Northern Ireland

Bacteria clean up blackened aftermath of Mourne blazes

Walkers against a background of smoke
Image caption Hillwalkers skirt the smoke during last year's fires in the Mourne mountains

Twelve months ago forest and heath fires were burning across Northern Ireland.

Accidental or deliberate, they left a trail of charred devastation in their wake.

Specially protected environmental areas and commercial forests were destroyed.

In a few hours it was the only part of Europe where the tree count actually declined. It already was amongst the lowest.

Retracing the steps I took last year to cover the fires for the BBC, I passed hectares of burnt forest.

Lifeless tangle

Trees had fallen over on top each other. Every one of them was charred. It was a silent lifeless tangle.

This would have been a busy time for nesting birds but there were none. Their nests, eggs and food supplies had all been destroyed a year ago.

Heading further up the mountain path, I passed the last of the incinerated trees and the Mourne mountains finally hove into view.

From the sea they look pristine and as dramatic as always. But close up the scene is grim. Your eyes search for the heather that should be green and vibrant this time of year. You look for sedges, grasses and wild flowers, dotted with bog cotton.

Black emptiness

But in some places it was just huge areas of black emptiness. It was as if the glaciers that formed this corner of the world 12,000 years ago had just left. There were hectares of boulders and little else.

The fires that swept through seems to have burnt long and deep in some areas. There were signs of life but only just. Here and there a few wisps of emerging heather or a tiny tinge of green sedge. It will take many years for vegetation to reclaim the hillsides.

While many areas of the Mournes were left untouched by fire, it's the areas accessible to the popular pathways that have sustained the damage. So it's the innocent walkers who have to put up with the depressing results of a moment of madness last year.

Amongst those scouring the burnt valleys for life is Mike Larkin. He's a professor of microbial biochemistry at Queens University, Belfast. Last year he and a team of students started examining the blackened peat at the seat of the fire. To their astonishment they found more than they had bargained for.

"After last year's fires we decided to look at the levels of bacteria in the soil on either side of the burnt and unburnt areas of what is an upland heath", explained Mike.

Surprise

"The surprise was that there were about ten times as many bacteria in the burnt area than there were in the unburnt area. What was really happening was, over a brief period, the bacteria were starting to grow in numbers. They were growing on the tarry material that was left over by the plants after they'd burnt.

"It's the ideal foodstuff for the micro organisms to grow on. They are the keepers of this soil and they're cleaning it up, preparing it for plant life to take over. They are actively working here today on our behalf."

Mike Larkin says that they've calculated that in the unburnt ground there are around ten million bacteria per gram of soil. In the burnt side the numbers shoot up to a hundred million bacteria per gram.

A surprising amount of nitrogen-fixing bacteria were also detected. They are effectively fertilising the soil for the returning plants. So there is some good news.

Fragile

But the bacteria may not have all the answers. On the foothills around Slieve Lamagan, one of the bigger mountains in the Mourne range, the peaty soil is very thin. Even after thousands of years its very fragile.

Now, cleared of plant life following a fire that burnt for several days the soil is exposed to the elements. A fairly benign winter means that only a little has eroded away. But a few violent summer rain storms could be disastrous.

Even in the light rainfall, the peat is washing off and "pooling" in hollows. With no roots of plants to fix it in place it can be seen visibly blowing away in the wind.

Informed opinion puts the time scale for a return to near normal plant cover at around four to five years. That doesn't allow for erosion or young shoots nibbled by wandering sheep. There is always the risk of another fire. And unfortunately, if recent history is anything to go by, that seems almost inevitable.