Compliance review of UK biodiversity indicators and England biodiversity indicators

Overview

At the time of this report, the UK biodiversity indicators and England biodiversity indicators are published as accredited official statistics. They are produced jointly by the Department for Environment, Food and Rural Affairs (Defra) and the Joint Nature Conservation Committee (JNCC).

The statistics summarise annually the state of biodiversity in the UK and in England and how this is changing over time. The 39 UK indicators are used to report the UK’s progress against goals and targets agreed under the Convention on Biological Diversity (CBD). The 23 England indicators are used to support work in the UK Government’s Environmental Improvement Plan (EIP). Each indicator chapter comprises one or more measures used to form the related indicator. An overview chapter then looks at changes across the full set of indicators.

Changes have been, and will continue to be, made to these two sets of statistics in response to developments, such as the adoption of the CBD’s Kunming-Montreal Global Biodiversity Framework in 2022. This review considered whether these developments and the production of the two sets of statistics are consistent with the principles of Trustworthiness, Quality and Value in the Code of Practice for Statistics (the Code).

Why we did this review

The two biodiversity indicator publications were last assessed by OSR in 2012. The indicators and how they are used have changed since then.

In 2016, the Defra and JNCC team recruited a panel of independent experts to review the indicators that focused on species. In 2022/23, Defra and JNCC conducted a user engagement exercise and review of the sets of indicators. In 2025, Defra and JNCC looked at users’ needs and necessary changes for alignment with the 2023 EIP and the new Global Biodiversity Framework (GBF) brought in as part of the CBD. Additionally, reproducible analytical pipelines were introduced to production, and the indicator ‘Status of all-species: relative abundance’ was added to the statistics to support reporting against Environment Act targets.

Defra and JNCC requested a review by OSR both to provide feedback on the developments made to the statistics since the original assessment and to inform potential improvements to the compendia for users. Both sets of biodiversity statistics are compendia publications, which compile sets of statistics into a single collection with an overarching narrative. OSR’s review considered the overview chapters for each publication (‘indicator assessment summary’/ ‘assessment of change across all indicators’). A small subsample of indicator chapters was examined in more depth, including looking at underlying data sources or associated publications.

Findings

The statistics are presented impartially and objectively, sources are clearly labelled, and the importance of these statistics for international reporting and for tracking progress against national targets is clearly and prominently explained. Indicator chapters follow a consistent layout, which aids navigability and accessibility.

In 2016, independent challenge was provided by academics on how the indicators are produced and presented, and the producers have engaged with known users on some of the recent indicator changes. This engagement contributed to an indicator development plan which is clear about where indicators will be discontinued or modified in future publications.

Specific indicator chapters are examples of good practice in communicating uncertainty, explaining the rationale behind methodological decisions, and flagging potential misuse and limitations. For example, the ‘mammals of the wider countryside’ chapter links to academic articles showing why bats are a good proxy for mammals, includes confidence intervals and explains limitations with some of the roost data. However, some chapters lack equivalent information. For example, the ‘Spring index’ indicator does not provide measures of uncertainty or discuss the impact of low sampling in some UK areas. This is particularly a problem for chapters which are based on Official Statistics in Development or where the chapter is the only publication on the topic.

The overview chapter in each publication clearly communicates trend changes and includes breakdowns by indicator type. However, there is no communication of how uncertainty and limitations may differ between indicator measures and how this might impact interpretation of the overall trends.

The inclusion of indicator type in individual chapters linking that indicator to the natural capital framework classifications is useful in enhancing their value and allowing them to be more easily understood and used. However, what indicator type relates to is not fully explained within each indicator chapter.

Defra has published all of the organisational policy documents and statements required by the Code’s Standards for Official Statistics. Publishing these documents enhances transparency and demonstrates the producers’ commitment to statistical leadership.

Our judgement

We conclude that the UK and England biodiversity indicators statistics continue to meet the standards set out in the Code of Practice for Statistics and should retain their accredited official statistics status. The statistics are presented impartially, and the team’s user engagement, and how this fed into the published review and development plan, is a particular strength.

Based on the findings of this review, we have identified three recommendations that Defra and JNCC should address to further enhance the statistics’ Trustworthiness, Quality and Value:

Recommendation 1:

To support users in better understanding limitations of the data and what to consider when reading the report and to enhance trustworthiness in the outputs, the Defra and JNCC team should improve the consistency of the detail provided in relation to quality information and methodological decisions across the full suite of indicator chapters. In doing so we suggest that they consider:

where there is scope for adding discussion of risks with data sources, for example more discussion of risks with citizen science or where measures involve an element of judgement by field staff, and how this has been offset.
explaining how the overall indicator is produced for that chapter based on the data within it, for example, identifying why some series are combined to form an indicator and others are not.
the accessibility of language and communication used. OSR’s guidance on presenting uncertainty might be useful.

Recommendation 2:

Defra and JNCC should add additional information to the ‘indicator assessment summary’/‘assessment of change across all indicators’ chapter on where indicators may be subject to quality issues or biases and how this impacts interpretation of changes. This will help ensure that users can have confidence in using the statistics to make decisions and take actions.

Recommendation 3:

Further information should be added to each indicator chapter explaining what indicator type represents. This could be done by adding additional text or adding a link to the relevant Natural Capital Framework explanation in the indicator assessment summary chapter.

Next steps

We have completed this review shortly before Defra and JNCC are due to publish the annual statistics in November 2026. As such, we expect the recommendations to be addressed by publication of the next annual statistics, currently due in November 2027. We will engage with the team six months after the publications to discuss progress.

Statistics on Sustainability and the Environment in England and the UK