The innovative scheme has come from members of the Llanbedr and Pensarn Yacht Club, who are worried that they will lose their sheltered boat moorings unless the erosion slows down.
Now people are being urged to donate their Christmas trees, which will then be secured along the dunes to encourage sand to accumulate behind the new barrier.
Between 50 and 60 boats belonging to yacht club members are moored in the Artro estuary during the summer months, but fears are mounting that the estuary will become exposed if something is not done about the problem soon.
David Robinson, the yacht club's secretary, said: "The dunes at the back of Llandanwg beach are being washed away year by year as a result of wave action and winter storms.
'We are now afraid that the sea will destroy them completely, making a wide opening for the sea to come into the estuary.
"We cannot find an official body willing to undertake a coastal protection scheme, but we think that with the help of local people we may be able to delay erosion by collecting Christmas trees and securing them on weak parts of the dunes.
"We hope that they will cause sand to accumulate and stabilise sufficiently to support the growth of maram grass."
Cllr Evie Morgan Jones, of Dyffryn Ardudwy, said: "There is an erosion problem there, but 1 don't think that it would be appropriate to spend a lot of money on sea defences because the sea will only start to take land somewhere else along the coast - the sea always finds its own way.
"Sea defences work by stopping erosion where they have been placed, but more often than not, the sea will erode somewhere else.
"I think that what the yacht club members are doing is a very good idea, and is the best way of dealing with the problem."
A spokesperson for Gwynedd Council said that from the councils perspective there are a number of difficulties.
It was explained that, in the first place, the land-owner is, unknown. Part of the dunes fronting St Tanwg's church is owned by the National Trust, but erosion is currently taking place to the south of this area.
Secondly, the scheme is unlikely to be eligible for grant aid under the Coast Protection Act of 1949 because the benefits would not outweigh the costs.
The spokesperson said: "The council has in the past contributed money, without prejudice, towards fencing and access management initiatives.
'"There is currently an application with the National Assembly for Wales for funding for a pre-feasibility study, to be carried out by consultants, to determine whether any works can be justified economically."
A meeting attended by council representatives is to be held on the site on 16 January.
Mr Robinson added that volunteers are needed to help to place the trees on the dunes, on 20 January.
Anyone who has a tree to dispose of can drop it off at the car park next to Pensarn station, or call 01341-241415 for more details.
People who are able to come along with pick-up vehicles or trailers to transport the trees are asked to call 01341-241247 beforehand.
