INITIAL CHANGES IN SPECIES COVER FOLLOWING SAVANNA RESTORATION TREATMENTS IN WESTERN IOWA

Study areas in the Iowa Loess Hills were used to evaluate short-term responses of understory species to three treatment methods designed to facilitate restoration of Quercus macrocarpa savanna. Treatments included burning alone, burning with thinning, and burning with clear-cutting. Plant abundance and diversity were compared before treatment and one year after treatment. Ninety-nine plant species were identified during the study, of which 40 were new following treatment, although most of these were forest associates. Increases in diversity of understory species were observed after treatment, particularly in plots with combined burning and thinning. The forb group was most consistent in response to treatment, increasing in cover an average of9% in burn-only plots to 33% in burn-clear plots. Carex spp. and Eupatorium rugosum were the species most consistently responsive to treatments, but responses varied widely among other species. Density of canopy tree species generally did not decline with burning, indicating fire alone is ineffective in short-term removal of established trees. Although short term, our results suggest that a combination of prescribed burning and thinning of canopy trees is most likely to provide environmental conditions suitable for increasing the amount and diversity of herbaceous species comparable to a savanna ecosystem, while also increasing fine-fuel loads that will facilitate future prescribed burning