Phenology of Beech and Oak

The entry date of certain phases in plant development (phenology) shifts over the years, among other things, depending on temperature changes. From many years of observations, the influence of changed climatic conditions on the development of plants and ecosystems can be determined. Unlike direct temperature measurements, phenology thus reflects a reaction of nature to its environment. It is therefore an important and particularly sensitive bioindicator for climate change. The leaf shoot as well as the length of the vegetation phase of the beech and oak are used as an indicator. The period of time between leaf shoot and leaf discoloration is defined as the vegetation phase. It is calculated as follows: Calendar day leaf discoloration minus calendar day leaf shoot. Leaf shoots are depicted as a day in the year and the vegetation phase as the number of days per year. The data is collected visually on six (beech) or eight (oak) areas of intensive forest environmental monitoring in North Rhine-Westphalia (ForUm NRW) annually since 2001. Data is collected from 20 to 50 forest trees per research stock. The beech is observed on the Lower Rhine, in the Ruhr area, in the Eggegebirge, in the Sauerland and in the northern Eifel. The oak is observed on the Lower Rhine, Münsterland, Sauerland and Northern Eifel. The data of the areas are averaged.