Control and forecasting of the fructification of European beech (Fagus sylvatica L.) for the stand Zierenberg 38A and the level I stand in Hessen by climate factors

Correlations between regularly documented fructification data and climatic factors (monthly means between 1951-2001) from the weather station Kassel-global radiation R, sunshine duration SSD, temperature T, precipitation N and relative air humidity rF-were tested on at least 60 year old beeches from Zierenberg 38A and Hessen. Following results are important: 6.1. The fructification of the beech is influenced by climatic factors over a time interval of 3 years. 6.2. This influence is easily readable from the WISF (weather index sum formula) which consists of all significantly joined summands of climatic factors. The influences are separated in years and in positive and secondary and negative (positively made) correlations (Tab. 3). 6.3. Radiation R, sun shine duration SSD and temperature T only in the months July and September of the pre-previous year x-2 (P-period) have the strongest influence (0,77>r(2)<0,91) on flower formation (s. Tab. 2, Fig. 1, 2a, 2b). The bud meristems obviously will be induced in mixed bud primordia or pure bud primordia, when the climatic factors (R, SSD, T) are low respectively high (phase of induction) in this P-period. 6.4. The R-, SSD- and T-data during September and October of the previous year x-1 are also important for the mixed bud development (flower buds, Tab. 3, 6). They are correlated positively to the fructification (0,43<r(2)<0,53) and especially promote the reserve compounds (phase of flower buds and storage compound formation). 6.5. Fructification models were developed from the climate-fructification relations with a high exactitude (r(2)>0,98) for the stand Zierenberg 38A and for the Level I-stands in Hessen (Tab. 3, Fig. 3). 6.6. It was shown, that the fructification during the last 15 to 20 years occured more frequently and intensivly than during the three decades before (Fig. 4b). 6.7. Fructification forecasting models were developed from the climate-fructification relations. (Fig. 5, 6, Tab. 4, 5). Thus it is possible to forecast the fructification for one or two years with a high exactitude (r(2)>0,93) for the stand Zierenberg 38A and for Hessen. 6.8. The fructification forecasting for the year 2002 from the models based on weather data showed good agreement with the real recorded fructification data (Zierenberg: according FFModell: 2,96 and FFAufnahme=:3,18; Level I stands in Hessen: according FPModell:98% and FPAufnahm:91%).