Dynamika wiosennych zjawisk fenologicznych w drzewostanie dębu bezszypułkowego (Quercus petraea [Matt.] Liebl.)

Numerous studies show that in the pedunculate and sessile oaks there are two forms that differ in terms of the spring development of leaves – one can distinguish early and late variants. Acceleration of leaves development gives the particular tree a chance to gain advantage over others, as well as enables to avoid herbivory caused by insects. However, it is fraught with the risk of damage caused by the late frosts. In turn, trees that develop leaves later can avoid losses, but they have to face the shortened growing season. The article presents the results of repeated observations of the spring development of sessile oak trees in about 90−year old stand in central Poland (19.920365° E, 51.837381° N). The trees were observed every week and classified into one of six classes of leaves development – from the absence of bud burst symptoms to the fully−developed leaf. It was found that over time, the share of trees was gradually increasing at higher and higher stages of development, while at the end of the observation period the rate of development of trees was very high. Importantly, at each stage of development, the trees emerged, which proceeded to much faster development than previously, and their share was increasing over time, as shown in the elaborated model of stand development.