A group of scientists and forest managers at OSU and the US Forest Service are asking community members who experienced the June 2021 Pacific Northwest heat wave event to participate in foliage scorch research. Community members are invited to observe the heat impacts to foliage and report their observations using a website created by the Oregon Department of Forestry to survey drought impacts on forests.
Following two years of drought, many areas of the Pacific Northwest and British Columbia experienced unprecedented air temperatures during an extreme heat wave in late June and early July of 2021.
This event led to numerous reports of foliage scorch and leaf drop in westside forests of the Oregon coast range and the Cascades mountain range. Western hemlock (Tsuga heterophylla) and Western Red Cedar (Thuja plicata) seem to have been the most impacted tree species, but Douglas fir (Pseudotsuga menziesii) and various alder and maple species were also affected. Notably, trees and saplings with direct solar exposure and on south-facing slopes seemed to suffer the worst foliage scorch.
Researchers do not know what the near- and long-term physiological causes and consequences of foliage scorch and heat stress will be, at either leaf or tree scales. The impacts could range from impaired metabolism on surviving leaves to reduced stem diameter growth to eventual tree mortality. This event provides a unique opportunity to probe the physiological and ecological responses to an extreme heat wave in important tree species of the Pacific Northwest.
Researchers ask that anyone participating in the research please note in the “Description and/or caption information” of the survey that participants are reporting ‘impacts of the June 2021 heat wave‘ and also use the phrase ‘foliage scorch‘ so researchers can retrieve these observations later for mapping and analysis of this extreme event.