Dr Thomson has a strong academic background, with a PhD in heather management and an MSc in environmental resources.
She comes to the trust with a range of experience from working in the public sector and land management and will work part-time in order to continue managing her small farm, which is stocked with Galloway cattle and sheep.
The Trust hopes that Dr Thomspon will expand their work into new areas alongside supporting existing projects.
One of her roles will include investigating the feasibility of establishing a fund in order to provide grants for research in the uplands.
The director of the Heather Trust, Simon Thorp, said: “I am delighted to welcome Marion to the Trust.
“Her knowledge and experience will be invaluable in developing the Trust further and providing us with additional capacity to meet existing and new commitments.
“I look forward to introducing her to members and supporters.”