The Biological Recording Company was commissioned by The Royal Parks through the Help Nature Thrive project to investigate whether routine leaf litter removal influences earthworm populations in Bushy Park and Kensington Gardens.
Using a standardised survey design, we compared earthworm abundance and species diversity between areas where leaves were routinely cleared and adjacent areas where leaves were left undisturbed. The findings provide an evidence base to help inform future park management.
The Challenge
The Royal Parks wanted to better understand whether routine leaf litter clearance was affecting soil biodiversity and the ecosystem services provided by different ecological categories of earthworms. While leaf removal is often undertaken for aesthetic, safety or conservation reasons, there was little evidence to demonstrate whether this management practice influenced earthworm communities within these urban parks.
Our Approach
The Biological Recording Company designed and delivered a comparative earthworm survey across five paired sampling locations within Bushy Park and Kensington Gardens. Each location included one transect where leaves were routinely cleared and an adjacent transect where leaves were left undisturbed.
Standardised soil pit surveys were undertaken along each transect, with adult earthworms identified to species level before statistical analysis was used to compare earthworm abundance and species diversity between the different management approaches.
All verified records generated during the project were submitted to the National Earthworm Recording Scheme, ensuring that the data contributed to regional, national, and international earthworm datasets.
What did we find?
A total of 2,441 earthworms were recorded during the project, with 666 adult specimens identified to species level, representing twelve different species. Statistical analysis found no evidence that routine leaf litter removal significantly affected either earthworm abundance or species diversity across the surveyed sites.
These findings should, however, be interpreted with caution, as the survey provides a snapshot of earthworm communities at a single point in time. The report recommends further surveys before and after leaf clearance, alongside recording additional environmental variables such as soil moisture and pH, to better understand any longer-term impacts of leaf litter management.
Despite these limitations, the survey demonstrated that both Bushy Park and Kensington Gardens support healthy and diverse earthworm communities. Together with existing records from the two parks, the project showed that they are home to more than one-third of the earthworm species known from natural habitats in the UK, including the nationally rare Allolobophora icterica and Aporrectodea nocturna.
Allolobophora icterica is a rare deep bioturbator that prefers grassland habitats, particularly synanthropic sites such as amenity lawns and parks.
Although considered rare nationally, this species is commonly recorded in grassland habitats across London, suggesting it may be under-recorded in parks and urban grasslands elsewhere in the UK.
Aporrectodea nocturna is an intense tunneller species that closely resembles A. longa and is thought to favour grassland habitats.
Although currently classified as rare, relatively little is known about its ecology, as it was only recognised as a distinct species relatively recently. Its apparent rarity should therefore be interpreted with caution.
The project also established an important baseline against which future monitoring can be compared, while providing evidence to help inform future park management decisions.
Project Outcomes
This project provided The Royal Parks with an evidence base to support future decisions on leaf litter management while establishing a robust baseline for future monitoring. Although no significant differences were detected during this study, the report identifies opportunities for further research to improve understanding of how soil biodiversity responds to management practices over time.
The survey also highlighted the importance of urban parks for earthworm conservation, demonstrating that well-managed parkland can support diverse and functionally important earthworm communities. The report concludes with a series of practical recommendations to help maintain healthy soils and enhance earthworm populations within urban greenspaces.
Download the full report
This article provides an overview of the findings from the Leave The Leaves Bushy Park and Kensington Gardens Earthworm Survey Report. The full report includes the complete methodology, statistical analyses, species accounts, site-by-site results, and recommendations for urban park management for earthworms.
Download the full report below
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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.
