Managed ecosystems cover the greater part of the global land area and have the greatest potential to alter [CO2]. They facilitate the use of manipulable variables and help to detect new insights into the effects of e[CO2] on plant growth, development and processes in the soil.
FACE studies now provide our most realistic estimates of how ecosystems in the open will respond to the atmospheric [CO2] predicted for the middle or end of this century. They are our best validation data for models predicting the responses of managed ecosystems and natural vegetation to this ongoing change. Production changes and other effects due to elevated [CO2] in FACE differ significantly from observations made in chamber and greenhouse studies, suggesting that responses are signigicantly modified in protected environments and that models parameterized from such data might be in serious error.
Elevated [CO2] affects ecosystem processes via a multitude of mechanisms at different timescales. The relationships between the C and N metabolism in the plants and the N availability in the soil are key factors that influence the direction and magnitude of the response of ecosystems to a [CO2]-enriched atmosphere.
Projections of ecosystem responses to elevated [CO2] must incorporate the reality of multiple factor influences. Many suggestions in this volume guide to the development of testable hypotheses for experiments which could provide basic information for predictive computational models. The findings have important implications for public policy decisions and adaptations of management systems.
KeywordsLeaf Photosynthesis Global Change Biol Plant Stand World Resource Institute Soil Organic Carbon Sequestration
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