Wednesday 11 May 2022

Escape to the Orchid Field: Pete's Big Day Out

As many regular readers will be aware, BSBI's Science Team (Kevin Walker and Pete Stroh) have been working flat out for the last three years (it probably seems a lot longer to them!) on the third BSBI plant distribution atlas which will contain, summarise and interpret the data collected by thousands of BSBI members and supporters during the twenty years of fieldwork towards the Atlas 2020 project

For months now, anyone asking Pete what he has been up to recently, has received a glazed look and the muttered response "Atlas captions..."

But it is springtime, when botanists need to get out into the field, even if only for a few hours, so I was delighted to receive the below message from Pete last Friday:  

"I escaped the Atlas for the afternoon to survey Terry Wells's Green-winged orchid plot at Upwood Meadows NNR (image at the foot of the page) in Huntingdonshire. I've been doing this each year since 2007. The plot was set up in 1978, and I wrote it up for British & Irish Botany in 2019. 

"Anyway, I thought I'd send you some pics, just in case you wanted to mention it on the blog and social media. 

"The crucial bit to mention is that the methodology uses two tape measures attached to permanent (feno)markers (image on left). Coordinates are taken for each individual, so that they can be relocated by triangulation each year. 

"That means that you can see if a plant has survived, assess flowering performance, know how old it is (at least from 1978), etc.  

"When I got to the plot, it looked like it was a 'bad year', with very few flowering orchids. However, I found 94 individuals - only four were missing from last year (possibly dead), and there were five new plants. So a net gain of one from last year, which itself was a 'good year'! 

"Of the 94, 61 produced flowering stems BUT 46 stems had their heads bitten off by deer and rabbits, so would not have been seen without using this method. 33 were vegetative (so would have also been missed). 

"Without using triangulation, I would have counted about 15 orchids, instead of 94! That's a lesson to reinforce for anyone counting orchids (or anything else), I think". 

Many thanks to Pete 'Two Tape-Measures' Stroh for this account - he also took all the images on this page during last Friday's brief orchid outing; you can see the distinctive green 'wings' (i.e. the lines on the tepals) very clearly on the pink example above right - click on the image to enlarge it. 

So, we have now sealed up the escape tunnel and Pete is back hard at work editing those Atlas captions. 

We hope soon to be able to tell you more about his progress and when we can expect to see the Atlas in print or online, so watch this space!

Meanwhile, if you are planning to get out and enjoy looking at and identifying our native orchids, many of which are at their best right now, you'll want to check out the resources and links we've pulled together for you on our Orchid ID page. 

We'll leave you with a pic (below) of Terry Wells's Upwood Meadows plot where Pete's population of Green-Winged Orchids resides safely within the well-managed boundaries of a protected site. 



  1. Triangulation seems the way to go when the plants are not always obvious; 94 instead of the 15 that they were in flower.

  2. We have just completed a survey of Green-winged Orchids on "First Church Meadow" which is part of Martin' Meadows a Suffolk Wildlife Trust reserve. This is also a long-term project started in 1979. The number of flowering spikes in 5 metre square areas is recorded and the whole meadow is surveyed (the method is fairly involved so I won't go into detail here) and the results display nicely in a spreadsheet representation of the meadow. I have yet to process this year's results but the yearly average is around 2500 spikes. Given the ratio above the population could be as high as 15000! A similar method is used for Pyramidal Orchids, Early Purple Orchids and Snake's-head Fritillaries. For the latter I would estimate that there are even greater numbers of juvenile and predated plants that are not recorded. However the method does provide an interesting measurement of flowering trends over the years which shows some very interesting results.


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