Stepping stone habitats

Definition

Stepping stone habitats are small, distributed patches of natural or semi-natural habitat within urban areas that enable species movement between larger habitat areas.

What this strategy does

Provides intermittent habitat nodes that support dispersal, foraging, and refuge across fragmented urban landscapes, without requiring continuous corridors.

Context

In Aotearoa New Zealand cities, high fragmentation, limited Indigenous vegetation cover, and intensive land use constrain species movement; stepping stones offer a pragmatic connectivity response at the urban scale where continuous habitat is infeasible.¹

Technical considerations

Design considerations

Connectivity placement

Locate stepping stones to bridge existing parks, reserves, waterways, and vegetated streets, prioritising routes that minimise animal movement resistance.¹

Patch size and spacing

Provide the largest patches feasible; closer spacing improves functional connectivity, particularly for less mobile species.²

Edge treatment

Reduce edge effects through compact patch shapes, dense perimeter planting, and layered vegetation structure.²

Native planting

Prioritise Indigenous species that provide food, shelter, and seasonal resources for native fauna.³

Functional diversity

Incorporate canopy, understory, and ground layers to support a range of feeding and nesting behaviours.³

Building-integrated vegetation

Use green roofs, green walls, and planted structures as supplementary stepping stones in dense urban areas.¹

Blue–green integration

Where possible, integrate wetlands, swales, or riparian planting to increase habitat diversity and connectivity.⁴

Implementation considerations

Design priority

Coordinate stepping stone placement at neighbourhood, urban, and watershed scales rather than site-by-site.

Key constraint

Habitat provision alone is often insufficient for sensitive species without concurrent pest management in Aotearoa.²

Issues & barriers

Land availability

High land values and competing urban uses limit opportunities for larger or optimally located and spaced habitat patches in dense urban areas.⁵

Fragmentation legacy

Existing green spaces are often small and isolated, reducing stepping stone effectiveness.²

Minimum habitat thresholds

Indigenous vegetation cover in many Aotearoa New Zealand cities remains below levels required to sustain native biodiversity.²

Edge effects and quality risks

Small or poorly designed patches can function as ecological traps if quality is low.²

Predator pressure

Without ongoing predator control, recolonisation and persistence of vulnerable species are unlikely.²

Synergies and opportunities

Climate change – urban cooling and stormwater management. Vegetated stepping stones contribute to heat mitigation and stormwater attenuation when integrated with blue–green infrastructure.⁴
Climate change – adaptation and resilience. Improved connectivity supports species movement and adaptation under changing climatic conditions.⁶
Human wellbeing – mental wellbeing. Access to biodiverse green spaces is associated with reduced stress and improved psychological wellbeing.⁷
Human wellbeing – physical health and social cohesion. Distributed green spaces encourage walking, recreation, and community interaction.⁸
Cultural value. Stepping stones can reconnect urban communities with Indigenous ecosystems.⁹

Financial case

Value type

Reduced stormwater infrastructure demand, urban cooling benefits, and biodiversity co-benefits from multi-functional land use.⁴

Cost-effectiveness: Investment logic

Strategically placed small patches can achieve connectivity gains at substantially lower cost than continuous corridors.¹⁰

Monitoring and evaluation metrics

Core metric

Indigenous vegetation cover (%) and spatial distribution across the urban area.²

Advanced or long-term metrics

Patch size, edge-to-interior ratios, and connectivity indices derived from spatial analysis.¹
Presence and abundance of indicator native species.²

Additional resources or tools

Upper Hutt Sustainable Landscape Design Guide. Guidance on integrating habitat stepping stones into urban and peri-urban landscapes.
Guide to Backyard Biodiversity (Tiaki Tāmaki Makaurau). Practical guidance for creating small-scale urban habitat patches.
How to Put Nature into Our Neighbourhoods. Guidance on cost-effective nature-based solutions in urban areas (international).

References

MacKinnon, M., Pedersen Zari, & Brown, D. (2023). Improving urban habitat connectivity for native birds: Using least-cost path analyses to design urban green infrastructure networks. Land, 12, 1456. https://doi.org/10.3390/land12071456
Saura, S., Bodin, Ö., & Fortin, M. (2014). Stepping stones are crucial for species’ long-distance dispersal and range expansion through habitat networks. Journal of Applied Ecology, 51, 171–182. https://doi.org/10.1111/1365-2664.12179
Wallace, K., & Clarkson, B. (2019). Urban forest restoration ecology: A review from Hamilton, New Zealand. Journal of the Royal Society of New Zealand, 49, 347–369. https://doi.org/10.1080/03036758.2019.1637352
Molné, F., Donati, G., Bolliger, J., Fischer, M., Maurer, M., & Bach, P. (2023). Supporting the planning of urban blue–green infrastructure for biodiversity: A multi-scale prioritisation framework. Journal of Environmental Management, 342, 118069. https://doi.org/10.1016/j.jenvman.2023.118069
Soanes, K., et al. (2023). Conserving urban biodiversity: Current practice, barriers, and enablers. Conservation Letters, 16. https://doi.org/10.1111/conl.12946
Keeley, A., et al. (2018). New concepts, models, and assessments of climate-wise connectivity. Environmental Research Letters, 13. https://doi.org/10.1088/1748-9326/aacb85
Schebella, M., et al. (2019). The wellbeing benefits associated with perceived and measured biodiversity in urban green spaces. Sustainability, 11, 802. https://doi.org/10.3390/su11030802
Sharifi, A., et al. (2021). A systematic review of the health co-benefits of urban climate change adaptation. Sustainable Cities and Society, 74, 103190. https://doi.org/10.1016/j.scs.2021.103190
Mihaere, S., et al. (2024). Centring localised indigenous concepts of wellbeing in urban nature-based solutions. Frontiers in Environmental Science. https://doi.org/10.3389/fenvs.2024.1278235
Xiao, W. (2023). Stepping stone strategy: A cost-effective way to address habitat fragmentation of endangered wildlife. Ecosystem Health and Sustainability. https://doi.org/10.34133/ehs.0073