Living Structural Systems in Soil Bioengineering

An overview of the more structural side of soil bioengineering, including wattle fences, live reinforced earth walls, live smiles, and related living systems for difficult slope and channel problems.

Soil bioengineering includes both simple revegetation techniques and structural living systems. The distinction matters because each responds to different site forces and construction constraints.

A living structural system is a soil bioengineering treatment that provides an immediate physical function while also rooting, growing, and improving with time.

Examples from the legacy PES material include:

These are not just planted slopes. They are engineered assemblies built from living material.

People sometimes hear "bioengineering" and assume a soft, low-strength treatment. The PES legacy says otherwise. Many of these systems were developed precisely for sites where:

The living part is the advantage, not the weakness. Once established, the root systems deepen, the structural matrix densifies, and the treatment often performs better over time rather than worse.

Wattle fences are one of the clearest examples of living structure. They create a series of small retaining steps across an over-steepened slope. The terraces reduce erosion immediately, while the willow cuttings root and create long-term cohesion across the face.

They are especially strong where moisture is available and the slope is globally stable but surface erosion and shallow instability are active.

The highway presentation material is especially useful here. It shows that live reinforced earth walls are not just landscape treatments. They are substantial structural systems that combine soil, reinforcement, and living plant material into a retaining assembly that can root into the slope and improve with time.

That makes them relevant where a conventional retaining solution would be expensive, visually harsh, or ecologically dead.

It also helps that the public slide set shows more than one mode of evidence: conceptual diagrams, early-condition structural examples, and later growth. That combination makes the system easier to understand than a plain text description ever could.

The old methods material also references live smiles, a more specialized system for flowing mud and difficult unstable slope conditions. Even without promoting every legacy technique as a standalone service page, it is useful to surface the term publicly because it shows the depth of the PES toolkit and the site-diagnosis logic behind it.

The broader lesson is that the method library includes treatments for very different failure mechanisms, not a single generic slope recipe.

These systems express the central PES worldview:

This is why the methods can be both practical and ecological at the same time.

Structural living systems are most relevant for:

The Bowker Creek and highway examples matter here because they show these systems in exactly the kinds of constrained public settings where conventional practice often defaults to hard armouring or repeated cosmetic repairs.

Living structural systems go beyond planting cuttings or seeding disturbed ground. They use living materials to build systems that perform real engineering work under defined site forces and construction constraints.

Some of the most effective PES solutions are living structural systems that solve stability problems now and keep getting stronger as they grow.

Living structural systems are easiest to understand when the same treatment is shown at different moments: as a built structure, as an early growing system, and finally as a slope or channel edge where vegetation has taken over much of the engineering work.

A living structural system starts with a physical job. In this diagram, posts and woven live material create a small retaining face. The structure holds soil immediately, while the planted cuttings are positioned to root into the same assembly.

Wattle fences supporting the Bowker Creek channel edge.

The best sign of success is that the structure becomes less obvious. Once vegetation is established, roots and stems share more of the work, and the installation reads less like construction and more like a recovering stream edge.

A live reinforced earth wall beginning to green up.

The RPP time sequence shows why these treatments should be judged over time. At installation, the living material is still mostly structure and intent: a set of lines across a steep till slope, built to catch soil and create rooting sites.

First strong vegetation response after wattle fence installation.

Long-term views matter because living structures are designed to improve. By 2005, the treatment is no longer mainly a set of installed fences; it is a vegetated slope surface with rooted material doing the stabilizing work.

The recovered slope edge in 2009.

• Source decks: David Polster, Highway Bioengineering and RPP Early Wattle Fences.
• Wattle Fencing
• Live Smiles
• Brush Layers for Slope and Bank Repair

We can help interpret the conditions on your slope, streambank, shoreline, or disturbed site and recommend the right combination of soil bioengineering methods.