Sunday, 11 August 2013

New Forest Damaged by Ragwort Madness

There are so many things to blog about today it is a real job to know which one to pick. However, there is a story in circulation about the New Forest's ecosystem being damaged by do-gooders acting out the hysteria 
over ragwort.

It quotes Buglife's Steven Falk.

"Ragwort pulling in the New Forest is a truly ill-informed and damaging activity that is totally unnecessary. There are so many rare insects in the Forest, and it is well known that a general reduction in the number of flowers in the Forest over recent decades has placed many insects under severe threat of extinction there. Examine any patch of flowering ragwort in fine weather and you will see an astonishing array of bees, butterflies, hoverflies and beetles".

 Quite right and it is also illegal in a number of ways both under the Wildlife and Countryside Act and under Countryside and Rights of Way Act. The first prohibits the removal of wildflowers unless you are a landowner, occupier, someone authorised by them or certain unusual kinds of public official. The second prohibits damage to  Sites of Special Scientific Interest including the New Forest.

But how did this get encouraged, well our old friends the British Horse Society who got hammered by Advertising Standards for false information are involved again.

I think, on  the basis of the evidence, it is quite fair to say if the British Horse Society gives you a piece of information on ragwort, it has a high likelihood of  being wrong.

This example is one of many they have put out on press releases

They have been pushing their misleading, unscientific survey on the New Forest National Park Authority

This is an item on the National Park's website. It does not make the National Park look good.
It is a very very badly designed survey. It is known to some of us as "The yellow plant survey" and it is based
on a very unscientific false premise.

More than 75 percent of cases of ragwort reported in the 2010 survey involved land that animals were grazing on or near. Across the UK a total of 13,189 horses were identified as grazing on ragwort-infested pasture, with the figure for cattle and sheep being estimated as approaching 20,000.
Well so what! The animals have co-evolved with these plants and we know from the science that the level of resistance of an animal species relates to its likelihood of encountering the plant. There is no evidence at all that the mere presence of the plant is a problem. Do they make a fuss about all the other plants with the same
problem alkaloids in them that commonly occur in the presence of grazing animals , of course they don't!

And another amusing apparent illustration of bad science. This was the 2011 survey and  they said this.

Conducting the survey during one week means that results can be compared to the same week in subsequent years, enabling trends to be identified
What happened in 2012. They moved the week!  It is perhaps co-incidental that the change made it coincide with the school holidays when perhaps more people would be available to get higher figures.

But if you want real hysteria. There was a piece in  the New Forest edition of the Bournemouth Echo a few years ago.

It has such scary gems like this

Teams of Forestry Commission workers and seasonal staff have been toiling since July to uproot tons of the poisonous plant with its bright yellow flowers before it can be eaten with fatal results by ponies and other livestock roaming the open forest.

Lets get this straight we have good of evidence from the science to explain why the horses , which have been co-existing with the plant for thousands of years, don't eat poisonous plants. Any animal that commits suicide by eating poison does not pass on its genes. Nature therefore shapes them to avoid poisons. Like these that occur in 3% of the world's plants. It is only a problem in hay, or in cases of cruel starvation.

Then we have this piece of bizarre misinformation.

Just two pounds of ragwort is enough to kill a horse and the poison, which attacks the liver, is cumulative, untreatable and invariably fatal, leading to an agonising death for affected animals.
All the scientific papers I have seen in over a decade of detailed  study of this issue quote figures in percentages of body weight for toxicity which for a horse is a lot more than two pounds. The breakdown products that cause the toxicity, can react harmlessly with lots of things in the liver and it appears can even be detoxified by water. So they are only cumulative in action if each dose goes over the threshold set by these detoxification routes. It is certainly not invariably fatal since there are examples of recovery in  the literature, which of course implies that there is at least some element of treatability.

Then we have this exaggeration:-

Seeds produced from the profuse flower heads on stems up to 5ft high can be spread over a wide area to lie dormant for up to 20 years before germinating another deadly harvest.
The seeds do not spread over a wide area, they have parachutes, not wings and fall within a few metres of the parent plant. Quite a lot of them never even leave the plant. The 20 years figure is an estimate of possibility in unusual soil conditions where the germination rate would fall to 1%

You'll see on the Ragwort Myths page that it appears that the British Horse Society were circulating false information that after 20 years 70% percent would germinate. You see what I mean by them being a bad source?

We have ecological damage in a national park as a result of bad information being circulated and people getting hysterical about ragwort.
Ragwort Hysteria latest entries

No comments:

Post a Comment