Why Fire Is Needed

for the Survival of the Animals and Plants 
of Tallgrass Prairie, Savanna, Woodland, and Wetland 

To put it simply, we will certainly lose an important part of the genetic heritage of planet Earth if we don’t give needed fire and other good care to our remnant natural ecosystems. Currently, we are losing them. 

The quickest answer to the question “Why do they need fire?” is that thousands of species and ecosystems have been adapted to burning for millions of years. 

Many people ask for details to help understand, and scientists are gradually discovering them, so, here are some examples:

• A burned prairie produces twice the biomass and many times the weight of flowers and seeds in a year after a burn compared to any other year.

• Fire recycles nutrients and invigorates many important species of bacteria, algae, fungi and other less visible but crucial components of the ecosystem. 

• Because the thatch of unburned vegetation insulates the ground from warming sunlight in no-burn years, the growing season during those years is two or three weeks shorter.

• Many species of plants only or mostly flower and set seed after a burn. Many species of animals depend on the rich diversity of plants (leaves, flowers, or seed) that survive and flourish only in regularly burned areas. 

• Many species of problem brush and weeds are controlled by fire. Burning helps diverse nature and eliminates or reduces most invasives.

One way to convey the difference is to show some before and after photos, like those below:

The first photo shows dense buckthorn brush that grew up where a high-quality prairie was left unburned for decades:

That prairie is lost and gone, choked out by these invaders, but below is a similar one that was restored by fire and seed:

After a burn (left) - and what then emerges in a savanna (right):

Fire maintains health in both the grassland and woodland components of the savanna. Without it shrubs and trees (including "native" to the region species like box elder, maple, and basswood) gradually shade out and kill off the thousands of species of animals and plants of the savanna.  

For diagrams that show how fire is controlled, see Endnote 1. 

Below are some comments from some of the Midwest's best authoritative sources. Experts know fire is needed. Most people don't. We need more and better education.

Doug Ladd, director of science and stewardship for The Nature Conservancy of Missouri, wrote about fire and the conservation of prairies and woodland. 

Here flourish long-lived, deep-rooted perennial plants annealed by the frequent Native American fires, searing summer droughts, frigid winters, episodes of intensive grazing and trampling, and rapid, recurrent freeze-thaw cycles that exemplify the Midwest. These plants in all their varied magnificence in turn support myriad animals ranging from minute prairie leafhoppers that spend their entire lives in a few square meters to wide-ranging mammals and birds that travel hundreds or even thousands of miles in a season.

And of the woodlands Ladd wrote:

Our original Ozark timberlands, also shaped by fire, climate, and water, have much of their flora directly descended from the grassland biome.

Gerould Wilhelm, at the top of the list with the most respected Illinois conservation botanists and author of Plants of the Chicago Region and Flora of the Chicago Region, wrote in the latter of a savanna habitat:

These natural areas cannot sustain without regular implementation of fire. In a savanna system, the sun is the most important criterion for the plants to grow and reproduce and hence for the insects to sustain and reproduce. When observing an intact savanna, one only has to squint his eyes and observe a wash of yellow from the blooms of the Amaryllidaceae, Asteraceae, and Orobanchaceae (in June when Hypoxis and Krigia bloom and in August when the Aureolaria, Helianthus, and Solidago bloom) that fill nearly every space. This is a savanna! The insect community that depends upon this habitat is spectacular, and we have only just begun to understand it. (in his discussion of Hieraceum gronovii)

 About a now-rare species of the oak woods, he wrote:

Now uncommon and extirpated from many stations where it once was frequent, this species occurs in rich wet to mesic woodlands, including seeps. It thrives in regularly burned mesic savannas and open woodlands that consist primarily of Quercus alba. (Trillium flexipes)    

And about another:

For years we had a hard time determining the native habitat of this plant, but with the burning of our woodlands in recent years, it has become apparent that this species is conservative to oak savannas. Such habitats had all but disappeared by the 1970s and 1980s, so where we found it most often was at the edges of paths and clearings in remnant, albeit degraded, woodlands. (Cirsium altissimum)   

Rich Henderson, a highly-respected conservation researcher at the Wisconsin Department of Natural Resources, wrote in the context of a report on a 20-year study of the regal fritillary butterfly:

Tallgrass prairie, arguably the most fire-dependent system in North America, is a Biome that has been essentially eliminated and is now exceedingly rare. … Regal fritillary butterflies (Speyeria idalia) exemplify this problem, with sharp population declines in recent decades … Habitat quality was one of the most important factors explaining populations and was positively associated with prescribed fire. Burning every 3-5 years maximized regal fritillary abundance, but even annual burning was more beneficial to regal populations than no burning at all. Unburned refugia are important in maintaining populations, but creating and maintaining high quality habitat with abundant violets (Viola spp) and varied nectar sources, may be the most impactful management and conservation tool. 

