Ips typographus: Could Norway spruce be banished from Britain?

THE natural distribution of European native tree species has always been a source of fascination for me, with Norway spruce a prime example. Norway spruce is naturally distributed across Scandinavia, within the Baltic States and parts of Russia, and in upland areas of central and southern Europe (e.g. the Alps and Pyrenees). However, that relatively short stretch of water called the North Sea apparently kept it from colonising the British Isles. Yet arrive it did, by man’s hand, in 1548. 

Picea abies was almost certainly the first exotic conifer to be introduced and grown here on a large scale for timber. By the 17th century it was being grown on estates, and it was one of the mainstays of plantation forestry by 1800. Norway spruce continued to feature in UK forestry expansion before suffering heavily from wartime felling. In 1947 there were 130,000 acres of Norway spruce, forming eight per cent of high forest, making it the third most important conifer in UK forestry. At 150 million hoppus feet, it accounted for three per cent of timber resources, according to H. L. Edlin. Norway spruce has since been displaced from pole position by Sitka spruce and now accounts for no more than five per cent of the conifer area within the UK.
In a separate role, Norway spruce was Britain’s number-one Christmas tree from the 19th century until around 30 years ago, when it was overtaken by Nordmann fir.

IPS TYPOGRAPHUS CHANGES EVERYTHING

There are countless large Norway spruce trees in gardens, parks and on common land, many of which were planted after use as Christmas trees. (Image: Stock)

Though not a native species (but domiciled at least), the disappearance of Norway spruce from the UK landscape and forest industry would clearly be a huge blow, but this is now a distinct possibility since Ips typographus established in the south of England. You might think any loss of Norway spruce would be as a direct result of damage and death caused by Ips. After all, Norway spruce is the primary host for this particular spruce bark beetle within its natural European distribution. 

But there you would be wrong, for by far the greater threat to the existence of Norway spruce in the British Isles is no less than the Forestry Commission (FC), the very body responsible for establishing a once vibrant commercial forestry industry in the UK. The FC is understandably demanding the removal of stands of Norway spruce actually infested with Ips, but at the same time is actively promoting the removal of damaged or stressed stands of trees, with even healthy stands of Norway spruce perhaps within its sights.

The FC appears to be engaged in a scorched-earth policy against Norway spruce, all in the cause of saving Sitka. And who can blame them when Sitka now accounts for 50 per cent of commercial conifer plantings and 25 per cent of total forest cover? If Sitka goes, so essentially does UK commercial forestry.

Ips typographus, with its unwieldy common name (larger eight-toothed European spruce bark beetle), is native to Europe and has probably been around for almost as long as Norway spruce. 
Pest outbreaks have been recorded in Europe since the 15th century, with huge volumes of timber infested and damaged in a range of countries during the 20th century. 

Among the most notable losses were 7 million m³ of spruce standing timber in northern Poland (1981–87) and 6.7 million in the Czech Republic (1991–99). Since the turn of the 21st century, outbreaks have developed across Europe, accelerated, it is claimed, by extensive wind-throws (uprooted or broken trees) caused by hurricane-like events. They include Storm Lothar (1999) causing 185 million m³ wind-damaged trees across Europe and Storm Kyrill in 2007, which accounted for 45 million m³ of damaged standing timber. The beetle initially makes a ‘B-line’ for damaged or stressed Norway spruce, but will attack healthy trees when pest populations are very high.

WANT MORE LIKE THIS? 

• Ips typographus discovered in Wales for the first time
• Ips typographus discovered on Sitka spruce for the first time
• The indications and implications of Ips typographus on Sitka spruce

Ips first turned up in the UK as an established breeding population on two sites in the Ashford area of Kent in 2018, although forestry contractors on the ground judged that the infestations had festered for a number of years, with some erstwhile healthy Norway spruce also attacked. 
Long-distance pest spread, which would clearly include movement from mainland Europe into the UK, is traditionally ascribed to movement of infested-bark-covered sawlogs and timber. 

