Turning Pasture into Paradise: How SWEL Achieved 122% Biodiversity Net Gain in Somerset
The introduction of mandatory Biodiversity Net Gain (BNG) presents a fantastic opportunity to transform low-value land into thriving ecological hotspots. Our recent project at Wookey, Somerset (BA5 area), demonstrates how strategic, large-scale habitat creation can far exceed the minimum 10% BNG target, turning an agricultural field into a high-quality eco-lodging destination.
From Modified Grassland to 29.3 Habitat Units
SWEL was commissioned in late 2024 to prepare the BNG assessment for the conversion of an existing six-hectare farming field into a sustainable lodging development.
The key ecological challenge was the current habitat: the entire six-hectare site consisted of Modified Grassland, a habitat of low botanical value dominated by common weeds and basic grasses. Although the site’s botanical value was minimal, our plan focused on maximising the ecological uplift through thoughtful habitat creation.
Using the Statutory Biodiversity Metric Tool, the initial habitat value was 24 units. The regulatory minimum for a 10% gain was 26.40 units. Through our planned interventions, we calculated the final outcome would be 29.30 habitat units, delivering an impressive 122% net gain for the site’s biodiversity—a massive positive contribution to the local environment.
A Strategy Built on Habitat Creation
To achieve this substantial gain, the development plan focused entirely on introducing diverse, high-value native habitats:
Pond Creation (1.4 Hectares): The introduction of two new lakes, totalling 1.4 hectares, is a cornerstone of the mitigation. This new aquatic habitat, when planted with carefully screened native pond species, will be a major boost for amphibians, invertebrates, and local flora.
A Relatively “Blank” Canvas
Native Tree and Shrub Planting: We required the planting of 0.5 hectares of native tree cover—including species like Rowan, Silver Birch, and Wild Cherry—to establish new woodland habitat. Additionally, 3.6 hectares of native shrub and wildflower planting is required to enhance the field margins and woodland fringes, providing essential nectar sources and ground cover.
Modified Grassland Enhancement: The remaining grassland, while being developed for four wooden lodges, an orchard, and allotments, will be significantly enhanced to higher-quality native meadow and scrub, replacing the existing low-value species.
Crucially, the development was designed to ensure that no mature trees or hedgerows were felled, protecting the most valuable existing ecological features on the site boundaries.
Beyond BNG: Supporting Local Wildlife
To further cement the development’s commitment to nature, SWEL provided several additional suggestions to benefit specific local species:
Invertebrate Habitats: Promoting the creation and retention of deadwood piles and ‘insect hotels’ to support the declining invertebrate population.
Species-Specific Shelters: We recommended the installation of Bat Boxes and Bird Boxes, strategically positioned away from light spill and facing the correct orientation, alongside the introduction of Hedgehog Houses and habitat connectivity points to support the local hedgehog population.
Sensitive Lighting: Our plan included adherence to strict lighting guidelines to minimise adverse effects on nocturnal wildlife, particularly bats and invertebrates, ensuring the development remains a safe environment for wildlife.
Conclusion: Setting a New Standard for Rural Development
The Wookey project showcases SWEL’s ability to transform a functional rural site into a significant ecological asset. By replacing low-value Modified Grassland with 1.4 hectares of new pond habitat, 0.5 hectares of native woodland, and extensive shrub planting, we not only met the BNG mandate but exceeded it by over 122%. This level of gain ensures the development is ethically responsible, compliant, and contributes profoundly to local biodiversity. Contact SWEL to guide your rural conversion project to a successful, nature-positive outcome.