Remove shrubs bushes

Hi guys, our small 'forest' of around 8000m2 should have mostly deciduous trees but is mostly overgrown with alive and dead (very)stinging bushes/shrubs between 1 and 2 meters high. Yesterday i managed to make an entrance to the forest and clear a pathway using an electric hedge trimmer, brushcutter and chain saw.

Without hiring expensive contractors, how do i make sure the pathway doest get overgrown again? Do i really need an (expensive)excavator? Can i spray something over the other 'weeds/shrubs' to remove them but that grass or trees can still grow there later? Thanks!