عنوان مقاله [English]
Small diameter timbers have many used in wood and paper industries such as veneer and plywood, furniture industry, wood working and their particle for papermaking and particleboard. Diameter of small diameter poplar is between 15 to 35 cm and poplar trees are planted in excess of 23 provinces of Iran. Small diameter poplar are visual graded to lumber of sawmill. Since, small diameter poplars are graded on the basis of traditional rules of grading and then outputs of timber production are investigated by standard rules of lumber. Experimental results are showed that small diameter poplar and their timber production have more firsts and selects of grades than others grades on the basis of national grading of Iran (1275 and 8073), United State Forest Service and National Hardwood Lumber Association. Defects such as frost cracks in small diameter poplar and core in poplar timber are influence onto application usage and ranges of grades scales and effective defects are determined by average measured of defects, national standard rules and field research. Also, their application usages are very sensitive to the effective defects, in the practical condition.