First Thoughts

Some Recent Posts On This Site 

Orchids As Weeds

Brood Parasites (Birds)

Toxic Plants of  Field and Gardens I and II

Some More Fungi (Deer Mushroom)

Florida Bay Islands in the 1990s

Beverage Plants I-IV (Stimulating & Non-stimulating)

          Our Own Ecosystem- Lawn ecology

Many of us are fortunate to have a tiny piece of the earth’s land surface under our control.  What do you want to do with it?  One option is to manage it  like a golf course. At the other extreme, and much commoner, would be to give it over completely to natural processes.  Yes, that requires redefining what we mean by the term “weed”.  Or maybe we can manage our land as a mix of the two extremes–leave some lawn but also leave other areas where nature is allowed to take charge.  We could intervene selectively, encouraging some species while removing others.  Of course, whichever of the latter options you choose, there may be neighbors who sniff in disapproval.  They likely would favor the first option which offers you hope that you can have that lush, deep green turf that the corporate purveyors of lawn equipment  and chemicals hope you want. Environmental implications of this choice are up to you to determine or to ignore.  The other choices are, to my mind and I hope some of yours, more interesting and wise in an ecological context. These thoughts are worth pursuing further, and I hope to engage you on them in the future.

The satellite image (below) of Southwest Water Management District lands in Pasco County, Florida, reveals a wide range of ecosystems and surface features reflecting man’s varying influence.

conner-preserve

The land use types run the gamut from natural ponds (dark features) and adjacent cypress wetlands which although appearing natural, likely have been subject to disturbances of their hydrologic and nutrient cycles and quite possibly their animal and plant communities.  Meanwhile the overmowed sandy soils, roads, and former grazing lands (light features) clearly reflect stripping away of soil organic matter and the virtual extirpation of natural biotic communities.  Clearly, lawns, as typically managed in the United States, more resemble the highly disturbed end of the landscape gradient, although often  much greener in the growing season as a result of irrigation and fertilizing.  Nudging our yards along  towards the less disturbed end of the gradient is not necessarily a major chore and can be approached in different ways.  More about this later.               

 

Lawns- a few numbers to ponder

Lawns  |  a few numbers to ponder:

From the Environment Protection Agency  (epa.gov), we learn that an American family of four  uses 400 gallons of water per day; about 30% of that is used outdoors. Over half  of the outdoor  water is used for irrigating lawns and gardens. The total water use nationally for this purpose is more than 7 billion gallons daily!

Today 30 to 40 million acres are given over to lawns in America, 20 million acres of  which are residential.  Think of what is required to maintain a so-called healthy lawn-gasoline to run the mowers, fertilizer and supplemental water to keep the grass dense and actively growing , pesticides to control plant and animal competitors (designated as pests), and time and effort to keep on top of lawn management. Looking further, fossil fuels are, of course, burned to generate the electric power needed to make the equipment  and to manufacture fertilizer and pesticides (for a lawn that’s the envy of the neighborhood, you’ll need to buy insecticides, herbicides and maybe fungicides, rodenticides and nematicides!). And, of course, anytime fossil fuels are combusted, residual chemicals are emitted into the atmosphere. One estimate is that 5% of the nation’s air pollution is attributable to lawn maintenance. Operating a typical gasoline-powered mower for one hour emits the same quantity of smog-forming hydrocarbons as driving a typical car almost 200 miles.  And, of course, these emissions add to the greenhouse gas loadings that affect our climate.

In citing these figures, we grant  that lawns provide benefits- exercise,  picnics, barreling around on a tractor mower,  jobs, and for some, a reason to be outdoors.  On the other hand there are even more concerns: For example,  wildlife  poisonings.  Over 200 pesticides  are approved by EPA for lawn care although  most applications are restricted to abut 35 of these.  Homeowners use up to 10 times more chemical pesticides per acre than farmers do on crops, according to the U.S. Fish & Wildlife Service. 

Recent Canadian studies found that pesticides applied on farmland may explain three to 14 bird deaths per acre.  In the State of New York, testing of dead birds provided for West Nile Virus assessment  in 2001 found that, of the more than 80,000 birds tested,  the leading cause of avian deaths was pesticide poisoning not the virus (ens-newswire.com/wp-content/uploads/2010/05/2001-06-22-06.html).  Other concerns include insect pollinators (especially bees and  butterflies) essential for many crops such as squash and tomatoes, which are declining across much of the country.  One of chief causes appears to be pesticides. Fish and amphibians also are apparently declining and pesticide applications are partially responsible (ehhi.org).

Much more could be said about confirmed and suspected impacts of lawn-applied chemicals upon aquatic and terrestrial  environments.  There is considerable controversy over the efficacy of treatment approaches recommended to home owners  and over  the effects upon non-target species and ecosystems.  In fact, it is a vast topic, which does not include  human health effects and well water contamination which are  real concerns but  beyond the purview of this site. I mention only that at least the state of Connecticut has recognized the need to prevent pesticide applications (with exceptions for mosquitoes and biting or stinging insects) in and around day care centers and schools (www.cga.ct.gov/2005/act/Pa/2005PA-00252-R00SB-00916-PA.htm). And  lastly, what  about all that noise! Couldn’t  less intrusive mowers, blowers, pruners and power saws be offered in the market (electric mowers are quieter, of course, but are limited to small lawns on flat terrain and still fossil fuel-based)?

Here are a few simple approaches to advancing your yard to a point where it can begin to be thought of as habitat for plant and animal wildlife.  The first photograph shows a patch of a native wild flower that can succeed in lawns without becoming a “problem”. It is growing  in a portion of a lawn that has not been subsidized via pesticides, fertilizer, or water for at least seven years.  Yes, the photo is taken in the late summer of central Florida when rain is plentiful. But the patch has also gone through the hot dry season each year  when water is limiting. And by late April, water stress effects will be evident.  But with the rainy season, growth recovers nicely.  The site was mowed once every several weeks roughly from May through October.  Six  plant species are visible here in a patch of 500 cm2 competing with the grass but not overwhelming it and  forming a much more diverse and to my eyes, more pleasant view.

1lawnQuer

The photograph centers on the rosettes of Erigeron quercifolius, a native biennial  that produces pleasing aster-like flowering heads and succeeds in the coastal plain of Georgia and Florida where lawns are not mowed too closely. In the spring-summer flowering period, the plant bolts to about 20 cm high. Because it tends to occur in groups mowing can avoid them at this period. The plant produces seeds which can be collected or left to disperse, and then dies, limiting any invasive tendencies. Its first year is spent as a basal rosette shorter than most mowing heights. Comparable species are likely to be available in other states.

The second photo shows the tiny Dichondra carolinensis, a stoloniferous species of the morning-glory family that gets along well with lawn grasses where there’s some protection from summer sun and and , of course, from  herbicides. Throughout the southeastern coastal plain this species will thrive where soils are wetter and shadier than optimum for grasses. 

Dichondra

Where trees are present, possibilities multiply.  Beneath hardwood trees, lawns generally fail even if sparse grass plants hang on. Fortunately they can be replaced by ferns which are perennial, shade-tolerant, need no fertilizer and are naturally pest-resistant. Below see  two ferns, a Nephrolepis and a Thelypterus established at the base of a live oak in a central Florida yard. This  small patch of semi-natural habitat has been observed to give shelter and,or food to anoles, toads, Black Racers, Florida Brown Snakes, gray squirrels, birds, and invertebrates. 

Each of the photographs has illustrated three simple ways a lawn can be given greater interest and diversity while at least decreasing if not eliminating some of the fossil-fuel derived lawn maintenance products conventional lawns depend on. 

Fernsandoak