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Planting Completed at All Demonstration Sites

In spring 2013, the Feedstock Team completed planting all four of the AHB project demonstration sites by planting  the Pilchuck (north of Seattle, WA) and  the Clarksburg (near Sacramento, CA) sites. The sites are designed to test and showcase all aspects of growing hybrid poplar as a renewable resource for home-grown transportation fuels in the Northwest. The Feedstock Team planted each demonstration site with multiple varieties of hybrid poplar to compare the growth and efficiency of different poplar clones under various conditions in the Northwest. In spring 2012, a 65-acre site was established outside Hayden, ID (panhandle region), and an 85-acre site was established near Jefferson, OR (Willamette Valley).

Powering engines and economies

Developing a biofuels industry in the Northwest is expected to revitalize the region’s agriculture industry and the region’s economy. Because hybrid poplars are fast-growing and highly adaptable to a wide range of sites, large and small farmers will be able to grow the trees on land that is not suitable for other crops. This fledgling industry is also expected to introduce new feedstock management jobs to rural communities and create new biorefinery plant operator jobs throughout the region.

Hybrid poplar cuttings (22 inches long and 3/8 inch in diameter) are hand planted in rows at the Pilchuck Demonstration Site.
Hybrid poplar cuttings (22 inches long and 3/8 inch in diameter) are hand planted in rows at the Pilchuck Demonstration Site.

Pilchuck near Stanwood, WA

At the 92-acre Pilchuck site near Stanwood, Washington eight different clones were planted in two- to ten-acre monoclonal blocks. The clones were selected for their growth characteristics and site adaptability and will be evaluated for disease resistance and rate of growth.  The team also planted native red alder as an alternative feedstock and to test alder’s nitrogen fixing ability to enhance poplar growth. Before the planting as a demonstration site, the acreage was used for pasture and hay production.

Native red alder is interplanted with poplar to improve nitrogen fixation.


A combination of plentiful rainfall, moderate marine climate, and deep and fertile soils at the Pilchuck site is expected to result in four to eight feet of growth the first year and over 10 feet in following years.  Alleys of grass between the trees help keep weeds from taking root, reduce erosion, and allow equipment to move through easily.

Because hybrid poplars have a propensity to quickly re-sprout from cut stems, rapid growth is expected following the first harvest, which is expected to occur after two or three growing seasons. The cycle of harvest and re-sprouting can occur for several years.  The established root system allows the above-ground plant growth to rapidly re-occupy the site after each harvest. This not only speeds up production of the feedstock, but also lowers the costs of managing competing vegetation.


Clarksburg Demonstration Site.
Hybrid poplar cuttings are planted in the fertile soil near the Sacramento River at the Clarksburg Demonstration Site.

Clarksburg, CA

The southernmost demonstration site at Clarksburg, CA, near the Sacramento River, is a 50-acre site with abundant ground water that allows for good poplar growth. The Clarksburg site will evaluate the performance of 75 new hybrid poplar varieties and the effects of crop density, season of harvest, and intercropping with nitrogen-fixing alder. Eleven of the hybrid poplar varieties for this site were selected based on performance data from a test plot established in 2008.  Yields at this site are expected to be highest compared to the other three sites due to warmer temperatures and fertile, well-drained soil.


Plans for Harvest

At all four demonstration sites hybrid poplars will be grown on very short rotations and the trees are growing as rapidly as expected.

A modified forage harvester will cut and grind the saplings as it moves down the crop rows, feeding the chips into a truck that moves alongside. After the first harvest, multiple shoots of re-growth at the root stalk can be harvested again in two to three years.

All sites will be monitored annually for survival and growth. The performance of various clones at the different sites will help determine which areas are best suited for bioenergy farms that can support a sustainable biofuels industry in the Northwest.