Restoring a Savanna: Report on a Prescribed Burn

by Ezra Staengl

April 5, 2022

Smoke plumed into the sky, and trees crackled and popped as they were consumed by the roaring fire.  It was difficult to see through the smoke to the top of a small hill where the burn was happening, but occasionally massive tongues of flame flickered into view, reaching high into the sky.  Devin and I stood along a small creek that marked one firebreak on my family’s property in northern Albemarle County, wondering if we needed to change plans to better control the fire.  The prescribed burn was a thrilling first step in what my family hopes will be an effective, inspiring, and educational journey towards restoring an acidic oak-hickory savanna, but at that moment I was feeling a bit tense. 

When my family bought the property in December 2020, almost the entirety of its 22 acres was planted with young loblolly pines (Pinus taeda) of varying densities.  We determined from growth rings that most of the pines were about seven years old, a conclusion supported by aerial imagery.  Aerial imagery from 2013 shows the property covered in mature loblolly pines.  Those pines are completely cleared by the 2016 imagery.  It’s likely that the young pines were planted immediately after the old ones were logged, sometime between 2013 and 2016.  Looking farther back in time, the older pines seem to be present on the property since the oldest available imagery, from 1996.  However, significant thinning, as well as soil disturbance around the current house site, is visible in the 2005 imagery.  Regardless, the property has been under loblolly pine cultivation for many years. 

Although loblolly pine may have been historically native to parts of Albemarle County, it is not a significant component of local grassland ecosystems.  Instead, local savannas and woodlands would have historically contained other species of pines, as well as oaks and hickories.  Many of these species are present on our property as small seedlings under the loblolly, including shortleaf pine (Pinus echinata), Virginia pine (Pinus virginiana), southern red oak (Quercus falcata), post oak (Quercus stellata), scarlet oak (Quercus coccinea), and mockernut hickory (Carya tomentosa).  The native herbaceous vegetation under the loblolly pines is also dense and well developed in places on the property.  Although we have not yet had the chance to quantitatively assess the vegetation, incidental surveys have already revealed many interesting species.  Broomsedge (Andropogon virginicus) is dominant throughout the property, and is joined in places by poverty oatgrass (Danthonia spicata), and a large array of panic grass species (Dichanthelium sp.), thoroughwort species (Eupatorium sp.), and goldenrod species (Solidago sp.). 

It’s unclear how long this assemblage of grassland flora has existed under the pines, but it seems possible that the periodic disturbance associated with loblolly pine cultivation may have allowed a grassland plant community to survive and develop on the property since before the first pine planting.  Since many grassland plants are intolerant of soil disturbance as well as shade, this would also require that pockets of the property had been spared from the heavy machinery used in timber harvest.  It’s possible that there are elements of grassland flora on the property that represent a remnant of a larger savanna from precolonial times.  However, there’s also no doubt that the property has been subject to heavy disturbance in recent years, so it’s also likely that much of the grassland flora present is of more modern origin. 

The primary purpose of the burn was to re-introduce the disturbance regime to the property historically responsible for the maintenance of grassland ecosystems in our region.  Speaking generally, fire has a critical regenerative effect on grassland plant communities.  It recycles nutrients from old vegetation back to the soil.  It limits the development of woody vegetation, which ensures that enough sun reaches the herb layer to support the rich array of herbs characteristic of these types of communities.  It also cleans out old vegetation and woody debris, which allows sunlight to reach the ground, a necessary factor for the germination of many grassland plants.  Other plants actually need the heat of fire in order to germinate — table mountain pine (Pinus pungens)  is one well known example, although admittedly a plant more associated with the Blue Ridge Mountains than the Piedmont.  In the context of our restoration project, we hoped the burn would control woody vegetation (including the loblolly) and promote the germination of grassland plants, and in so doing increase the species richness and diversity of the developing grassland plant community. 

My family worked hard to prepare for the burn over the last year, thinning the loblolly stands by at least 50% and cutting and raking 8-foot-wide firebreaks around the perimeter.  Our driveway formed a firebreak on one side of the property, while a small stream with hardwoods on either side was utilized on another.  The remainder had to be cut through the young pines, and the broomsedge cut low and raked away.  On the day of the burn, we helped the CUH crew leaf blow small sections of the firebreak through the hardwoods to connect the creek to the pines, and then we were ready for ignition. 

We started the burn at the corner of our driveway and the parking area, in a small patch of broomsedge under loblolly pines.  At first the fire burned calmly, but then a loblolly flared up, sending flames 20 feet in the air.  The first few moments were nerve wracking, but slowly the fire consumed all the available fuel along the firebreak and began to move deeper into the burn area.  CUH staff walked ahead of the fire with drip torches, igniting clumps of particularly volatile fuel so that the fire would be calmer when it reached them.  Eventually we split into two teams, so one team could start burning along the firebreak on the other side of the property before the main fire reached it. 

When the fire was done, we walked slowly back over the hill that used to be covered in loblolly pine and broomsedge, where Devin and I had watched some of the most intense fire behavior from the creek.  Now the pines were leafless black skeletons standing over a barren landscape of gray ash.  Stumps and logs still smoked in some places, but it was hard to tell how intense the fire had been here only moments ago.  It was inspiring to think that from the destruction around us would come the regeneration of a beautiful plant community.  I’m excited to see what plants respond to the fire, and how different the landscape will look in only a few months.