© 2007 Heron Publishing—Victoria, Canada
Leaf- and shoot-level plasticity in response to different nutrient and water availabilities
Jennifer L. Funk (1, 2, 3, 4), Clive G. Jones (1) and Manuel T. Lerdau (5)
1. Institute of Ecosystem Studies, Box AB, Millbrook, NY 12545, USA / 2. Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY 11794-5245, USA / 3. Present address: Department of Biological Sciences, Chapman University, Orange, CA 92866, USA / 4. Corresponding author (jlfunk@chapman.edu) / 5. Blandy Experimental Farm and Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904, USA / Received January 22, 2007; accepted April 24, 2007; published online September 4, 2007
Summary
Phenotypic plasticity in response to environmental variation occurs at all levels of organization and across temporal scales
within plants. However, the magnitude and functional significance of plasticity is largely unexplored in perennial species.
We measured the plasticity of leaf- and shoot-level physiological, morphological and developmental traits in nursery-grown
Populus deltoides Bartr. ex Marsh. individuals subjected to different nutrient and water availabilities. We also examined the extent to which
nutrient and water availability influenced the relationships between these traits and productivity. Populus deltoides responded to changes in resource availability with high plasticity in shoot-level traits and moderate plasticity in leaf-level
traits. Although shoot-level traits generally correlated strongly with productivity across fertilization and irrigation treatments,
few leaf-level traits correlated with productivity, and the relationships depended on the resource examined. In fertilized
plants, leaf nitrogen concentration was negatively correlated with productivity, suggesting that growth, rather than enhanced
leaf quality, is an important response to fertilization in this species. With the exception of photosynthetic nitrogen-use
efficiency, traits associated with resource conservation (leaf senescence rate, water-use efficiency and leaf mass per area)
were uncorrelated with short-term productivity in nutrient- and water-stressed plants. Our results suggest that plasticity
in shoot-level growth traits has a greater impact on plant productivity than does plasticity in leaf-level traits and that
the relationships between traits and productivity are highly resource dependent.
Keywords:
adaptive plasticity, leaf initiation, photosynthesis, Populus deltoides, productivity, relative growth rate, resource availability, seasonal patterns.
