A system for mechanically gathering trees, bushes and branches, bark, leaves and toppings strewn upon the ground as the result of felling or thinning trees in forests, involving three essential stages: (1) Mechanical collection of trees, bushes, branches and by-products strewn upon the ground and placement thereof in rows; (2) Mechanical collection of these rows by means of travelling equipment which feeds a shredding, crushing or milling machine preferably mounted on its same chassis; and (3) Pneumatic foliage extraction.