Effects of Forest Management Legacies on Spruce Budworm Outbreaks
Event Website
http://www.nafew2009.org/
Start Date
6-23-2009 9:00 AM
End Date
6-23-2009 9:20 AM
Description
It is postulated that landscape structure changes connectivity of insect populations by affecting movement and dispersal. Spruce budworm outbreaks that have become more severe than in the past may be due in part to the effects of forest management on landscape structure, although this hypothesis remains to be tested. The main objective of this study was to evaluate the effects of landscape structure resulting from different types of management on spruce budworm outbreaks under similar biophysical conditions. The Border Lakes Landscape, with its contrasting management legacies on each side of the Canada-U.S border, provides an opportunity to study the effect of landscape structure on outbreak dynamics. We compared spruce budworm outbreak characteristics between forests managed at a fine scale (e.g., 10 hectare harvests) in Minnesota, USA, forests managed at a coarse scale (e.g., 100 hectare harvests) in Ontario, Canada, and a conservation zone overlapping the US-Canadian Border (i.e., Boundary Waters Canoe Area Wilderness and Quetico Provincial Park). We sampled sites to minimize the effect of other confounding factors such as climate and host abundance that also have an effect on spruce budworm cycle. Dendrochronological reconstructions of outbreaks in each zone allowed the detection of differences in the periodicity and synchrony of outbreaks. In comparison to the conservation zone where periodicity varied between 15 to 40 years, outbreaks were more frequent within the fine-scale managed zone (6-12 years) in the United States. Managed Canadian forests had an intermediate periodicity of 13 to 30 years. Results are consistent with the hypothesis that fragmentation and reduction of host abundance reduced the synchronization of outbreaks in the fine-scale zone thus explaining the difference in periodicity.
Effects of Forest Management Legacies on Spruce Budworm Outbreaks
It is postulated that landscape structure changes connectivity of insect populations by affecting movement and dispersal. Spruce budworm outbreaks that have become more severe than in the past may be due in part to the effects of forest management on landscape structure, although this hypothesis remains to be tested. The main objective of this study was to evaluate the effects of landscape structure resulting from different types of management on spruce budworm outbreaks under similar biophysical conditions. The Border Lakes Landscape, with its contrasting management legacies on each side of the Canada-U.S border, provides an opportunity to study the effect of landscape structure on outbreak dynamics. We compared spruce budworm outbreak characteristics between forests managed at a fine scale (e.g., 10 hectare harvests) in Minnesota, USA, forests managed at a coarse scale (e.g., 100 hectare harvests) in Ontario, Canada, and a conservation zone overlapping the US-Canadian Border (i.e., Boundary Waters Canoe Area Wilderness and Quetico Provincial Park). We sampled sites to minimize the effect of other confounding factors such as climate and host abundance that also have an effect on spruce budworm cycle. Dendrochronological reconstructions of outbreaks in each zone allowed the detection of differences in the periodicity and synchrony of outbreaks. In comparison to the conservation zone where periodicity varied between 15 to 40 years, outbreaks were more frequent within the fine-scale managed zone (6-12 years) in the United States. Managed Canadian forests had an intermediate periodicity of 13 to 30 years. Results are consistent with the hypothesis that fragmentation and reduction of host abundance reduced the synchronization of outbreaks in the fine-scale zone thus explaining the difference in periodicity.
https://digitalcommons.usu.edu/nafecology/sessions/disturbance/4