The quality of aspen logs (Populus tremula) was studied by s

The quality of aspen logs (Populus tremula) was studied by sawing sample logs.For grading of aspen logs and sawn timber,the proposed system of Keinanen et al.(1995) plusthe reject-grade was used.The length of the knot-free section at the base of an aspen stem is short.Green knots are concentrated in the top logs and red knots at the top of the butt logs and first middle logs.Most of the decayed knots are located in the second middle logs and top logs.