Fire on the Mountain, Fire in the ‘Burbs
I walked out of the house Thursday morning when my nose detected it – a forest fire! Having worked for two years in the piney woods of southwest Georgia, I had become accustomed to and, actually, come to love forest fires. That classic line kept coming into my mind, “the scent of fire in the morning reminds me of healthy forests.” The scent can be better than a campfire. It can be a little sweeter. That morning, it filled the entire town. Firefighters were just beginning to quench the fire. As of Saturday night, it had burned about 40 ha (ca 100 acres), but was still uncontained on its northern end. I might have been one of the few people to be thrilled to be in a smoke-filled town. It reminded me that we lived in a heavily forested area, and an active ecological event was playing out just up the hill.
It was fascinating to see the coverage of this fire. There were many resources thrown at it. It is understandable. Clausland Mountain is beautiful, beautiful enough that it is ringed by expensive houses. Twenty-six fire units, composed of about 150 firefighters, were actively fighting the fire (about one fire unit for every 1.5 hectares (3.8 acres)). Two helicopters were brought in to douse the flames. The breathless words of the reporter are fascinating as well, “remote areas” and “extremely dangerous.”
The large response is what happens in the wildland-urban interface, especially outside of one of the largest cities in the world. The conflict between humans and ecological processes has been on the rise as we move out into natural areas and as we become more aware of important ecological processes that maintain ecosystems and the services they provide for humanity. Fire is one of these processes.
So, Sunday we went on a hike to see the impact of the fire. Bushwhacking, we went into the northern end where the fire was still smoldering (though the fire took care of many bushes). It is steep and the ash makes the slope a bit slippery. Much of the leaf litter was consumed, though not completely. In some places, logs were consumed down to the mineral soil. Death shadows are evident. The potentially severe rainstorms approaching from the west should put out the fire. (Update: they did.)
It will be interesting to see how the forest responds. Fire is an important ecological process. It reduces the disease and pest load in an ecosystem; it is an antiseptic in a way. It favors some plants more than others. Like me, fire favors blueberries! Oak trees in the eastern United States do not seem to be regenerating very well over the last 40-50 years. The re-introduction of fire is today’s response to a lack of oak regeneration. Much money is being spent on prescribed fires and education about fire. The lack of oak regeneration seems complex. It is said that the rise of mesophytic species, the species “taking the place” of oak, is changing the forest in such a way that it ecologically dampens the forest, making it hard for fire to take hold. However, the re-introduction of fire doesn’t seem to be having its hypothesized impact – oaks still do not seem to be regenerating in experiments employing fire, while mesophytic species seem to be handling the fire pretty well. Important for the context of this ecological scenario, many changes have occurred in the forest over the last 50-100 years, all of which could be a factor of a reduction in oak regeneration – increased deer populations, loss of important megafauna, and changing land-use and cultural patterns (Hello Smoky Bear!). And, climate change might be playing a direct role in the “mesophication” of the East.
One physical mechanism has been detected – flammability of and differential drying of forest fuels (leaves). Fire is a very physical process. The variation in forest fuels, especially the finer fuels that carry fire in wetter regions, plays an important role in flammability. Thinner leaves absorb moisture more easily. Large, curling leaves, especially lobed leaves, dry faster. Curling leaves make the duff (or “litter”*), the fuel layer, fluffier, allowing better oxygenation of fire, to literally fuel the fire even more. One hypothesis for why eastern forests burn less is the loss of the great American icon, the American chestnut tree. Research by Morgan Varner supports this hypothesis.
It will be especially interesting to see how the Clausland forest responds to this fire. It is getting much wetter in this part of the world. Deer populations are high because of the high human density and the amount of forest preserve in the county (there is no hunting in the area, and deer have learned home gardens are a smörgåsbord). And, the diversity in this little patch of woods is pretty amazing. On our 0.5-mile hike, if that (our 2-year-old doesn’t hike great yet), I spotted 13 major broadleaf tree species, one conifer, the fading eastern hemlock, and two small tree species (I wasn’t even trying to seek out species; there must be more). Amazingly, yellow birch, a boreal species more common to the Adirondacks, New England and southeastern Canada, is mixed in with pignut hickory and sweet birch, species more common to Virginia.
The understory might respond a little differently, though in the little patch we hiked, the wineberry looked just fine. Guess we’ll have to go back out and hike a little more next spring. Shucks.
A pictorial of the aftermath of the November 2013 Clausland Mountain fire.
We met a colleague and his wife on the trail. They were out to check out the fire. They live near the burn and watched the fire grow and the efforts to stop the fire. She noted that it was like a ring of fire. Absolutely!
* = really? Can we get rid of the term “litter”? Fallen leaves, twigs, branches, bud scales, etc., enrich the soil by returning nutrients back to the Earth and increasing the soil’s ability to retain moisture. If that is “litter,” call me trash.