Friday, 27 April 2018

Spring Beetles

Beetled heather, which was then frosted in February-
This plant will probably recover
There haven’t been many sightings of heather beetle as they start to disperse for the spring this year. Cold winds have made for a cool March and April and held back the warmth that beetles need to fly, but a few individuals have been sighted in Derbyshire and Argyll - the beasties are on the move.  In the article below, the Trust’s Project Manager, Patrick Laurie gives his own experience of heather beetle on a piece of moorland he owns near Dumfries.

As part of a livestock exclusion experiment, a single acre of our hill ground was fenced off in 2010 to learn more about grazing pressure. After a year to recover, heather grew very strongly in years two and three. It looked like the entire fenced-off area would grow into a uniform spread of heather, but heather beetle struck in 2012, 2013 and 2014. Heather beetle has long been associated with wet ground, and this seemed to be proof of that old wisdom. Many heather plants were killed, but plenty of vegetation bounced back after some pretty severe damage.

Wetter moors are often challenged by invasive grass species, and the uniform heather coverage was soon broken up by tussocks of deer grass and some early signs of molinia growth. Rather than manage the damage on a single acre, I decided to leave things alone to see what would happen next.

Beetle was absent in 2015, but returned again in 2016 and 17. Last year’s damage was lighter than usual, but it has been interesting to see heather recover and restore itself year after year. Heather is no longer dominant in the fenced-off area, and wet ground has also led to a slow invasion of star moss.

This has been an interesting little project for all kinds of reasons, but it’s worth writing about the plot now because while much of the beetle-damaged heather currently looks wretched and tatty (this wasn’t helped by some heavy frosting/windburn in February), it will soon be greening up and springing back to life again. This picture was taken on Saturday and could hardly look less hopeful, but plants like these have looked worse in previous years and gone on to have flowers in July.  

It's hard to draw big-picture conclusions from a single small plot in isolation, but it makes me wonder 

1) whether beetles are one of several mechanisms which drive heather loss on wet ground; 

2) whether heather will often recover from beetle damage provided there is light touch, adaptive management;

and 3) would the heather have recovered if there had been livestock grazing in this fenced off area?

Some interesting food for thought.

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