Why are evergreen leaves so contrary about shade?

TitleWhy are evergreen leaves so contrary about shade?
Publication TypeJournal Article
Year of Publication2008
AuthorsLUSK, C, Reich Peter B., Montgomery Robert, ACKERLY D, and CAVENDERBARES J
JournalTrends in Ecology & Evolution
Pagination299 - 303
Date Published06/2008
Keywordsevergreens, genetic correlations, phenology

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.