Recent Trends of Tree Growth in Relation to Climate Change in Hungary

Abstract

The paper addresses two related issues. One is whether, and how, growth patterns of stand mean height have changed in Hungary in the last few decades, and the other is whether recently observed increases in mean annual temperature might have caused changes in growth trends. Changes in tree growth were investigated for beech (Fagus sylvatica), sessile oak (Quercus petraea) and Turkey oak (Quercus cerris) by comparing stand mean heights over age using data from the forest inventories of 1981 and 2001, and for sessile oak using stand mean height data from permanent sample plots since 1961. Tree growth was found to have accelerated for each species mentioned, with Turkey oak showing the largest acceleration. To study the second issue, stand mean height was related to elevation, wich in turn was related to mean annual temperature and precipitation. For these analyses, too, data of many thousands of stands in the forest inventory was used. Stand mean height was found to increase with decreasing elevation, i.e. with increasing mean annual temperature, for each of the three species. As the annual precipitation and air humidity decreases with decreasing elevation, it was concluded that increases of mean annual temperature could positively have affected tree growth in the last few decades. However, this effect is expected to be soon limited by water availability.