The effects of burning and other prairie management techniques on the growth of Rubus flagellaris at Pine Rock Nature Preserve

During the past few decades fire has been recognized as an important factor in maintaining prairie plant communities. Spring prairie burning in several locations has indicated that this practice may increase production by certain prairie plants, due to removal of litter and release of nutrients. This study was conducted at Pine Rock Nature Preserve in Ogle County, Illinois, which is a heterogeneous area with respect to agricultural history, soil types, and vegetational associations. The preserve supports fine populations of native prairie species which have begun to invade formerly plowed areas, but a number of woody species including Dewberry (Rubus flagellaris) have overtaken large sections in the northeast quarter of the area, forming dense thickets. R. flagellaris is a low-growing woody shrub which each year sends up a number of biennial canes from subterranean crown and lateral root buds. Spring burning during dormancy was found to have stimulatory effects on the growth of dewberry thickets. Burning increased the density of stems, possibly due to removal of litter and improved conditions for seed germination. Increased densities were also recorded for the next season after the burn. Burning was responsible for higher biomass per plot during the season after each spring fire. These increases were undoubtedly due to increased absorption of nutrients, since nutrient levels in the plants of each plot were higher than untreated plots. Two herbicides were tested for their effectiveness on Dewberry and both defoliated the plants, but the mixtures in oil produced more stem kill. Several other methods of controlling R. flagellaris offer promising alternatives to these techniques but require more research so that a management plan for the preserve can be developed quickly.M.S. (Master of Science