IUFRO - thinning trial - a programme of rationalization of spruce tending [Czechoslovakia]

aclareo arbre arbre brise-vent arbre forestier arbre pour bois de construction checoslovaquia conifere conifers crops cultivation cultivo cultivos czechoslovakia economic plants europa europe forest trees forestry operations gimnospermas gymnosperme gymnosperms methode methods operaciones forestales picea picea abies pinaceae plantas plantas protectoras plante plante de culture plante de protection plante pour construction plants pratique culturale protective plants structural crops thinning timber trees trees windbreak trees