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Pilchuck Demonstration Site

Location: Stanwood, WA
Acres: 95
Planted: 2013
Initial Harvest: 2014
Second Harvest: Planned winter 2018
Land Restoration: Planned spring 2018

In spring 2013, the Pilchuck demonstration site was established near Stanwood, Washington on three fields totaling 95 acres. The Pilchuck site was established with a planting density of 1,452 stems per acre with rows aligned on 12-foot centers and 2.5 foot intervals within each row. The site gets its name from the adjacent Pilchuck Tree Farm, which is leasing the land for the AHB project. At an elevation of 700 feet, the site features rolling hills and is surrounded by managed forestland. Located near the foothills of the Cascade Range, the sites soil is clay loam with coarse gravel fraction. Formally, the site was used as a hayfield and pasture. The site receives an average of 54 inches of precipitation per year, which is ample for good poplar growth.

A view of the poplar trees growing at the Pilchuck demonstration site with Mt. Rainier in the background.

The majority of the Pilchuck demonstration site features commercial feedstock production trials with 12 varieties of hybrid poplar each occupying several acres. The commercial trials aim to demonstrate biomass yields, management practices, the cost of production, and harvesting logistics. The site also has multiple research plantings looking at topics such as alternative spacing, new poplar varieties, and colonizing the poplar with endophytes to aid in drought resistance. Researchers are also looking at wildlife populations and soil sustainability at the site. You can learn more about the research here.

Alder Trials

In addition to poplar, the potential of alder trees for biomass production is being investigated at the Pilchuck demonstration site. In the spring of 2014, four varietal blocks of red and hybrid alder were established in field trials at the site. Developing hybrid alder strains that can be managed by coppice regeneration will broaden the range of sites that can economically produce biomass feedstock for biofuels and biochemicals. Some research plots also have alder interplanted with poplar to determine if alder’s nitrogen fixing abilities can boost poplar growth.


Deer browse significantly impacted the Pilchuck site during the initial establishment. The growth and yield of several varieties was significantly less than anticipated at the first harvest. Now that the trees have an established root system, the hope is that the trees will rapidly grow beyond deer browse height and be more productive for the second harvest. To protect a portion of the research trials, a deer fence was installed in spring 2014.

Poplar trees growing behind a deer fence at the Pilchuck Demonstration Site on a sunny day in Washington state.
A deer fence was installed in spring 2014 to protect some of the research trials from deer.


The initial harvest of the Pilchuck Site occurred in November 2014 at the conclusion of the site’s second growing season. Due to the relatively low yields and lack of markets for chips in the area, the chips were left on site. At harvest, the tallest trees in the Pilchuck demonstration site averaged 11 feet tall.

Future harvests are anticipated to yield more biomass from coppice growth. Currently, the poplars are growing at a much faster rate than during the initial establishment cycle. The Pilchuck site will be harvested again in winter 2018, three growing seasons after the initial coppice harvest. At that time, the site will be restored to its former land use as pasture and hay fields.