First Minister Nicola Sturgeon and Tory leader Ruth Davidson were among those to pay tribute to a politician who had been at Holyrood since the onset of devolution and was widely respected across the Holyrood chamber. He passed away after a short illness.
Ms Davidson said Mr Johnstone “embodied politics at its best”.
She added: “He was a big man with a big heart. He embodied politics at its best: trenchant in his views, always up for a political fight, but respected and admired by all sides of the political divide for his decency and generosity.
“The North-east of Scotland could not have had a greater friend over the 17 years he served as their MSP. He was utterly devoted to championing the area.”
The First Minister said she was “very sad” to learn of Mr Johnstone’s passing.
“Holyrood has lost one of its most well-known and well-liked parliamentarians, and he will be sorely missed,” Ms Sturgeon said.
“Alex was of course one of the Scottish Parliament’s original 1999 intake, and he quickly established himself as a champion of the North-east. He was never afraid to stand up robustly for the causes he believed in – but always did so with good humour and respect for his political opponents.”
Labour leader Kezia Dugdale said: “Alex had a reputation around the Scottish Parliament as a great character. When our politics can feel divided, he was always quick to inject some much needed humour.
Greens leader Patrick Harvie worked with Mr Johnstoine on a number of committees and groups at Holyrood.
“While he and I were never short of issues to disagree about, he always had those disagreements in a spirit of respect, good humour and courtesy,” Mr Harvie said.
Mr Johnstone had been married to wife Linda for 36 years. The couple had two children and six grandchildren.
He remained an active member of the local Church of Scotland throughout his life.
Born in Kincardineshire in 1961 and educated at Mackie Academy in Stonehaven, Mr Johnstone spent his entire life in the North-east of Scotland, where he built a successful career as a dairy and arable farmer. Elected at the age of 38, he brought his experience in rural Scotland to the parliament and was the inaugural convener of the rural development committee. He became the Conservatives’ chief whip and business manager and sat on Holyrood’s business bureau.