The effect of tree shelter on the stem anatomy of cork oak (Quercus suber) plants

Abstract

The effect of tree shelter on the growth and anatomy of bark and wood of cork oak (Quercus suber L.) seedlings was evaluated one year after planting. Stem cross sections were examined and percentage of tissues (vessels, axial parenchyma, rays and fibres) and diameter of vessels analysed. The cork oaks responded to the effect of shelter tubes with a 22% increase in apical growth and a 35% decrease in radial enlargement resulting into highly significant differences in the diameter-to-height ratio (0.099 and 0.193 respectively for sheltered and unsheltered plants). The stem anatomy showed adaptations to the protected environment of the shelter: the sheltered plants had a significantly higher percentage of parenchyma (30% vs. 19%, P < 0.001) and lower percentage of wood fibres (40% vs. 47%) compared with unsheltered plants. Annual rings were less clearly visible in the sheltered plants. These observations suggest that trees grown in protective shelters are less able to withstand the environment than those directly subjected to it.