title: Why are evergreen leaves so contrary about shade?
abstract: Leaf mass per area (LMA) is one of the most widely measured of all plant functional traits. In deciduous forests, there is similarity between plastic and evolutionary responses of LMA to light gradients. In evergreens, however, LMA is lower in shaded than sunlit individuals of the same species, whereas shade-tolerant evergreens have higher LMA than light-demanders grown under the same conditions. We suggest that this pattern of 'counter-gradient variation' results from some combination of (i) close evolutionary coordination of LMA with leaf lifespan, (ii) selection for different leaf constitutions (relative investment in cell walls versus cell contents) in sun and shade environments and/or (iii) constraints on plasticity as a result of genetic correlations between phenotypes expressed in sun and shade.
authors.affiliation: Department of Biological Science, Macquarie University, Sydney, NSW 2109, Australia. clusk@bio.mq.edu.au
authors.forename: Christopher H
authors.initials: CH
authors.lastname: Lusk
authors.forename: Peter B
authors.initials: PB
authors.lastname: Reich
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Montgomery
authors.forename: David D
authors.initials: DD
authors.lastname: Ackerly
authors.forename: Jeannine
authors.initials: J
authors.lastname: Cavender-Bares
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D005075:Biological Evolution; D017753:Ecosystem; D008027:Light; D018515:Plant Leaves / Q000502:physiology*; D064028:Tracheophyta / Q000502:physiology*