COEFFICIENT OF CONSERVATISM

The “CC” value given to a native plant suggests the plant’s “fidelity” to a particular habitat. It serves as an important mathematical tool to gauge the “purity” of a piece of land.

We have roughly 3,000 different plant species growing in Missouri.  Many of them are not growing in the same place they were before shovels and plows cut through the soil. Some plants don’t care – they’ll grow anywhere. But other plants are finicky and will only grow in their favorite, undisturbed habitat. When those finicky plants are missing, it means that the habitat has changed.

Some pieces of land might look pristine. Other pieces of land might be littered with tires and old washing machines. But don’t be fooled. It’s very possible that the pristine land used to be a parking lot, while the junk-strewn land has never been touched with a shovel. It’s like a forensic lab. If you can read the plants, you can read the history of the land. The trick is to know which plants are the “finicky” ones.

In the 1990’s a couple of far-sighted Missouri field botanists (Douglas Ladd and Justin Thomas) assigned each of our Missouri plants a so-called “CC value” – a numeral from 0 – 10.  Click HERE to find that published list of Missouri plants and their CC values, called the “Ecological Checklist of the Missouri Flora for Floristic Quality Assessment“. (The list is found between pages 32 and 109.)

During the growth of the environmental movement of the 1960’s and 1970’s, there was a drive to preserve natural areas.  But with limited funds, it was important to know which areas of land were most worthy of preservation. 

In the mid-1970’s, Illinois botanist Gerould Wilhelm developed a mathematical tool to quantify the “quality” of a piece of land – that is, how much disturbance it had suffered.  His insight was that the plants themselves can tell us the extent of land disturbance (such as whether the land had ever been plowed), or whether it is a true, undisturbed remnant.  This word “remnant” – a remaining unspoiled bit of land – is sacred to conservationists.  Once a remnant is gone… it’s gone.  Here’s a wonderful interview with Gerould Wilhelm (the father of Floristic Quality Assessment) who explains it all: VIDEO (1:15:17)

Wilhelm assigned each plant a numerical value of 0-10 (known as its “Coefficient of Conservatism” value – abbreviated to “C of C” or “CC” or simply “C”).  This value reflects the fidelity a plant has to its particular habitat.  

Plants with a high fidelity (say, CC values of 5 and higher) have an increasingly “you and you alone” attitude towards a habitat.  High-fidelity plants are likely to be the true natives of a habitat – plants that were growing there before the first foreign settlers arrived.  

In contrast, plants with a low fidelity (say, CC values of 4 and lower) have an “I ain’t picky, this is good enough for me” attitude towards a habitat.  They’re happy to hang their hats anywhere.

​In addition to “fidelity”, there’s another way to think of a “CC” value: intolerance to change

Plants that are more intolerant of change (say, CC values of 5 and higher) are increasingly “finicky” about their habitat (recall the fairy tale “The Princess and the Pea“).

In contrast, some plants are just fine with change (say, CC values of 4 and lower).  They’re Jacks-of-all-Trades.  “Clay? Sand? Sure, I can do it!”  “Dry? Swampy? Sure, I can do it!”  “Sun? Shade? Sure, I can do it!”  “Tune your piano? Remove your gallbladder? Sure, I can do it!” 

Illinois has its own list of plants with their own CC values.  Missouri has a somewhat different list of plants with a somewhat different set of CC values.  These differences are expected because the habitats are different.

Once a region has created its list of CC values, magic can happen.  Any piece of land can then be surveyed to determine which plants are growing on it.  The “CC values” of those plants can then be plugged into a mathematical formula to assess the so-called “Floristic Quality” of that land.  Just by looking at a piece of land, it’s hard to tell its history of disturbance.  But although our eyes may get fooled by looking at a piece of land, the plants won’t. Their presence or lack of presence will give us concrete, objective numbers to work with.

What gives plants this power to choose between quality remnants and disturbed sites?  It’s because there’s so much going on underground.  When the finicky specialists can’t tolerate the underground conditions and are forced out of an area, the tolerant Jacks-of-all-Trades move in for business. And once they’re in, they might never leave.

If a farmer plows a natural area, the threadlike networks of fungal hyphae that live in the soil will get torn apart.  This will create a huge chain reaction affecting the other soil microorganisms and disrupting the soil food web.  The bacteria will likely become dominant and change the soil chemistry – maybe even the soil structure itself.  The “finicky” plants will probably disappear because they can’t tolerate such soil changes.  The finicky plants (those with high “CC” values) seem to depend on a special balance of fungi, bacteria, protozoa, nematodes and other creatures that live in the soil.  When that balance disappears, so do they.  In their place come the generalists, the weedier plants (those with low “CC” values).  Once a habitat is disturbed and the dependent, obligate plants leave, it is possible that neither they nor the habitat will ever fully return. 

“CC” values are very important to the conservation of our lands.  A plot of land with plants of higher “CC” values is more “native”, more pristine, more valuable to conservationists, and worthier of preservation than a plot of land that only has plants of low “CC” value.  Sure, there is subjectivity involved.  Probably everybody feels that this or that plant should have a different “CC” value.  But the accuracy of the “Coefficients of Conservatism” system comes not from the “CC” value of this or that plant, but rather from the overall value of the many different plants that grow in a habitat.  Like county fair participants trying to guess how much the hog weighs or how many jellybeans are in the jar, it’s the “wisdom of the crowd” that shows us the way.  “CC” contributes to conservation by giving the public a practical mathematical tool for deciding which land should be preserved as a park and which land should be allowed to become a Walmart parking lot.

– Michael Laschober

​Justin Thomas gave a wonderful Zoom presentation on this topic.  The title of his webinar (1:36:00) was “Plants in Place: the Nature of Native“.  Hopefully a recording of it can still be found on this MONPS webpage.

​For free online calculators that can solve floristic quality equations:
Universal FQA Calculator 
Pennsylvania Land Trust