Beetle’s Back

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Fresh beetle damage – heather looking red and sore

It was interesting to find that the small plot of heather which I fenced off to study in 2010 has been utterly destroyed by heather beetle over the last few weeks. I had originally planned to use this plot to show how grazing pressure was altering the vegetation on the hill, but after two years of impressive regeneration and growth, beetles struck in 2013. This was a marginal outbreak and caused some patchy damage, but beetle would soon become a recurring theme in this story.

When I visited today, the heather was looking very red and sore. I would estimate that  the damage extends to over 95% of the heather coverage, and there were only two or three sprigs of pink flowering tips in the whole quarter acre. Beetle larvae were still actively munching the growing stems, and many of the plants looked horribly parched and dry. It remains to be seen how the heather will recover into the autumn, but I am encouraged by the way that the plants have bounced back in previous years. At the same time, every time that heather is checked by beetle, it allows grasses and other plants to gain a foothold. Diversity is great and I don’t want a monoculture of heather, but there comes a point at which patchy heather coverage becomes weak and is easily over-grown altogether by more invasive plants.

Historically, heather beetle has been a driver for heather loss on our hill. Family members recall extensive outbreaks of beetle which took place in the eighties and annihilated large areas of heather. A failure to address this damage resulted in a shift towards the grass-dominated vegetation which defines the hill today. The rule is generally that heather will often recover from a beetle outbreak, but it often needs careful stewardship and management to do so. Conditions in the immediate aftermath of an outbreak can require careful handling, and heather is soon lost without attention to grazing. This is a key advantage of grouse moor management in that care is always given to heather coverage, which means little to the farmer but is everything to the keeper. Heather beetle damage is usually restored where grouse are a financial interest, but it is generally viewed as an irrelevance in marginal areas where sheep rule the roost.

Looking at case studies from across the western half of Britain, it seems like wetter conditions and agricultural overgrazing have put heather on the back foot over the last Century. Rather than emerge as a destructive, apocalyptic bolt from the blue, heather beetle outbreaks have simply been the last straw. It is hard to prove it, but there is little doubt that beetles have been the mechanism by which a great deal of moorland has moved from heather to grass on a national scale.

Reviewing the progress of this experimental enclosure last year (full blog here), I wrote that:

It seems that moorland in Galloway (at least in the early 21st Century) is grassier than it was a Century ago, made up of a varied blend of species with heather on the back foot, fighting to hold its own. This much is obvious in the Galloway hills a few miles further West, most of which run very green in summer and then white in winter. This boggier, peatier kind of ground is less ideally suited to red grouse, but its grassiness makes it popular with voles and pipits, which then encourage specialized predators like harriers, short eared owls –

The picture varies nationally, but heather beetle is often linked to wetter conditions, and wetter moors are often grassier. This may be a consequence of climate change, but that is not to say that we should not make the best of what we have. My situation is pretty unusual, and the extent of the damage is confined to the small area where heather is obvious enough to invite beetles. I won’t be doing anything to remedy or restore the damage because this is a study plot and the story is most interesting without intervention. However, if the situation was more dramatic and extensive, I would be considering a range of options to help the damaged plants recover.

I’ve been working with the Heather Trust to run their annual heather beetle survey over the past five years, examining trends and patterns in beetle outbreaks across the country. If you’ve seen red, beetle-damaged heather this year, we’d love to hear from you – download a survey form, fill it in and let us know what’s happening…

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