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

Riverside 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: Mt. Hood National Forest, Clackamas River Ranger District.

Nearest town: Estacada, OR.

Species: Douglas-fir (Pseudotsuga menziesii.)

Site characteristics: The site sits on a 10 to 30 percent northeast-south-southeast slope at 2,600 ft of elevation. The soils are deep, well drained silt loams formed from thin loess over glacial till or colluvium. The plant association is Western Hemlock/Oregon grape-salal. Mean annual temperature is 46 °F (coldest month: 35 °F, warmest month: 59 °F,) and mean annual precipitation is 2283 mm (180 mm as snow.)

Site history: The site, likely originally a conifer mix, was clearcut and replanted with Douglas-fir in the 1960s. A commercial variable density thinning prescription was being executed at the site in the summer of 2020 when it burned with high severity in the Riverside Fire.

Planting date: Spring 2023.

Contact person:

Stephanie O’Dell, Silviculture Forester, USDA Forest Service, Mt. Hood National Forest-Clackamas River Ranger District.

Robert Slesak, Research Forester, USDA Forest Service, Pacific Northwest Research Station.
 

Riverside site conditions at the time of planting. Photo by James Dollins.

Management objectives and other considerations: The main goal for this site, in addition to research, is fiber production. The site is designated as “Wood Product Emphasis” in the Mt. Hood Land and Resource Management Plan.  Planting prescriptions in this area are site-specific but generally a mix of native species are planted at a spacing of approximately 14 feet. This site differs in the single species choice, but otherwise resembles operational planting for the area.

Site preparation: None.

Pre-planting site conditions: Since wildfire reached the unit while it was being commercially thinned, some logs that had been cut but not yet removed remained on site after the fire, partially burned. One year post-fire, virtually no live trees remained in the overstory and there was very little understory regeneration. However, there are some nearby areas with live conifer trees that are a potential seed source for natural regeneration.

Experimental design: The experimental design in this site is 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 Riverside site. Map by Laura Gonzalez Mantecon.

Silvicultural treatments: Two different planting densities (see below.)

Planting density: Operational contract crews planted 200 and 250 trees per acre.

Seedling stock type: Containerized.  
Monitoring: The site will be monitored to track and compare seedling survival among seed sources and silvicultural treatments. Measurements are planned for 1-, 5-, 10-, and 15-years post-planting.

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

Melted glass on a fire engine that burned at the site during the Riverside Fire. Photo by Laura Gonzalez Mantecon.

Crews planting the Riverside site. Photo by Laura Gonzalez Mantecon.