Agriculture Reference
In-Depth Information
Chapter 8
Exogenous Influences on Leaf Longevity
Early spring ice storm, Ithaca, New York
The normal value of leaf longevity for a species reflects functional relationships at
the foliar and whole-plant level, but longevity can be both prolonged and shortened
by environmental conditions. From first principles, leaf longevity is expected to
increase in environments where critical resources are scarce. This generalization is
rooted in a cost-benefit analysis of leaf longevity arguing that the nature of leaves
in resource-limited environments imposes a long payback period on the cost of
their construction (Chabot and Hicks 1982; Kikuzawa 1991). In this view, selection
pressure is expected to act to prolong leaf longevity in light-, water-, or nutrient-
limited environments. This expectation is consistent with observations among spe-
cies and plants in differing resource environments, but not within individual plants.
The expectation applies to conditions of resource limitation, not stress conditions
that near or exceed the limits to a species' survival and reproduction. Stress events
such as deep drought, unseasonal frost and freezing, lengthy flooding, salinity, air
