Document: CLI-3-23-3

Plant resource heterogeneity: When is it signal and when is it noise?

JONES, C.G.*

Institute of Ecosystem Studies, Millbrook, NY 12545 USA ¹

Abstract:
Plant chemistry affects the performance of consumers, and plant chemistry varies markedly at virtually all temporal and spatial scales. Consequently, many have postulated that chemical heterogeneity is an important factor determining patterns of variation in consumer distribution and abundance. And yet good evidence that chemical heterogeneity affects consumer population dynamics, community structure and dynamics, or ecosystem-level producer/consumer relationships is scanty at best. Why is this so? Does it mean that, although chemical variation may be important to individual performance, at higher levels of organization other factors are always more important determinants of consumer distribution and abundance? Or is it a reflection of inadequate testing of the general hypothesis arising from the lack of a clear framework for when, how and why we should expect chemical heterogeneity to make a difference to consumers at different scales? Evidence from many other systems (e.g., the role of lignin in decomposition, atmospheric impacts of plant volatiles) as well as a number of "success stories" in plant-consumer interactions (e.g., host plant demic adaptation, evolutionary patterns of host specialization) suggests that there are circumstances in which causal chemical signals can be seen at higher levels of organization, and other situations where lower level chemical resource heterogeneity is just noise. I will analyze these examples and present a framework for integrating scales of resource heterogeneity with scales of variation in consumer distribution and abundance.

Keywords:

This abstract is being presented at: 4:35 PM in session:
Symposium # 23: Why Variation is Not Just Noise: The Influence of Variability on Plant-Herbivore and Plant-Pathogen Interactions.