The Fell-and-Burn Technique

The "fell and burn" technique was developed by Abercrombie and Sims (1986) as a low-cost, post-harvest site-preparation tool for pine-hardwood ecosystems in South Carolina. This technique uses prescribed fire in combination with properly timed felling of unmerchantable trees (Abercrombie and Sims 1986; Phillips and Abercrombie 1987).  As the name suggests, "fell and burn" treatment consists of two steps. After clearcutting hardwood or pine-hardwood stands, residual stems over 6 feet tall are felled with chainsaws. Felling is conducted during early spring following full leaf development when carbohydrate reserves in the roots are low. The presence of leaves on the felled trees also serves to speed the drying of small twigs and branches. Burning is conducted in mid-summer within 24 to 48 hours after a soaking rain, to ensure that a residual forest floor and root mat will provide protection against erosion and that heat penetration into the soil will be minimal. Pine seedlings are planted the following winter. In the southern Appalachians, shortleaf pine or white pine is planted, often at a 10 x 10 foot spacing. In the piedmont, loblolly pine is often planted at a wider spacing.

The fell-and-burn technique allows planted pines to become established by controlling hardwood growth (Danielovich and others 1987). Studies have shown that this treatment also increases the density of other non-planted pine species typical of the southern Appalachian sites (pitch pine, Virginia pine) (Vose et al.1994, Clinton et al.1993). In addition to restoring the commercial viability of these stands, this treatment may also be an effective means of restoring pre-existing (i.e., before fire suppression) levels of species composition and productivity (Clinton et al. 1993, Clinton and Vose 2000).

Despite the usually numerous amount of hardwood sprouts following fell-and-burn treatments, pine survival is high (over 90% and 75% after 1 and 4 years, respectively) and pines are taller than competing oaks (Phillips and Abercrombie 1987). Sprouts that develop after chainsaw felling are forced to develop from below ground buds and are less vigorous because they are top-killed. Another advantage of this technique is that burning removes over 65% of the woody fuels less than 3 inches in diameter (Sanders and Van Lear 1987), making the site more accessible for planting. Often the primary objective of the fell-and-burn treatment is to reduce the competitive influence of mountain laurel sufficiently to allow planted white pine and hardwood sprouts to become established. However, Clinton and Vose (2000) point out that prescribed fire rarely completely eliminates mountain laurel, and therefore competition for light and other resources may intensify over time.

Studies have shown that the fell-and-burn technique has few adverse effects on soil. For example, although burns can remove much of the surface forest floor, most of the root mat remains (Danielovich 1986). Root mats act similar to mulch, increasing water holding capacity, reducing evaporation, and preventing erosion. Other studies have shown that the fell-and-burn technique does not cause significant erosion (Van Lear and Danielovich 1988, Swift et al. 1993). Lack of erosion following is attributed to large stems and stumps acting as debris dams, vigorous shrub and herbaceous regrowth, and burning under moist conditions so that the root mat remained intact. Swift et al. (1993) also reported other benefits of this treatment including increased soil moisture and increased soil temperatures. Clinton et al. (1996) found that losses of aboveground N pools were large following a fell-and-burn treatment in the Nantahala National Forest, losses which equaled or exceeded N losses expected from whole-tree harvest. Despite these above-ground losses, forest floor N was 90% of its pretreatment amount. Knoepp and Swank (1993) found that the same burn increased available soil N (NH₄) but found little movement of dissolved inorganic N off site during the first year after burning.

The fell-and-burn technique was first developed as a less expensive alternative to pine plantation management that would attract private landowners to put their unmanaged stands into timber production. During 1988, the total cost of regenerating by the fell-and-bum technique was less than $100 per acre, including site preparation and planting costs (Phillips and Abercrombie 1987). More recent estimates of the fell-and-burn technique range as high as $250 per acre; BROKEN-LINK BROKEN-LINK stand replacement fires have been suggested as a lower-cost alternative (Vose and Swank, 1993).