Working Buffers

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Forested buffers along waterways help filter runoff, reduce erosion, keep water cool for fish, provide wildlife habitat, increase carbon sequestration, and more! ‘Working buffers’ allow farmers to widen these forested areas without losing farmable land by integrating perennial trees and shrubs into their agricultural systems. Tree crops such as fruits, nuts, and timber are mixed with understory crops such as berries, floral industry greens, mushrooms, and livestock forage. The farmer benefits in many ways including diversification of products, improved soil health, pollinator habitat, and protection against flood damage.

Below are four ‘working buffer’ techniques that may fit the goals of your farm: forest farming, alley cropping, short rotation biomass, and silvopasture. Where to use and how to manage these alternative farming methods is specific to each site’s conditions and each landowner’s needs. None of these techniques are to be used in an existing forested buffer. Rather, these are ways to expand a newly planted or existing buffer to increase its functions while at the same time earning more income for your farm.

Forest Farming

Forest Farming can include shiitake mushrooms growing on logs.

Forest farming is a multi-story cropping system where taller trees form the overstory and the understory plants are grown for a variety of niche markets. Instead of shade from the tall tree canopy being a negative, it’s used to help grow marketable plants that need part or full shade such as salal, mushrooms, and ferns. The overstory may incorporate fruit, nut, and other crop trees or be thinned for timber. 

Some examples of crops and products that can be harvested from a forest farming system include syrup, boughs for wreaths, native plant starts, spices, and medicinal herbs. While the taller trees are growing and haven’t developed their full shade canopy, sun-loving plants such as berries can also be grown. 

Forest Farming Examples

  • Shiitake Mushrooms

  • Pine Nuts

  • Salal

  • Elderberry

  • Goldenseal

Alley Cropping

Alley cropping involves planting short or ground level crops in the ‘alleys’ between rows of trees. Rows of highly productive tree or shrub species can be managed for crops such as fruits, nuts, and timber. ‘Alley crops’ between rows can produce hay, small grains, vegetables, ground cover fruits, and even vines such as berries and grapes. Combining these two production methods can help farmers cope with market fluctuations and crop failures by diversifying outputs. Alley cropping can either be a long or short-term approach to maximizing farm production while establishing a forest canopy in a buffer area. 

Alley Cropping Tree Examples

  • Serviceberry

  • Cider Apples 

  • Walnuts

  • Christmas and Ornamental Trees

Short Rotation Biomass

This method involves densely planting fast-growing woody tree or shrub species and then harvesting parts of the plants every few years to consistently provide biomass. Plants are harvested by periodically cutting them back to the ground to stimulate growth. This method is ideally suited for marginal areas such as drained or disturbed wetlands, low elevation depressions within a floodplain, saturated soils, or barely productive farmland.

Plant material harvested from these fast-growing species can be used for livestock feed and bedding, biofuels, paper pulp, biomass combustion, and other emerging markets. Several native willow, dogwood, and cottonwood species can also be grown to harvest live stakes that can be sold to the nursery market or for habitat restoration projects. 

Short Rotation Biomass Plant Examples

  • Shrub Willows

  • Hybrid Poplar/Cottonwood Trees 

In recent years, research has been conducted using shrub willows and hybrid poplars to produce hardwood biomass for the renewable energy sector (heat, power, and biofuels). Currently, there are no biorefineries in Washington State, making biofuels a speculative emerging product. Landowners interested in producing biomass for renewable energy markets or paper production are strongly encouraged to partner with other producers, researchers, and buyers before starting in order to increase chances for success.

Silvopasture 

Silvopasture involves combining forestry and livestock grazing on the same land. Trees can benefit livestock by providing cooler temperatures and a longer forage-growing season, which has been shown to increase livestock health and growth rates. Silvopasture also includes the application of best soil practices, such as using introduced or native pasture grasses, nitrogen-fixing legumes, and intensively-managed grazing periods to maximize plant growth and harvest. 

The trees are managed for fruit or nut production, timber, or any combination of forest products. Silvopasture methods are most successful on well-drained upland areas free from seasonal flooding. Spacing trees to provide even shade coverage for livestock and forage maximizes tree growth and improves the ripening of fruit and nut crops. Fences are used to exclude livestock from buffers along waterways and to help manage rotational grazing.

Silvopasture Tree Examples

  • Chestnuts 

  • Alder 

  • Black Walnut 

  • Filberts

To learn more 

Funding may be available to help you get started on your new working buffer! Contact a farm planner at 425-335-5634 ext. 4 or farmplanners(at)snohomishcd.org.