John Burton will step down after 30 years as chief executive of the World Land Trust, the conservation charity he co-founded, at the end of the month.
He will be succeeded by Jonathan Barnard, the former head of international conservation programmes at the bird conservation charity the RSPB.
Burton and his wife Viv, who is also retiring from her role as partnerships coordinator, set up the trust in 1989 and will continue to support the trust as founders, according to a statement by the charity.
The organisation operates in 20 countries, buying land to create reserves that it then passes on to local organisations to oversee.
The charity, which had an income of £4.5m in the year to 31 December 2017 and spent £3.3m, has directly funded the acquisition of more than 774,000 acres of land for conservation and leveraged the protection of several million more. It has also funded the planting of more than two million trees.
Burton said: "Without the help and support of many friends and colleagues such as Sir David Attenborough, Bill Oddie, Chris Packham, Steve Backshall, Gerald Durrell and many, many other high-profile conservationists and naturalists, we would not have been able to achieve this.
"And I would also like to thank all our supporters, without whom we wouldn’t be the force for conservation that WLT now is. It has always been very much a team effort, of the staff, the WLT board, all supporters and our conservation allies."
Barnard, who is due to take up the chief executive role at the beginning of September, has been director of the sustainable resource-management consultancy Proforest since August last year.
Before that he spent seven-and-a-half years at the RSPB, heading its international conservation programmes and tropical forests unit, and eight years as senior programme manager at BirdLife International.
He said: "I am delighted to be joining the World Land Trust. The importance of saving habitats for nature and fighting the climate crisis has never been more urgent, and the trust is recognised as a global leader having a genuinely positive impact on the ground.This is an exciting time to be joining the organisation. I'm looking forward to getting started and leading its contribution to saving nature around the world."
Rohini Finch, chair of WLT, said in a statement: "We welcome Jonathan to our hard working and committed team at the WLT. His knowledge, experience and track record speak for themselves and we look forward with excitement to his leadership in this, the next chapter for the trust."