Effects of Microsites Created by Selective Harvesting on Growth of Microstegium vimineum in a Central Hardwood Forest
Disturbances related to silvicultural activities are inevitable and may facilitate the spread of established populations of exotic species. Microstegium vimineum is an annual exotic grass that has spread throughout the eastern United States. Different categories of understory microsites resulting from cutting and the operation of logging machines within three selective harvest units were identified and characterized by measuring several environmental variables. M. vimineum was sown within the microsites categorized. Differences in growth of M. vimineum across different microsites were quantified. As percent canopy cover increased, M. vimineum percent cover, mean length, and mean number of nodes decreased. Also, as litter depth increased, M. vimineum percent cover and stem length decreased. In undisturbed microsites in which M. vimineum was not sown, the exotic grass was not a dominant species, whereas in all other microsites created by logging machine operation M. vimineum was a dominant species whether those areas were sown or colonized by wild populations. These results suggest that unique microsites created by logging may facilitate M. vimineum invasion of central hardwood forests. The apparent connection between soil and canopy disturbance and invasion by M. vimineum provides further impetus for careful planning and use of haul roads and skid trails.