McKenzie site in the Experimental Network for Assisted Migration and Establishment Silviculture (ENAMES)

McKenzie site 3D map showing experimental plots color-coded by the climate scenario each seed source is adapted to. Map by Laura Gonzalez Mantecon.

Land manager: USDA Forest Service.

Location: Willamette National Forest, McKenzie River Ranger District.

Nearest town: Rainbow, OR.

Species: Douglas-fir (Pseudotsuga menziesii).

Site characteristics: The site sits on a 15–40-percent, south-southeast slope at 1,700 ft elevation. The soils are deep, well-drained stony/gravelly loams derived from colluvium and residuum from basalt and sandstone. The mean annual temperature is 50°F (coldest month: 36 °F; warmest month: 65 °F,) and mean annual precipitation is 1823 mm (92 mm of which is snow.) The plant association is Western hemlock/Pacific rhododendron-salal. 

Site history: This site was a second growth Douglas-fir stand that was clearcut and regenerated sometime around 1955, followed by a commercial thinning and some associated fuels treatments around 2010–2012. The Holiday Farm Fire burned the site in 2020 and killed almost all trees. The stand was then salvaged in 2021 followed by pile burning in 2022.

Planting date: Spring 2023.

Contact person:
Scott Kolpak, Regional Geneticist (formerly Southwest Oregon Area Geneticist); USDA Forest Service, Pacific Southwest Region.
Cal Miller, Silviculturist; USDA Forest Service, Willamette National Forest, Middle Fork Ranger District.
Robert Slesak, Research Forester; USDA Forest Service, Pacific Northwest Research Station.

Site conditions at McKenzie site in the summer of 2023. Photo by Tessa Franklin.

Management objectives and other considerations: The site lies within the Northwest Forest Plan’s Central Cascades Adaptive Management Area, which is generally used for intensive research on ecosystem and landscape processes, and forest management experiments and demonstrations of varying scales. Aside from seed source selection, this site reflects operational planting density and distribution, although operational plantings would generally include some minor species in addition to Douglas-fir. Short-term non-research objectives include forest cover restoration that is resilient to disturbance, including fire and climate change. Longer term goals are to provide multiple benefits, including research opportunities, fiber production, wildlife habitat, recreation opportunities, and other ecosystem services. 

Site preparation: The site was salvage harvested after the fire, 2 years before planting.

Pre-planting site conditions: The site was covered in moderate to dense understory, including fireweed, blackberry, and vine maple, as well as some light woody debris and scattered heavy log piles.  One small group of standing dead and live Douglas-fir remained on the higher end of the site, and there was a small amount of scattered natural Douglas-fir regeneration.

Experimental design: A randomized complete block with four replications per treatment applied to 0.5-acre plots.

Assisted migration treatments: The team used the Seedlot Selection Tool to choose four planted seed sources (see table below.)

Seed source locations matching historical and predicted future climates for the McKenzie site. Map by Laura Gonzalez Mantecon.

Silvicultural treatments: None.

Planting density: Operational contract crews planted 200 trees per acre.

Seedling stock type: Containerized.

Monitoring: The site will be monitored to track and compare seedling survival and growth among seed sources. We took initial measurements in the first year after planting, with follow-up measurements planned for 5, 10, and 15 years after planting.

The site may also serve as a demonstration plot for managers to visit and visually compare seed source performance.

Crews planting the McKenzie site in the snow after an unexpected late spring cold spell. Photo by Scott Kolpak.