French to English Science Forestry / Wood / Timber Forest management

This occurs in a table listing different stages ('stades') of forest development. 'Coupe semis' occurs first, before 'coupe travaux' and then 'peuplement mûr'.
Another line of the table has 'coupe semis'; 'perchis'; 'jeune futaie'; 'peuplement mûr'.

I do not known the sense in which 'coupe' is being used here, and this in turn affects the sense in which 'semis' is used.
Ditto for 'coupe travaux', although I intend to post that as a new question.

I would say that the table is for use by foresters and so can freely use technical terms. I have no context for the table: it stands alone on a solitary page sent for translation.