Taher Mechergui;Marta Pardos;Douglass F. Jacob

Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria (INIA), Centro de Investigacion Forestal, Madrid, Spain;Faculté des Sciences de Bizerte, Laboratoire des Ressources Sylvo-Pastorales (Institut Sylvo-Pastoral de Tabarka), Sejnane, Tunisia;Department of Forestry and Natural Resources, Hardwood Tree Improvement and Regeneration Center, Purdue University, West Lafayette, US

Zeen oak;Mulching;Tree shelters;Plantation;Survival rate;Growth;SUBER L. SEEDLINGS;POLYETHYLENE MULCH;ESTABLISHMENT;TREESHELTERS;ROOT;DECOMPOSITION;SHEETS;SHOOT;SITE;AI

We assessed the effect of mulching and tree shelters on the establishment and early growth of zeen oak (Quercus canariensis Willd.) during the first 4years after planting in Northwestern Tunisia. Five mulch types (Italian Stone Pine (Pinus pinea L.), Lentisk (Pistacia lentiscus L.), and a combination of Italian Stone Pine and Lentisk (organic mulches), gravel (inorganic mulch) and control), and three tree shelter types (non-vented and vented tree shelters, and control) were tested. An increase in the number of internodes occurred under the gravel mulch, while a reduction in survival was found for the lentisk mulch. Tree shelters had no effect on survival, but increased mean height growth and reduced mean diameter growth during the 4years (excepting a non-significant effect for vented tree shelter at year four). Comparison of the annual shoots and growth units (GU) between sheltered and unsheltered plants according to year of formation revealed two growth phases. In first phase, shoots were totally or partially inside the shelters; mean length of annual shoots and GU were greater for sheltered plants. The second phase was characterized by shoots emerging from shelters; mean length of annual shoots and GU were similar for all plants, with or without tree shelters. Results suggest that the use of tree shelters, particularly vented shelters, could contribute to the improvement of the artificial regeneration of zeen oak. The use of mulching alone or in combination with tree shelters did not improve zeen oak performance in the field.