The question is why it took so long for the beetle to arrive and establish, given that huge infestations have raged across Europe for well over 200 years. 

IPS NOW ESTABLISHED

Ips typographus – the recently established alien spruce bark beetle, causing much grief to the UK’s longest-serving exotic commercial conifer (Image: Stock)

Over the years, beetles have been trapped at various sites in the UK, including around sawmills, but the pest never established a breeding population. This time is different, with a succession of breeding populations found since 2018. 

In October 2023, the FC said 750 sites had been inspected during the preceding five years, but only six per cent were found to be infested. The FC was clearly in its regular ‘play down’ mode, because by my counting that is still 45 infested sites, which sounds like an awful lot to me and definitely cause for concern. 

So why has there been this great change in the last five years, compared with the previous 50?

The FC is adamant that adult beetles are flying in or being blown in from continental Europe in what it terms ‘blow-over’, and that every single outbreak discovered so far is due to separate incursions via this mode of insect pest movement and transfer. There is no spread within the UK, it says. 

However, almost a century of research across Europe unwaveringly ascribes long-distance pest travel to movement of infested bark-covered sawlogs and timber, while the calculated distances of travel via airborne movement, documented over the last half century, misses by miles the distances required for air-borne movement from, for instance, eastern France in mainland Europe to the county of Surrey in the UK.

Could it be that a change in the use of imported Norway spruce is responsible? Go back half a century and virtually all Norway spruce imported from Europe would have been high-grade timber destined for UK sawmills. In recent years there has been a massive increase in wood imported for firewood and biomass, clearly lower-grade material more likely to be infested. A UK forester visiting central Europe recalled to me watching the felling, extraction and clearance of Norway spruce heavily infested with Ips. He asked the contractor if the material was destined for biomass burning nearby. He was told it was indeed bound for biomass burning, but in the UK. You only have to look at the websites of some of our biggest suppliers of firewood to see that much of their wood now comes from the Baltic states and other central European areas where the beetle is endemic and infestation rates high.

FC AND FOREST RESEARCH COME CLEAN

There’s not very much Norway spruce in the extreme south-east corner of England, but in the Surrey Hills there are plenty of fine-looking stands. (Image: Stock)

Early this year, the FC and its European collaborators finally released strong evidence for their ‘blow-over’ hypothesis, having sat on the same information and kept everyone in the dark for over a year. The evidence is compelling, but I cannot understand why they were so hush-hush, especially since it goes right against centuries of work and documentation which showed the flight capacity of adult Ips beetles to be a fraction of the 500 km these beetles have apparently travelled from Belgium to England.

If correct we can expect the regular arrival of Ips beetles by ‘blow-over’ from continental Europe and for the FC to be engaged in a programme of continuous spruce bark beetle management, with new outbreaks springing up as soon as existing ones are eradicated. 

Sadly, the only sensible option would appear to be the complete removal of all susceptible spruce trees from the area of Britain which beetles are able to reach through the combined effects of insect-wing power and air currents. The demarcated area currently extends as far west as Wales, but there is no reason to doubt that the landing area for Ips beetles could extend much further. 

NORWAY SPRUCE IN THEIR SIGHTS

So what are the implications for plantation Norway spruce in all of this? Dire is the word that comes to mind, especially after a recent statement from the FC which said: “Over the next 10 years (2024 to 2034), the Forestry Commission is encouraging landowners to remove susceptible spruce (stressed, windblown) from the demarcated area within the South East and replant with other species.” But will it stop there? I don’t believe so, and I think large areas of southern England and the Midlands are destined to become Norway spruce-free zones. And since an adult Ips was found in Scotland there could be no stopping the spread of a Norway spruce-free zone.

There is not a lot of plantation Norway spruce in south-east England besides the remnants of nurse crops planted alongside broadleaves but not taken out, and ‘abandoned’ Christmas trees. 

