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prairie: relicts and rainfall

I am sending this draft for your corrections and additions by e-mail.  It
will be reconfigured and simplified thereby.  (I do not know how to e-mail
original form of text).  I suggest that you  hit Select All and then Copy,
then switch onto a new sheet on Word.  There it will reproduce as it was
originally configured.  Good luck!

K3 prairie rainfall uptake        990319 /3


PRAIRIE:        RELICTS  &  RAINFALL  UPTAKE

a discussion by e-mail on  prairie@mallorn.com



INTRODUCTION

This is a fascinating exchange.  Here I have tried to extract the wheat from
the chaff.  If I have made errors in transcribing, please tell me at
gstanf@swbell.net

This is how this e-mail exchange started:  09 Mar 1999 18:03:

Mary Jane Hatfield
"I had a message asking for documentation for the statements :
1.   Native prairie soaks up ~12 inches of precipitation/hour
2.   less than 1% of native prairie is left in Iowa

The number I usually hear is "less than 0.1 of 1% or less than 1/2 or 1% of
Iowa's native prairie remains".  I think how they define native prairie is
important in backing these numbers.  Can anyone be of help?
Here are the replies, edited lightly



REMNANT  ACREAGE

James C. Trager
1.  Your State Geological Survey or Department of Natural Resources should
have authoritative maps and figures (and their sources) on the actual land
area of remnant native vegetation. The 0.1% figure sounds right.  Also, a
good estimate of the past extent of prairie might be arrived at by getting
the figures on corn and soybean acreage, since it's mostly original prairie
that has ended up with that present fate.

Brett Roberts
The present acreage of corn and soybean acreage would overestimate the
acreage of original prairie. There is a vast amount of land that is now
devoted to these two crops that formed under forest vegetation. The best way
to get accurate figures is to consult soil surveys and determine the acreage
of soils classified as "Mollisols" these soils formed under prairie
vegetation.. Much of our corn and soybean acreage is grown on "Alfisols" and
were formed under forest vegetation.

Terri Rogers
Daryl Smith has given the statistic that less than 0.1% of native prairie
remains in Iowa.  Daryl has done extensive research into prairie ecosystems
(SMITH Daryl  D. 1992  in  Proc 12th North Amer. Prairie Conf.,  p 195
Tallgrass prairie settlement:  prelude to demise of the tallgrass prairie
ecosystem).






K3 prairie rainfall uptake   990319  /3     p 2



Stephen Louis Winter
The following book chapter gives the figure of 4% of tallgrass remaining.
Steinauer, E. M. and S. L. Collins. 1996.
Prairie ecology - the tallgrass prairie.
In F. B. Samson and F. L. Knopf, Prairie conservation: preserving North
America's most endangered ecosystem. Island Press.
This chapter also has a table that quantifies the historic amount (ha),
current amount, and percent decline for each State and Province in the
tallgrass region. The source of this information that they cite is
Samson, F. B. and F. L. Knopf. 1994.
Prairie conservation in North America.
Bioscience 44:418-421.

Ruth A Green
I know that for Illinois, once there were 22 million acres of tallgrass
prairie; but, today there is approximately 2400 acres or only 0.01%
remaining. NOT 1%, but 1/100 of 1%.

I have documentation for Illinois from the Prairie Restoration Handbook
published by the Illinois Dept. of Natural Resources. I could send a copy of
this publication if I was given this person's address.  I would check with
the other state departments for accurate figures.



RAINFALL  UPTAKE

James Trager
2.  J.E. Weaver's work on uptake of precipitation by prairie in Nebraska is
thoroughly researched, classic and still valid. It is reviewed in his book
"The North American Prairie".

Brett Roberts
Water infiltration of native prairies at a rate of 12 inches per hour?  That
would depend on the soil type and antecedent moisture condition when the 12"
of water would be poured onto the soil.  I am sceptical that there are any
soils, prairie, forest, pasture or other, that could infiltrate 12" of water
in an hour although that might be possible possible on deep, level, sands
that are very dry and have no restricted subsoil layers in the soil profile
The last time that 2" of rain fell in an hour, Noah built an ark!   12" of
rain is about a third of the rainfall for a whole year in most of Illinois;
to see that much precipitation in one hour would be a remarkable event and I
doubt the prairies that are left will infiltrate that much water that fast.

Austin Moseley
Under certain circumstances this can occur. Let me illustrate one.  Our
soil, a vertisol, when it has not rained in several months, forms huge
cracks which widen and deepen to as much as 8 inches across and 5 feet deep.
I have watched the runoff drain, from 1/3 of our 2100 square foot home in a
2 inch event, into one of these cracks and never overflow. (I also think
there are pockets underground, due to the crawdads, but can’t prove this,
yet. )

Further, unique soil formations, called gilgai, which are giant cups
surrounded by ridges, form and deepen in unplowed soil.  In heavy rains
which exceed the capacity for the soil to absorb, these cups will fill up
with water which the soil can then absorb in its leisure.  Given a drought
and gilgai, I dont see why a 12 inch rain, say a hurricane dying over North
Texas, would not be completely captured by a native prairie remnant that is
fairly level.-


K3 prairie rainfall uptake   990319 / 3     p 3



Brett Roberts
I want to stand corrected on the potential of a native prairie to infiltrate
up to 12" of water per hour. I visited with one of my agronomist colleagues
in Missouri who ran some infiltration tests on a Mexico silt loam near
Columbia, Missouri. He ran these tests under three conditions
1. a conventionally tilled corn-soybean field
2. a no-tilled corn soybean field
3. an unaltered stand of native prairie vegetation

He used a device called a ring infiltrometer, which is a metal cylinder that
is depressed partially into the soil surface with 6 inches left above the
ground. He filled the cylinder with water and recorded the time that it took
to soak in.

I don't recall his exact measurements on the conventionally tilled corn and
soybean field but the no-till field had ten times the infiltration.

On the prairie soil, he applied six inches of water which emptied his tank.
By the time he could obtain more water from his truck (parked just 25 feet
form where he ran these tests) to refill the cylinder the water had already
soaked down into the prairie soil.  He refilled the infiltrometer a second
time and went to fetch more water again, and the second six inches soaked in
in just a few seconds! He never did establish an accurate reading on the
infiltration rate of the prairie soil because he couldn't take the readings
because he had to keep getting more water. It is safe to say that this soil
was intaking 12" of water in an hour easily!  An important note is that
Mexico silt loams are claypan soils! That is that they ultimately are
limited in their infiltration due to the impeding clay layer in the subsoil.
The effect that several thousand years of prairie vegetation has on the
porosity of this soil is amazing!


SOME  ADDRESSES


Mary Jane Hatfield   oneota@ames.net

Ruth A. Green, : rgreen@mail.inhs.uiuc.edu
Greenhouse Manager, Supportive Scientist  llinois Natural History Survey,
Office of the Chief Division of the Illinois Dept. of Natural Resouces 172
Natural Resources Building, MC-652 607 East Peabody Drive, Champaign, IL
61820 Office: 217-333-7091 FAX: 217-333-6294

Austin Moseley   amoseley@csac.com

Brett Roberts   brett.roberts@il.usda.gov
State Conservation Agronomist Natural Resources Conservation Service- USDA

Terri Rogers   trogers@hawkeye.cc.ia.us

James C. Trager   jtrager@ridgway.mobot.org
Shaw Arboretum  P.O. Box 38  Gray Summit MO 63039  PH# 314-451-3512

Stephen Louis Winter   swinter@ksu.edu






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