Shonaig Macpherson has stepped down as chairman of the National Trust for Scotland, with a permanent successor yet to be found.
Macpherson's tenure was due to end in September but she announced last September that she would not seek another term of office and would leave the charity as soon as a replacement could be found.
A statement from the trust on Friday said Macpherson was standing down with immediate effect to be replaced on an interim basis by deputy chair Dick Balharry.
The trust is undergoing a major governance review, conducted by former presiding officer of the Scottish Parliament George Reid, after a financial crisis last year culminated in 65 redundancies and the closure of several of its loss-making properties.
A spokeswoman for the organisation said Macpherson did not think it was appropriate for her to remain in office throughout the course of the governance review, which is expected to finish in June. A permanent replacement would be appointed some time after that, the spokeswoman said.
Balharry said following in the footsteps of Macpherson was not going to be easy task.
"However, it is an honour to be asked and a challenge I am prepared to undertake," he said. "The obligations, commitments and responsibilities that the council and the board need to discharge are demanding and vital to the progress of the trust."
A spokesmand for In Trust for Scotland, a group of more than 2,500 concerned members of the NTS, said Macpherson's resignation had broken one link with the "discredited management policies that contributed to the current crisis".
He added: "It is necessary to rebuild the trust's governance structure from the top down and we are hopeful that George Reid's review will learn from past mistakes."
The president of the National Trust for Scotland, the Duke of Buccleuch, said it was to Macpherson's "great credit" that the charity's financial position had been stabilised and its long-term sustainability was now being addressed.