Atlas 2020 in Oxfordshire

This page is dedicated to progress in Oxfordshire with recording for the BSBI's Atlas 2020 project. The project is a repeat of the Society's previous two pioneering atlases of 1962 and 2002 based on a national survey of all vascular plants within 10km x 10km national grid squares (hectads). Extensive guidance on where and what to record is available on the project's website. In a nutshell:

  • Atlas 2020 will be based on records gathered between the years 2000 and 2019 inclusive.
  • Hectad distribution maps will be published for all vascular plant species, be they native or naturalised aliens. This is everything from trees to grasses, wildflowers of our most iconic habitats to invasive aliens species.
  • The basic recording unit for Atlas 2020 is the 2km x 2km square (tetrad), or even 1km x 1km square (monad). 
  • To adequately sample each hectad across the country, it is recommended that about 20% of the tetrads in a hectad be recorded. Done thoroughly this ought to turn up 70-80% of species recorded prior to 2000.

If you would like to become involved with recording for the Atlas in Oxfordshire (vice county 23) then please do get in touch with the county recorder David Morris. You will see below how much there is to be done in the county — we need your help!

Progress so far

Botanical recording in Oxfordshire has been re-invigorated over the last three seasons or so with the impetus provided by Atlas 2020: over 20,000 records were gathered in 2016, contrasting with very low numbers before 2014, and over 65,000 records have now been submitted that will contribute to Atlas 2020. A big thank you to everyone who has contributed to this surge in data, including the previous county recorder Sue Helm. A data sharing agreement with Thames Valley Environmental Records Centre has recently been struck and once processed their data holding should make a significant difference to Atlas 2020 in the county also.

Progress at hectad and tetrad scales can be seen in the interactive map below - hover over a hectad and/or tetrad to see information about recording there. Some observations:

  • Coverage of the county is making progress with most hectads with records from at least a fifth of their tetrads. Most of these have at least a fifth of their tetrads with more than 100 taxa also. Some hectads are significantly under-sampled, notably SP42 and several boundary hectads. The Chilterns are also remarkably poorly recorded.
  • Sampling of hectads by the current strategy, which is mostly single visits (square bashing), and even when covering most of a hectad, only achieves a re-recording rate of around 50%.
  • There are a large number of tetrads with a small number of records, and this obscures the picture. The distribution of squares with 100 or more taxa gives a clearer idea of where effort has been expended (click to remove layers from map).
  • The majority of tetrads now have many taxa recorded that are new there, around 70 on average. Does this reflect a substantial change in our flora? Some additions may reflect differing recording methods and priorities (naturalised garden plants versus natives) or be down to fairly trivial taxonomic differences (Rumex acetosa versus Rumex acetosa subsp. acetosa). We shall see if this change is real once the Atlas is published.

SP50 (Oxford) is an interesting square, with a modest re-recording rate (60%) but the subject of much recording effort (857 taxa). This is a diverse square (1289 taxa in total) with a range of rich semi-natural habitats and being a city historically has also a large alien flora. The discrepancy perhaps is a result of recorder bias, as recent records reflect mostly the native element, but it would be difficult to re-record alien plants if they were only ever transient. This contrasts with SP51 which is botanically very rich but also very rural (73% re-recording rate, 891 taxa).

Looking to 2019

There are three seasons left until the close of the Atlas recording period. Here are a few thoughts if you are planning recording:

  • There is much more to be found: the pre-2000 tetrad average is 280 taxa while that for the Atlas 2020 period so far is 95. The large number of tetrads with under 50 taxa obscures the picture somewhat and removing them gives an average of 165.
  • Atlas 2020 data need to be based on a representative sample of each hectad and such a sample should find 70-80% of the taxa recorded previously.
  • To address this recorders should re-visit tetrads throughout the season and record from a representative sample of habitats.
  • The BSBI’s data under-pins national plant conservation policy and thorough recording is essential if Atlas 2020 is to provide a rigorous basis for an understanding of our changing flora.

If you are interested in recording and would like to see if your local area is in need of records then do examine the interactive map below. Alternatively contact the county recorder, David Morris, by email. There are also ample opportunities across the county to contribute to Atlas 2020 as part of a group recording effort. See the 'Meetings' tab for dates of recording meetings or visit the websites of local natural history societies to see details of their field programmes (see right-hand side panel for links).

Atlas 2020 Progress

Updated 8th March 2017


Hover over a tetrad to view statistics


Hover over a hectad to view statistics


  1. Wow! This is a really brilliant resource David - thank you! There is certainly a lot to do. What is your advice, please, on which tetrads to target: is it better to go for those with no records, or very low numbers, or to try to increase records for tetrads which already have a reasonable number? Or doesn't it matter which tactic we use? Would it be useful for recorders to indicate which tetrads we are going to target this year so that we don't duplicate effort? Thanks.

  2. Thanks, Sarah. I would say that in the first instance it is best to think about recording at a hectad scale, and therefore choose the tetrads within that in order to maximise the taxa likely to be recorded. Thus, see what habitats are available and get a good sample of them, and spread the visits out to sample seasonality. Particularly rich sites might benefit from several visits (essentially a stratified sample). The sample may be spread over many or few tetrads, but 5 well-recorded tetrads within a hectad (or the number equivalent to 20% for partial hectads) is supposedly sufficient to re-find 70-80% of previous taxa.

    That's one way of doing it. My own recording of SP51 has been typically obsessive, and I've been recording all tetrads (or almost all), all interesting sites and am trying to maximise the tetrad totals. It's a great way of getting to know ones neighbourhood (without using a car), generates interesting records and I'm blessed with having Otmoor on my doorstep. Even after all this work SP51 is still at a 73% re-recording rate (253 taxa missing) and it has kept my attention from some rather poorly recorded squares next door. Rectifying this is my task for next year.

    I don't think there's much risk of duplication of effort - I think I know where the most active recorders are and they are not many and well scattered about the place. However, it is still worthwhile for recorders to let me know where they will be recording. I encourage this on the 'About Recording' page.

    Finally, notwithstanding the above verbiage, all contributions are much appreciated. We can only do what we can in the short period left to us for Atlas 2020.