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 with the impetus provided by Atlas 2020, with over 260,000 records gathered so far for the project. A big thank you to everyone who has contributed to this surge in data, including the previous county recorder Sue Helm, and Thames Valley Environmental Records Centre (TVERC), with which the BSBI has a data sharing agreement.

Progress at hectad and tetrad scales can be seen in the interactive map below — hover over a hectad or tetrad to see information about recording there. The colour of a square indicates the number of taxa recorded for the Atlas period, while the coloured proportion of each tetrad equals its re-refind rate, i.e. the proporation of taxa recorded before 2000 that have been re-recorded since then. Some observations:
  • At the hectad level the county is doing well: compared with the recording period for the last atlas (1987-1999), approximately 70% of hectads covering the vice county have had 70% or more of previously recorded taxa re-recorded since 2000. As the published Atlas 2020 will be based on hectad distribution maps this is good news.
  • At the tetrad level there are many gaps in coverage, and the further from the centre of the county the more patchy has been recording. Thus, the county boundary and more remote areas of the Chilterns and Cotswolds are patchily covered. Large predominantly arable areas such as the north of the county and the Thame catchment are also not well represented.
  • There have been considerable numbers of new hectad records within the Atlas 2020 period (97 on average): coupled with the probable declines since the last atlas this suggests considerable changes to the county's flora. We shall have to wait for the publication of Atlas 2020 to learn what this means.

The final season

There is now just one recording season, 2019, to go until the close of the Atlas recording period. Here are a few thoughts if you are planning recording:
  • With the pre-2000 tetrad average at 280 taxa but that for the Atlas period at 170, there is clearly much still to be found in already surveyed tetrads, and good totals to be had in newly visited tetrads. Generally, a minimum of 200 taxa for a single visit to a tetrad is achievable and should pick up around 60% of previously recorded taxa.
  • Fewer well-recorded tetrads is preferable to more partly-recorded tetrads, so when identifying tetrads for survey it is worth looking for 'easy wins' as well as blank tetrads. Tetrads where a good start has been made but with a modest recording rate can be boosted by additional visits to pick up further taxa, e.g. those missed on previous surveys due to timing or habitat coverage.
  • If you are interested in recording but would like guidance on where to record or would like records to focus your recording, then contact the county recorder, David Morris, by email. He will be more than happy to help!
  • There will be many opportunities across the county to contribute to Atlas 2020 through 2019 as part of group recording efforts — see the 'Events' tab for a calendar.
If you are submitting records note that the deadline will be 31st December 2019. Please therefore submit your records well in advance of this.


  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.