City Biodiversity Index: Measuring Urban Ecosystem Health

Cities are often seen as the opposite of nature, all concrete and traffic with little room for wildlife. Yet urban areas hold surprising amounts of biodiversity, from backwater wetlands to roadside trees that host birds and butterflies. The challenge has always been how to measure that natural wealth in a consistent way. The City Biodiversity Index was created to do exactly this, giving local governments a structured method to assess how well their city protects and manages the living systems within its boundaries.

What the City Biodiversity Index measures
The three components and 23 indicators
Native biodiversity in the city
Ecosystem services provided by biodiversity
Governance and management of biodiversity
How the scoring works
Benefits and applications
Indian cities putting the index to work
The 2021 revision and what it changed

What the City Biodiversity Index measures

The City Biodiversity Index, commonly called the Singapore Index on Cities’ Biodiversity, is a self-assessment tool that helps cities evaluate and monitor their biodiversity conservation efforts over time. The core idea is simple but powerful. A city scores itself against a set of fixed indicators, establishes a baseline in its first assessment, and then repeats the exercise every few years to see whether it is improving or slipping back.

The index was developed in 2008 by Singapore’s National Parks Board together with the Secretariat of the Convention on Biological Diversity (CBD). It was formally launched as part of the Convention on Biological Diversity’s Technical Series and later adopted at the international level as a recognised monitoring tool. What makes it distinctive is its focus on cities rather than countries. Most earlier environmental indices were designed for national use, so urban biodiversity rarely received dedicated attention. The City Biodiversity Index filled that gap by being the first tool of its kind created specifically for the urban scale.

Because it is a self-assessment instrument, a city does not compete against others for a ranking. Instead, it measures its own progress against its own past performance. This matters because cities differ enormously in geography, climate and size. Comparing a coastal city with a mountain town on a single scoreboard would be misleading, so the index encourages each city to track its own trajectory.

The three components and 23 indicators

The classic version of the index uses 23 indicators grouped under three core components: native biodiversity in the city, ecosystem services provided by biodiversity, and governance and management of biodiversity. Each component looks at a different dimension of how nature and the city interact.

Native biodiversity in the city

This is the largest component, covering ten indicators. It examines how much natural and semi-natural area a city retains, the diversity of ecosystems present, and how fragmented those green spaces are. Fragmentation matters because animals and plants need connected habitats to move, feed and breed. A city full of small, isolated parks supports less life than one where green spaces are linked through corridors.

This component also counts species across several groups. Plants, birds and butterflies are fixed categories, while each city chooses two additional native species groups that are most relevant to its local environment. The focus on native species is deliberate. Counting introduced or invasive species would not reflect the health of the original ecosystem, so the index rewards cities that conserve the species naturally belonging to their region.

Ecosystem services provided by biodiversity

The second component looks at the practical benefits that nature provides to residents. The original index measured this through four indicators. These include the role of vegetation in regulating water, its contribution to climate regulation through carbon storage and the cooling effect of green cover, and its value for recreation and education, measured partly through the area of parks with natural zones and the number of educational visits children make to these spaces.

This component connects biodiversity directly to human wellbeing. Trees that cool a neighbourhood reduce the need for air conditioning. Wetlands that absorb rainwater reduce urban flooding. Parks that children visit build environmental awareness in the next generation. By scoring these services, the index makes the case that protecting nature is not a luxury but a contribution to liveability and public health.

Governance and management of biodiversity

The third component contains nine indicators and focuses on what the city government actually does. It examines budgets allocated to biodiversity, the existence of dedicated plans and policies, the presence of trained staff, partnerships with non-government bodies, and outreach to citizens. It also looks at how biodiversity considerations are built into the city’s wider planning processes.

This component is important because good intentions mean little without institutional support. A city may have rich biodiversity simply through luck of geography, but sustaining it requires committed governance. By scoring management capacity, the index pushes cities to formalise their conservation efforts rather than leaving nature to chance.

How the scoring works

Every indicator is scored on a scale from zero to four points. A city adds up its scores across all indicators to produce a total, with the 23-indicator version giving a maximum of 92 points. The number itself is less important than what it represents. The first time a city completes the assessment, the result becomes its baseline. Future assessments are then compared against this starting point.

The handbook recommends that cities repeat the exercise every three to five years. This interval is intentional. Biodiversity changes slowly, and conservation actions such as planting native trees or restoring wetlands take time to show results. Measuring too frequently would capture noise rather than genuine change. The scoring process also forces a city to gather data it might never have collected otherwise, which itself builds knowledge and capacity.

Benefits and applications

The real value of the index lies in how cities use the results. Once a baseline exists, gaps become visible. A city might discover that it scores well on green cover but poorly on governance, or that its ecosystems are highly fragmented. These findings help set priorities for conservation actions and budget allocation. Rather than spreading limited resources thinly, a city can target the weakest areas first.

The index also builds capacity and creates networking opportunities. Completing the assessment requires collaboration between ecologists, planners and administrators, which strengthens institutional knowledge. Cities that apply the index join a wider community of urban governments learning from one another, and the indicators themselves act as a checklist for master planning. In this way the tool guides not just measurement but action.

Indian cities putting the index to work

Several cities in the country have adopted the index, often with support from ICLEI South Asia. Kochi became one of the first, releasing its City Biodiversity Index report after evaluating all 23 indicators. The assessment confirmed that Kochi holds a large number of native species, especially in its backwaters, while also facing pressure from rapid urbanisation. Importantly, Kochi linked its index to the Climate Smart Cities Framework 2.0 launched by the Ministry of Housing and Urban Affairs, embedding biodiversity within national urban policy.

Gangtok followed as another early adopter, with its assessment showing a high presence of native species and strong governance practices. The index there fed directly into a Local Biodiversity Strategy and Action Plan, turning measurement into a concrete roadmap. Other cities including Dehradun, Pune, Faridabad and Raipur have also worked towards adopting the framework, signalling growing interest in mainstreaming biodiversity into urban governance. For fast-growing cities balancing development with green cover, the index offers a structured way to ensure that trees, wetlands and wildlife are not treated as afterthoughts.

The 2021 revision and what it changed

The framework was updated and re-launched in September 2021. The revised version expands the original set of indicators to a broader series and includes wider coverage of the services that biodiversity and ecosystems provide to people. It also simplifies the measuring tools and offers clearer guidance on application. The update was designed to help cities contribute to the global biodiversity framework agreed after 2020, recognising that urban areas play a growing role in conservation worldwide. Cities that began with the 23-indicator version, such as those in this country, established their baselines using that framework, while newer assessments can draw on the expanded edition.

Whether a city uses the original or revised version, the underlying logic stays the same. The index turns the abstract idea of urban biodiversity into something countable, comparable over time and useful for planning. It reminds us that even the densest city is a living system, and that what we measure, we are far more likely to protect.

What do you think? If your own city were to complete a biodiversity assessment, which component do you think it would score lowest on, and why? And do you believe a self-assessment tool is enough to drive real conservation, or should cities be compared against one another to create stronger pressure to improve?

References

PDF 📄

City Biodiversity Index: Measuring Urban Ecosystem Health

Table of Contents

What the City Biodiversity Index measures 🔗

The three components and 23 indicators 🔗

Native biodiversity in the city 🔗

Ecosystem services provided by biodiversity 🔗

Governance and management of biodiversity 🔗

How the scoring works 🔗

Benefits and applications 🔗

Indian cities putting the index to work 🔗

The 2021 revision and what it changed 🔗