As hydrologic changes occur, many inland wetlands will be gradually dried or increasingly flooded. As in the case of boreal peatlands, thle net effects on gas flux have major portent for atmospheric feedback. As in the case of coastal marshes, nutrient and contaminant fluxes will be fundamentally different and are not easily predicted. In addition, changes in biological communities will evoke need for attention to management alternatives appropriate for protection and maintenance of desired resources. Again, the net effect of changing hydroperiod cannot be simulated in mesocosms and requires experimentation at the ecosystem scale.