An environment watchdog report into a fire that burned for weeks on a Denbighshire mountain says it wants to use helicopters to re-seed the slopes.

The Natural Resources Wales (NRW) study into the fire on Llantysilio Mountain above Llangollen in 2018 made the suggestion because of the extent of damage to the area.

The blaze raged from mid-July until late August 2018, resulting in approximately 250 hectares (617 acres) of mountain habitat suffering “catastrophic damage”.

The fire site is in the Bryniau Clwyd a Dyffryn Dyfrdwy/Clwydian Range and Dee Valley Area of Outstanding Natural Beauty (AONB).

Vast areas of upland heath – on which heather, bilberry and gorse grew – were completely destroyed down to the subsoil.

So re-seeding the area is dangerous according to the report due to the instability of the ground on the steep slopes, where peat has been burned almost completely away in some areas.

NRW proposes a little-used technique in the UK, helicopter hydroseeding, to re-seed the areas of land scorched by the fires.

The method involves using a mulch and “tackifier” which could be added to water or used dry and distributed from a bucket slung under a helicopter.

It’s a process that’s been used successfully in places like New Zealand and the USA – but described as “novel” for the UK.

The report said: “Neither (wet or dry) methods are currently widely used in the UK and both require discussions between hydroseeding contractors/suppliers and the helicopter operators to allow a workable method to be developed.

“Other moorland restoration projects (Moors for the Future and Yorkshire Peat Partnership) have been approached but have confirmed they are not currently using aerial hydroseeding (wet or dry), meaning this would likely be a novel approach if undertaken.”

A nurse grass mix and heather seed would be distributed on areas of the greatest damage, with small coir logs and areas of jute mesh used to stop the mulch washing away off the fragile land.

The affected area is privately owned but constitutes unenclosed Registered Common Land, used predominantly for sheep grazing, said the report.

In the past landowners and graziers had undertaken controlled burning and management of the land in agreement with NRW.

The environment watchdog compensated landowners for this work but a study by Denbighshire council revealed the last five-year agreement ended in September 2014.

The NRW report added “there has been no significant heathland management in recent years”.

It said it is confident the soil can sustain hydroseeding via helicopter but said  the creation of fire breaks in the new and existing vegetation, grazing levels and management, and the development of a fire management plan for the whole site were needed.

Speaking to a meeting of Denbighshire council’s communities scrutiny committee, Nick Thomas of NRW said he was meeting with graziers this week. He said: “We need to agree with them. They need to be happy with what we propose.”

He said the organisation was hoping to get some preparatory work done this spring.

The watchdog also revealed it has contributed £20,000 per annum towards a Moorland Management Officer for the county to liaise with landowners.