Climate and altitudinal limits of beech woods in the Northern Apennines

The spatial pattern of the northern Apennine upper timberline and its correlation with the heat requirements of Fagus sylvatica was studied. The pattern of the timberline was described on a scale of 1: 25 000, using a digitized map derived from phytosociological vegetation maps. The present altitudinal range of the upper wood limit in the Northern Apennines is from about 1400 m a.s.l to 1875 m a.s.l.. This limit stretches for 354 km. The most of such limit is human-made. The natural limit lies entirely above 1600 m a.s.l and stretches only for 163 km. The present upper beech timberline (1875 m) corresponds to a mean temperature of the coldest month (January) of -2.5 °C, to a mean annual temperature of 4.2 °C, to a summer mean of 11.0 °C, to a mean of the warmest month (July) of 12.7°C and to 132 days with maximum temperatures above 10 °C. The values were calculated by linear regressions of fifty years (1951-2002) data from five weather stations. Dendrochronological analyses in two study areas (Mt. Giovo and Mt. Prado) lead us to suppose that on Mt. Giovo the wood limit at 1738 m a.s.l. could be near to its local upper altitude whereas on the Mt Prado the present altitudinal wood limit at 1677 m a.s.l is far from a natural condition, because of a heavier human impact until a few decades ago.