Effect of sheep and horse grazing on species and functional composition of sub‐Mediterranean grasslands

Abstract

Questions: How does horse or sheep grazing affect species richness, diversity and functional composition of plant communities in sub-Mediterranean grasslands? What are the implications of grazing management for species conservation?\ud Location: Pastures dominated by Bromus erectus grazed by either sheep or horses in the Umbria-Marches Apennines (central Italy).\ud Methods:We examined grasslands at altitudes ranging from 1000 to 1200 m a. s.l. on north-facing slopes and with a slope angle of 20–40 °. In 20 plots of 1 m2 for each management type, canopy height and above-ground phytomass were recorded. In 120 plots (60 for eachmanagement type) of 1 m2 the cover value of each species was recorded. Floristic diversity and community similarity of the sheep- and horse-grazed conditions were compared. Functional plant traits and strategies or ecological requirements were also evaluated.\ud Results: The sward was shorter and supported less above-ground phytomass in the horse-grazed area. The sheep- and horse-grazed areas had similar floristic diversity. Accidental species were the species most affected. Plants with lownutrient\ud requirement spread in horse-grazed pasture. Functional traits of species were filtered by the system, resulting in diverse cover values of species. Horse grazing promoted plants with a robust defence strategy (avoidance and tolerance) that ensured leaves were replaced when horses were not grazing, as well as species with clonal growth. In the sheep-grazed area, a higher level of selective defoliation and a delayed start to the grazing period promoted species with low palatability, a late-flowering strategy and those intolerant to trampling by large herbivores (chamaephytes). The value of forage feed was slightly higher in\ud horse-grazed pasture. Grazing of horses was more effective than that of sheep for controlling dominant unpalatable tall grasses.\ud Conclusion: In terms of biodiversity conservation, horse grazingmay be considered as useful as sheep grazing, but only if managed at optimal stocking rates, because the increase in short grasses and annuals (growth forms with poor root systems) does not ensuremaintenance of soil on steep slopes

Plant species selection by sheep in semi-natural dry grasslands extensively grazed in the south-western Italian Alps

“…considered grazers (sensu Hofmann 1989) and they are relatively non-discriminatory among plant species at the patch scale (Gordon 2003), our results highlighted that in semi-natural dry grasslands they exert a selective foraging behaviour, as also pointed out by other authors (Calaciura and Spinelli 2008;Catorci et al 2012). Rook et al (2004 indicated that sheep can behave as grazers (feeding mainly on graminaceous plants) or intermediate feeders (feeding on a mixture of woody and non-woody dicotyledonous and graminaceous plants) depending on botanical composition.…”

Wild boar rooting intensity determines shifts in understorey composition and functional traits

“…Finally, clonality allows a quick vegetative colonization that is especially effective when disturbance operates at very small scales, such as in the studied forest (Catorci et al 2012), where the great majority of the rooted patches had a size between 0.02 and 0.5 m². A more detailed analysis of spatial patterns of rooting activities (e.g., such as the size and configuration of rooting patches, see Welander 2000) would have allowed to more detailed conclusions with respect to some key traits (e.g., clonality).…”

“…In the long-term, this selective predation may also favour certain tree species compared to others, and may affect the successional trajectory of the stand (Nuttle et al 2014). Mechanical damage may instead favour clonal species, since clonality may allow a rapid recolonization of rooted patches (Catorci et al 2012). This may lead to the development of a long-lasting layer of ferns or other browse-tolerant species that, in turn, may suppress or delay the recovery of other species after the cessation of the disturbance Carson 2006, Nuttle et al 2014).…”

Effect of Red Deer Grazing on Alpine Hay Meadows: Biodiversity and Management Implications

“…The highest number of indicator traits was found under mowing management ( Table 5), while red deer grazing fostered plants with vegetative propagation based on lateral spread of runners and runner-like rhizomes, that are strategies allowing to face heavy disturbance intensity and flower consumption by herbivores (Catorci et al, 2012b). Moreover, such strategies are aimed at maximizing the species competitive ability when there is higher exploitation of soil resources in productive environments, allowing individuals to explore the neighbouring areas and find unexploited soil niches (Friedman and Alpert, 1991).…”

“…Thus, its spread in the grazed site might be a side effect of the spread of B. rupestre and D. cespitosa. In general, with reference to the management of coarse tall grasses, it was demonstrated that overstocking in fenced stands by domestic herbivores may be useful (Catorci et al, 2014a), especially if performed by equines (Catorci et al, 2012b) or cows (Schütz, 2003). Mowing has the same output (Bonanomi et al, 2009).…”