a cultural operation eliminating or suppressing undesirable vegetation, mainly woody (and including climbers), during the thicket stage of a forest crop and therefore before, or at the latest along with, the first thinning, so as to favour the better trees; may include unwanted crop species as well as intrusive vegetation, a release treatment made in a stand not past the sapling stage to free the favoured trees from less desirable species of the same age that overtop them or are likely to do so