Physiological implications of anthropogenic environmental calcium depletion
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In: The Tree 2000. Isabelle Quentin Ed. IQ Press, Montreal: 295-300.
Recent evidence indicates that numerous anthropogenic factors can deplete calcium (Ca) from forested ecosystems. Although it is difficult to quantify the extent of this depletion, some reports indicate that the magnitude of Ca losses may be substantial. The potential for Ca depletion raises important questions about tree health. Only a fraction of foliar Ca is physiologically important and labile, but this Ca exchanges membrane structure and function, and serves as a second messenger in the perception of environmental signals. Ca signaling may initiate plant response and defense systems that function to maintain plant health in the face of environmental change. Acid deposition leaches Ca associated with mesophyll plasma membranes (mCa) in red spruce (Picea rubens). This loss destabilizes cell membranes and increases their susceptibility to the foliar freezing injury responsible for red spruce decline. Acid-induced perturbations of mCa and membrane stability also occur in other tree species, and soil-based treatments can limit mCa accrual and membrane integrity. These findings suggest that mCa disruptions may be more pervasive than the direct acid-induced foliar alterations noted for red spruce. We hypothesize that disruptions of biologically available Ca may impair tree stress response systems, and compromise tree responsiveness to otherwise inconsequential stresses.
Borer, Catherine H.; Schaberg, Paul G.; DeHayes, Donald H.; Hawley, Gary J. 2001. Physiological implications of anthropogenic environmental calcium depletion. In: The Tree 2000. Isabelle Quentin Ed. IQ Press, Montreal: 295-300.