Building Soil in the Forest Preserves
Nature Bulletin No. 561-A April 5, 1975
Forest Preserve District of Cook County
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation
BUILDING SOIL IN THE FOREST PRESERVES
The Little Red Schoolhouse nature center stands on worn-out soil in a
tract of land that, before its purchase in 1921 by the Forest Preserve
District, had been farmed since about 1840. In its old fields and
woodlands you can see some interesting examples of how nature, given
protection and lots of time, gradually heals man-made scars and
rebuilds soils that he has plundered. The preserves are protected against
fires and from grazing by livestock. The interiors are protected against
damage by automobiles and intensive human uses, such as picnicking,
by confining them to the borders. Nature does the rest.
The great forests, fertile grasslands and cultivated fields of America
were made possible by long, long processes of living and dying by
untold generations of plants and animals. In the clearing west of the
schoolhouse and the old orchard, you can see the beginnings of such a
When we acquired that sloping old field, almost all of its topsoil was
gone -- washed downhill -- and it became a weed patch dotted with
young sumacs and hawthorns from seeds dropped by animals. Weeds
are nature's scar tissue. They hold soil particles in place and prevent
erosion. They hold moisture and reduce the runoff of rainfall and
melting snow to harmless trickles. Their roots create channels that let
moisture and air into the soil. They pave the way for grasses and
legumes which they shade and protect until established .
Along the west edge of that field there used to be a fire lane, plowed to
protect the adjacent woods but abandoned because the raw mineral clay
was eroding so rapidly that a gully had been started. Parts of this strip
are thinly clothed with three pioneers of the plant world: lichens,
mosses, and poverty grass. The lichens, primitive plants which grow
where nothing else will, came first. They appear to be merely greenish-
gray crust-like patches but, if you look closely, they are studded with
stout little stalks. Those are the fruiting bodies that produce spores. On
the Pixy Cup lichen each stalk has a tiny funnel-like cup at the top. On
the British Soldier lichen, each stalk has a scarlet cap. Poverty grass,
so-called because it is found only on barren soils, followed the lichens
and the mosses. It grows in clusters of greenish-gray curly blades.
Eventually the seeds of other plants will sprout and grow.
The woods, too, have made a comeback since we acquired them almost
40 years ago. Until then they had been grazed by livestock and burned
over frequently "to make better pasture." There were no wildflowers, no
tree seedlings, no shrubs. Many trees were dead or badly damaged. The
hard-packed clay ground was bare. Today those woodlands have a
healthy understory of seedlings, saplings, shrubs and vines. In spring
they are carpeted with wildflowers. Beneath the litter of fallen leaves,
twigs, and other bits of dead plants is a dark layer of decaying and
decayed vegetation -- teeming with fungi, bacteria, insects and other
kinds of soil life -- manufactured from the litter of other years.
Plants depend upon soil. Soil depends upon the plants that build it,
enrich it and protect it. Man and his animals depend upon plants. We
are no richer than the soils on which we tread.
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Update: June 2012