Traditional lairds whose shooting estates are wrecking the natural environment "embody the selfish greed of a Victorian era", according to one of Scotland's most respected conservationists.

In a powerful and emotional swansong yesterday (Saturday), Dick Balharry, who has played leading roles in four major environmental organisations over the last 50 years, condemned the vested interests of most private landowners in Scotland as "outdated and ludicrous".

Balharry was speaking after being awarded the Royal Scottish Geographical Society Geddes medal for his outstanding contribution to conservation at a ceremony in Glenfeshie in the Cairngorms. Aged 77, he has been diagnosed with terminal cancer of the oesophagus.

His trenchant critique of the damage being done by the landed gentry won warm plaudits from fellow conservationists, who thought he was saying what many felt - and that history was on his side. He was also congratulated by the landowning lobby, though it pointed out that there were many different opinions.

Balharry, born in Muirhead on the outskirts of Dundee, was a gamekeeper, a deerstalker, and then warden of the 10,000-acre national nature reserve at Beinn Eighe in Wester Ross. He went on to become chief warden for northeast Scotland, then area manager for the government's conservation agency, Scottish Natural Heritage.

After he retired in 1997, he was chairman of the John Muir Trust, which campaigns to protect wild land, and interim chairman of the National Trust for Scotland. He was also president of Ramblers Scotland, and was given an honorary doctorate of science by the University of Abertay in 2010.

In his speech in Glenfeshie yesterday he accused traditional sporting estates across Scotland of maintaining "artificially high" numbers of deer in order to make more profit from shooting them. Too many deer damage native Caledonian pine forests by eating saplings and preventing natural regeneration (see below).

Balharry also criticised landowners for erecting fences to protect native woodlands from marauding deer. This damaged the landscape, inhibited public access and deprived deer of shelter.

"I see this as a major injustice," he said. "If people wish to manage land exclusively for the benefit of the few without regard to the wider public interest then they will never have my support."

He added: "To those who argue that fences are required to make sport shooting economically viable I would simply say that you are inviting society to question the legitimacy of your ownership model - one that places trophy stags higher than the long term interest of the public and the planet."

Balharry pointed out that keeping deer numbers high meant that more die every winter, for which landowners tried to evade responsibility. "Traditional sporting estates cannot stand on the moral high ground of estate ownership as they have tried to claim for over the last 200 years," he said. "Rather they embody the selfish greed of a Victorian era, outdated and ludicrous."

There were a few landowners trying to show that there were better ways of running sporting estates, Balharry said. He highlighted the efforts being made by the owner of Glenfeshie, Anders Holch Povlsen, a Danish billionaire fashion retailer and Scotland's second largest private landowner.

More visionary leadership was required, he argued. "The moral high ground of the future will be for those who wish to hunt deer in a natural environment, free of fences, where deer have access to the food and shelter they require; where there is a natural tree line and the public are welcomed."

The Geddes medal, named after the legendary Scottish town planner, Patrick Geddes, is awarded every year by the Royal Scottish Geographical Society. Balharry was described as "one of the wisest of heads" by the society's chief executive, Mike Robinson.

"He is a relentless and passionate advocate for improving and protecting Scotland's natural landscapes and has influenced, advised, inspired and encouraged so many people and organisations."

For Dave Morris, the former director of Ramblers Scotland, Balharry was "one of Scotland's greatest guardians of nature". Balharry had "demonstrated by his intellectual and practical approach to deer management that too many of Scotland's private landowners still think they are living in the Victorian era," he said.

Mike Daniels, head of land management at the John Muir Trust, called Balharry a "courageous pioneer". History was on his side, Daniels argued, as more people realised that "the current deer management system is failing badly."

Balharry's critique has significant, if muted, support in governmental circles. "The highland sporting estate, essentially a Victorian construct, is a busted flush," said one influential insider. "Times have changed, and they better watch out."

Another veteran, mountain ecologist Adam Watson (85), pointed out that Balharry had done crucial research on the poisoning of golden eagles by organochlorine pesticides like DDT in Wester Ross. This had helped get the pesticides banned in the 1970s and 1980s.

Balharry's award was "a well deserved honour", according to Scottish Land and Estates, which represents landowners. "He has long expressed trenchant views on deer management and, whilst many in the sector hold different opinions, the debate itself has focused attention on the way ahead," said chief executive, Douglas McAdam.

"Many private landowners - including the example of Glenfeshie where Dick received his award - are forward looking and committed to delivering a range of public goods including the conservation of the natural heritage."

The Scottish Government accepted that deer populations were too high in some areas. "Legislation currently being developed through the Land Reform Bill will provide Scottish Natural Heritage with further powers to intervene where deer management measures are failing to meet the public interest," said a government spokesman.

Balharry was pleased his remarks had caused a stir. He told the Sunday Herald he was proud to accept the Geddes medal, which would be shared with his wife, Adeline.

He seemed reconciled to his cancer, which had spread from his oesophagus to his liver and lungs. "I'm on my way out," he said.