CHANGES IN ATMOSPHERIC CIRCULATION PATTERNS AFFECT MIDCONTINENT WETLANDS SENSITIVE TO CLIMATE

Twenty-seven years of data from midcontinent wetlands indicate that th e response of these wetlands to extremes in precipitation - drought an d deluge - persists beyond the extreme events. Chemical changes transc end such simple relations as increased salinity during dry periods bec ause drought provides mechanisms for removal of salt by deflation and seepage to groundwater. Inundation of vegetation zones including roote d or floating mats of cattail (Typha glauca) can stimulate sulfate red uction and shift the anion balance from sulfate to bicarbonate dominan ce. Disruptions in the circulation of moisture-laden air masses over t he midcontinent, as in the drought of 1988 and the deluge of 1993, hav e a major effect on these wetlands, which are representatives of the p rimary waterfowl breeding habitat of the continent.