Land next to an important natural habitat could lose its green belt status allowing new homes to be built.
Flitwick Moor's peatland is a haven for wildlife and rare plants
Councillors are due to meet to decide the fate of Flitwick Moor, said by environmentalists to be one of the most important wetlands in Bedfordshire.
It is home to an ecosystem of bog moss, woods, rare plants, insects and birds.
Campaigners opposing the move claim this could all be under threat if nearby green belt land loses its protected status.
Open land between Maulden Road and Flitwick Moor is protected but if councillors in Mid Beds follow advice from their officers it stands to lose that status.
Campaigners say an unfavourable decision will pave the way for development which would have a detrimental and irreversible affect on the Moor.
A decision is due to be made on Wednesday.