Abstract:
Problem definition and objectives: Soil is one of the important site factors that affects wood properties. Precise understanding of its influence on wood characteristics is essential for optimizing forestry practices and better utilization of wood resources. The present study aimed to investigate the effect of altitude and the physical and chemical properties of soil on the biometry and mechanical characteristics of eldar pine (Pinus eldarica) wood in the western region of Mazandaran province.
Methodology: To this end, 9 healthy trees were selected from three altitude levels of 500, 1200, and 1400 meters, and disc samples were taken at breast height. A soil profile sample was collected from the base of each tree. Wood properties measured included density, modulus of rupture, compression strength parallel to the grain, tracheid length and diameter, and cell wall thickness. Simultaneously, soil characteristics such as texture, pH, macro-and micronutrients, organic matter, lime content, and electrical conductivity were evaluated.
Results: The results of analysis of variance showed that altitude had a significant effect on most wood properties, with many mechanical traits, including bending and compression strength, reaching their highest values at 1200 meters, while density and cell wall thickness were highest at 500 meters. Soil properties indicated that the silty-clay texture at 500 meters had a higher capacity for water and nutrient retention but offered limited drainage, whereas the clay-loam texture at 1200 meters, with relatively low acidity and the presence of key elements such as iron, manganese, and copper, provided optimal conditions for wood growth and development. At 1400 meters, an increase in sand content accompanied by decreases in nutrients and calcium led to reduced wood quality. The results of Pearson’s correlation analysis and the multiple regression model showed that wood density had a positive relationship with soil calcium and a negative relationship with sand. The modulus of rupture, bending strength, and tracheid length exhibited positive correlations with clay and copper, while tracheid diameter showed a positive relationship with soil copper, nitrogen, and iron. These findings highlight the key role of soil conditions, especially clay, copper, and calcium, in improving the biometry and mechanical quality of wood.
Conclusion: The altitude of 1200 meters, due to balanced soil texture, suitable pH, and micronutrient richness, provides the best growth conditions for eldar pine and can be recommended as the optimal elevation for afforestation of this species. Conclusion: The altitude of 1200 meters, due to balanced soil texture, suitable pH, and micronutrient richness, provides the best growth conditions for eldar pine and can be recommended as the optimal elevation for afforestation of this species.