Promoting a nature-positive future: how to measure biodiversity to assess habitat restoration success

Biodiversity is essential for ecosystem services and resilience to global change but is declining globally. Recent regulatory shifts requiring biodiversity reporting, offsetting and nature positive outcomes are creating a market for private finance of conservation, but broadly applicable mechanisms for this are lacking: something recognised by NERC through its recent 'Economics of Biodiversity' calls.

The supervisory team, collaborating with a wide range of stakeholders, has been awarded NERC funding to develop the "Biodiversity Credits Project (BCP)". Development of a biodiversity credit standard, allowing credits to be bought to ensure increases in biodiversity, will open up large-scale investment in biodiversity conservation. There is tremendous investor interest, with 4.2 million biodiversity credits already sold. Our BCP team is working to ensure it delivers real benefits (learning lessons from carbon credits). To ensure reliable assessment of biodiversity improvement, our project is developing widely applicable and rapid biodiversity survey techniques and testing them across a range of habitats.

In my PhD project I will conduct additional data collection during 2024 and 2025 that builds on baseline BCP data being collected spring/summer 2023 at the Knepp Estate Rewilding Project, Sussex, and the Attenborough Nature Reserve, Nottinghamshire. Specifically, aiming to:

1. Extend the range of biodiversity metrics considered to include geochemical and stable isotope analyses
2. Test how biodiversity metrics respond to changes over time
3. Test how key taxa respond to restoration management
4. Develop methodology for (semi-)automated recognition of bird species from audio recordings - a priority for our CASE partner, Operation Wallacea

Research will be centred around collection and subsequent lab-analysis of field data from The Knepp Estate rewilding project, Sussex, and the Attenborough Reserve, Nottinghamshire.

BCP surveys have included a series of rapid measures (vegetation structure; vegetation form and colour; acoustic monitoring for bats, birds, insects and frogs; eDNA surveys of freshwater invertebrates and vertebrates; rapid-sampling of freshwater invertebrates and terrestrial invertebrates), to be compared against more detailed surveys (bat, bird and insect transects; vegetation surveys; habitat surveys), and tested for repeatability. Through my PhD, I will conduct repeat surveys of a subset of these metrics during 2024 and 2025, plus additional collection and lab-analysis of soil, plant, invertebrate and vertebrate stable isotope samples (based at the British Geological Survey, BGS), and identification of insect specimens (based at the University of Nottingham). Bespoke audio recordings in 2024-25 will be added to those made in 2023 by BCP. These data will be analysed using a range of appropriate statistical modelling approaches to address aims and generate novel outcomes, as follows:

1. Assess the value of stable isotope approaches for determining biodiversity differences and therefore potential for inclusion in a biodiversity credit system.
2. Compare 2023-2025 data to assess change in the metrics through time
3. Assess differences in taxa and food webs in relation to restoration/rewilding stage, management practices and environmental perturbations.
4. Use audio recordings of bird song, validated against expert species identification, to develop specific algorithms for our study sites and a workflow for creating algorithms elsewhere. Testing both full automation and semi-automation, where fragments of recordings are flagged for expert attention (to avoid experts listening to thousands of hours).