Britain is on fire!

I find it very difficult to associate this with England's verdant land.

“And did those feet in ancient time

Walk upon Englands mountains green:
And was the holy Lamb of God,
On Englands pleasant pastures seen!”

---William Blake

Fires Burn Across the UK

NASA,

30 April, 2019

It is not even summertime, but already the United Kingdom has seen a significant number of wildfires. The map above shows cumulative fire detections across the United Kingdom from January 1 through April 30, 2019. The data come from the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite.

Each red dot depicts one fire detection from the VIIRS 375-meter active fire data product. A “fire detection” is a pixel in which the sensor and an algorithm indicated there was active fire on any given day. Many fire detections can be generated by a single burning fire.

Notable fires this year include blazes in February and April in England’s Ashdown Forest—the setting that inspired the Hundred Acre Wood in A.A. Milne’s Winnie the Pooh stories. In late February, following the United Kingdom’s warmest winter day on record, the Marsden Moor fire burned in West Yorkshire, England. Scotland has seen burning too, including a major wildfire that burned near a wind farm in Moray.

January 26, 2014 - April 30, 2019

The chart above shows that there is a seasonal trend to the number of fire detections. Vegetation that was previously frozen and dried during the winter becomes fuel for wildfires during spring and summer months.

Notice that there have been more fire detections since 2017 compared with previous years. According to the annual report on forest fires by the European Commission’s Joint Research Center, warm, dry weather was responsible for the rise in wildfire numbers across the United Kingdom in 2017. A similar situation played out in 2018.

“Drier-than-normal conditions can boost fire detections in two ways,” said Wilfrid Schroeder, a scientist at the University of Maryland and principal investigator for the VIIRS active fire product. He noted that dry conditions favor the ignition and spread of fire. There also tends to be less cloud coverage, making fires more likely to be detected from space.

High fire counts and warm, dry weather have been a continuing trend. By the end of April 2019, the United Kingdom had already seen more fires through this point in the year than in the record-breaking year of 2018.

NASA Earth Observatory images by Lauren Dauphin, using VIIRS data from the Suomi National Polar-orbiting Partnership. Story by Kathryn Hansen.

Ash dieback: one of the worst tree disease epidemics could kill 95% of UK’s ash trees

the Conversation.

7 May, 2019

Ash dieback – a fatal disease of Britain’s native ash trees (Fraxinus excelsior) – is one of the worst tree disease epidemics the UK has ever seen. The disease is caused by a fungus that originated in Asia but is thought to have arrived in Europe on exotic plants in the early 1990s, where it has devastated native ash species which have very little natural immunity.

Ash dieback has since spread ferociously throughout Europe due to airborne spores and trade in ash saplings which have no visual symptoms of the disease. In 2012, the disease was confirmed in the UK and later shown to have been imported on saplings to multiple sites across the country. It is now found throughout the UK. There’s no cure and very few trees show signs of long-term resistance.

The environmental impacts of the disease are likely to last a long time, but as our new paper explains, they’ll also carry a shockingly high economic cost.

Wilting leaves are a symptom of dieback – a fungal infection of ash trees. Courtesy The Food and Environment Research Agency (Fera), Crown Copyright

There are 150m mature ash trees in the UK, making ash one of the most common native tree species in the country. We estimate that ash dieback will kill at least 95% of ash trees and cost the UK economy £15 billion – a cost one third greater than that reported from the foot-and-mouth disease outbreak in 2001. Half of this cost will arise in the next ten years.

Putting a monetary value on ecosystem services – the beneficial effects that trees provide for people and the economy - helps people understand the scale of the problem. Roughly £10 billion worth of ecosystem services will be lost as ash trees disappear.

Losing these services will have wide-ranging consequences. Less carbon dioxide will be absorbed from the atmosphere and the risk of flooding will increase. Studies have also shown that losing trees from a community is linked to poorer physical and mental healthamong the people who live there. Tackling climate change calls for an enormous effort to plant trees but ash dieback will rob the UK of using this valuable native species.

Ash trees often border roads and paths in the UK – making their removal more difficult.Photodigitaal.nl/Shutterstock

Clearing up dead and dying ash trees will carry another major cost, particularly where they present a risk to human safety. Stricken ash trees are prone to shedding limbs or collapsing completely, either directly due to the ash dieback fungus or a secondary pathogen such as honey fungus infecting the weakened tree. More than 4m ash trees line Britain’s roadsides. Felling these will be expensive and involve road closures and power and communications outages as work is carried out.

Ash trees in towns and cities will need the same treatment. A major national replanting effort could reduce the total cost of losing ash trees by as much as £2.5 billion, but a diverse mixture of native species will need to be planted to improve the resilience of new trees to pests and diseases. Replanting should also be carefully managed to ensure habitats are connected throughout the landscape.

Rising from the ashes

Exotic disease is not a problem limited to ash trees. People move plants – and unwittingly, their diseases – around the world at rates that far outstrip natural disease spread. The international trade in plants, travel and climate change are all contributing to an acceleration in the rate of new tree diseases emerging and spreading.

More tree pests and diseases have arrived in Britain in the last 40 years than at any time before then. As more native species are threatened, the effects will combine and multiply. Losing most ash trees will be bad enough, but what if the UK loses oak next, or birch? The idea of a landscape largely devoid of trees is appalling, and the economic costs incalculable.

People aren’t powerless in this story though. The science is clear that the largest pathway for spreading tree diseases is the international trade in live plants and soil. Stricter controls on this trade could better protect our trees for generations to come.

The international trade in trees has helped spread diseases to places where native species have little genetic resistance. Tramp57/Shutterstock

Most countries prioritise the value of trade in live plants over the risks to their native flora. Our paper shows that the value of the annual trade in ash saplings amounted to only 2% of the estimated cost of ash dieback.

The costs of restricting trade and improving border controls have long been used to block the introduction of stronger biosecurity measures for plants. But we now know that the costs of diseases like ash dieback have been wildly underestimated and this new evidence demands an urgent rethink.

The health of native trees, in fact of all wildlife, needs to be valued far more highly. We must recognise not only the essential benefits that the natural environment provides for us, but how severe the consequences are for society when new pathogens are spread.