Fire as a Once-Dominant Disturbance Process in the Yellow Pine and Mixed Pine-Hardwood Forests of the Appalachian Mountains

Abstract

In the southern and central Appalachian Mountains, dendroecological techniques conducted on fire-scarred trees in the yellow pine and mixed pine-hardwood forests of the Appalachian Mountains have shown that widespread fires burned about once every 7 years (range from 5 to 13 years) from the mid-1700s until 1925–1945 when a policy of widespread fire suppression was introduced and human-ignited fires were greatly reduced. This recent absence of fire has contributed to major changes in tree establishment rates, structural changes in forest stands, and changes in species composition. Major pulses of establishment in the first half of the twentieth century feature tree species that are shade-tolerant and fire-intolerant, replacing species adapted to repeated fires. Southern pine beetles have also dramatically reduced the abundance of yellow pines in xeric upland forests in recent decades. Yellow pines soon may be lost as a major component of Appalachian pine-oak forests as the forest floor develops a thick litter layer covered by ericaceous shrubs that were historically controlled by fire, especially on dry, low quality sites such as ridgetops and south- and southwest-facing slopes. Efforts to restore these pine/mixed hardwood ecosystems by reintroducing fires may be ineffective as land management agencies face forests best characterized as hybrid landscapes where effects of fire are largely unknown.