First-year Effects of Microstegium Vimineum and Early Growing Season Herbivory on Planted High-quality Oak (Quercus Spp.) Seedlings in Tennessee

—Continuing difficulty in the successful natural regeneration of economically important oak species (Quercus spp.) on highly productive sites has led to considerable research regarding the use of artificial oak regeneration to ensure recruitment of oak as an important component of future stands. Two obstacles to the success of some oak plantings in Tennessee are herbivory by white-tailed deer (Odocoileus virginianus (Boddaert)) and competition from an invasive non-native grass, Nepalese browntop (Microstegium vimineum (Trin.) A. Camus). We examined the effects of both deer herbivory and the Nepalese browntop on the first-year growth of outplanted, high quality, locally adapted, 1-0 northern red oak (Q. rubra L.) seedlings on the Ames Plantation in Tennessee. Northern red oak seedlings were outplanted under four overstory treatments (no cut, high grade, commercial clearcut, and two age). Seedling growth, deer browse pressure (defined as browse on terminal or lateral shoots), and herbaceous biomass were monitored monthly through the 2002 growing season. Browse pressure accounted for approximately 67 percent of the variation in total seedling height growth, and exhibited a strong negative relationship with total growth (r = -0.82; slope= -0.48). Additionally, Tukey-Kramer multiple comparison tests detected seedling height differences between the no-harvest treatment as compared with the three harvest treatments. Herbivory was prevalent early in the growing season when the seedlings first flushed, then declined during the remainder of the growing season. Analysis indicated that seedlings with a height of 148 cm or greater escaped browse. Thus, with larger seedlings planted, it may be expected that many seedlings will surpass this “browse line” in the first or second growing seasons. Linear regression revealed a strong negative relationship between Nepalese browntop biomass production and mean seedling height growth (r = -0.74; slope= -0.0046). No differences in Nepalese browntop biomass production were found between treatments (P = 0.29) with first year results, but means ranged from 45 percent in the two-age treatment to 23 percent in the no cut treatment. This range may broaden with additional time and significant differences arise. These results still suggest that canopy disturbance may encourage a growth flush of this competitive species.