The effects of overstory retention on species composition and height growth following clearcut and group selection regeneration harvests in the Missouri Ozark Highlands

Abstract

The objectives of this study focus on whether treatment and aspect significantly influence tree regeneration. This study utilizes data from 16-year-old clearcuts and group openings within the Missouri Ozarks to assess the height and quantity of regenerating tree species. Additionally, a qualitative review of the efficacy of height reference charts developed by Vickers et al. (2017) was completed. Analysis of the sampled population revealed that trees had significantly greater mean heights within group openings compared to clearcuts, and the mean height of trees regenerating on protected slopes was significantly greater than trees on exposed slopes. The white oak group had significantly greater mean heights on protected slopes compared to exposed slopes and in group openings compared to clearcuts. Red and white oaks had significantly more individuals within clearcuts compared to group openings. When only trees within the tallest ten percent (90th percentile of height) of all sampled individuals were analyzed, there were significant differences in mean height and trees per hectare for regenerating oaks between the two treatments and aspects. Specifically, there were significantly more oaks above the 90th percentile within clearcuts, but oaks were significantly taller within group openings compared to clearcuts. Review of the height reference charts developed by Vickers et al. (2017) show that the charts can be effectively used to assess the 90th percentile of 16-year-old trees within clearcuts. Trees growing within group openings analyzed with the reference charts show that there were consistent differences from the data collected and the charts developed for clearcuts. For example, the red oak species group measured within group openings was consistently below the 90th percentile threshold shown for clearcuts, and white oaks within group openings on exposed slopes were taller than the expected 90th percentile line. Therefore, reference charts should be developed specifically for trees within group openings.