Stand-replacing disturbances associated with storms in mature forests are traditionally seen as events that revert forests to early stages of succession. Many mature upland forests historically were fire-dependent open woodlands. The closed-canopy conditions seen today are a product of many years of fire suppression. Hence, the extent to which such communities transition to early stages of succession following a major disturbance may be an artifact of fire suppression. Furthermore, following storm damage, land managers are often compelled to quickly initiate timber recovery operations, which may have qualitatively different effects on vegetation than the storm itself. Here, I present initial (2-yr) results of a study of the effects of tornado damage and the combined effects of tornado damage and salvage logging on groundcover plant communities in mixed oak-pine forests in north central Mississippi. Replicate 10 x 30 m plots divided into eight subplots were established in salvage-logged areas adjacent to pre-existing plots in unsalvaged areas spanning a gradient of storm damage intensity. 

Results/Conclusions

Principal coordinates analyses revealed a modest effect of the storm on groundcover composition. Most change was attributable to a post-storm increase in the native disturbance indicator, Erechtites hieraciifolia, near tip up mounds, a dramatic increase of a perennial grass indicative of upland forests, Chasmanthium sessiliflorum, away from downed crowns, significant increases in a few open woodland indicators, and declines in two parasitic species indicative of mesic forests. Flowering of many open woodland indicators, which were frequent before the storm, increased as a result of damage to the canopy. Pre- and post-storm compositional differences were small compared to differences between salvaged and unsalvaged plots. Salvage logging apparently resulted in a dramatic increase in many species indicative of disturbed habitats at the expense of upland forest indicators. I hypothesize that tornadoes historically had small impacts on groundcover vegetation in non-successional, open-canopy fire-maintained woodlands and suggest that the more substantial post-storm changes typically seen in upland forests today are largely an artifact of past fire suppression and post-storm salvage logging.