GROWTH, BROWSING AND MORTALITY IN MIXED OAK AND PINE PLANTINGS

The purpose of this project was to determine if different oak/pine arrangements elicited potential beneficial interactions that affected seedling growth, mortality and overall protection from deer browsing. Northern red oak (Quercus rubra L.) and shortleaf pine (Pinus echinata Mill.) were planted together and alone in six different planting patterns and spacings, replicated over three blocks in recent clearcuts in east Tennessee, USA. Each block consisted of two monocultures planted at a 3.0 by 3.0 meter (m) spacing and four multi-cropped treatments planted at varying spatial arrangements (0.3 m, 1.0 m, 1.5 m, and 3.0 m) from neighboring shortleaf pine seedlings that were planted on a 3.0 m X 3.0 m grid. Each block was located on a distinct site with its own aspect and slope position. Seedlings were planted in late winter in 2018 and measured in the spring of 2019 and 2020. Height in centimeters (cm), root-collar diameter (cm), and presence of deer browsing were collected for live seedlings. In general, differences in these variables among treatments were not statistically significant except for deer browsing analyzed in the first-year measurements. The 1.0 m treatment appeared to have an influence on the level of deer browsing observed on the northern red oak seedlings. The lack of significant differences in nearly all areas of interest can also suggest there may be minimal negative effects to tree species in multi-cropping systems. This study was designed to build from previous research that investigates if multi-cropping treatments can improve the overall health and resiliency of a forest from the adverse effects of a shifting climate or increasing stress from insects or diseases. This study is also the first installment of a multi-year research project focused on detecting possible synergistic trends between northern red oaks and shortleaf pines.