortunately grasslands are sensitive and easily destroyed. Merely walking through a grassland can damage the surface vegetation and introduce unwanted weed species. Driving a vehicle causes damage on an even greater scale. This damage is irreversible. Signs prohibiting vehicles from driving on grasslands are there for the following reasons:
· EROSION: Vehicles break up the soil crust forming tracks which accelerate wind and water erosion. These tracks increase surface run off and slope wash which buries plants. The soil sediments produced by slope-wash degrade forest streams. Even small quad-bikes cause 15-20 times as much erosion as hikers. In the Wolkberg tracks are causing irreparable erosion on the lower slopes of Serala Peak.
· COMPACTION: Vehicle tyres compact the deeper soil layers. This can lead to as much as 97% less rainwater infiltration, soil surface temperature is increased and soil fertility decreased. The micro and macro soil fauna in the area are also damaged, negatively influencing soil fertility.
· WEEDS and PATHOGENS: Vehicles crush vegetation and introduce weed seeds and plant pathogens. A small seep in the Wolkberg contains three different species of rare bladderworts which are regularly damaged each time a vehicle plunges through them.
· POLLUTION: Fuel gasses produce air pollution and poorly maintained vehicles can leak oil and fuel.
· FIRES: Vehicles provide an increased ignition source for wildfires.
· FAUNA: Animals are killed directly by vehicles and their burrows and shelters destroyed. Road noise disturbs and disrupts the search of food and water. A dirt track is just as much of a barrier to small mammals, reptiles, amphibians and invertebrates as a tar road of the same width. On the forest margins of the Haenertsburg grassland, an endangered golden mole inhabits surface burrows which are sensitive to vehicle damage.
· WETLAND DESTRUCTION: Vehicles damage wetland areas on the grasslands by degrading water quality, damaging plants and animals and introducing exotic vegetation. The bladderworts, orchids and frogs occurring in the spring on the slopes of Serala Peak are constantly disturbed by vehicles compacting this sensitive area.
We are also inhabitants of our special grasslands but we must tread lightly if we wish to keep and use these areas.
Information taken from:
Buckley, R. 2004. Environmental impacts of off highway motorized vehicles. In Buckley, R, Environmental Impacts of Eco-tourism, CAB International 2004.
Goodall, J. Witkowski, E. T. F., Morris, C. D. & Henderson, L. 2011. Are environmental factors important facilitators of pompom weed (Campuloclinium macrocephalum) invasion in South African rangelands?Biological Invasions13(10): 2217-2231
Zaloumis, P. & Bond, W. J. 2011. Grassland restoration after afforestation: No direction home?Austral Ecology36, 357–366.