Indirect interaction webs propagated by herbivore-induced changes in plant traits

Introduction This volume is the first to survey trait-mediated indirect effects in a wide variety of plant-based indirect interaction webs in terrestrial systems. In the introductory chapter we proposed four questions about important patterns in indirect interaction webs: (1) What novel interaction linkages are produced by plant-mediated indirect effects? (2) What complex interactions are generated by plant-mediated indirect effects in multitrophic systems? (3) What are the effects of plant-mediated indirect effects on community structure and biodiversity? and (4) What are the evolutionary consequences of plant-mediated indirect effects? In this chapter we will review the progress that has been made in answering these questions. We will examine the conceptual framework that the study of plant-mediated indirect effects provides for future research on the ecology and evolution of multispecies and multitrophic interactions. We will also explore the impact of these effects that influence the structure of ecological communities and biodiversity. Ohgushi (2005) surveyed indirect interactions between herbivores through herbivore-induced changes in plants. The key features identified in these interactions are found in the interactions considered in this volume. First, plant-mediated indirect effects are common and widespread because trait changes in plants induced by a range of organisms are ubiquitous in terrestrial plants. Second, plant-mediated interactions occur between temporally separated, spatially separated, and taxonomically distant species. Third, there are often mutualistic interactions between species sharing the same plant because of enhanced resource availability due to compensatory regrowth, and changes in sink-source relationships.