The effect of storage time of smuggled wood on the wood physical and mechanical properties stored in the yard of the natural resources department

Background and objectives: One of the factors that cause forest destruction is timber smuggling. In order to transport this timber secretly, smugglers have to cut it into smaller pieces. A percentage of this smuggled wood is confiscated by the forest guards and will be transferred to a depot at the Natural Resources Departments. The wood that is accumulated in the depot must be sold through auction according to Article 28 of the Forests and Rangelands Organization Law and it usually remains in the office yard for several months. Long-term storage causes a decline in the wood quality. The purpose of this study is to investigate the effect of storage period of these woods in the depot on decline of wood quality by measuring some wood physical and mechanical properties such as hardness, bending strength, impact resistance, thickness swelling and water absorption.

Materials and Methods: The first sampling of beech, hornbeam and alder wood logs was conducted in the yard of the Natural Resources Department of Sari County during the winter. In the next stage, after approximately 8 months, sampling was repeated again before the auction and sale of the wood at the depot. After sawing and cutting of the log into the required dimensions, some mechanical and physical properties included bending strength, impact resistance, hardness, water absorption, and volumetric swelling were performed according to the related standards on oven-dry wood samples.

Results: Results showed that the highest density loss was related to alder wood (25% decreases) and the density loss values of alder and beech were 8 and 3 percent respectively. The bending strength after 8 months depot for beech, hornbeam and alder was 60, 54 and 80% respectively and also, the bending modulus loss for each three species was 99%. The hardness decrease after 8 months of depot was 66, 65 and 33% for alder, hornbeam and beech respectively. The decrease of impact resistance after 8 month depot was 49, 38 and 36 percent for beech, hornbeam and alder respectively. The highest water absorption after 5 days of immersing was observed in alder wood, while the water absorption values for hornbeam and beech were approximately 7%. The volumetric swelling of beech, hornbeam and alder was 17, 28 and 20% respectively.


Conclusion: According to the results, it can be found that the wood depot caused a considerable damage to the wood after eight months. From comparison view, the maximum decrease of bending strength and hardness was observed in alder wood and the maximum decrease of impact strength was observed in beech wood. From physical properties view, the beech wood showed a considerable water absorption increase compared the two other species; however the volumetric swelling of hornbeam was higher than the two species. These physical and mechanical properties changes can turn the 1st grade wood into 2nd and 3rd grade and even unsaleable wood. The lack of wood storage facilities in the natural resources departments, the negligence of officials due to the fact that the property is owned by the state and the lack of responsibility for the wood until the auction, causes such a problem. Roofing the depots in the yard and keeping the smuggled wood in dry places, reforming the administrative affairs and preventing the sale of wood through auctions and selling wood at a fixed rate can be ways to reduce these damages.