Tree Regeneration and Sapling Damage of Pedunculate Oak Quercus robur in a Grazed Forest in Galicia, NW Spain: A Comparison of Continuous and Rotational Grazing Systems

Abstract

Forest grazing has been recognised as being a useful tool in fire-risk reduction, in addition to having the potential to preserve or enhance forest biodiversity if managed correctly. Concern for natural regeneration of forest trees in Europe has also prompted interest in the effects of large herbivores on seedling and sapling growth and mortality. An investigation was carried out into sapling damage and density of natural regeneration of oak (Quercus robur) in a mature, pony-grazed, Pinus radiata forest in Galicia, NW Spain under two different grazing regimes (continuous and rotational). In all treatments significantly more oak seedlings and saplings were recorded in areas of grass sward than areas dominated by taller ground flora species. Damage to oak saplings was assessed from the form (height and canopy) relative to stem diameter. The height and average canopy diameter of similar-aged saplings were found to be significantly greater in ungrazed (control) than both continuous and rotationally grazed treatments. Height and canopy diameters of similar-aged oak were not significantly different between the two grazing treatments. Significant differences were observed in tree form, with unbrowsed saplings having the greatest height to canopy width ratio and those in the continuously browsed plots having the smallest. An obvious decrease in the goodness of fit (R 2 ) of regression analyses were found in continuously grazed areas compared to rotational and control plots for both height and canopy data. The differences in damage observed were not significantly different enough to suggest one method of grazing over the other as being better for minimising sapling damage. Management requirements are more likely to dictate grazing regime. Overall, stock density is likely to have a more significant effect on damage than stocking system.

The Impact of Grazing on Plant Natural Regeneration in Northern Slopes of Mount Kilimanjaro, Tanzania

“…This finding indicates that livestock grazing may be one of the factors facilitating plant species regeneration in least and moderately grazed areas mainly due to the role it plays in reducing competition through grazing and browsing which promotes plant species diversity. This is consistent with the observation made by [15] that low level of livestock grazing increases natural regeneration through reducing competition among plant species in a community. This study observed low diversity of regenerants in ungrazed areas ( Table 3).…”

Effects of livestock exclusion on tree regeneration in church forests of Ethiopia

“…It has been suggested that a light level of grazing can increase tree regeneration by removing competitive vegetation, reduce fire hazard and fertilization from manure (Kuiters et al, 1996;McEvoy et al, 2006). Large herbivores can also create patches of bare ground through grazing and trampling.…”

Effects of Grazing Intensity on the Regeneration of Woody Species in an Oak Woodland

“…Lempesi et al (2013) results in a grazed oak woodland in northern Greece confirmed the moderate grazing hypothesis (Noy Meyer, 1995;Tilman, 1997) that light and moderate grazing results in an increase of biodiversity. Thus, managed woodland grazing systems are increasingly recognised as being beneficial to woodland biodiversity (McEvoy et al, 2005).…”