Creating a Buzz: Insect Outbreaks and Disturbance Interactions

Abstract

Dendroentochronology is the study of insect outbreaks as recorded in tree rings. This type of research has been going on in earnest since the 1950s but the number of publications has rapidly increased from the 1980s to the present. Most of the work has been completed in Canada and the United States with some important work in Europe and Asia. Insect outbreak studies have been conducted in Australasia and more recently in South America, but very little work has been done in Africa. From tree-ring research on insect outbreaks we have been able to document the outbreak dynamics of more than 20 species of insect around the world. Insects can be grouped into three classes based on their impacts on trees: defoliators, cambium feeders, and root parasites. Using tree rings, we have been able to document periodic occurrences of insect outbreaks, their effects on the volume of wood production, climatic triggers to outbreaks, and the spread of insect outbreaks across landscapes over decades to more than a millenium. Dendrochronologists are now exploring the interactions of multiple insect outbreak systems and their interactions with fire and weather phenomena. From this work, we can see that the cumulative effects of multiple disturbances can be greater than the individual effects and that one disturbance can hinder or enhance a different type of disturbance. Overall, dendroentochronologists have been able to demonstrate the important role of disturbances in natural systems and provide important insight into the management of these ecosystems.