Effects of Mowing and Raking on Collembola

On a patch of prairie near Northfield, Minnesota, four treatment factors (early mowing and raking, late mowing, raking, and fertilizing) were each applied or not applied to plots of a quasi—Latin square. Five epigeic collembolan species (Entomobrya bicolor, Orchesella ainslei, Tomocerus flavescens, Lepidocyrtus cyaneus, Isotoma viridis) were shown to have noncongruent but overlappihg distributions on the plots. Early mowing and raking raised the number of E. bicolor, Arion fasciatus (a slug), Labidostommid mite, Lycosid spiders, and spiders in general, O. ainslei and L. cyaneus decreased, as did a species of Oribatid mite (family Belbidae). Late mowing decreased the numbers of E. bicolor, O. ainslei, I. viridis, and harvestmen but increased the number of spiders. An interaction between early mowing and raking and late mowing resulted in a decrease in E. bicolor and an increase in O. ainslei. Regression analysis indicated that slope (topography) was a good predictor of the numbers of E. bicolor. O. ainslei, and T. flavescens, positively correlated for the former, negatively for the latter two species. The number of I. viridis was positively correlated with the density of other species. The number of L. cyaneus had a high, but nonsignificant, correlation with the productivity biomass ratio. Total collembola had a significant negative correlation with standing crop (but the multiple correlation coefficient was not significant). It was hypothesized that the five collembola are competitors whose areas of residence expand and contract with seasonal climatic change because of competitive interaction and changes in their microclimate and environment.