Tarzan has in the past dragged logs from the Migdale Rock Site of Special Scientific Interest in Ledmore and Migdale Woods in Sutherland.
The horse caused less damage to rare plants than modern forest machinery.
Tarzan has been put to use at the Highland Folk Museum in Newtonmore where woodland is being thinned out.
Trees in a dense plantation of Scots pine have been felled to improve it as a habitat for wildlife including red squirrels.
Meanwhile, Scots pine woods on a nature reserve at the most northerly estuary on Scotland's east coast are to be given greater protection.
Scottish Natural Heritage (SNH) plans to control deer numbers and remove non-native plants at the site at Loch Fleet near Golspie in Sutherland.
SNH said Scots pine trees in the area were in an "unfavourable condition".
Work to remove rhododendron and sycamore, which are both not native to the UK, will start next month.
Loch Fleet National Nature Reserve covers a large tidal basin surrounded by dunes, salt marsh and pine woods.

Instead of the broad shoulders and square jaw of Colin Firth there is a modestly-sized chest and pointy chin.
There is little description of him in Pride and Prejudice, so the academics used historical fashions from the 1790s, when it was written.
This version also wears a powdered wig.
"Our Mr Darcy portrayal reflects the male physique and common features at the time," says Amanda Vickery, professor of early modern history at Queen Mary University of London.
"Men sported powdered hair, had narrow jaws and muscular, defined legs were considered very attractive," she says.
Colin Firth got the nation's collective hearts racing in 1995 with his depiction of the mysterious Mr Darcy in the BBC's adaptation.
Further adaptations since have followed in the style of Firth's portrayal including  Matthew Macfadyen in the 2005 film of Pride and Prejudice.
But the academics say their muscular chests and broad shoulders would have been the sign of a labourer and not a gentleman at the time the book was written.
The fans' favourite Mr Darcy moments - when Colin Firth walked out of a lake dripping wet and Matthew Macfadyen crossed a field in the mist, both showing off their chests - would not have looked the same with the historically accurate Mr Darcy and his sloping narrow shoulders.
Some fans have not been impressed by the portrait.
Professor John Sutherland, from University College London, who led the research says they only had "scraps" of physical description of the character Fitzwilliam Darcy.
As well as looking at the fashions of the day they also looked at Austen's relationships and the men who may have inspired her characters.
"He is our most mysterious and desirable leading man of all time, says Prof Sutherland.
And he appears frequently in modern culture.
Further depictions of Mr Darcy include Matthew Rhys who played the character in the TV adaptation of the Pride and Prejudice "sequel" Death Comes to Pemberley.
He also inspired the character of Mark Darcy in Bridget Jones's Diary by Helen Fielding, also portrayed by Colin Firth in the film versions.
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A horse used in logging operations in a fragile wildlife habitat has been hauling timber in woodland at a museum of Highland life.
[NEXT_CONCEPT]
Academics have revealed what they claim is the first "historically accurate" portrait of Jane Austen's Mr Darcy - and he's a world away from the romantic hero of films and TV.