A farming union is calling for a rewilding project to be scrapped.
Farmers' Union of Wales (FUW) said the project would make it impossible for farmers to continue to live in their communities.
The Summit to Sea project aims to increase biodiversity and restore ecosystems in 10,000 hectares of mid-Wales and almost 30,000 hectares of sea in Cardigan Bay.
FUW said it was hosting a meeting to discuss the issue.
Rewilding Britain is a partner of Summit to Sea, and farmers say they are concerned by some supporters of the charity who advocate ending grazing, taking down fences and letting the land grow wild, as a method of restoring ecosystems and increasing biodiversity.
Nick Fenwick, FUW's head of policy, said: "It shouldn't exist - it shouldn't be here.
"It's not good for the economy, for the communities and for the species that live here.
"There's every scope for working with organisations that recognise the importance of farming and the dangers to our eco-systems of getting rid of farming from habitats in which they've operated for thousands of years.
"There's no room for working with those who wish to see land abandoned on a huge scale."
Tegid Jones has a 430-acre farm near Machynlleth where he keeps a small herd of cattle and more than 700 sheep. His farm is in an area of mid-Wales which has been identified as a place that could be richer in wildlife.
Mr Jones said: "They say they want to talk to the local community and talk to relevant experts. Well, obviously farmers in this area are irrelevant to them.
"They've arbitrarily put a line on a map... are they going to move us off our land?"
Melanie Newton, the project director of Summit to Sea, said: "Involvement in the project is entirely voluntary, we want to help build a resilient, nature-based economy that offers more financial stability in uncertain times."