Tree growth in temperate forests of the USA Mid-South

Background/Question/Methods: The University of Mississippi Field Station (UMFS) is located in north Mississippi, and 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 harvesting infected trees 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 sampled on a regular basis. Study objectives are: (1) to survey overstory plants of the UMFS, (2) to measure growth using increment borings of tagged trees in forested plots, and (3) to examine the overall health of tagged trees. Within 20m x 20m plots, overstory vegetation was identified and basal area was determined. Once tree specimens were cored, comparisons were made between upland and lowland individuals of the same species.

Results/Conclusions: Sampling results in 1996 indicated that the dominant overstory species was Liquidambar styraciflua, followed by pine saplings [P. echinata and P. taeda], Quercus alba, Quercus stellata, and Sambucus canadensis. By 2013, the dominant overstory species were Liquidambar styraciflua, Pinus echinata, Pinus taeda, Acer rubrum, and Quercus alba. Increment borings were obtained from common trees in six plots in 2007, and obtained from the same trees, where possible, in 2018. All species measured occur in both lowland and upland plots. The 2007 comparisons indicate that Diospyros virginiana and Liquidambar styraciflua had higher growth rates per year in upland plots, while Juniperus virginiana, Pinus taeda, Quercus alba, and Quercus falcata had higher growth rates per year in lowland plots. By 2018, Liquidambar styraciflua was the only species with higher growth in upland plots. Within all plots there was a decrease in density among all species during the most recent sampling.