 

For references to and details about the above statements, see Endnote 2.

More local details on ecosystem fire in northern Illinois 
can be found in these blog posts:  

A horrifying, shameful (but ultimately a good news story) about what happens if you leave one of Illinois’ most important biodiversity preserves unburned for ten years:
https://woodsandprairie.blogspot.com/2014/08/survivor-langham-island.html
 
And one uplifting story about grassroots folks coming to the rescue of a very long and narrow prairie:
https://woodsandprairie.blogspot.com/2020/12/cameo-old-plank-road-prairies.html
 
How fire is needed for the biodiversity of animals as well as plants:
https://woodsandprairie.blogspot.com/2017/02/campaigns-to-save-oak-animals.html

Endnotes

Endnote 1: How exactly do you do this?

To burn, legally and safely, you need expertise, equipment, a crew, and permits. 

But if you'd like to understand the principle of how fire is controlled, the diagrams below may help. They illustrate a small burn with minimal equipment and a small crew. 

In drawing a, the crew lights the fire at the downwind edge. Note wind direction indicated by arrow. Then the burn boss sends two teams to draw fire along the upwind side of the fire break. In this case the firebreak along the top and left sides of the diagram are footpaths. On the bottom, the break is a road. On the right, it's a line mowed to make the needed break. 

In drawing b the crew (perhaps in each case one person with a drip torch, one person with a water backpack pump, and one to four people with "flappers" have completed a "backburn" on the upwind edge and are starting "flank fires" or "side fires".  

In drawing c, the flank fires are nearly complete, the burned-out areas are widening, most of the crew stays close to the drip torch, because that's where the most attention is needed, because the burning grass is closest to the area that you don't want to burn. The main job of the person with the drip torch is to keep any eye on all the crew and all possible concerns, to go slow enough to assure safety and fast enough to get the work done efficiently, and to re-direct the crew if some concern arrises. Note that one or more people keep an eye on the downwind edge as long as needed. 

In drawing d, the short flames of the back and side fires have coompleted wide breaks along the three edges of concern, and the "headfire" is started along the bottom edge. 

In drawings e and f, the headfire is completed and its larger flames rapidly move with the wind. Most work is now done, but the crew stays alert. This is especially true in a woodland fire, where a dead tree may ignite and threaten to fall across the firebreak. The crew looks for potential problems and deals with them.

As was planned, in drawing g, the backfire and headfire come together and extinguish. After the fire, the crew re-checks the edges, stows all the gear, and discusses how we all did and what we could learn. Some folks talk with any interested observers during this "teachable moment" - to assure there's good understanding of what may have looked like a very dramatic event. 

Larger burns would have larger crews and possibly an ATV or two with a large-capacity water sprayer and long hose. 

Endnote 2. Expert Citations and Links 

Doug Ladd's important essay on natural areas values and needs can be found on page 4 and 5 here and in another context here. 

Gerould Wilhelm's comments refer to hairy hawkweed, declined trillium, and tall thistle. His books are:

Swink, Floyd and Gerald Wilhelm, Flora of the Chicago Region. The Morton Arboretum. 1994

and

Wilhelm, Gerould and Laura Rericha, Flora of the Chicago Region. Indiana Academy of Science. 2017.

Rich Henderson's study of the regal fritillary butterfly can he found here or at: 

"Disentangling effects of fire, habitat, and climate on an endangered prairie-specialist butterfly"
• February 2018
•  in Biological Conservation 218(12):41-48. 
• DOI: 
• 10.1016/j.biocon.2017.10.034
• 
  

Acknowledgements

Fire diagrams courtesy of the Tallgrass Restoration Handbook, edited by Stephen Packard and Cornelia Mutel, Island Press, 1977.

Thanks for proofing, edits, and suggestions to Rebeccah Hartz, Eriko Kojima, and Christos Economou.