We conducted a 10-year study in oak-hickory stands in the Arkansas Ozarks to investigate the effects of intermediate thinning and nitrogen (N) fertilization on the annual production of understory vegetation. A total of 101 experimental plots was thinned to residual overstory densities of 40%, 60%, 80%, or 100% of full stocking. Nitrogen fertilizer (336 kg N/ha) was applied to a subset of plots in each thinning treatment. Understory species composition and biomass were estimated 1, 2, 3, 5, and 10 years after treatment. Thinning and fertilizing increased (P < 0.01) the total biomass of understory plants and production of preferred browse species through the first 5 years after treatments. Fertilized plots thinned to 40% of full stocking produced 392 kg/ha of preferred browse, a 5-fold increase over control plots. Peak understory production occurred in the third year after thinning and the second year after fertilization. Production of total biomass and preferred browse was declining on all plots by the fifth year, as overstory canopies closed. Thinned plots continued to have significantly higher understory production through the tenth year, but fertilizer effects were not evident after the fourth year.
