Collecting Data


  • The Priority Habitats Inventory data on MAGIC is not definitive.
  • They have a lot more data still on paper that they can’t afford to digitize.
  • Some of the data is obviously crap or out of date, but they can’t afford to check it and change it.
  • Other organisations have better data, at a local level, that may not be on the MAGIC site.
  • The data is so poor that it is impossible to check whether Priority Habitats are being destroyed.

Let’s run that last one again…there is no way of knowing at a national level whether National Priority Habitats are being destroyed year on year.

I asked the responsible politician to investigate a specific legal issue involving the supporting information for creating a SSSI, the National Statistics mark, and the England Biodiversity Figures.

IMG_7587Example of the Coastal and Floodplain Grazing Marsh layer being obviously crap. The layer is information from 1976 before the shopping centre was created but ‘fitted’ to the modern map. Ironically there is some saltmarsh adjacent to the brown markings (mudflats); it’s not present on the database layer for saltmarsh but it is a Local Wildlife Site.

Back in early August I contacted the environmental statistics department at Defra because I felt that they hadn’t actually understood what their data was revealing about Priority Habitats.

I wrote …”on page and the section 2a on Priority habitats. You have included a caveat in the Background section to 2a.1. Extent of priority habitats for the Indicator Assessment on Extent of Priority habitats, saying that (to paraphrase) due to the way the data is recorded that you don’t actually know the extent of the habitat and so can’t assess any change in extent.

Logically, if this is the case, you can’t actually say the extent of each priority habitat because you don’t measure it, you only measure the area within which there is priority habitat present. So at the beginning of the document the first sentence “There are 1.87 million hectares of terrestrial and coastal priority habitats across England, representing around 14% of the total land area (Figure 2a.1).”  is incorrect and should say ‘There are 1.87 million hectares of land within which terrestrial and coastal priority habitats can be found, but we don’t know the extent of the priority habitats because we don’t actually record that data.’ “

I then questioned how they could state the Priority habitats were in favourable condition if they didn’t know their extent; measuring the extent would be necessary for the condition assessment. I also made a point of saying I was aware of the lack of funding to carry out their statutory duties, something the Chair of Natural England confirmed on 21 Nov 2018


Example of data being out of date; what was apparently Lowland Meadow in 1991 but you can see clearly from the photo has since been ploughed up.

The answer (28 August) from the technical person (in charge of the Priority Habitat layer for the MAGIC website) was:-

“1) There have been three published versions of the Priority Habitats Inventory which represent improvements in our mapping of the extent of priority habitats in England.  In order to provide a consistent baseline for reporting on the condition of priority habitats (Biodiversity 2020 indicator 2a.2) version (1) of the inventory has been used each time.  The figure of 1.87 million hectares reflects this baseline extent and, as per indicator 2a.2, the condition of this overall area of priority habitat is improving.

2) There are uncertainties over calculating the exact extent of priority habitat in England, which are reflected in the caveats outlined below.  This does however include elements of under-reporting (where areas of priority habitat have yet to been included in the national inventory) as well as over-reporting (where the exact extent of the habitat within a land management unit has not been mapped).

3) Caveats: The Priority Habitats Inventory represents the best available information on priority habitats at an England-wide level; it is not and will never be a definitive dataset for priority habitats across England.  Users of the Priority Habitats Inventory should take into account:

  • For parts of the country, or for specific habitats, there may be more recent or better quality data available, such as that held by local partners, which Natural England has either not had access to or permission to publish.  We also still hold datasets that have not yet been processed for inclusion in the Priority Habitats Inventory and which will be included in future updates.
  • The quality of the inventory is variable: some polygons are derived from recent survey with habitat boundaries mapped accurately and high confidence in the determination of the habitat.  However, for other polygons the information available may be insufficient to confidently confirm the presence of priority habitats.
  • In some cases habitats may not have been mapped in the original data, such as where the original inventory polygons originate from a point dataset, database or from local wildlife site citations (see Table 2 and Table 4 for information on sources), so the site boundary or land parcel has been used as a proxy for the extent of the habitat.

4) To summarise: The new priority habitats’ inventory does not allow for assessing changes to the extent of habitats, as changes to the inventory itself would represent improvements in current knowledge of the extent of priority habitats, rather than actual changes in the extent of habitats. As a result, no assessment of change has been made. Defra, Natural England and JNCC are working to improve the quantity and quality of data on priority habitats, for example by improving standards for habitat mapping, and by investing in research that is developing new methods that combine satellite, remote sensing and field data to provide better information on the stock and change in habitats.

5) We plan to publish the Priority Habitats Inventory methodology/user guide on our website alongside the Open Data download, but we have attached a copy to this email for your information.”

[they did attach a copy – I haven’t read it yet; some more blogs to do be fore there is time for that]


Not Lowland Meadow, but “good quality semi-improved grassland”… except that was in 1991…Natural England’s own photos show it’s been ploughed up and is now arable land.

Given the caveats mentioned above, and that recently the Natural England board have taken the legal step to designate Malvern Common as a Site of Special Scientific Interest using supporting evidence (scroll down for a .pdf here ) stating there is less than 10,000 ha of Lowland Meadow Priority Habitat in existence in England, then the data published by Defra must be wrong because it differs from the Natural England figure which has been used in a legal manner. There is also a National Statistics mark on the Defra web page, so it calls into question Defra’s use of that mark or alternatively the quality of National Statistics as a whole.[I suspect the issue is one of people not understanding precisely what the statistics relate to rather than anything Machiavellian, but we’ll see in time]

I’ve written (26 Nov) to the Parliamentary Under Secretary of State for the Environment – who is, at present, Thérèse Coffey MP – and asked that the matter be investigated and that I am informed of the outcome. (I actually used the defrahelpline email rather than the MP email as I thought the email should be in the Defra capacity rather than their MP capacity so hopefully someone will forward it on). I copied in the National Statistics people and they have already replied and are investigating.


Don’t get me wrong here, the MAGIC site is really amazing – it’s only because it is there and easy for me to use that I can point to evidence of lack for funding in mapping the extent of our shared national cultural heritage of Lowland Meadow plant communities. It just needs better funding.

And if you are wondering why I write such long technical blogs…


This is their map of how much Lowland Meadow there is in my area (the small green bits)


And by way of comparison, this is the extent of Ancient Woodland in my area.

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