How can we monitor changes in our wildflower populations
more effectively?
This question has recently been on the minds of many of
Britain’s botanical movers and shakers, across the various societies who take
an interest in such things.
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The group assembles to start work; Kevin Walker on right
Image: M. Pocock |
These organisations are looking at a range of survey
methods that might be used in a new national plant monitoring scheme, similar
to ones already up and running for birds, bats and butterflies.
LM: What’s your involvement with this, Oli, and how are
these trials connected to the proposed national plant monitoring scheme?
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Woodland trials: Oli Pescott (right); Bob Ellis (centre)
Image: M. Pocock |
OP: "My employer, the Centre for Ecology and Hydrology (CEH),
has long been involved in botanical monitoring through the links between the
Biological Records Centre (based at CEH) and the BSBI. CEH also co-authored a
review of the need for a new plant monitoring scheme, jointly published with BSBI, Plantlife and the British Trust for Ornithology in 2010.
The reason for the recent field tests was to try and see if
methods utilising randomly selected plots would be practical for the national
plant monitoring scheme currently being developed. We wanted to field test survey methods, which have been designed by BSBI in collaboration with CEH, Plantlife and JNCC.".
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Felicity Harris (Plantlife) and WFC volunteers
Image: M. Pocock |
LM: So you held a workshop to trial some methods? What were
you hoping to achieve?
OP: "We wanted to find out how different ways of selecting
plots for monitoring might affect the practicality and see how volunteers experience
the survey. We decided to field test three different methods of plot selection
(the scheme will be based around volunteers recording up to 5 plots within a 1
km square)".
LM: Why was that so important?
OP: "It’s very important to have randomisation at the heart
of any monitoring scheme. The benefits of randomised plots are not only for the
quality of the information provided, but they can also mean that surveyors have
fewer choices to make in the field.
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The team, with Pete Stroh, Bob & Oli
Image: M. Pocock |
We often found that self-selecting plots
for recording can be fraught with difficulty: should you include or exclude the
scrub from your chalk grassland plot? Do you put your woodland plot in the nice
open glade one side of the ditch or the empty shady area where you are
standing?
One idea is that by giving a largish (25-30) selection of random
plots to volunteers, some accessible plots can be found and surveyed, but the
unknown bias inherent in surveyor’s self-selecting locations is minimised as
far as possible".
LM: So you all held a workshop at Juniper Hall to trial some
of the different methods currently on the drawing board. Who was there?
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Pete, Kevin and the volunteers
Image: M. Pocock |
LM: And what happened when you went out in the field to test
the three methods?
OP: "Well, we spilt into three groups and each group was
assigned one of three methods to try out on a grid square. So, essentially we
were all traipsing around a 1 km square trying to work out how many of the plot
locations on our maps were accessible! We also tried out laying our plots in
different habitat types, and attempted to see how different plot sizes would
affect how many ‘target’ species were recorded in any one habitat.
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Gridded plots Image: O. Pescott |
We had prepared maps for a number of 1 km squares around Box
Hill. For any one square, three different plot selection methods were used to
generate 1 km square OS maps overlaid with the potential plot positions for any
one method. All the groups had a chance to try each one of the methods
trialled. For example, one of the methods trialled uses gridded plots.
Here (on left) is
an example of a systematic plot selection method with the plots laid out in a
regular grid, so you can see what I mean".
LM: So, what do you see as the main challenge with this
approach?
OP: "Well, the main challenge when volunteers self-select
plots is that they may choose the nicer locations containing the species that
we are asking them to monitor. This means that the starting point of the scheme
is a set of fairly species-rich plots, and so any indicator that might be
produced and used to inform on the state of the countryside is far more likely
to go down (i.e. most plots are better than average and are therefore more
likely to get worse than better).
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Volunteers try out one of the survey methods
Image: M. Pocock |
We need plots in all type of situations so
that we can detect increases in plant populations as well as declines. Ultimately
it’s about knowing that the approach will provide information that is as
accurate as possible, but still remains fun and interesting for volunteers".
LM: Did you find anything interesting while you were out in
the field?
OP: "Yes! One of the squares had good populations of one of
Britain’s rarest woodland plants, Cynoglossum germanicum (Green Hound’s-tongue)! Box Hill is one of it
strongholds but we had no idea we would find it in the woods we were surveying.
This came to light as we were walking to a random plot location in the evening
gloom".
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Cynoglossum germanicum
Image: K. Walker |
LM: And here is BSBI's distribution map for C. germanicum. Oli, can you close by giving us an idea of what the next step
is and tell us a bit more about how these trials are connected to ideas for a new national
plant monitoring scheme?
OP: "The next step is to review all of the results from these
trials. This year Wildflowers Count volunteers have also been given the option
to use plots in their surveys, although these were all self-selected. We have
to review the feedback from those volunteers as well, and then finally
recommend a particular approach to JNCC. The scheme is currently out to tender,
but the organisation (or organisations!) that are successful in their bid will
roll-out the scheme for an initial three year period using the methods that we
have developed.
It’s a big challenge, but it would be fantastic if the plant
world finally had something to rival the Breeding Bird Survey or the UK Butterfly
Monitoring Scheme!"
Thanks Oli, I couldn't agree more! Let's close with a few words from Kevin Walker, BSBI's Head of Science:
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Pete, Felicity, Kevin and one of the WFC volunteers
Image: M. Pocock |
"The absolute key for this scheme is to make it as straightforward and enjoyable as possible for volunteers. We therefore wanted to road-test the different methods to help us select which approach worked best, as well as to iron out as many 'bugs' with the methods as possible.
"It was great to be able to discuss these issues in the field with colleagues whom we've been working with for a number of years, developing the methods and producing the guidance. It was also very sobering to see how things did or didn't work, but great to be able to make decisions on the spot when it was clear that aspects of the scheme weren't practical. We are now much more confident that the scheme will work, and that it will provide an enjoyable and rewarding experience for volunteers!"