After a 43-year career in Doc and its precursor organisations, Mr Thomas' role was disestablished in the department's latest restructure.
Representatives of Otago's many conservation organisations gathered at Doc's offices in Dunedin yesterday to pay tribute to the wealth of knowledge and leadership Mr Thomas had brought to the organisation.
''It is incredibly humbling,'' Mr Thomas said.
Otago acting conservator Ken Stewart said Mr Thomas started work as a clerical cadet in 1970 before becoming a reserves ranger in Rotorua, then spending 10 years on Stewart Island from 1977 as a senior ranger, and in 1987 when Doc was formed, becoming Otago Southland district conservator.
His role changed in a successive reorganisation to become operations manager and then in 1997 he was appointed the Coastal Otago area manager, based in Dunedin.
Highlights of his career included a leading role in the development of the Otago Central Rail Trail and later the Far North cycle trail, the Nugget Point redevelopment and championing the cause of the jewelled gecko.
Doc deputy director-general Sue Cosford said Mr Thomas had made a huge contribution to Otago and not just in the projects he had been involved in but in the support he offered people and the encouragement he gave.
''It's been a tough change process ... you have a huge amount to look back on with pride.''
His work for Doc with boating and four-wheel-drive training was also recognised.
Representatives from groups and organisations around Otago thanked him for his work, including that on the rail trail, the development of Nugget Point, in the Clutha District, with Orokonui Ecosanctuary, Ngai Tahu, search and rescue, parks and reserves, Forest and Bird and the Otago Peninsula Trust.
