This title for this essay was inspired by an infamous phrase quoted by war correspondent Peter Arnett. Bến Tre City had been heavily bombed and shelled in an effort to drive out the occupying Viet Cong, and an unnamed officer remarked that “It became necessary to destroy the town to save it.”
How is that relevant? Every year, smoke rises from forests in the coastal plain. Some folks might be appalled to see forest managers with drip torches, running strings of fire through their woods. It looks like a case of destroying the woods, but we really are trying to save it.
In south Georgia we have the remnants of an ecosystem maintained through natural and man-caused fire (The former by lightning, the latter by Native Americans and later by the settlers who supplanted them). The longleaf pine, one of our more fire-tolerant trees, thrives in a community which is not only well-adapted to frequent fire, but encourages its spread. Depending on where the particular habitat is, there may scores of plant species mixed together: bunch grasses, legumes, wildflowers and other forbs– including many not found anywhere else. The fauna of these communities are equally rich and varied, and include a number of grassland birds such as bobwhite quail, meadowlarks, field sparrows, and indigo buntings. Some threatened and endangered plants and animals are only found in this ecosystem.
What brings these species together to form a community? In the highly competitive natural world, resilience to fire gives these species an edge over others. Vegetation that can survive periodic burning enjoys the benefits of abundant sunlight and less competition; highly flammable parts such as dried grass and pine needles actually promote a fire’s spread. The insects, birds, reptiles, and mammals present here have evolved to exploit the local vegetation’s bounty of seeds, fruit, and accompanying insects; those animals who aren’t fleet enough to escape the flames will utilize burrows or make their own (literally hundreds of species of invertebrates, reptiles, mammals and even birds will find shelter in gopher tortoise burrows).
Now, you’ve probably seen the western fires, with roiling smoke and flames tearing through the treetops. That’s not what we’re talking about here. Generally speaking, we see low-intensity fires in frequently-burned longleaf forests – flames rising to three or four feet high. The grasses, fallen pine needles and other detritus act as fuel to carry fire across the landscape, killing hardwood seedlings and any other plants that aren’t adapted to fire (and occasionally some that are – survival of the fittest and all that).
What happens when you take fire out of the equation? First, some plants require fire to stimulate a good seed crop; without regular burning, the seed source dries up, meaning no seedlings, and no seeds for birds and small mammals. Shrubs and hardwood trees, which are easily damaged by flame as seedlings, now can grow and spread, shading out the forest floor. A hundred plant species fade away, replaced by a dozen or so shade-tolerant forbs and vines. Long-lived species such as the gopher tortoise hang on, able to eke out a living for decades without being healthy enough to reproduce. Last to go are the scattered long-lived pines whose seeds are unable to survive on the shadowed forest floor. I have nothing against hardwood climax communities, but the open forest community is rare enough, easily lost, and nearly impossible to bring back in any time scale humans would appreciate.
Southern longleaf forests aren’t the only ecosystems maintained by fire. For the prairies of North America, fire is perhaps the greatest defense in the war against woody invaders. Wetlands such as the Okefenokee would cease to be if fires didn’t burn down the peaty build-up in times of drought. Where fire comes less frequently, it may level whole stands, but even then it heralds renewal.
Fire destroys. Life renews. In some landscapes, the balance between destruction and renewal is so fine-tuned that you find forms of life here that can’t survive under calmer conditions.
For More Information:
The Long Leaf Ecosystem from the Longleaf Alliance
“Fire Slow, Fire Fast, Fire Deep”, a lecture by Stephen Pyne on the podcast “Seminars About Long-Term Thinking”
Looking for Longleaf: The Fall and Rise of an American Forest by Lawrence S. Earley