POTENTIAL EFFECTS OF CLIMATE-CHANGE ON AQUATIC ECOSYSTEMS OF THE GREAT-PLAINS OF NORTH-AMERICA

The Great Plains landscape is less topographically complex than most o ther regions within North America, but diverse aquatic ecosystems, suc h as playas, pothole lakes, ox-bow lakes, springs, groundwater aquifer s, intermittent and ephemeral streams, as well as large rivers and wet lands, are highly dynamic and responsive to extreme climatic fluctuati ons. We review the evidence for climatic change that demonstrates the historical importance of extremes in north-south differences in summer temperatures and east-west differences in aridity across four large s ubregions. These physical driving forces alter density stratification, deoxygenation, decomposition and salinity. Biotic community compositi on and associated ecosystem processes of productivity and nutrient cyc ling respond rapidly to these climatically driven dynamics. Ecosystem processes also respond to cultural effects such as dams and diversions of water for irrigation, waste dilution and urban demands for drinkin g water and industrial uses. Distinguishing climatic from cultural eff ects in future models of aquatic ecosystem functioning will require mo re refinement in both climatic and economic forecasting. There is a ne ed, for example, to predict how long-term climatic forecasts (based on both ENSO and global warming simulations) relate to the permanence an d productivity of shallow water ecosystems. Aquatic ecologists, hydrol ogists, climatologists and geographers have much to discuss regarding the synthesis of available data and the design of future interdiscipli nary research. (C) 1997 by John Wiley gi Sons, Ltd.