ENVIRONMENTAL RESPONSES OF PLANTS AND ECOSYSTEMS AS PREDICTORS OF THEIMPACT OF GLOBAL CHANGE

An understanding of plant responses to fluctuations in environment is critical to predictions of plant and ecosystem responses to climate ch ange. In the northern hemisphere, the northern limits of distribution of major biomes are probably determined by the tolerance of their domi nant physiognomic types (e.g., deciduous hardwood trees) to minimum wi nter temperatures and can thus be predicted from long-term patterns of temperature fluctuations. At a more detailed level, the responses of functional groups of plants to altered climate can be predicted from t heir known responses to fluctuations in soil resources (nutrients and water) and the expected effect of climatic change on these soil resour ces. Laboratory and field experiments demonstrate the feasibility of t his approach.