It was an interesting trip last week to the two sites in the Peak District where the Heather Trust’s beetle damage studies are currently being run. I’ve seen quite alot of the Peak District over the past year, and getting to know this extraordinary area has been a real pleasure.
The heather beetle studies are based on two sites near Buxton, both of which have seen serious damage over the past few years. The most worrying damage has been inflicted on Combs Moss, which has been badly hammered for several consecutive years. After the initial outbreak, the damaged heather was burnt off and began to recover very nicely, but the beetles returned the following summer and stripped away the regeneration. This cycle of depressing destruction continued for several years until the regeneration began to weaken, suggesting that the natural seedbank was becoming exhausted. The burns produced more and more cottongrass until it reached the stage where heather presence was becoming worryingly sparse, and Natural England interceded to restrict a burning rotation which had become annual.
Combs Moss is a very wet moor with difficult access but a history of extremely high grouse productivity. Despite the fact that this year’s stock of grouse looks promising, I have never seen a situation caused by heather beetle which threatened the viability and very existence of a moor, and the damage was staggering last year when I first visited. Compare Combs Moss with Crag Estate, which runs up to the Cat and Fiddle Pub between Macclesfield and Buxton and there are a range of notable differences. For a start, Crag is much drier and has easy access straight onto damaged heather from the main road. The damage at Crag is more typical of beetle outbreaks I have seen elsewhere, and while it has been dramatic, the terrible cycle of destruction has not taken hold as it did at Combs. The two moors represent very different ends of the same spectrum of damage, and they were chosen as study moors towards the end of last year.
As is necessarily the case with beetle damage, the problem can never be tackled “head-on” by taking out the beetles themselves. Management has to have its basis in picking up the pieces and restoring the damage, and the Heather Trust’s project focusses on how the heather beetles change the habitat and how it can be restored with greatest efficiency. Consultant ecologists have been employed to monitor plots of damaged heather as they recover from the outbreaks, as well as study the effects of various treatments, including burning in the back-end, burning in the spring and cutting. The project will take several years to complete and analyse, but hopefully it will provide some hard scientific data to back up exisiting management strategies. At Combs Moss, very badly damaged areas are being reseeded and that too is being monitored. The seed was applied in April and has not yet shown fruit, so it will be interesting to see how and when it finally catches.
As if to throw a further spanner into the works of heather beetle complexity, the damage I found on the Chayne during July and then covered on this blog took a definite turn for the worse during August, but now seems to have almost recovered. Some of the most severe damage has created a number of dead heather plants, but the majority of red heather has turned green again, and some of the plants are trying to put on some late flowers.
The reason why heather plants die after beetle outbreaks is down to dehydration, so I wonder if the mild, wet weather we have been having since late August has allowed the slightly damaged heather to recover and return to health again. If it had been a dry period, I suspect that many more plants would have died. The moisture seems to have allowed the heather to recover, but it also sustains the dormant beetle pupae in the sphagnum, which seem to take great pleasure in being wet and soggy. I am interested to see the hatch of adult beetles when they come in the autumn, and I hope that their short period of feeding before dispersal won’t set the recovering heather plants back again.