SW Hamilton St Case Study

Before and After

Before: A conventional 5,500-square-foot suburban lawn dominated by turf grass, offering minimal habitat value, food production, or ecological function.

After: A layered, native forest system composed of more than 40 Oregon native plant species, designed to support wildlife, produce food, improve soil health, and function as a resilient ecosystem with minimal long-term maintenance.

Case Study: Converting a Front Lawn into a Native Forest Ecosystem

Project Overview

This project transformed a 5,500-square-foot suburban front yard in Portland, Oregon, from a traditional grass lawn into a biodiverse, multi-layered native forest.

The planting design incorporates over 40 native Oregon species, arranged to mimic natural forest structure—from canopy trees to groundcover.

The primary goals of the project were to:

• Increase food production for humans and wildlife

• Create habitat for birds, insects, and small mammals

• Improve soil health and water infiltration

• Reduce long-term maintenance and external inputs

Rather than relying on chemicals, fertilizers, or intensive upkeep, this system is designed to become increasingly self-regulating over time.

Site Details

Location: Portland, Oregon

Soil Type: Sandy loam with good drainage

Irrigation: Existing in-ground sprinkler system

Design Goal: Establish a food-producing native forest that supports pollinators, birds, small mammals, and people while improving soil structure and site hydrology

Soil Preparation & Lawn Removal

To remove the existing turf grass, we apply an 8–12 inch layer of wood chips directly over the lawn, followed by a biologically active soil blend that we plant and seed into.

This method suppresses grass by excluding light while maintaining oxygen exchange and soil biology. As wood chips decompose, they increase organic matter, enhance aggregation, and support fungal and microbial communities essential to long-term plant establishment.

We avoid plastic solarization because it overheats and sterilizes soil, reducing microbial diversity and disrupting soil structure. We also do not use cardboard, which can create an anaerobic barrier, slow water infiltration, and persist longer than expected in the soil profile.

Wood chips break down gradually and predictably, improving moisture retention and nutrient cycling while encouraging deep root development. Layering soil directly over wood chips mirrors natural forest soil formation, creating a stable, biologically rich growing environment that suppresses turf and supports a resilient ecosystem.

The soil layer added on top further enhances drainage and moisture balance while providing an immediate planting medium. Together, these layers replicate natural soil-building processes found in forest systems.

Additional benefits of this approach include:

• Reduced summer watering through moisture retention

• Suppression of invasive grasses and weeds

• Improved root development for new plantings

• Increased soil oxygen and microbial diversity

This simple, effective strategy prepares the site for long-term ecological success.

Plant Lists:

Tree Layers: Canopy and Understory

Forest ecosystems are structured in layers. Two of the most important are the canopy and the understory. Together, they regulate light, temperature, moisture, and habitat, creating the conditions that allow diverse plant and animal communities to thrive beneath them.

Canopy Trees

The canopy is the uppermost layer of the forest. These trees grow tall and wide, intercepting sunlight, moderating temperature, and buffering wind and rainfall. Canopy trees are the primary drivers of carbon storage, long-term soil building, and hydrologic regulation.

Canopy species used in this project:

• Western Red Cedar

• Western Hemlock

• Douglas Fir

• Bigleaf Maple

These long-lived species form the structural backbone of the forest. Their deep roots stabilize soil, while falling leaves and needles provide continuous organic inputs that build soil over time.

Understory Trees

The understory sits beneath the canopy and includes smaller trees and large shrubs adapted to partial shade. This layer increases species diversity, provides food and habitat at a human scale, and creates a gradual transition between groundcover and canopy.

Understory species used in this project:

• Bitter Cherry

• Cascara

• Douglas Hawthorn

• Pacific Dogwood

• Beaked Hazelnut

• Vine Maple

Understory trees flower and fruit at different times than canopy species, extending food availability for birds, insects, and mammals throughout the year. They also fill ecological gaps, reducing open space where invasive species might otherwise establish.

Why These Layers Matter

A multi-layered forest is more resilient than a single-layer planting. Canopy and understory trees work together to:

• Distribute light more evenly across the site

• Reduce temperature extremes and moisture loss

• Increase habitat complexity for wildlife

• Support diverse fungal and microbial networks

• Improve long-term stability and self-regulation

By designing with both canopy and understory layers, this forest functions as an interconnected system rather than a collection of individual plants.

Shrub Layer

The shrub layer sits between the trees and groundcover, adding vertical complexity, seasonal food, and habitat for wildlife. Shrubs support pollinators, birds, and small mammals while stabilizing soil and suppressing weeds.

