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Cooke, Julia; Bourne, Aimee; Medlyn, Belinda and Ellsworth, David
(2015).
Abstract
Plant functional ecologists argue that there is a spectrum of plant types defined by fast versus slow strategies of resource acquisition and use across the whole plant (Reich 2014). Plant traits are likely to be correlated to yield this kind of spectrum. Stomata serve as the portals for regulating CO2 and water vapour transfers between plants and the atmosphere, and in so doing they link plant carbon and water economies. However, it is not clear how stomatal behaviour fits into the spectrum of traits and strategies. The stomatal optimisation formalism recently proposed by Medlyn et al. (2011) provides a trait (g1) that allows characterisation of stomatal behaviour. High values of g1 indicate a low marginal cost of water per unit carbon gain to the plant and in theory should be linked to fast growth traits. We undertook a study of stomatal optimisation in six co-occurring tree species, which we combined with a recently published study of four eucalypts on the same site using similar methodology, for a robust comparison involving ten species. The study investigates correlations between g1 and other plant traits to investigate how g1 fits into the plant economic spectrum. Our aims in this study were to apply stomatal optimisation theory to test if leaf and plant traits relating to water loss and carbon gain are related to optimal stomatal behaviour.