Nature Bulletin No. 377-A April 11, 1970
Forest Preserve District of Cook County
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation
Illinois is the Prairie State. Perhaps we should not mention it here but
the curious fact is that some of our original midwestern prairies were
actually preserved as such by fire -- fires started every spring by the
Indians to drive out the game hidden in that tall thick growth; fires to
deprive their enemies of cover through which they might creep
unobserved. Trees and shrubs grew along the streams, on wooded
knolls or ridges, and in occasional "oak openings", but any woody
seedlings that managed to get started in the adjacent prairie were
killed by fire. The prairie plants survived because the sod was so thick
and they were largely perennials with deep root systems or had other
protective habits of growth.
In the Chicago region, in autumn and early spring, it was customary
for people to burn off vacant lots in built-up areas and set fire to the
grasslands in outlying subdivisions where there were but a few
scattered homes. When it was windy and the vegetation thick and tall,
these became leaping crackling flames that raced faster than a man
can run. Some fires spread into nearby forest preserves and did
irreparable damage Thousands of acres were left black and bare.
It was a foolish dangerous custom. It originated from the mistaken
notion that fire destroys the weeds and gives desirable grasses a better
chance to grow. In outlying subdivisions, isolated home owners burned
to "improve" the pasture for their cows, goats or other livestock and,
also, to protect their homes against fires started accidentally or by
mischievous youngsters when the men were away at work.
It is far better to mow such vacant lots and meadows in early fall, and
rake or plow a narrow firebreak around adjacent buildings. The
mowed vegetation protects the soil and, as it decays, adds humus and
fertility. Burning robs the topsoil of its fertility, kills the valuable
forage plants such as bluegrass, clover and timothy, and actually
increases the growth of quackgrass, weeds, and other unwanted,
troublesome, perennial plants -- most of them introduced from foreign
lands. Many of these have hardy seeds so well protected that they are
not destroyed by fire; or vigorous rootstocks that remain undamaged.
There was a time when burning was also advocated as means of
controlling insect pests. It is now known that burning encourages them
by destroying beneficial insects, such as those that prey on other
insects, and by destroying the necessary cover and food for ground-
nesting birds such as the meadow lark, horned lark, bobolink, the
native sparrows, killdeer, spotted sandpiper, quail, pheasant and
marsh hawk. Some of these, and their young, feed largely on insects.
Grasshoppers, and other insects pass through the winter as eggs within
the soil where fire cannot reach them. Others hibernate there as pupae.
White grubs and wireworms burrow below the frost line. Many insect
pests harmful to crops -- such as the army worm, chinch bug, corn
borer and others -- burrow deep into large plant stalks which
frequently are not consumed by a grass fire.
admittedly, was an ally of the native plants in our original
prairies but only a few remnants of them remain. In their place we
have many pesky worthless weeds and grasses from other countries
Annual burning helps these spread and replace the valuable Plants we
need. Fire is their friend.
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Update: June 2012