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Is browsing the major factor of silver fir decline in the Vosges Mountains of France?

Authors
Journal
Forest Ecology and Management
0378-1127
Publisher
Elsevier
Publication Date
Volume
217
Identifiers
DOI: 10.1016/j.foreco.2005.06.003
Keywords
  • Silver Fir–Beech Forests
  • Spruce
  • Silver Fir Decline
  • Deer Browsing
  • Understory Cover
  • Silviculture
  • Wildlife Management
Disciplines
  • Ecology
  • Geography

Abstract

Abstract For many years, browsing wild ungulates have been considered the major cause for the decline of silver fir ( Abies alba) in Europe. To better understand the dynamics of silver fir–beech forests hosting important deer populations, we studied forest renewal using a synchronistic approach, i.e. by comparing similar stands of different ages. Regeneration in a series of forests, where seedlings (<150 cm) were submitted to an increasing browsing pressure, was examined initially. We then analysed young stands (>2 m), which have grown in similar ecological conditions and also under increasing browsing. Published results on regeneration have identified three key factors as modulators of the effects of deer browsing on the composition of regeneration: understory abundance, stand composition and orientation to sun. This paper deals with the second part of the study. It examines the influence, over time, of the three environmental characteristics, identified at regeneration stage, by analysing the composition and the structure of young stands grown under comparable conditions. A total of 152 plots of 150 m 2 each were selected, spread over 30 km 2 of an ancient game reserve and core analysis was used to identify whether trees were under 150 cm when browsing became noticeable. Our results confirmed the critical role of stand composition, orientation to sun and understory—the latter being far predominant. Indeed, previous stand composition (i.e. seed trees at the time of regeneration) and orientation to sun did not explain current young stand composition alone, but when a south-exposed slope was previously occupied by mature spruce, then young spruce trees were frequent. Understory clearly played a positive role in the conservation of fir, despite increased browsing by deer. In fact, fir was abundant in the young stands when understory above seedlings was important at the time of regeneration, but when understory was poor, spruce became the dominant species and fir was seldom observed. Overall, silver fir was often the dominant species among young stands, despite a progressive increase in spruce numbers. The dominance of fir may be explained by the particular sylvicultural history of the studied forests. However, in the future, the expansion of spruce, favoured by deer foraging on fir and by even-aged sylviculture, may lead to localized failure of fir regeneration. To promote silver fir–beech forest renewal, forestry practices should change towards a system more closely resembling natural forest dynamics.

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