When we think about restoring nature, our attention is often drawn to the wildlife we can see – birds, butterflies, wildflowers, and mammals. Yet some of the most important indicators of ecosystem health are hidden beneath our feet.
As part of the Sapperton Wilder project in Gloucestershire, the Biological Recording Company was commissioned to establish a baseline understanding of earthworm communities before large-scale habitat restoration and regenerative land management began. The project is testing how nature-friendly farming can improve biodiversity, soil health, and long-term sustainability by adopting five core principles of regenerative agriculture: minimising soil disturbance, keeping the soil covered, maintaining living roots, increasing crop diversity, and integrating livestock.
To understand whether these approaches deliver measurable benefits, robust baseline data are essential. This earthworm survey provides one of the first benchmarks against which future changes in soil biodiversity can be assessed as the landscape evolves over the coming decades.
Why establish a baseline?
Sapperton Wilder is an ambitious long-term landscape restoration project that is transforming around 380 acres of marginal Cotswold farmland. The site has been divided into 19 fields across three main blocks, allowing different approaches to nature-friendly land management to be tested and monitored over the coming decades. Three additional fields on farms in the local area are being monitored as control sites, providing a benchmark against which changes at Sapperton Wilder can be compared.
Each block has its own restoration focus. Together they will explore how regenerative agriculture, species-rich grassland creation, agroforestry, and other habitat restoration measures influence biodiversity, soil health, and food production over time. Rather than relying on assumptions, the project is designed to gather robust scientific evidence that can help inform future land management decisions.
Before these interventions could begin, it was essential to understand the condition of the site. Without baseline data, it would be impossible to know whether future changes in wildlife and soil health were the result of restoration or simply reflected natural variation between years.
Earthworms were chosen as one of the project’s key indicators because they respond quickly to changes in soil management and play a fundamental role in maintaining healthy soils. By establishing a three-year baseline before restoration takes effect, future surveys can objectively measure whether the project’s interventions are improving the health and functioning of the soil ecosystem.
How were the surveys carried out?
Between 2023 and 2025, soil pit surveys were undertaken across all 19 experimental fields within the Sapperton Wilder site, alongside three nearby control fields managed under either conventional or regenerative farming. Each field was surveyed using five standardised soil pits, with all adult earthworms identified to species wherever possible.
Repeating the survey over three consecutive springs was particularly important. Earthworm populations naturally fluctuate from year to year depending on weather conditions, especially soil moisture. By collecting data across multiple years, the project has established a much more reliable baseline than would have been possible from a single survey season.
What did we find?
Across the three years of surveying, almost 4,900 earthworms were recorded from the study sites. In total, nine earthworm species were identified, representing just over a quarter of the 33 species known from the UK and Ireland.
One species, Allolobophora chlorotica, dominated the survey results and accounted for well over half of all identified adult earthworms. This species is widespread throughout the UK and is well adapted to agricultural soils. Several other common farmland species were also regularly encountered, while one rare species (Murchieona muldali) and one uncommon species (Satchellius mammalis) were recorded in small numbers.
Perhaps the most striking finding was how much the results varied between years.
Both earthworm abundance and the number of species recorded were significantly higher in 2024 than in either 2023 or 2025. Statistical analysis confirmed that these differences were highly significant rather than simply random variation.
This doesn’t necessarily mean that earthworm populations suddenly increased and then declined. Instead, the differences are likely to reflect changing weather conditions. The exceptionally wet conditions leading into spring 2024 created ideal soil moisture for earthworm activity, making them much easier to detect during surveys. By contrast, the drier spring of 2025 probably encouraged many earthworms to retreat deeper into the soil, reducing the numbers found within the shallow survey pits.
This highlights an important lesson for soil monitoring: a single year’s results rarely tell the whole story, and a good baseline survey should be conducted over a multi-year period.
Regenerative management shows encouraging signs
Although Sapperton Wilder is still in the early stages of its restoration journey, the inclusion of control sites provides useful context.
The conventionally managed control fields consistently supported the lowest earthworm abundance and species richness throughout the study. In contrast, the regenerative agriculture control field regularly supported higher numbers of earthworms and more species, with values comparable to or exceeding many of the Sapperton Wilder fields.
These observations suggest that regenerative farming practices can create soil conditions that are more favourable for earthworm communities. While long-term monitoring will be needed before firm conclusions can be drawn, the results provide encouraging evidence that changes in land management have the potential to improve soil biodiversity.
More than counting worms
The survey looked beyond simple numbers to examine the different ecological roles performed by earthworms.
Healthy soils contain species that live in leaf litter (litter dwellers), species that mix organic matter through the soil (shallow bioturbators and deep bioturbators), and deep-burrowing species that create channels for air and water (burrowers and intense tunnelers). Together, these groups drive nutrient cycling, improve soil structure, and support countless other organisms.
At Sapperton Wilder, however, the earthworm community was heavily dominated by shallow soil-dwelling species. Deep-burrowing and surface-dwelling groups were comparatively scarce, suggesting that some important soil processes may currently be underrepresented.
As restoration progresses, one of the most interesting questions will be whether these missing ecological roles begin to return.
Looking to the future
Perhaps the greatest value of this work is not the snapshot it provides today, but the benchmark it creates for tomorrow.
Future surveys will allow changes in earthworm abundance, species richness, and functional group composition to be measured against this robust three-year baseline. Counting more earthworms is only part of the story. A healthy soil ecosystem also needs a balanced community of species performing different ecological roles, from recycling leaf litter and mixing organic matter to creating deep burrows that improve soil structure, drainage, and aeration.
The baseline survey showed that the site’s earthworm community is currently dominated by shallow bioturbator species, while burrowers, intense tunnelers, and litter dwellers are comparatively scarce. This suggests that some of the soil processes provided by these groups may currently be underrepresented. One of the key questions for future monitoring will therefore be whether regenerative agriculture and habitat restoration lead to a more balanced earthworm community, with a greater representation of the functional groups that support healthy, resilient soils.
By comparing future surveys with this baseline, researchers will be able to determine not only whether earthworm populations increase, but also whether the underground ecosystem becomes more functionally diverse as the landscape continues to recover.
Nature recovery doesn’t happen overnight. By continuing to monitor the wildlife beneath our feet, projects such as Sapperton Wilder will be able to demonstrate how soil ecosystems respond over time and whether restoration is rebuilding the natural processes that support biodiversity above and below ground.
Download the full report
This article provides an overview of the findings from the Sapperton Wilder Baseline Earthworm Survey. The full report includes the complete methodology, statistical analyses, species accounts, site-by-site results, and recommendations for future monitoring.
Download the full report below
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Earthworm surveys provide a powerful way to assess soil health, establish ecological baselines and monitor the success of habitat restoration, regenerative agriculture and land management projects.
If you’re an environmental, conservation, ecological, or agricultural professional looking to commission an earthworm survey, visit our Earthworm Consultancy, Surveys and Training page to learn more about the specialist surveys and consultancy we offer.
