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Ecophysiological responses of woody plants to past CO₂ concentrations

David J. Beerling

Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, U.K. / Received May 10, 1995

Summary

An approach is detailed for calculating historical rates of CO₂ uptake and water loss of leaves from measurements of leaf δ¹³C composition and climatic information. This approach was applied to investigate leaf gas exchange metabolism of woody taxa during the past 200 years of atmospheric CO₂ increase and in response to the longer-term atmospheric CO₂ increases plants experienced over the Pleistocene. Reconstructed net assimilation rates and water use efficiencies increased in response to increasing atmospheric CO₂ concentrations in both sets of material, whereas stomatal conductance, showing the combined responses of changes in stomatal density and leaf assimilation rates, was generally less responsive. Woody temperate taxa maintained a nearly constant c_i/c_a ratio in response to the increase in atmospheric CO₂ concentrations over both timescales, in part, as a result of changes in stomatal density. The reconstructed leaf-scale physiological responses to past global climatic and atmospheric change corroborated those anticipated from experimental work indicating the adequate capacity of experiments, at least at the scale of individual leaves, to predict plant responses to future environmental change.

Keywords: assimilation rate, climate change, CO₂ uptake, leaf δ¹³C composition, Pinus flexilis, Salix herbacea, stomatal conductance, water use efficiency.

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ISSN 0829-318X Copyright © 2002–2008 Heron Publishing