Occasionally you might find a plantation of Norway spruce that doesn’t fit into one of these two categories. I encountered one in mid-Hertfordshire several years ago when I was writing a feature on the company tasked to manage it. The owners had no intention of cutting the trees for timber, but simply admired the aesthetic qualities of Norway spruce. I purposely did not give the exact location in the site in the article, knowing full well the FC’s Norway spruce police would be sniffing around.

A new national monitoring project which aimed to help prevent the potential spread of Ips was announced in March 2024. Offered via Forest Lab and run by the Sylva Foundation, Forest Research and the FC, it wanted volunteers from England, Wales and Scotland with spruce growing in woodland they own or manage, and who are willing to host and collect samples by installing a spruce bark beetle trap.

An accompanying Forest Research statement said: “By taking part in the project, volunteers will become part of an early-warning system and help action to limit the impacts of this pest. They will also be contributing crucial data to science that will help researchers to better understand the biology of Ips typographus and help shape policy and guidance for the sector.” 

On this, and based on my experience, I would say two things. Firstly, the FC and Forest Research are traditionally very much organisations which operate on a ‘we know best’ basis, whose attempts to enlist outside assistance are a relatively recent tactic, potentially a sign of desperation. 

Volunteering spruce-containing woodland for survey work could be a double-edged sword for landowners. It’s clearly helpful all round if an infestation is detected in your spruce-containing woodland, but the likelihood at this stage is it will not be, unless of course Ips is a lot more widespread than they are letting on. But it could also be a covert way of mapping where Norway spruce is in the country so that the plant health authorities’ stated aim of removing Norway spruce in future becomes quicker and more precise. 

And there are also implications for another less well-known spruce. That is Serbian spruce (Picea omorika), which is botanically close to Picea abies and with which it hybridises where the natural ranges of these two trees coalesce in south-east Europe. 

Norway spruce grown on Christmas tree farms is another matter, with standard-size commercial Christmas trees largely escaping because trees have to be of minimum dimensions and development in relation to the bark-covered bole before Ips attacks. However, south-east England is surprising well-endowed with Christmas tree farms, many of which will be growing larger Norway spruce as Christmas trees, and these could be an entirely different matter. Three metres in height appears to be the present cut-off point before concern arises.

Last but not least are the countless thousands of large Norway spruce trees in urban and suburban gardens, many former Christmas trees that were planted post-yuletide by homeowners. Will these attract the attention of the FC?

Forestry Commission getting to grips with Norway spruce and cashing in on its investment which was planted in 1960 and harvested in March 2011. (Image: Stock)

Sadly my predictions about the fate of Norway spruce already appear to be coming true. In early October, the FC announced a ban on new spruce tree (Picea A Dietr.) planting in the Demarcated Area (DMA) as it currently stands. 

According to the latest official map, the DMA currently covers parts of Lincolnshire, Bedfordshire, Cambridgeshire, Hertfordshire, Buckinghamshire, Berkshire and Hampshire; and the entire area of Norfolk, Suffolk, Essex, Surrey, East and West Sussex, Kent and Greater London.   

Planting spruce trees for ornamental and scientific purposes, growing on nursery sites for trade, or the planting of Christmas trees, will be permitted in specific circumstances detailed in the notice. Christmas tree growers in the affected area can continue to grow an unlimited number of spruce trees up to three metres in height above the root collar before authorisation is required.

All this is in response to events throughout summer and ongoing with adult Ips beetles secured in pheromone traps as far afield as Scotland and Wales, the finding of a breeding population in East Anglia, and with unconfirmed reports that more breeding populations of the pest continue to be found. But clearly the most mind-focussing event was the Ips infestation found on Sitka spruce in southern England in July. 

This appears to be the beginning of the end for Norway spruce as a softwood timber tree. Let’s hope and pray it is not the end of the beginning for Sitka spruce.