No abstract

No abstract

Abstract. Radial growth of the trees and its relationships with other factors is one of the most important research areas of forestry for a long time. For measuring intra-annual growth there are several widely used methods: one of them is measuring the girth of trees regularly, preferably on weekly basis. However, the weekly measured growth data may have bias due to the actual precipitation, temperature or other environmental conditions. This bias can be reduced and using adequate growth functions the discrete growth data can be transformed into a continuous curve.In our investigations the widely used logistic, Gompertz and Richards sigmoid growth models were compared on intra-annual girth data of beech trees. To choose the best model two statistical criteria, the Akaike weight and the modified coefficient of determination were examined. Based on these investigations and the view of applicability, Gompertz model was chosen for later applications. However, we came to the conclusion that all three models can be applied to the annual growth curve with sufficient accuracy.The modified form of the Gompertz function gives three basic curve parameters that can be used in further investigations. These are the time lag, the maximum specific growth rate and the upper asymptotic value of the curve. Based on the fitted growth curves several other completely objective curve parameters can be defined. For example, the intersection of the tangent drawn in the inflection point and the upper asymptote, the distance between upper intersection point and the time lag, the time and value of the inflection point etc. and even different ratios of these parameters can be identified. The main advantages of these parameters are that they can be created uniformly and objectively from the fitted growth curves. This paper demonstrates the application opportunities of the curve parameters in a particular study of tree growth.

The influence of meteorological parameters on the health status of beech (Fagus sylvatica L.) was analyzed using long term datasets (1989-2010) collected in 15 sample plots located in Hungary’s main beech regions. Leaf loss values were correlated with different meteorological parameters as explanatory variables. Analysis was performed by the CReMIT (Cyclic Reverse Moving Intervals Techniques) method. Weather, stand, and site parameters were also examined with PCA for comparison. Leaf loss levels showed stronger correlations with maximum monthly temperatures than with monthly precipitation sums. The monthly number of summer days and monthly number of hot days displayed a similar correlation to leaf loss as the maximum monthly temperature did. The correlations were regularly stronger and more frequent on more arid sites where the climate is less favorable for beech. Temperature affected leaf loss more than precipitation did. Our results show that beech forests may suffer heavy damage if climate change continues as projected.

We investigated the canopy recovery of 3 tree species (pedunculate oak, Turkey oak, European beech) at two locations in the Veszprém county (Western Hungary) after severe defoliation by gypsy moth caterpillars in the spring of 2005. The Turkey oak has evidently the best recovery potential, and it almost completely replaced the lost foliage in 4 months. The pedunculate oak and beech needed 2 years to reach the same level of recovery. The pedunculate oak suffered from a heavy infection ofMicrosphaera alphitoidesafter defoliation and it probably slowed down its recovery. Neither the presence ofAgrilus biguttatusin the oak plot nor the appearance ofAgrilus viridisin the beech plot was observed during the study period. Population density of the buprestidCoraebus floerentinusshowed a considerable increase in the oak plot, but remained under the damage level. Neither other harmful appearance of other pests nor significant tree mortality were observed within 4 years from the defoliation. These results provide information for the evaluation of longer term influences of the gypsy moth defoliation and may support the decisions concerning pest control.