European beech (Fagus sylvatica L.) and silver fir (Abies alba Mill.) rotation in the Carpathians-A developmental cycle or a linear trend induced by man?

A detailed historical survey was made to assess the impact of humans on fir-beech forests in the northern Carpathians. Research findings are compared with results from repeated tree layer measurements in eight of the most well-preserved reserves of fir-beech stands in the region. Documentary evidence is provided showing that the historical and contemporary spontaneous development of fir-beech stands throughout the northern Carpathians is identical. The replacement of beech by fir occurred predominantly in the period from the 15-18th centuries, primarily due to grazing and litter raking. Starting in the 19th century, fir was replaced predominantly by beech under the influence of changing social conditions, since the dieback of the grazing fir generation had not yet been completed. Air pollution damage and other factors in the fir dieback were only secondary accelerating phenomena. These changes of tree species cannot be interpreted as the natural rotation of two beech generations within the life cycle of one fir generation, as has been the previous explanation. The development is rather a linear trend induced by man, which has occurred simultaneously throughout the northern Carpathians. The current dynamics of spontaneous development are affected by the high stock of hoofed game and by the absence or reduced numbers of predators. (C) 2009 Elsevier B.V. All rights reserved.