The effect of the precipitation on the tree ring width

The increased frequency of drought observed since the early nineties drew the attention to analysing the role of precipitation in tree growth. We carried out a study in three areas in Transdanubia (Zselic, Bakony and Pilis mountains) on how the total precipitation of different periods influence tree-ring width of different tree-species (Turkey oak, pedunculated oak and beech) and different age classes. We have found significant correlation with the April, May and June precipitation. The intensive growth period (May-June) and the weighted total precipitation also play an important role in tree-growth. High Gleichlaufigkeit was found between the tree-ring and the drought indexes. We studied the growth trends of middle-aged and mature trees in the same samples. The analysis of the last eighty years did not provide unquestionable evidence of increasing growth of trees in Hungary, although we observed this phenomenon in several cases, mainly for beech.