Transformation of Alberta forests by mountain pine beetle René Alfaro1, Brad Hawkes1, Jodi Axelson2, Lara vanAkker1

1Pacific Forestry Centre, Victoria BC 2BC Ministry of Forests, Lands and Natural Resource Operations

Methodology

• 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

Introduction

Permanent plots established in Waterton Lakes

National Park during the 1980’s MPB outbreak

were re-measured in 2010 to:

Results

• 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)

• High degree of variability in stocking

between stands

• Post-outbreak composition made up almost

entirely of shade tolerant species • 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.

• The result is stands that have variable canopy and

cohort structure.

• 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.

Conclusions

Acknowledgments

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.

PSP’s measured in new and historic MPB range.

Historic

range

New

range

Diameter and height distributions for even- and uneven-aged stands

Regeneration Saplings Overstory

Disturbance cycle in historic and new mountain pine beetle habitat.

Red Rock Canyon, Waterton Lakes National Park (photos: Rob Watt) Coarse woody debris post MPB-outbreak, Waterton Lakes National Park

Measuring characteristics of

canopy layers

1982 2008

• 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

2010

Beetle

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.

MPB strip scars from 1980s

outbreak near Crandell

campground

Fire scar on lodgepole pine in

Waterton Lakes National Park