Definition
Living stabilisation systems are bioengineered walls and slopes that integrate vegetation and natural materials into retaining, shoreline, and slope infrastructure to reinforce soils while providing ecological function. Examples include vegetated retaining walls, planted crib walls, living crib walls using live stakes, brush mattresses, and living shorelines.
What this strategy does
Combines engineered structural systems with living plant material to reduce erosion, improve slope stability, and introduce habitat into otherwise hard or low-complexity surfaces. Avoids purely ornamental planting that does not contribute to long-term structural or ecological performance.
Context (Aotearoa New Zealand)
In Aotearoa New Zealand, urban slopes, stream banks, and coastlines are frequently stabilised using hard engineering approaches that provide limited ecological value. Bioengineered solutions are increasingly relevant where space is constrained, and climate-driven erosion, flooding, and coastal stressors are intensifying.
Technical considerations
Design considerations
Vegetation selection
Select locally appropriate native species matched to slope angle, substrate depth, moisture regime, and exposure to improve establishment success and long-term resilience.
Structural and surface complexity
Incorporate ledges, crevices, open joints, rough textures, varied substrates, or biodiversity tiles to increase habitat availability and improve the ecological performance of engineered surfaces.
Vertical layering
Where space allows, provide multiple vegetation layers (groundcover, shrubs, small trees) to support a wider range of species and microclimates.
Coastal applications
For shoreline and marine walls, integrate water-retaining features and textured surfaces to reduce thermal and desiccation stress and better mimic natural rocky shore habitats. These conditions can sometimes be retrofitted onto existing hard surfaces as biodiversity tiles.
Implementation considerations
Substrate and growing media
Provide enough soil depth and moisture retention to support long-term plant survival and invertebrate communities on engineered structures. Where appropriate, use live stakes on slopes to improve stabilisation as roots establish or planted crib walls.
Bioengineering materials
Use durable natural fibres (e.g. coir-based systems) in live crib walls and brush mattresses to improve plant establishment and structural performance, particularly under flood stress. For seawall biodiversity tiles these can be cast from concrete or 3D printed.
Environmental stressors
Design responses must be tailored to dominant site pressures such as wave energy, flooding, desiccation, or temperature extremes.
Dynamic systems
Living shoreline designs should accommodate sediment movement and, where feasible, allow landward migration to maintain function under sea-level rise.
Issues and barriers
Ecological performance risk
Poorly designed bioengineered walls may support lower biodiversity than natural reference habitats if moisture, complexity, or species requirements are not adequately addressed.
Structural and maintenance risk
Vegetated crib walls and brush mattresses can fail during extreme flood events if not properly engineered, creating downstream blockages or asset damage.
Policy and consenting constraints
Planning and coastal management frameworks may favour hard engineering solutions, creating approval barriers for living shoreline approaches.
Synergies and opportunities
Climate change – Improves adaptive capacity to erosion, flooding, and extreme weather while maintaining ecosystem function.
Human wellbeing – Enhances visual amenity and everyday exposure to vegetation in dense urban environments.
Financial case
Ecosystem services and performance value
Erosion and risk reduction
Vegetated slopes and shorelines reduce erosion and landslide risk, lowering long-term infrastructure repair and disaster response costs.
Cost-effectiveness
Lifecycle value
When appropriately designed, nature-based stabilisation systems can deliver multiple services — stability, habitat, amenity — with lower whole-of-life costs than single-purpose hard infrastructure.
Monitoring and evaluation metrics
Core metric
Vegetation or animal survival, structural integrity, and erosion rates can be assessed through repeat site inspections, particularly after storm events.
Advanced metric
Biodiversity response can be measured through plant diversity, invertebrate presence, and species use of vegetated structures or coastal biodiversity tiles.
Case studies
- Mōtū Manawa – Pollen Island Marine Reserve
- Kete Tiles
Related design strategies
- Artificial micro-habitats
- Building-integrated vegetation
- Planting for biodiversity
- River daylighting and culvert naturalisation
- Urban riparian restoration and shading
Additional resources or tools
MBIE – Retaining Walls Guidance
https://www.building.govt.nz/building-code-compliance/b-stability/b1-structure/module-6-earthquake-retaining-wall-design
Ministry for the Environment – Coastal Hazards and Climate Change Guidance
https://environment.govt.nz/publications/coastal-hazards-and-climate-change-guidance/