Key Shrub Species:

• Tall/Upper Shrubs: Serviceberry, Mock Orange, Osoberry, Red Flowering Currant, Evergreen Huckleberry, Red Huckleberry, Western Azalea

• Low/Mid Shrubs: Blueblossom Ceanothus, Douglas Spirea, Oceanspray, Thimbleberry, Wood Rose, Highbrush Cranberry, Gooseberry, Rhododendron

Together, these shrubs extend bloom and fruiting across seasons, provide dense cover and nesting sites, support native insects, and enrich soil through leaf litter and fine roots. By stacking heights and functions, the shrub layer becomes a productive, wildlife-rich part of the forest ecosystem.

Groundcover & Herbaceous Layer

The groundcover and herbaceous layer form the foundation of the forest, covering soil, conserving moisture, suppressing weeds, and supporting a vast array of insects and small wildlife. This layer also plays a key role in nutrient cycling and soil formation.

Key Species:

• Ferns: Sword Fern, Lady Fern, Deer Fern, plus other native Oregon ferns

• Flowering Herbaceous Plants: Goldenrod, Beach Daisy, Wild Strawberry, Bluebells, Bleeding Heart, Monkeyflower, Penstemon, Mugwort, Showy Milkweed, Shooting Star, Rattlesnake Plantain, Sedum, Sneezeweed, Lupine, Umbrella Plant, Streambank Clover, Wallflower, Pearly Everlasting, Jacob’s Ladder

• Grasses & Sedges: Prairie Junegrass, California Oatgrass, Roemer's Fescue

These plants provide continuous blooms and nectar for pollinators, habitat and forage for insects, small mammals, and birds, and dense soil cover that reduces erosion. By combining ferns, flowering perennials, and low grasses, the ground layer supports a resilient, self-regulating ecosystem that strengthens the health of the entire forest.

Projected Benefits Over 20 Years

🌿 Imagine this: a thriving native forest in your yard, alive with the buzz of pollinators, the songs of birds, and the rustle of leaves. Over the next twenty years, this rewilded space won’t just be beautiful but bountiful. Let’s take a closer look at what this forest will do: how much food it will produce, the wildlife it will support, and its incredible impact on our environment. 🌳✨

1. Food Production

Once established (approximately year 7), the forest is expected to produce significant quantities of edible fruit, seeds, and nuts annually.

Estimated Annual Yields:

• Evergreen & Red Huckleberry: 30 lbs

• Red Flowering Currant: 20 lbs

• Osoberry: 39 lbs

• Serviceberry: 5 lbs

• Gooseberry, Thimbleberry, Highbrush Cranberry, Wild Strawberry: 14 lbs combined

Total Annual Fruit Production: ~153 lbs. Additional Production: Beaked Hazelnut (~10 lbs/year)

Estimated Total Food Yield Over 20 Years: ~3,260 lbs

This food supports both people and wildlife, strengthening the local food web.

2. Habitat Creation

The forest's layered structure provides year-round habitat for a wide range of species. We mimicked the forest's structure with this log drop, creating planters around the logs and providing small sticks and other debris for bugs to hide.

Birds: Habitat for at least 20 species, including cavity-nesters, fruit-eaters, and insectivores

Pollinators: Dozens of native bees, butterflies, and moths are supported by continuous bloom periods

Small Mammals: Shelter and forage for squirrels, rodents, and other small mammals

3. Insect Biodiversity

Dense native plantings are expected to support more than 150 insect species.

• Cascara and Oceanspray act as host plants for moth and butterfly larvae

• Milkweed supports monarch caterpillars

• Mulch and groundcover create habitat for decomposers that improve soil fertility

4. Carbon Sequestration

Large trees and long-lived shrubs will capture and store significant carbon over time. Smaller plants and grasses also do their part.

• Estimated Sequestration: ~8,000 lbs of CO₂ per year

• 20-Year Total: ~160,000 lbs (80 tons)

5. Ecosystem Services

• Soil Health: Root systems and decomposing organic matter improve structure and nutrient cycling

• Water Management: Increased infiltration, reduced runoff, and lower irrigation needs

• Biodiversity: Native plant dominance limits invasive species and supports ecosystem balance.

Maintenance Timeline

Years 1–3

• Regular watering during establishment

• Invasive plant removal

• Annual mulch replenishment

Year 4 and Beyond

• Minimal maintenance

• Occasional pruning and spot weeding

As the system matures, it becomes increasingly self-sustaining.

Conclusion

This project demonstrates how a conventional lawn can be transformed into a productive, resilient native forest. Over 20 years, this yard will generate thousands of pounds of food, provide habitat for birds and insects, store significant carbon, and function as a living ecosystem—without chemicals or intensive upkeep.

The result is a landscape that works with, rather than against, natural processes, benefiting both homeowners and the surrounding environment.