Transformation of Alberta forests by mountain pine beetle René 1Pacific
1 Alfaro ,
Forestry Centre, Victoria BC
1 Hawkes , 2BC
2 Axelson ,
Ministry of Forests, Lands and Natural Resource Operations
Introduction Permanent plots established in Waterton Lakes National Park during the 1980’s MPB outbreak were re-measured in 2010 to: • Determine historic distribution and return interval of MPB outbreaks • Describe impacts on ecosystems
• Provide information required to anticipate the short and long term consequences of MPB on stand characteristics in new and historic MPB habitats
• Marked decline in lodgepole pine density from 1981 to 2010 • Increase in non-host species such as spruce and fir • With the exception of stand 1, sapling and seedling densities have increased in all stands from 2002 to 2010 (spp other than Pl)
Coarse woody debris post MPB-outbreak, Waterton Lakes National Park
Red Rock Canyon, Waterton Lakes National Park (photos: Rob Watt)
• High degree of variability in stocking between stands
• Post-outbreak composition made up almost entirely of shade tolerant species Overstory
• Stand replacing fires initiate even-aged lodgepole pine stands. • Multiple MPB disturbances create openings providing opportunities for natural regeneration (a regeneration delay may take place) and for growth release in the existing advance regeneration.
• Frequency and severity of MPB outbreaks determine the structure and composition of the residual stand. Intense outbreaks lead to regeneration by shade intolerant species. Low intensity outbreaks favour regeneration with shade tolerant species.
PSP’s measured in new and historic MPB range.
• The result is stands that have variable canopy and cohort structure.
• Collected forest inventory data in permanent sample plots (PSPs) in new and historic MPB range • Collected increment cores from overstory trees and basal discs from saplings, coarse woody debris and scarred trees
Diameter and height distributions for even- and uneven-aged stands
Disturbance cycle in historic and new mountain pine beetle habitat.
• In the absence of fire disturbance MPB will play a dominant role in directing stand dynamics and structure in AB. • We speculate that beetle impacted Jack pine stands will sustain similar transformations, leading to stands of complex structure.
Acknowledgments Beetle Fire scar on lodgepole pine in Waterton Lakes National Park
MPB strip scars from 1980s outbreak near Crandell campground
Measuring characteristics of canopy layers
Transformation of from even-aged post-fire lodgepole pine stands (left) to complex multi-storied stands (right) as a response to repeated mountain pine beetle thinning.
Project funded by the Foothills Research Institute (AB), BC Forest Innovation Investments Ltd. Forest Research Program and the federal MPB Initiative. Field and lab assistance was provided by Vince Waring, George Dalrymple and Peter Sprague.