Establishment of Quercus ilex L. subsp. ballota [Desf.] Samp. using different weed control strategies in southern Spain

Formerly cropped sites on Mediterranean areas that have been planted with hardwoods are typically associated with low tree survival and growth, with an enduring influence of agricultural weeds in the herbaceous stratum. This study evaluates the survival and growth of planted Holm oak ( Quercus ilex L. ballota [Desf.] Samp.) in response to three weed control treatments on a cropland site in southern Spain. The weed control treatments (cultivation, herbicide, and mulch) were applied in combination with tree shelters. Survival, relative growth rate, biomass, and root architecture were monitored over a 1-year period. Shelter microclimate was measured 1 year after establishment. Trees in the ground management treatments consistently had greater levels of survival than the control. Although these effects were not significantly different between weed control treatments, we found that tree shelters had a significant effect on growth and biomass. There were also significant treatment effects on root architecture. The response of trees to weed control treatments and tree shelters are consistent with other studies, which suggest a positive effect related to the interplay of microclimate change and resource availability. Our results suggest that weed control may improve early survival in forest plantations and, in combination with tree shelters, merit consideration in Mediterranean afforestation programs.