Article

Landscape Ecology

, Volume 14, Issue 2, pp 105-120

Plant-pest interactions in time and space: A Douglas-fir bark beetle outbreak as a case study

  • Jennifer Sarah PowersAffiliated withDepartment of Forest Science, Oregon State University, 020 Forestry Sciences Laboratory
  • , Phillip SollinsAffiliated withDepartment of Forest Science, Oregon State University, 020 Forestry Sciences Laboratory
  • , Mark E. HarmonAffiliated withDepartment of Forest Science, Oregon State University, 020 Forestry Sciences Laboratory
  • , Julia A. JonesAffiliated withDepartment of Geosciences, Oregon State University

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Abstract

A conceptual model of Douglas-fir bark beetle (Dendroctonus pseudotsugae) dynamics and associated host tree mortality across multiple spatial and temporal scales was developed, then used to guide a study of the association between the occurrence of beetle- killed trees and factors that might render trees more susceptible to attack. Long-term records of beetle kill showed that beetle epidemics were associated with windstorms and drought at statewide and local spatial scales. At the landscape scale, beetle kill was associated with (i) portions of the landscape that were potentially drier (southern aspects, lower elevations) and (ii) portions of the landscape that had more mature and old-growth conifer vegetation. The patches of beetle-killed trees were aggregated with respect to other patches at scales of approximately 1 and 4 km. At the scale of the individual tree, there was not a strong relationship between beetle kill and resistance to attack measured by tree growth rate prior to attack. Our results show that landscape-scale phenomena and temporal patterns were more strongly correlated with beetle-kill events than was recent growth history at the scale of individual trees. We suggest that the multi-scale approach we employed is useful for elucidating the relative roles of fine- versus coarse-scale constraints on ecological processes.

bark beetle epidemic Douglas-fir hierarchy theory multiple spatial and temporal scales