Planting for biodiversity and urban habitat.

Te Auaunga: Walmsley and Underwood Reserves project. Photo from Urban Ark Manawa Taiao https://urbanark.nz/events/restoring-aucklands-streams-and-wetlands/

Diverse and resilient plantings support ecosystem health, and especially in urban settings enhance urban resilience, and provide a number of benefits to communities. Planting for biodiversity and urban habitat is a nature-based conservation and restoration strategy intended to provide habitat, protect against pests and environmental hazards, prevent erosion, improve soil, air and water quality, and improve ecosystem services. Planting can be done in various settings and in conjunction with other nature-based design strategies like wildlife corridors, urban wildlife sanctuaries, pollinator pathways, and ecological islands. Indeed, planting is widely perceived as a key component of climate change mitigation and adaptation (Aerts & Honnay, 2011). 

In contrast to simply ‘revegetation’ exemplified by planting initiatives like Aotearoa New Zealand’s One Billion Trees programme which often employ exotic species (such as pinus radiata) or mixed exotic and native afforestation plantings which can have negative impacts on biodiversity, or food forests or agroforestry focused on human food production, planting for biodiversity ensures that ecosystem functioning is protected and enhanced by promoting the planting of appropriate native species in areas where forest cover would have historically occurred, or where existing forest biodiversity is degraded (Suryaningrum et al., 2022; Veldman et al., 2015). The emphasis is on supporting native biodiversity and planning for natural succession. 

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Name of NbS

Planting for biodiversity and urban habitat.

Type of NbS

Combination, Created or constructed living ecosystems, Ecosystem restoration

Location

  • Urban,
  • Peri-urban
  • Rural
Aporosa Ramulo Livani. Photo from Ministry of Forestry, Fiji https://unu.edu/publication/advancing-forest-landscape-restoration-tropics

Relationship to Indigenous knowledge

Indigenous people worldwide often have broad, generational understandings of their local ecosystem. Relying on natural provisioning of resources and therefore needing to live in dynamic balance with natural systems, there are many examples of Indigenous knowledge and practices enhancing biodiversity at a landscape level (Gadgil et al., 1993). 

In Te Moananui Oceania, ecosystems are highly variable and exhibit rich endemic terrestrial species. Loss of traditional ecological knowledge through colonisation in Te Moananui Oceania has driven rapid biodiversity decline, alongside increased population pressure, spread of invasive species and increased frequency of climate change-related disasters. 

Indigenous communities have historically and many still do rely on ecosystem services delivered through subsistence agriculture (such as the diverse agroforestry practice that occurs throughout Te Moananui Oceania) fishing and hunting through strong socio-ecological and customary systems which sustain biodiversity (Gadgil et al., 1993). These customary practices are invaluable in their potential application for biodiversity planting and urban habitat establishment.

Climate change benefits
  • Biomass cover loss
  • Increased incidence/distribution of disease
  • Increased pests or spread of weeds
  • Loss of other ecosystem services
  • Reduced air quality
  • Reduced soil quality
  • Reduced water quality
  • Urban heat island effect

Planting for biodiversity and urban habitat increases biomass cover loss by restoring and reintroducing vegetation into environments where it has been lost or removed, especially in urban areas where biodiversity is often greatly diminished (Aerts & Honnay, 2011; Suryaningrum et al., 2022). By improving the health of the overall ecosystem and increasing genetic diversity, species become less susceptible to specific diseases or pest threats. Other benefits include myriad ecosystem services similar to other NbS which employ vegetation, including reduction of the urban heat island effect, and improved soil, water and air quality.

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Societal / socio-cultural benefits
  • Biodiversity health and conservation
  • Climate change adaptation
  • Disaster risk reduction
  • Water security

Improved biodiversity health and conservation outcomes through planting and urban habitat initiatives offer societal benefits. These initiatives make urban settings tangibly more biodiverse and improve quality of life through enhanced health, community engagement, and active disaster risk reduction, such as reducing stormwater flows, providing windbreaks, offering storm protection, and stabilising soil (Aerts & Honnay, 2011). These factors contribute to more resilient landscapes, both urban and otherwise, that also serve as habitats and refuges for native species.

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Ecological and biodiversity benefits
  • Biological control (regulation of pests and diseases)
  • Climate regulation
  • Disturbance prevention
  • Genetic resources (diversity)
  • Habitat provision
  • Purification
  • Species maintenance

Biodiverse plantings host a variety of insects that can act beneficially to control pest populations (Suryaningrum et al., 2022). Through transpiration and shade produced, urban plantings especially can provide climate regulation benefits. As plantings establish and stabilise soil, erosion is less likely to occur (Brancalion & Holl, 2020). Planting a diverse range of plants crucially provides genetic diversity, while provisioning for species like birds, reptiles and insects. Some plants can filter pollution from the air and water, and can play a role in reducing runoff and therefore reducing contamination. Species maintenance occurs when the necessary resources are available for survival – a key outcome for planting for biodiversity and urban habitat projects.

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Technical requirements

Diverse strategies should be used when implementing planting for biodiversity and urban habitat. Ideally, the priority is to protect and restore existing habitats, integrating with existing conservation policies and outcomes. Following this, planting must be planned in ways that forefront biodiversity outcomes, while meeting local planning and land use regulations (Aerts & Honnay, 2011; Sousa-Silva et al., 2023). Funding projects for biodiversity and habitat protection and creation often happen as collaborative projects, and require government departments, NGOs and community groups to work together to secure funding and establish planting projects (Kingsford et al., 2009).

