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Resource dynamic plays a key role in regional fluctuations of the spruce bark beetles Ips typographus

Resource dynamic plays a key role in regional fluctuations of the spruce bark beetles Ips... Abstract 1 We analysed time series of spruce bark beetles (Nt) caught in pheromone traps from 1979 to 2000 in approximately 100 localities throughout south‐east Norway. 2 The analysis was performed at two spatial scales (whole area and 12 subregions), and included additional analyses of the time‐series sequences before and after a large windfelling (1987) that appeared to induce a shift in the dynamics. 3 Regression of Rt (logarithmic per‐capita growth rate) on Nt − d indicated that the endogenous dynamics were dominated by lag 1 density dependence. This was particularly so in the sequence after the large windfelling (R2 = 0.79), probably due to intraspecific competition for breeding substrate. 4 The sequence before the windfelling (1979–1987) was declining without significant density dependence. We suggest this to be a transition period, reflecting a drop in carrying capacity due to depletion of susceptible trees during the preceding outbreak period (1970s) and a drop in beetle number to below the density required to kill trees. 5 Windfelling (Wt − 1) appears to be an important predictor of the dynamics; however, it was difficult to evaluate the statistical significance of this factor due to only one large windfall event. 6 The weak influence of drought stress (Dt − 1) could be due to the absence of severe drought periods within the time series. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Agricultural and Forest Entomology Wiley

Resource dynamic plays a key role in regional fluctuations of the spruce bark beetles Ips typographus

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References (39)

Publisher
Wiley
Copyright
Copyright © 2004 Wiley Subscription Services, Inc., A Wiley Company
ISSN
1461-9555
eISSN
1461-9563
DOI
10.1111/j.1461-9555.2004.00214.x
Publisher site
See Article on Publisher Site

Abstract

Abstract 1 We analysed time series of spruce bark beetles (Nt) caught in pheromone traps from 1979 to 2000 in approximately 100 localities throughout south‐east Norway. 2 The analysis was performed at two spatial scales (whole area and 12 subregions), and included additional analyses of the time‐series sequences before and after a large windfelling (1987) that appeared to induce a shift in the dynamics. 3 Regression of Rt (logarithmic per‐capita growth rate) on Nt − d indicated that the endogenous dynamics were dominated by lag 1 density dependence. This was particularly so in the sequence after the large windfelling (R2 = 0.79), probably due to intraspecific competition for breeding substrate. 4 The sequence before the windfelling (1979–1987) was declining without significant density dependence. We suggest this to be a transition period, reflecting a drop in carrying capacity due to depletion of susceptible trees during the preceding outbreak period (1970s) and a drop in beetle number to below the density required to kill trees. 5 Windfelling (Wt − 1) appears to be an important predictor of the dynamics; however, it was difficult to evaluate the statistical significance of this factor due to only one large windfall event. 6 The weak influence of drought stress (Dt − 1) could be due to the absence of severe drought periods within the time series.

Journal

Agricultural and Forest Entomology – Wiley

Published: May 1, 2004

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