Comparative ecological investigations in Fagus forests of Japan, Italy and Mexico

The ecological requirements of the beech (Fagus sp. div.) are relatively well known for the species of the temperate zone, whereas little information exists on species of the subtropical mountain habitats. The present study is based on parallel ecological investigations, carried out on forest vegetation withFagus in Japan (F. crenata), Europe (F. sylvatica, in Central Italy) and Mexico (F. mexicana, in the Northern range of Sierra Madre Oriental). Observations in the field were carried out by the same working team, during a short period in autumn 2003; comparable methods and instruments were used. The climates of the three areas are different (table I): annual mean temperature 7-10o in Japan and Italy (see S 3 for the area in Italy) and 13.6o in Mexico, and similar differences remain also in the atmospheric temperature recorded during the days of field observations. Leaves have in general lower temperatures than the surrounding atmosphere (table II): the difference inF. crenata andF. sylvatica, is only 1-1.5o, whereasF. mexicana maintains leaves with 4-5o lower than air temperature. As a consequence, at noon during clear days and in the same period of the year, on the three studied beech species similar leaf temperatures were measured. This ecological convergence seems to be the effect of a mechanism of active regulation, which remains still undescribed. © 2006 Springer.