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Jean-Philippe Lepage


Master student

Department of geography, Université Laval

Abitibi-Price Building
2405 rue de la Terrasse
Université Laval
Quebec, Canada
G1V 0A6





Research project

Quantification of lodgepole pine prior growth following mountain pine beetle outbreaks in Yellowstone Park (USA)

The MPB (Dendroctonus ponderosae Hopkins.) is a forest insect that affects most significantly the lodgepole pine forests (Pinus contorta) of the North American West, outbreaks playing a important role in ecological processes such as forest succession. After an outbreak, mature trees infested are killed, creating a gap in the forest. Subsequently an accelerated growth spurt (also called relaxation or prior growth) occurs mostly in understory pine. This rapid increase in the diameter and height is visible in the rings of tree growth. However, trees do not all show prior growth and they are not simultaneously occurring in a population.

I suggest, both for MPB (Dendroctonus ponderosae Hopkins.), and the Douglas fir beetle (Dendroctonus pseudotsugae) to; (1) quantify the prior growth following a beetle outbreak, (2) determine the causes of the magnitude of the prior growth and (3) compare the prior growth patterns of these two insect-tree systems, identifying similarities or difference between explanatory variables and prior growth patterns.

Fifteen 25 to 35 years post-outbreak sites were chosen in both stand types according to aerial detection mapping of the US Forest Service from 1999 to 2006, and the National Park Service from 1960 to 1986, and recent maps the composition and succession of stages of the forest. A total of 10 sites were selected in lodgepole pine forests of Wyoming, and 5 sites in Douglas fir forests. For each site, a chronology of prior growth will be establish, based on the "boundary line" method. Multiple linear regression will be used to link the prior growth with a series of explanatory variables. Once the variables of these two insect-tree systems identified, they will be compared.

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