Wullschleger, S.D.; Lynch, J.P.; Berntson, G.M.


Plant and Soil, Volume 165, Issue 1, p.149-160 (1994)

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As atmospheric CO 2 concentrations continue to increase, so too will the emphasis placed on understanding belowground response of plants to edaphic and climatic change. Controlled-exposure studies that address significance of an increased supply of carbon to roots and soil biota, and consequences of this to nutrient cycling will play a prominent role in this process. Models will also contribute to understanding response of plants and ecosystems to changes in the earth's climate by incorporating experimental results into conceptual or quantitative frameworks from which potential feedbacks within the plant-soil system can be identified. Five examples (including forest trees) are presented of how models can be used in this analysis and how they can contribute to development of new hypotheses on root biology, soil biota, and ecosystem processes. Two examples illustrate the role of coarse and fine roots in N and P uptake from soils, respiratory costs associated with this acquisition ofnutrients, and significance of root architecture in these relations. Another example focuses on a conceptual model that has helped raise new ideas about effects of elevated CO 2 on root and microbial biomass, and on nutrient dynamics in the rhizosphere. Difficulties associated with modelling the contribution of mycorrhizal fungi to whole-plant growth are also discussed. Finally, several broad-scale models are used to illustrate importance of root turnover, litter decomposition, and N mineralization in determining ecosystem response to atmospheric CO 2 enrichment. It is concluded that models are appropriate tools for use both in guiding existing studies and in identifying new hypotheses for future research. Development of models that address the complexities of belowground processes and their role in determining plant and ecosystem function within the context of rising CO 2 concentrations and associated climate change should be encouraged.