Effects, interactions and consequences of air pollutant cycling in ecosystems

Atmospheric pollutants affect terrestrial ecosystems through a variety of mechanisms and over a wide range of time scales. Ozone and other gasses that enter ecosystems through leaf stomates typically have short-term effects on plant physiology, but can also cause longer-term feedbacks throughout other components of the system. Nutrients and acidic compounds that enter soils can alter important underlying site conditions, but years or decades can elapse before measurable effects are detected. Further, because some pollutants can exacerbate or offset the effects of others, studies that address interactive effects are greatly needed, if difficult to undertake. Finally, although pollutants such as nitrogen and ozone can appear independent in terms of their ecological consequences, linkages in their formation and chemistry should translate to coupled effects when viewed over broad spatial scales. This talk will discuss these and other related issues using examples from the ecological literature and a specific case study of multiple stress effects in the Northeastern U.S.