Agriculture Reference
In-Depth Information
Effects of Environmental Stress on Leaf Longevity
The form and function of each species comprise an evolved functional design suited
to a particular range of environmental conditions. In an environment within the
limits of their evolved capacity, plant species generally can respond effectively to
resource limitations, including through adjustments in leaf longevity of the cate-
gory discussed earlier in this chapter. Environmental stress arises when conditions
fall near or beyond the limits of a functional design, near the point where function
can no longer be sustained. In terms of foliar function and questions of impact on
leaf longevity, a stress might arise from any biotic or abiotic factor that incapaci-
tates a leaf to the point where its production potential no longer will yield a net
return on the resources invested in constructing and maintaining the leaf. In this
context, expectations rooted in a cost-benefit analysis of foliar function often must
be founded on analysis of carbon investments and gain at the whole-plant level, not
just single leaves in isolation. We illustrate this perspective with a brief discussion
of some important biotic and abiotic stressors.
Biotic Stressors: Herbivory and Disease
An herbivorous caterpillar,
Actias selene gnoma
The original framework of Chabot and Hicks (1982) for cost-benefit analyses of
foliar function included a term for leaf loss caused by herbivory or disease, but
