Guidelines for urban ecosystem restoration

In support of achieving the objectives of the UN Decade on Ecosystem Restoration, this Guide equips cities with knowledge about the importance of ecosystem restoration in urban areas and provides tools to build the necessary capacity to take restoration action.

What is ecosystem restoration?

According to the UN, “ecosystem restoration” refers to “assisting the recovery of degraded, damaged and destroyed ecosystems to regain ecological functionality and provide the goods and services that people value”. To fully understand what this means, we first need to define what an ecosystem is. An ecosystem is a geographic area where plants, animals, and other organisms, as well as weather and landscapes, interact to form complex units of life and which provide nature-based goods and services, also known as ‘nature’s contributions to people’ (NCP), that people need to survive and prosper. With this in mind, ecosystem restoration requires reclaiming degraded environments to enhance the health of that ecosystem. A healthy ecosystem is one that is intact in its physical, chemical, and biological components and their interrelationships, such that it is resilient to withstand change and stressors. It is a system that is not experiencing abnormal growth or decline of native species, the concentration of persistent contaminants, or drastic anthropogenic changes to its landscape or ecological processes.

When an ecosystem is healthy, it is able to provide NCP and services that humans need to sustain their livelihoods. These ecosystem services include:

improving water security
promoting healthy soils
minimizing erosion
improving flood attenuation
improving air quality
safeguarding animal and plant species
regulating changing climate

While ecosystems cannot always be restored to their original function, ecosystem restoration helps degraded environments recover to the extent that they can sustain more natural functions and processes that can support nature-based services to society.

Why ecosystem restoration?

Nature’s contribution to people provides benefits that are vital for human survival and well-being. As mentioned above, these contributions and services include cleaning our water and air, providing food and medicinal resources, and providing habitats for many organisms, including plant and animal species. Ecosystems such as forests, estuaries, peatlands and grasslands play a significant role in carbon storage and sequestration, making them a key resource in attempts to fix carbon and slow down the impacts of climate change. Healthy ecosystems are generally more resilient to the impacts of climate change, which means they have the ability to cope with and bounce back from natural extreme events such as volcanic eruptions, landslides, hurricanes, and wildfires. However, growing populations and subsequent demands for natural resources have exacerbated the loss of biodiversity in our global ecosystems, which makes them more vulnerable to the impact of climate change. Similarly, urbanization and the associated urban land expansion has a significant impact on biodiversity. Having an understanding of species’ habitat loss is critical for informed urban planning to safeguard biodiversity and people.

According to recent estimates, by 2050, the global population is projected to increase to ~9.8 billion, with around 6.7 billion people living in urban areas. Urban expansion is projected to grow significantly in the next 20-30 years, putting an estimated 290,000 km2 of natural habitat under threat from urban expansion, particularly in developing countries.

Human activities have placed ecosystems under threat across urban areas globally, including: i) putting pressure on water resources for agricultural and household use that adversely impacts water tables and aquifers, ii) water pollution resulting from poor waste management practices, iii) the removal of trees to make way for unsustainable logging, and iv) urban expansion which has caused habitat loss of numerous plant, insect and animal species. Due to reduced integrity and resilience of ecosystems, their ability to provide services crucial for sustaining human livelihoods have become compromised, resulting in an urgent need for ecosystem restoration as a way to enhance global resilience to climate change and to reconnect humans with wild natural spaces. This has intensified the need to integrate nature-based solutions (NbS) and/or ecosystem-based approaches in the global response to biodiversity loss and climate change.

What are ecosystem-based approaches?

The Convention on Biological Diversity (CBD) and Kunming-Montreal Global Biodiversity Framework adopted at the 15th Conference of Parties (COP) of the CBD in Montreal in December 2022, endorse ecosystem-based approaches (EbA) as an important strategy to maintain and increase resilience and reduce vulnerability of ecosystems and people to the adverse effects of climate change. Ecosystem-based approaches refer to the use of biodiversity and ecosystem services as part of an overall adaptation strategy to help people adapt to the adverse effects of climate change.

What are nature-based solutions?

The UN Environment Assembly has adopted the following definition of NbS: ‘actions to protect, conserve, restore, sustainably use and manage natural or modified terrestrial, freshwater, coastal and marine ecosystems, which address social, economic and environmental challenges effectively and adaptively, while simultaneously providing human well-being, ecosystem services and resilience and biodiversity benefits.’

Although NbS and EbA are increasingly receiving global recognition as a tool to support climate-resilient development, few cities have taken full advantage of NbS tools and emerging knowledge to address climate change. Ecosystem restoration is one of the most significant ways to deliver NbS to address societal challenges related to biodiversity loss, food and water security, and health, and disaster risk reduction among others. This can be done by allowing the natural regeneration of degraded ecosystems or by actively supporting their rehabilitation through targeted interventions and fostering species diversity (see Case Studies for more examples). NbS have proven cost-effective and inclusive when planned and implemented together with stakeholders, and can improve both urban and rural ecosystems to safeguard and restore nature’s contribution to people.

What can you expect from this Guide?

This is a general guide to ecosystem restoration in urban areas, and includes: i) a definition and examples of urban ecosystem restoration, ii) information about the types of restoration approaches used; iii) lessons learned and best practices from across the world, along with useful resources for cities; iv) how to leverage financial resources for your city; and v) how your city can get involved in the UN Decade of Ecosystem Restoration and other initiatives.

Our ecosystem guide offers case studies and resources that are useful to urban ecosystem restoration. We’ve presented these best practices in an accessible format that is easy to use and understand, to enable cities to apply these practices to ensure that they safeguard and protect their critical local ecosystems through ecosystem restoration.

This guide was produced through collaboration with the following partners: