Keyline Planning for Healthy Trees

About this pattern

Keyline Planning manages the existing landscape through enhancing soil quality, carbon capture and water holding capacity. Water naturally flows downhill running off ridges and concentrating in valleys. The basic site analysis for a keyline design includes identifying the ʻmain ridgeʼ (the watershed divide), ʻprimary ridgesʼ (convex slopes radiating off of the main ridge) and ʻprimary valleysʼ (concave basins receiving runoff between primary ridges). The ʻkeypointʼ is where the slope changes from convex to concave in shape and exists in valleys. It marks the highest point in the landscape to hold water.

The contour passing through the keypoint is known as the ʻKeylineʼ. Subsoil ploughing along the keyline decompacts degraded soils, improving water infiltration, and distributing water more evenly. Subsoil plough regime  helps restore a soil’s structure and water holding capacity. The keyline subsoil rips create mini drainage channels diverting water gently downhill and back out onto the ridges. 

This system uses the natural patterns of the landscape to catch and store water for use in cooling strategies.

Pattern Conditions

Enablers:

• Keyline Planning enables the rapid development of biologically active, fertile soil within a systematically planned landscape. During an average three-year conversion phase, four to six inches of new topsoil are typically formed each year. This new topsoil stores large quantities of water in the landscape.
• Run-off water, stored in small dams, can later be released for rapid, gravity-powered flood-irrigation.
• Roads, forests, buildings and fencing that follow primary water layout and fit together within the lay of the land.
• Keyline Planning enables a permanent landscape where infrastructure components help to passively ensure the maintenance and renewal of the topsoil within it.

Constraints:

• Existing trees constrain where land modelling and contour ploughing can take place.
• Endangered Ecological Communities will constrain layout.

Commoning Concerns

Access: People are unrestrained; restriction for vehicles.

Use: Open space recreation, channelling cool breezes.

Benefit: Improve & maintain soil quality, water management and carbon storage.

Care: Local Government and community of commoners.

Responsibility: Body Corporate, Local Government and community of commoners.

Ownership: Body Corporate, Local Government and building owners.