Site quality and stand structure in Pinus halepensis forests of north Greece

Pinus halepensis forests depend partly on the relatively adverse drought conditions prevailing in the area and on human management through the centuries. A major and decisive factor for the establishment and maintenance of these forest ecosystems is fire, which defines their expansion. The degradation of these forests as a consequence of constant pressure by natural and human-caused fires, grazing and clearance, has led to the formation of scrub associations of the Cisto-Micromerietea. The phytosociological study of the area and the analysis of the vegetation table showed the existence of three site quality types I, II and III. The structure of stands in these site types is mostly even-aged, occurring after a fire, in age classes 10-20, 25-35, 40-50 and 60-80 years. The biggest mean diameter, total basal area and mean dominant height of the overstorey, occurred on the more soil-fertile site type I.