Long term monitoring of common oak (Quercus calliprinos) population in response to drought conditions

Trees selected for the survey were visually evaluated for variables, such as canopy density, percentage of dry leaves in the canopy, level of acorn bearing, level of coverage by climbers, and resprouting of dry branches. In 2013, 240 trees in two plots of the western part of the park were monitored at the end of a long season without rain. Over 20% of the trees were dry and almost all of them were already dry during the survey of 2011. Many of the living oak trees showed signs of stress, and only few of them had a full canopy and had not dry leaves. Half of the trees in both plots showed a canopy density of 65% or less. Ten percent of the trees were severely stressed, with a canopy density of 20% or less. Beside the drought, climbers may be a burden on the trees, with live trees being covered by climbers to extent of nearly 50% on average. In view of the on going drought and particularly in the current year (2013-2014) with rainfall of only 54% of the 18-year mean, monitoring of the status of the oak trees in the park is planned to be continued.