Mineral stress: the missing link in understanding how global climate change will affect plants in real world soils

Many natural and agricultural ecosystems are characterized by sub-optimal availability of mineral nutrients and ion toxicities. Mineral stresses are likely to have important, complex, and poorly understood interactions with global climate change variables. For example, most terrestrial vegetation is supported by weathered soils with some combination of low P, low Ca, Al toxicity, and Mn toxicity. Each of these stresses has complex, yet distinct, interactions with global change variables, making it very difficult to predict how plants in these environments will respond to future climate scenarios. Important, yet poorly understood, interactions include the effects of transpiration on root acquisition of soluble nutrients, particularly Ca and Si, the effects of altered root architecture on the acquisition of immobile nutrients, particularly P, the effects of altered root exudate production on Al toxicity and transition metal acquisition, and the interaction of photochemical processes with transition metal availability. The interaction of Mn toxicity with light intensity and other global change variables is discussed as an example of the complexity and potential importance of these relationships. Current conceptual models of plant response to multiple resource limitations are inadequate. Furthermore, substantial genetic variation exists in plant responses to mineral stress, and traits improving adaptation to one stress may incur tradeoffs for adaptation to other stresses. Root traits under quantitative genetic control are of central importance in adaptation to many mineral stresses. An integration of quantitative genetics with mechanistic and conceptual models of plant response to mineral stresses is needed if we are to understand plant response to global change in real-world soils. (C) 2004 Elsevier B.V. All rights reserved.