Effect of site and elevation on wood density and shrinkage and their relationships in Carpinus betulus

Abstract

This study examined the effect of site and elevation on the oven-dry density and volumetric shrinkage of hornbeam (Car- pinus betulus) wood. For this purpose, 45 normal hornbeam trees from three different sites (Mazandaran, Guilan and Golestan) at three elevations, 300 m (low elevation), 700 m (intermediate elevation) and 1100 m (high elevation) from natural forest in northern Iran were selected. Disks were cut at breast height from mature wood and test samples were prepared to determine physical proper- ties, i.e., wood density and volumetric shrinkage. The results show that there are signifi cant differences between site and elevation on these physical properties of wood. The interaction effects between site × elevation on wood density and volumetric shrinkage were also statistically signifi cant. At any fi xed site, wood density and volumetric shrinkage increased with elevation. As well, their values at Guilan were higher than those at the other two sites. The relationship between wood density and volumetric shrinkage was deter- mined by simple regression equations. Strong, positive relationships between wood density and volumetric shrinkage at each site were found. Again, these were stronger at the Guilan site than at the other two sites. Given a fi xed site, the correlation at high eleva- tion was stronger than at the other two elevations.