Tuesday, 18 November 2003: 8:30 AM
Plant Community Response to Prescribed Fire and Thinning in the Southeast Missouri Ozarks
Several decades of fire suppression, grazing, and timber removal in Missouri Ozark forests have led to increased fuel loading and altered plant community composition and structure from pre-settlement times. The build-up of fuels in the understory may represent an increasingly hazardous condition for the human population, and the effect on plant communities is virtually unknown in this region. A study examining the efficiency and effectiveness of prescribed fire and thinning as fuel reduction tools on upland sites was initiated in the southeast Missouri Ozarks in 2001. Vegetation plots were established throughout 12 stands in each of 3 replicate blocks (36 stands total) to monitor the ecological effects of no treatment, fire, thinning, and a combination of fire and thinning on the overstory, understory, and ground flora plant communities. The study was stratified across north facing (protected) slopes, south facing (exposed) slopes, and ridge tops to discern the relative influence of topographic position on the treatments and on the resulting vegetation. Prior to treatment, overstory communities in all topographic positions were dominated by black oak (Quercus velutina) and white oak (Q. alba), and had relatively low diversity and evenness. Understory woody vegetation was dominated by red maple (Acer rubrum) on northern slopes, white oak (Q. alba) on ridges, and sassafras (Sassafras albidum) on southern slopes. Pretreatment differences in the herbaceous and woody understory vegetation were evident by topographic position, but physiognomic group composition was very similar across each aspect. Ground flora communities were consistently dominated by woody tree, shrub, and vine species, which greatly outnumbered herbaceous forb, grass, and vine species in both cover and frequency. Immediate and marked changes in the vegetative structure and species composition resulted from the initial burn, thinning, and combined treatments. Analyses comparing pre- and immediate post-treatment plant community characteristics may provide insight into the viability of using prescribed fire and thinning, not only as fuel reduction tools, but also as tools for ecosystem restoration.