Monday, March 04, 2013

Prescribed Burning

After the rain during the previous weeks, last week turned out to be a good week to burn with the season drawing to a close.  At Audubon's Francis Beidler Forest, we were able to burn two tracts, as was the Charleston Audubon and Natural History Society at their McAlhaney Nature Preserve.  Charleston Audubon posted images and descriptions of the procedures and goals for their burning.

As we have noted in previous posts, the main purpose of burning forest land is to reduce the fuel load and prevent disastrous wildfires like the one near Myrtle Beach four years ago.  Whether by lightning or careless human activity, forests will burn at some point.  Not only does less fuel equal a less intense fire, some ecosystems, like the Longleaf Pine savanna, have evolved with periodic fire and require fire to maintain their health.

The first site we burned was the Longleaf Pine restoration tract we planted in January 2007.
Longleaf restoration site preburn - Mark Musselman
Longleaf restoration site preburn - Mark Musselman
Longleaf restoration site (wiregrass) preburn - Mark Musselman
It appears that fire is essential for production of viable seed by these plants. Wire grass may actually be the most important, if not the most obvious, species in a longleaf pine savanna, because it is the plant that produces most of the fuel for the fires that sustain the community. Longleaf pines themselves do not produce enough fuel to keep their “home fires” burning. If it weren’t for wire grass and the fires it sustains, the savannas would cease to exist. That is exactly what happens when fire is suppressed in these communities. -- Carolina Environmental Diversity Explorations

Starting fire with drip torch - Mark Musselman
Drip torches containing a 4:1 mixture of diesel to gasoline were used to set the fire on the downwind side of the stand, which allowed the fire to burn into the wind at a slower, steadier pace than if the fire were started on the upwind side of the stand.
Burning into wind - Mark Musselman
A fire break was plowed around the entire stand to ensure the fire did not migrate beyond the stand's boundaries and interior dirt roads allowed the stand to be burned in seven separate sections.  However, in the event that fire were to find a way across a break, volunteers were ready to extinguish the flames by smothering the fire with flappers or shoveled soil or by spraying the errant fire with water.
Volunteers Howard Bridgman and Paul Cooler - Mark Musselman
Although ascetically unattractive immediately after the burn, wiregrass and forbs will quickly begin to sprout producing an enhanced habitat for wildlife like wild turkeys, bobwhite quail, and fox squirrels.  Longleaf Pine benefit from the elimination of competing hardwood tree species and the reduction of fuel on the ground, which if allowed to accumulate could generate a fire too hot for the Longleaf Pines to withstand.

Longleaf restoration site postburn - Mark Musselman

The next day we burned a Loblolly Pine stand at the northern end of the Francis Beidler Forest.  The 37 acres were divided by fire breaks into three unequal units.  We began with the smallest (3 acres) to see how the fire would travel through the stand.  The fire burned slowly into the gentle west wind.

Loblolly Pine stand preburn - Mark Musselman
Recent rains kept the site moist and east-west running furrows between the rows of planted pine kept the fire from burning south to north.
Loblolly Pine stand preburn - Mark Musselman
Loblolly Pine stand slowly burning - Mark Musselman
Fire burned slowly and steadily where not stymied by standing water.

Loblolly Pine stand slowly burning - Mark Musselman
In the end 75-80% of the fuel was burned across the site.  In drier areas, the burn rate was 100%, while other areas (image below) did not burn in the low, wet areas.

Loblolly Pine stand postburn - Mark Musselman

Both burns successfully accomplished our goal of fuel reduction and exceeded our expectations considering the moist conditions.  However, hazards remain until all the hot spots are extinguished and all of the equipment is properly stored back at the center.  There is little room for error when driving the ATV up the ramp into the bed of the pickup.  Pushing the accelerator lever instead of gripping the brake lever results in spectacular damage to the toolbox and quality entertainment for the bystanders.  To quote Homer Simpson, "Doh!"

ATV vs toolbox - Mark Musselman

No comments: