To create more ground cover sometimes its better to clear a ride by copicing the trees(cutting off at ground level) so the trees grow back bushier and giving more cover at ground level for maybe 10 years or so,it also lets light in giving other species a chance to get going.When this area starts getting tall again so providing more canopy cover than ground cover,copice another area,so that you've always got both canopy and ground cover,and keep rotating around the wood till you're happy with it,but dont let em get too thick.Obviously this takes years to fully acheive,but if you've got birch or