Would cutting down nearby clusters of the ferns prevent ferns from invading patches of the forest that have just been cut for timber?

Cutting the clusters would prevent ferns from invading a forest cut to produce wood if the clusters were cut before ripening.

Explanation:

Fern is a spore-forming plant. These spores can be spread by wind, water and animals allowing for other areas, allowing them to germinate and give rise to other ferns.

In the fern leaves, the spores appear in the reproductive season, they stay inside closed clusters, which open when they reach a certain maturity allowing the spores to invade other areas.

If you want the ferns not to invade a certain area, you must cut the clusters before they mature.