Precipitation and pollution interaction effect on the abundance of Collembola in hardwood forests in the lower Midwestern United States

The Collembola communities were studied in ecologically analogous oak–hickory forests in the Ohio River valley, USA, along a long-term atmospheric sulfur and nitrogen deposition gradient in Illinois, Indiana and Ohio. We found 71 Collembola species among which families of Onychiuridae and Isotomidae were the most abundant. Species diversity in study sites was not affected by atmospheric deposition. However, changes in the relative abundance of acidophilic and acidophobic species paralleled the deposition gradient. Total Collembola abundance was not adversely affected by the atmospheric deposition alone when the region received normal precipitation levels. Total numbers of Collembola were reduced by 50–85% in the high deposition sites compared to low deposition site during the drought period in the lower Midwestern United States in 1989 and during summer 1990. Collembola abundance was not adversely affected in the high deposition sites compared with a low deposition site when all sites received normal precipitation amounts. Results of the study suggest that total Collembola abundance can be adversely affected by the interaction of drought and pollution stress factors.