How can our habitat data help you?

Identifying Priority Habitats

Section 41 Habitats of Principle Importance are UK wildlife habitats protected from harmful development by the NERC Act and the National Planning Policy Framework. They should therefore be considered when planning development work.

TVERC has mapped S41 Habitats of Principal Importance in Berkshire and Oxfordshire using a mixture of field survey data and aerial photograph interpretation. The dataset is very high resolution, with polygon boundaries representing on-the-ground habitat boundaries as closely as possible. Areas of rare habitat as small as 0.1 hectares [1,000 m²] are mapped.

Natural England also provides an openly available dataset containing information on Section 41 Habitats of Principle Importance which is available to download from their website. This dataset is far less accurate than the TVERC habitats dataset for Berkshire and Oxfordshire and is not suitable for making decisions at a local level. 11 of the S41 Habitat types are completely missing from the Natural England dataset despite being present in the county and mapped in the TVERC dataset. The resolution of mapping used by Natural England is much lower, with many small patches of habitat not mapped (they take an Ordinance Survey land parcel and categorise it by dominant habitat type, if a field is split between two habitat types the second will not be displayed). An analysis comparing the two datasets has shown that this results in an overestimate of the areas of more widespread habitats that tend to occur in larger patches, and an underestimate of rarer habitats that tend to occur in small patches – which are often more at risk from fragmentation and degradation. Some results of this analysis can be seen below.

Section 41 Habitats of Principle Importance that are absent from NE data:

Differences in area of Section 41 Habitats of Principle Importance between Natural England (low resolution) and TVERC (high resolution) datasets:

We have visualised this below. The key takeaway from this comparison is the two key S41 habitat types that are excluded from the Natural England dataset in this region (which was randomly selected in Oxfordshire). The TVERC data shows that this area contains both reedbeds and fens, vital habitats for biodiversity. If one were to use exclusively NE data, the fen and reedbed would not be identified and could be mismanaged or destroyed.

A sample of the Natural England habitats data

The same area of TVERC Habitats data.

We strongly recommend contacting TVERC for information on Section 41 Habitats of Principle Importance in Berkshire and Oxfordshire, by submitting a data request form, rather than using Single Habitats Layer from Natural England.


Calculating Biodiversity Net Gain

The DEFRA Biodiversity Net Gain Metric (a new policy that requires all developers to provide a “net gain” in biodiversity) relies heavily on habitats data. TVERC hold data for all habitat types and this can be used to reliably calculate the biodiversity value of a site, or a number of sites. Due to the low resolution of the Natural England data and the mapping of solely S41 habitats, it would give inaccurate biodiversity unit calculations with large areas of missing habitat. There is no other habitat source across Berkshire and Oxfordshire of a high enough quality that it could give an accurate biodiversity net gain baseline score.

West Berkshire Council and Wokingham Borough Council are currently preparing Local Plans and as part of that process, a number of proposed development sites have been identified.  To be able to make decisions about where development is best located, councils require information about the potential impacts of developing these sites.

West Berkshire Council and Wokingham Borough Council asked TVERC to assess the biodiversity value of each of the sites in its emerging Local Plan to assign an outline cost for delivering a measurable net gain for biodiversity in West Berkshire and Wokingham.

An assessment of 276 Local Plan in West Berkshire sites found a net loss of between 2,379 and 13,577 biodiversity units.  Based on DEFRA biodiversity unit prices of between £9,000 and £15,000 units, the estimated cost of offsetting these units is between £21.4 million and £203.6 million

In Wokingham, TVERC calculated the minimum and maximum number of biodiversity units for 311 Local Plan sites. There are over 2,500 hectares of habitat on these sites, generating between 6,444 and 19,332 biodiversity units.  Based on per-unit costs published by DEFRA in the biodiversity net gain consultation document, these would be worth between £59 million and £290 million.

TVERC also offer training and consultation in the calculation and implementation of Biodiversity Net Gain, a service that West Oxfordshire District Council (WODC) have benefitted from. TVERC can run training days in using the metric calculator, can comment on net gain calculations to aid policy makers in their decisions and are willing to help in creating net gain standards, targets and policies for any Local Authority, with this document created for WODC as an example.

Posted: September 30, 2020