An example of how mowing can degrade former prairies

In a previous post, I talked about how mowing and its conjoined evil twin, the European-influenced lawn, destroys biological diversity and makes no logical or economical sense.  This post will show how such an outdated mindset can cause permanent damage to prairies.

Unfortunately, many people mow a prairie or oldfield prairie into severely degraded versions of its former self, not realizing the damage they are causing to the grasses and to the ecosystem as a whole.  Most people think of prairies as “just grass” (if they even think anything of them at all), instead of the miniature forest, the watershed filters, and the wildlife habitats they are.  People mow grass too short enough as it is in their outdated quest for a “perfect” green, monoculture lawn, yet do not realize they are creating more work for themselves in the form of unnecessary supplemental watering to compensate for the short cutting height.  As I’ve said in previous posts, if you find yourself having to mow, mow it high; tall grass isn’t gonna hurt anything and the aesthetics will be just fine.

According to the Natural Resources Conservation Service (NRCS) Web Soil Survey of the site pictured below,

“The historic climax plant community for this site is a Post Oak (Quercus stellata) and Blackjack Oak (Quercus marilandica) savanna with tall and midgrass understory. The grasses are primarily Little Bluestem (Schizachyrium scoparium), Indiangrass (Sorghastrum nutans), Big Bluestem (Andropogon gerardii) and Sand Lovegrass (Eragrostis trichodes). The sandy loam textured soils in a rainfall regime of 29 to 33 inches favor a tallgrass savanna. Little Bluestem and Indiangrass are the most commonly occurring grass species.”

The following pictures show what the site looks like currently.

A dozen lonely Post Oaks are all that remains of this former savanna.  Two Eastern Redcedar (Juniperus virginiana) trees remind us that with their presence, there is absolutely a lack of fire.
A dozen lonely Post Oaks are all that remains of this former savanna. Two Eastern Redcedar (Juniperus virginiana) trees remind us that with their presence, fire suppression strangles the health of this site.
Constant mowing in the same direction and pattern will form ruts over time. Eventually, the perennial tallgrasses in these ruts give way to midgrasses and then to shortgrasses. Ultimately, bare soil will appear in the ruts and sheet, rill, and gully erosion will follow.
Constant mowing in the same direction and pattern will form ruts over time. Eventually, the perennial tallgrasses in these ruts give way to midgrasses and then to shortgrasses. Ultimately, bare soil will appear in the ruts and sheet, rill, and gully erosion will follow.
A closer look at how close mowing has decreased the vigor and coverage of perennial bunchgrasses. The increase in patchy bare soil is a sign of degradation and a negative trend away from the historical plant community.
A closer look at how close mowing has decreased the vigor and coverage of perennial bunchgrasses. The increase in patchy bare soil is a sign of soil degradation due to a negative trend away from the historical plant community.
An example of sheet erosion; the most common erosion problem in overgrazed rangelands. As sheet erosion increases, rill and gully erosion follows. Leaving the grass at taller heights (6" or more) can help trap sediments, water, and organic matter and eventually build up the soil as it slowly becomes stabilized.
An example of sheet erosion; the most common erosion problem in overgrazed rangelands. As sheet erosion increases, rill and gully erosion follows. Leaving the grass at taller heights (6″ or more) can help trap sediments, water, and organic matter and eventually build up the soil as it slowly becomes stabilized.

This area is mowed repeatedly throughout the growing season as if it were a lawn, short and often and usually on a weekly basis; the most damaging way to mismanage a prairie.  The tallgrasses are long gone, the midgrasses are deteriorating, and the shortgrasses sprawl around almost lifelessly, dragging gnarled rhizomes and handicapped stolons into cracked earth.  In some areas, invasive species like Johnsongrass (Sorghum halepense) spreads in the ditches and KR Bluestem (Bothriochloa ischaemum) has taken over vigorously due to mowing.  (KR Bluestem spreads rapidly with mowing, as its culms flop over onto the ground and root at the nodes, sending up new shoots and increasing their spread).  The lack of fire over the last several decades (40+ years) has more than likely delivered this former prairie its death certificate.

“U.S. lawn maintenance annually consumes about 800 million gallons of gasoline, $5.2 billion of fossil-fuel derived fertilizers, and $700 million in pesticides. Up to two thirds of the drinking water consumed in municipalities goes to watering lawns.”  The American lawn is the epitome of unsustainability, “covering an estimated 41 million acres of the United States, making it the largest irrigated crop in the country.”
Sources: http://www.utexas.edu/news/2011/04/21/wildflower_native_grasses/
http://lawncare.about.com/od/lawncarebasics/a/historyoflawn.htm

All that precious water going into all that lawn space and not an ounce of food or wildlife habitat can be had from it; something’s gotta give.

Note: for further reading into native lawns and the archaic “weed” laws that cities and municipalities (incorrigible homeowners associations especially) try and ignorantly enforce, The John Marshall Law Review (Vol. 26 Number 4) on weed laws is an excellent, though lengthy read.

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