Leading researcher: dr. György Csóka (Forest Research Institute, Department of Forest Protection)
Collaborators: András Koltay, Anikó Hirka, Gergely Janik

Results:
The scheduled field surveys were executed in September 2009. The data are being analysed. The main results so far:
A definite positive trend in health status of Hungarian beech forests was observed for 3 years (2004-2005-2006) after the ending (2003) the severely dry period. The leaf loss decreased in all beech regions. But following the severe summer drought of 2007 again increasing leaf losses were recorded in autumn 2008, mainly at Alpokalja, Zala County and the Mecsek-Zselic region. The average leaf losses for these 3 regions were 17.4% – 16.9% and 12.1% respectively. This negative trend was far less definite in the Bakony and the Északi-középhegység. Due to the more favourable weather conditions in 2008 and 2009 a rapid canopy recovery was observed in beech stands of Alpokalja, Zala County and the Mecsek-Zselic. An average leaf loss around only 2.5% was recorded at these 3 regions.
The canopy closure of a given stand – particularly during an extremely dry period – has a major effect of the health status of the beeches. The negative influence of drought is much weaker in stands with well closed canopy. The healing process after dry periods is much slower and regularly incomplete in more open beech stands than in the stand with higher canopy closure. It is worth mentioning that the beech decline in Zala county in the years 2003-2006 was triggered by the combined effect of the severe droughts and the abundant presence of the stands with low canopy closure under the process of the stepwise regeneration fellings).

The sessile oak stand tolerated the 2007 drought much better than beech stands. The average yearly mortality was 1.8%, 1% and 1.5% in 2007 and the consecutive 2 years. These values are around the normal yearly mortality values. The values of the Health Deficit Index (HDI) were in the normal range (8.7% – 4.5% – 6.7%). These results support repeatedly our earlier assumptions, that sessile oak tolerates the drought influence better than beech.