Understory vegetation composition at the University of Mississippi Field Station

Background/Question/Methods: The University of Mississippi Field Station (UMFS) is located in north Mississippi approximately 18 km northeast of the Oxford campus. Acquired by the University in 1985, the Station includes pine and mixed hardwood forest, bottomland forest, open fields, springs, ponds, and wetlands. In 1995, the UMFS experienced a pine bark beetle infestation which led to unavoidable harvesting in several areas of the Station. The following year, a georeferenced 100m x 100m coordinate system was established, and 20 randomly chosen Long Term Monitoring Plots [LTMP] were established and have been sampled on a regular basis, with the most recent dataset completed in 2016. Study objectives are: (1) to survey understory vascular plants of the UMFS, and (2) to observe vegetation changes since the 1995 harvesting. Within 1m x 1m quadrats, understory vegetation was identified and percent foliar cover was visually determined. Once all quadrats were sampled, importance values were calculated by summing relative % cover and relative frequency. Data were gathered by undergraduate and graduate botany or plant ecology classes.

Results/Conclusions: Sampling results in 1996 indicated that the dominant undertory species was Lonicera japonica (a non-native invasive), followed by Eleocharis obtusa, Galium tinctorum, Panicum anceps, and 69 other species. By 2016, the dominant understory species were Chasmanthium laxum and sessiliflorum, Leersia oryzoides, Lonicera japonica, Microstegium vimineum, Vitis rotundifolia, and 89 other species. Importance values of Lonicera japonica decreased between the 1996 and 2016 sampling periods and appear to have stabilized, whereas Vitis rotundifolia (a native species) has increased in importance over the 20 year sampling period. Microstegium vimineum (an aggressive non-native invasive) had not been collected by botany professors Thomas Pullen or M.B. Huneycutt prior to 1996, appeared in one LTMP in 2004, and had spread to eight plots by the end of the 2016 sampling. Our suggestion is that monitoring of these eight plots continue for at least another decade, with annual supervised removal of Microstegium vimineum. In the most recent sampling, understory foliar cover decreased which is likely the result of shading of understory species as the overstory became more fully developed.