Forest response to a tornado on the campus of the Univesrity of Maryland

Background/Question/Methods

Natural disturbances provide environmental heterogeneity and allow contrasting successional stages to exist within a forest.  In 2001, a tornado struck a 22 acre tract of forest at the northern end of the University of Maryland campus in College Park, MD.  This area is commonly used for teaching and research by the campus, so this event provided a unique opportunity for students to observe forest succession.  The purpose of this study was to examine the manner and extent of forest regeneration in the affected area, and to determine the effect of the tornado on woody plant species diversity and forest composition.  

Transects were established both outside and inside the path of the tornado, and six 0.1 ac circular plots were set in each transect at a distance of 100’ from plot center to plot center.  Within the plots we identified and recorded the number of each species and its DBH.  We also determined species composition and estimated cover of the shrub canopy.

Results/Conclusions

Overall the forest was characterized as a mixed oak-beech forest typical of the piedmont of Maryland.  Species richness was greater in the disturbed transect with 30 species compared to 25 in the undisturbed transect, and tree density averaged 104 vs. 35 trees per plot (including saplings) for the disturbed vs. undisturbed transects.  The average tree size (DBH) was 5.7 cm in the disturbed transect and 13.2 cm in the undisturbed transect.  Shrub cover was greater in the disturbed transect.  Species diversity of woody plants was also found to be significantly greater in the disturbed transect vs. the undisturbed transect.  Despite differences in the number of classic early and late successional species between transects, the overall forest composition was fairly similar.  Regeneration of oaks was high in the disturbed transect, suggesting the future mature forest composition will be similar to that found in the undisturbed transect.  The predicted rapid return to an oak forest from an early successional forest type is probably a result of the narrow path of the tornado and the minimal gap opening in the forest.