Understanding existing vegetation through data collection like ecological surveys, and consultation of local and Indigenous knowledge can allow selection of appropriate plant species through eco-sourcing for ecosystem establishment or re-establishment. 

Eco-sourcing is the practice of sourcing seeds and growing seedlings as close to where they will be planted as possible, and especially within an ecoregion. Eco-sourcing can improve biodiversity and urban habitat outcomes by ensuring plant species are locally adapted and appropriate to the ecosystem and the species that exist there. Staged approaches that take into account seasons and ecological succession can increase the success of planting projects. Following establishment, consideration of maintenance is required, especially management of weeds and pest control until plantings are well established.

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Issues and Barriers

In Te Moananui Oceania, efforts to improve biodiversity and urban habitat through planting face a number of challenges. Jupiter et al. (2014) describe local governance in the region as often under-resourced, provided with limited data, and political positions that can prioritise economic development over ecological sustainability. 

Invasive species pose more tangible issues, including pressure from introduced predatory and grazing mammals, seed predation by rats and aggressive, invasive weeds. Barriers like these present the relationship between environmental policy and planning, historic degradation, and the current ecological condition in Te Moananui Oceania.

Opportunities

Incorporating Indigenous knowledge and traditional agroecological practices like agroforestry can improve biodiversity outcomes while providing co-benefits of socio-economic and community value (Quintus et al., 2019). Participatory and co-design processes should be used where opportunities allow to shape biodiversity outcomes. Incorporating the principles of biodiversity planting and conservation into other NbS strategies such as urban wildlife sanctuaries and green roofs and green walls can provide urban biodiversity refuges.

Financial case

There is potential to implement economic incentives such as carbon credits as a means to develop economic incentives for planting for biodiversity and urban habitat (Suryaningrum et al., 2022). Initial implementation of projects is generally not expensive compared to other green-space projects, and maintenance (such as addressing pest and weed pressure) is required to achieve desired outcomes and should be accounted for within financial estimates. Planting for biodiversity is already being integrated in regulatory requirements in Aotearoa New Zealand, where subdivision applications can be influenced by planting of native forest or wetland areas adding to the financial case (Goodwin, 2024).

References
  • Aerts, R., & Honnay, O. (2011). Forest restoration, biodiversity and ecosystem functioning. BMC Ecology, 11(1), 29. https://doi.org/10.1186/1472-6785-11-29
  • Brancalion, P.H.S., & Holl, K.D. (2020). Guidance for successful tree planting initiatives. Journal of Applied Ecology, 57(12), 2349–2361. https://doi.org/10.1111/1365-2664.13725
  • Gadgil, M., Berkes, F., & Folke, C. (1993). Indigenous knowledge for biodiversity conservation. Ambio, 22(2), 151–156.
  • Goodwin, M. (2024). Planting native bush – Subdivision & environmental benefit. https://catobolam.co.nz/news/planting-native-bush-subdivision-environmental-benefit/
  • Jupiter, S., Mangubhai, S., & Kingsford, R. T. (2014). Conservation of Biodiversity in the Pacific Islands of Oceania: Challenges and Opportunities. Pacific Conservation Biology, 20(2), 206. https://doi.org/10.1071/PC140206
  • Kingsford, R.T., Watson, J.E.M., Lundquist, C.J., Venter, O., Hughes, L., Johnston, E.L., Atherton, J., Gawel, M., Keith, D.A., Mackey, B.G., Morley, C., Possingham, H.P., Raynor, B., Recher, H.F., & Wilson, K.A. (2009). Major conservation policy issues for biodiversity in Oceania. Conservation Biology, 23(4), 834–840. https://doi.org/10.1111/j.1523-1739.2009.01287.x
  • Quintus, S., Huebert, J., Kirch, P.V., Lincoln, N.K., & Maxwell, J. (2019). Qualities and contributions of agroforestry practices and novel forests in pre-European Polynesia and the Polynesian outliers. Human Ecology, 47(6), 811–825. https://doi.org/10.1007/s10745-019-00110-x
  • Sousa-Silva, R., Duflos, M., Ordóñez Barona, C., & Paquette, A. (2023). Keys to better planning and integrating urban tree planting initiatives. Landscape and Urban Planning, 231, 104649. https://doi.org/10.1016/j.landurbplan.2022.104649
  • Suryaningrum, F., Jarvis, R.M., Buckley, H.L., Hall, D., & Case, B.S. (2022). Large-scale tree planting initiatives as an opportunity to derive carbon and biodiversity co-benefits: A case study from Aotearoa New Zealand. New Forests, 53(4), 589–602. https://doi.org/10.1007/s11056-021-09883-wVeldman, J.W., Overbeck, G.E., Negreiros, D., Mahy, G., Le Stradic, S., Fernandes, G. W., Durigan, G., Buisson, E., Putz, F. E., & Bond, W. J. (2015). Where tree planting and forest expansion are bad for biodiversity and ecosystem services. BioScience, 65(10), 1011–1018. https://doi.org/10.1093/biosci/biv118

Further resources