Landscape study of bark beetle herbivory and the lightning disturbance regime
Loading...
Date
1994
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
The goal of the research described by this dissertation was to examine characteristics of the lightning disturbance regime in relation to herbivory by pine bark beetles. The first of two data sets consisted of five years of southern pine beetle (SPB) (Dendroctonus frontalis Zimmermann) infestation records and estimated lightning strikes on Texas Forest Service administered lands in east Texas. The second data set consisted of the geographical coordinates for SPB infestations and actual lightning strike coordinates for one year in the Davy Crockett National Forest in east Texas. In the five-year data set, the relationship between cumulative bark beetle herbivory and cumulative lightning strikes was examined. In four of the five years of the data analysis, cumulative SPB infestations increased as a function of cumulative lightning strikes. The rate of change in infestations relative to cumulative lightning strikes indicated that the availability of lightning-struck hosts for colonization was not a limiting factor in SPB infestation occurrence. Characterization of the Davy Crockett data revealed a close spatial relationship between lightning and SPB infestation patterns. A proximity analysis of the two phenomena revealed a majority of the infestations had associated lightning strike activity within 800 m prior to the infestation detection. In an analysis of the role of lightning in the life history model of SPB, it was postulated that different periods of lightning activity played different roles in SPB population dynamics. Winter lightning-struck trees tend to remain attractive to SPB into the spring. Many of the spring infestations were associated with this winter lightning activity. Lightning occurring in the spring was also heavily associated with subsequent SPB infestation activity. Southern pine beetle exhibits its most active period of dispersal during the spring. Summer is characterized by infestation growth rather than SPB dispersal. However, there was still a strong association of lightning strikes and infestations during this season. The association of fall lightning and SPB infestations was moderate.
Description
Vita.
Keywords
Major entomology