Heather Beetle

 

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This heather is now well and truly dead – stressed by beetle in 2017, then killed by a bad growing year

I can hardly resist a quick post about heather on the Chayne. Long term readers will remember the “heather laboratory” which was set up in 2010 to explore the level of grazing pressure on a small area of our hill. I routinely publish updates on how the plant life has fared over the last eight growing seasons, and heather beetle has played a major part in that story.

Beetles first arrived in 2012 and decimated the fresh young growth. The plants bounced back, but they were hammered again in 2013 and 2014. Each season of damage knocked the heather back and meant it was less able to compete with rapidly growing mosses and grasses. The “laboratory” was becoming less heathery every year, and beetles were the main driving force behind the decline of heather coverage.

There has been beetle damage every year since 2012. The usual pattern has been damage in the autumn, followed by recovery in the spring. It’s hard for plants to make progress under these conditions; they stand still and are unable to break out of a cycle of suppression. Last year’s outbreak was fairly bad, but I was reassured by the knowledge that the plants would certainly bounce back in the spring. I wrote an article on the Heather Trust’s blog in April explaining my optimism, but I did not reckon on the cold start to the year and the long dry summer which followed. The heather was unable to recover as it normally does, and when I visited last week I was unable to find any heather plants which have survived the dry summer.

I’ve travelled across the country looking at heather beetle for the last eight years, and it is a common theme that heather usually bounces back from a beetle attack. Provided that grazing pressure is kept under control and outbreaks do not become cyclical, beetle damage often restores itself, although it can lead to structural problems which call for active management. The lesson I take from this patch of heather is that beetle is not always a standalone problem, but instead beetle damage drives change.

We often hear it said that beetle is more prolific on wet ground, and there are some links between wet conditions and beetle breeding cycles. At the same time, beetle outbreaks also take place on dry ground, and perhaps the crucial difference is that damage effects both, but plants which grow on wet ground are already on the back foot and cannot regenerate so easily as those in better conditions. Perhaps this magnifies the significance of the damage and means that beetle outbreaks are more serious when they take place on wet ground.

I have no doubt that my heather would have survived a cold spring and a dry summer if it was in good condition, and I am certain that this problem has only come about because the plants were first weakened by beetle.

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