IT covers 10,000 acres and has so many rare species living within it that environmentalists have described it as a “lost world”.

Now the conservation estate of Dundreggan in Glenmoriston is celebrating its 10th anniversary, marking decade of restoring the ancient Caledonian Forest at the acclaimed site.

Conservation charity Trees for Life bought the site for £1.65million which remains one of the UK’s largest ever areas of land bought for forest regeneration.

The former hunting estate was already home to ancient forest fragments, including outstanding areas of juniper and dwarf birch.

The charity has since planted half a million trees at the site, ensuring natural regeneration of woodlands and encouraging the return of rare wildlife, plants and insects. A rare non-biting midge and several other species have since been discovered after surveys of the estate.

In total, more than 3,300 species have now been recorded at the charity’s forest restoration site with at least 68 of these are priority species for conservation.

These include unusual species such as the strawberry spider with several never having been recorded in the UK before, or were feared extinct in Scotland.

Research also includes successfully encouraging aspen – a rare tree that rarely flowers or sets seeds in Scotland – to flower under controlled conditions, enabling it to produce seeds for propagation.

Other pioneering trials include introducing a mix of spores from mushrooms when planting and growing selected trees and seedlings, to improve growth and resistance to drought, heat and pests.

Doug Gilbert, Trees for Life’s Operations Manager at Dundreggan said: “This first decade of rewilding at Dundreggan has been an inspiring success story. Thanks to hundreds of volunteers, 1,200 hectares of new forest are now growing from valley to summit.”

“These flourishing woodlands full of life are helping us save the Caledonian Forest – one of the world’s magical forest habitats – from being lost forever. A renewed forest is being created that will benefit people and wildlife for centuries to come.”

Other key findings during the charity’s recent survey season included two rare gnats whose larvae feed on fungi. One of these (Sciophila varia) is only known from four other UK sites.

The other (Mycomya nigricornis) is only known in the UK from a handful of Scottish sites and had not been seen since 1990.

The charity also found two parasitic wasps, for which there are very few Scottish records, and – for the first time in Scotland north of the River Tay – a pseudoscorpion called the knotty shining claw.

A micro-moth, the small barred longhorn – only documented at three other locations in Scotland, and never before this far north – was also found during one of the volunteer Conservation Weeks.

Other new species for the UK discovered on the estate have been three sawflies; an aphid; two aphid parasitoids, three fungus gnats and a mite.

Dundreggan has also revealed the second-ever British record of a waxfly species, a golden horsefly only seen once before in Scotland since 1923, and the juniper shieldbug, thought to be the first Highland record.

Last weekend, the charity’s supporters and children from Invergarry Primary School attended a celebration event at the 10,000-acre biodiversity hotspot to the west of Loch Ness.

They visited Dundreggan’s tree nursery, where they squashed rowan berries to release seeds, and also joined wildlife tours to see the conservation in action.