By Dr. Tara Keyser, Southern Research Station, USFS
October 18, 2016 at 1pm central
Co-hosted with the Consortium of Appalachian Fire Managers & Scientists
Management on public lands across the eastern US is increasingly focused on the restoration of resilient structures and species compositions, with prescribed burning being the primary tool by which many landscape-level restoration efforts are implemented. In Appalachian hardwood forests, where altered disturbance regimes have contributed to an increase in shade-tolerant species and concomitant decrease in the relative abundance and competitiveness of oak species in the forest understory, prescribed fire is often recommended as a treatment that enhances the development of desirable oak species.
In 2002, three study sites (200 – 300 ha) were established on the Cumberland Plateau in eastern KY. Each site contained three treatment areas (58 – 116 ha) which were randomly assigned to one of three treatments: Frequent Fire (FF); Less Frequent Fire (LFF); Fire-Excluded (FE). Within each treatment area, 8 – 12, 0.04 ha subplots were established, with each subplot classified by moisture class (subxeric, intermediate, or submesic). At each subplot in 2002 and 2015, advance reproduction (<3.8 cm dbh) was enumerated by species into three size classes using a 0.004 ha plot. Size classes were: (1) small seedlings (stems <0.6 m tall), (2) medium seedlings (≥0.6 m and <1.2 m tall), and (3) large seedlings (≥1.2 m tall and <3.8 cm dbh). Prescribed fires were conducted in 2003 and 2009 (LFF treatment) and 2003, 2004, 2006, and 2008 (FF treatment). No burning or silvicultural manipulation occurred in the FE treatment. A randomized complete block experimental design with a split-split-plot treatment structure was used to test the effects of treatment, moisture class, and species (five species groups) on the tree seedling layer. Long- term changes in the abundance of understory tree species in response to fire frequency are presented, and potential effects on future species composition will be discussed.