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Significant mortality of old trees across a dry forest landscape in Oregon
August 27 @ 3:00 pm - 4:00 pm
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Aug 27, 2025
Noon – 1:00 p.m. PT / 1:00 – 2:00 p.m. MT / 2:00 – 3:00 p.m. CT / 3:00 – 4:00 p.m. ET
Continuing education credits are pending approval.
Webinar Presenter: Dr. James Johnston, University of Oregon
Description: Dr. Johnston will discuss recent forest mortality dynamics based on a network of 1617 trees in unlogged roadless areas in the Blue Mountains of eastern Oregon with precise age and growth data. There was extensive mortality of the oldest trees in stands—a quarter of trees greater than 300 years of age died over a ten-year period. There was little evidence for a difference in mortality between species in sites that experienced wildfire. Dr. Johnston will also describe a novel simulation model which demonstrated that succession of young trees is unlikely to replace recent losses of old trees. The confluence of a rare insect defoliator outbreak, drought, and past management decisions that increased competitive stress and fuel connectivity is the most likely explanation for the elevated mortality we observed. The protected areas where the team collected data are not achieving old tree conservation objectives. Active management to reduce forest competition is the most realistic pathway for old tree conservation in dry forests.