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The University of Massachusetts Amherst

Why are evergreen leaves so contrary about shade?

Authors:

C LUSK

Peter Reich

Robert Montgomery

D ACKERLY

J CAVENDERBARES

Publication Type:
Journal Article
Year of Publication:
2008
Secondary Title:
Trends in Ecology & Evolution
Pages:
299-303
Volume:
23
Year:
2008
Date:
06/2008

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.