PS 97-157
Overstory vegetation in long-term monitoring plots at the University of Mississippi Field Station

Friday, August 14, 2015
Exhibit Hall, Baltimore Convention Center
Marjorie M. Holland, Biology, University of Mississippi, University, MS
Background/Question/Methods   The University of Mississippi Field Station, comprised of land in the Eocene Hills, was opened in 1985.  Within the property are various types of natural and human-produced habitats, including numerous fish ponds, which were converted from swamp-like terrain.  When the property was purchased, the University acquired these ponds as well as 334 additional hectares of pine and mixed hardwood forest, bottomland forest, open fields, wetlands, ponds, and springs.  Generally, the land was left untouched, and vegetation was allowed to fill areas of the Field Station that had been artificially cleared.  In 1994 an ice storm killed many trees due to the weight of the ice on their trunks and branches, resulting in weakened immune systems of many pines, and allowing the invasion of pine bark beetles.  Many of the damaged pines were harvested in 1995, leaving large open bare areas throughout the Station.  In 1996, the graduate-level Plant Ecology class established 20 long-term monitoring plots with the goal of following the recovery of the Station's woody vegetation by measuring frequency, density, and dominance of vegetation within the plots, and calculating importance values for each species.  Botany classes have continued overstory sampling through 2013.

Results/Conclusions    Overstory vegetation was sampled every three to five years from 1996 to 2013.  Throughout the sampling period, the woody species with the highest importance values are Liquidambar styraciflua, Pinus echinata, Pinus taeda, and Quercus alba.  Sweetgum [Liquidambar styraciflua] is often a pioneer species, and became well established in three of the five plots that were totally cleared in 1995.  In fact, sweetgum specimens have been so important in erosion control that their importance values have increased from 9 in 1996 to 14 in 2013.  Species richness has increased from 20 woody species when sampling began to 36 in 2013.  The four most dominant tree species have effectively shaded seedlings of other woody species during the hot Mississippi summer months, allowing saplings of other species to grow into the overstory.