Ungulate browsing on European silver fir Abies alba: the role of occasions, food shortage and diet preferences

Abstract

European silver fir Abies alba is the most heavily browsed conifer in Central European mountain forests. Attempts to reduce ungulate browsing have often been unsuccessful, controversial or too costly. The aim of the work described here was to improve our understanding of the factors that lead to browsing on silver fir. The silver fir content in the diet of three sympatric ungulate species, chamois Rupicapra rupicapra, red deer Cervus elaphus and roe deer Capreolus capreolus, was determined by microhistological analysis of faeces collected at four sites in the Alps. Further, the supply of silver fir was assessed at the individual tree and patch scale and then extrapolated to site scale. Silver fir consumption was highest in winter, when diet composition varied among sites but not among ungulate species. Towards the summer, site‐differences decreased and differences among ungulate species increased. Red and roe deer reduced consumption of silver fir, whereas chamois kept it constant. The use of silver fir was unrelated to the supply at the various sites, but increased with the proportion of trees growing amidst palatable herbaceous species. At the individual plant scale, ungulates browsed on the saplings with the larger needles. These results indicate that silver fir as food does not rank high among the available plant species, but is eaten opportunistically, especially when it grows close to more preferred food plants. However, when alternative food is scarce, particularly in winter, it may also represent a shortage food supply, and larger quantities are consumed. Yet, the fact that feeding on silver fir is mostly opportunistic may offer forest managers a way to approach the ‘browsing problem’.

Herbivory and seedling establishment in Pyrenean forests: Influence of micro- and meso-habitat factors on browsing pressure

“…Contrary to some recent works conducted in other mountain systems (e.g. Häsler and Senn, 2012;, we did not find grass abundance to affect browsing probability in our study area. The high abundance of grasses present in all our plots is probably at the origin of this divergence.…”

“…On the other hand, wild ungulates are more selective and cause more abundant and severe damages than cattle to seedlings, often being described as 'browsers' (Didion et al, 2009;Liss, 1988;Mayer, 2005bMayer, , 2006. The browsing behavior is particularly important during winter, when other food resources are scarce and seedlings constitute a significant part of their diet (Häsler and Senn, 2012;Jackson, 2009;Motta, 1996).…”

“…The different duration of snow cover in the plots established in these areas might explain the observed patterns. Faster melting snowpack in gaps due to higher insolation can cause the seedlings to become available earlier in the year, during a period with potential scarcity of alternative food sources (Häsler and Senn, 2012;Jackson, 2009), hence increasing the pressure on them.…”

Long-term transformation of submontane spruce-beech forests in the Jizerské hory Mts.: dynamics of natural regeneration

“…Subsequently, these processes should lead to the arrangement tions Vacek 2017) and mechanical or repellents protection with focusing on support of fir, sycamore maple and other species largely suffering from browsing seems to be necessary (Olesen & Madsen 2008;Häsler & Senn 2012).…”

Colonization in Mediterranean old‐fields: the role of dispersal and plant–plant interactions

“…Both herbivores have contrasting foraging strategies: whereas sheep feed mainly on grasses (Zweifel-Schielly et al 2012;Ferreira et al 2013). Moreover, sheep either are moved to milder areas or remain stabled during winter, but red deer have to remain on the meager alimentary resources present during winter, when perennial woody plants become their main food supply (Bee et al 2010;H€ asler & Senn 2012). As a consequence, a feasible explanation for this contrast in plant-plant interactions between plots may be that, when sheep stopped grazing in plot 3 and red deer became the main herbivore, a much higher number of P. sylvestris and J. communis seedlings were predated by deer under J. sabina canopies.…”