Effects of livestock breed and grazing intensity on biodiversity and production in grazing systems. 4. Effects on animal diversity

Abstract

Finding an optimal balance between livestock production and grazing impact on animal diversity is important for the development of sustainable grazing systems. This paper tests the hypothesis that extensification of grazing management enhances animal diversity. Similar treatments were applied over a period of three years to sites in the UK, France, Germany and Italy. There were three treatments at each site: moderate grazing intensity with a commercial breed (MC), lenient grazing intensity with a commercial breed (LC) and lenient grazing intensity with a traditional breed (LT). Animal diversity was studied at the species level for birds, hares, butterflies and grasshoppers, and at higher taxonomic level for ground-dwelling arthropods. Bird and hare numbers were low and showed no overall treatment effects. Species richness and abundance of butterflies and grasshoppers were higher for treatment LC than for treatment MC, both for species preferring short open grasslands and those preferring tall grasslands. There was no difference in the impact of commercial or traditional breeds. Most ground-dwelling arthropod groups did not show consistent treatment effects but some taxa showed site-specific responses, generally indicating a greater abundance at lenient grazing intensity. Overall, the study showed that lenient grazing intensity enhanced animal diversity on grasslands at a small scale within 3 years. By comparison, the effect of livestock breed differences was negligible. Follow-up research is needed to elucidate the processes leading to increased biodiversity in patch mosaics and to establish the generality of these findings at larger spatial scales and longer time scales.

How do sheep affect plant communities and arthropod populations in temperate grasslands?

“…This could be related to increased prey availability and to tall and more complex vegetation structures benefiting web-building species. Different grazing intensities did not further affect spider abundance in three seminatural grasslands (Dennis et al, 2001;WallisDeVries et al, 2007;Dennis et al, 2008), whereas spider abundance progressively declined with each increase in stocking rate in an intensively grazed sown pasture (Hutchinson and King, 1980), where the reduction of habitat as stocking rate increased up to 30 sheep per ha was an obvious factor. Lepidoptera benefited from low or zero grazing intensities (Table 1).…”

“…The abundance of Collembola was positively correlated to herbage biomass in a fertilized grassland (Oliver et al, 2005) and consistently shot up in response to a decrease in stocking rate in another sown pasture (King and Hutchinson, 1976). Collembola abundance was unaffected by stocking rate in the only published survey conducted in a temperate seminatural grassland; however, this may mainly be due to pitfall traps being inadequate for sampling soil mesofauna (WallisDeVries et al, 2007).…”

“…Among the mechanisms that explain higher insect diversity in lightly grazed swards, one is that the trophic interactions between plants and herbivorous insects are not disrupted, that is, tall vegetation provides important food resources in the form of nectar for butterflies and live plant biomass for caterpillars and herbivorous insects (Ö ckinger et al, 2006;Dumont et al, 2009). A second explanation draws on the observation that tall grassland vegetation maintains a higher number of ecological niches, decreases predation risk and increases habitat quality for species that require buffered microclimates (Dennis et al, 1998;Morris, 2000;WallisDeVries et al, 2007). Exploiting plots during short grazing periods decreases the time grassland arthropods are exposed to disturbance compared with continuous grazing, with late grazing favoring phytophagous species that can benefit from higher food resources throughout most of the grazing season.…”

Inhabiting warm microhabitats and risk-spreading as strategies for survival of a phytophagous insect living in common pastures in the Pyrenees

“…Cattle in contrast do not select particular plant species and thus, enhance vegetation heterogeneity (Sebastià et al, 2008) and are effective in controlling shrub encroachment even at moderate stocking densities (Casasús et al, 2007). Several recent studies have documented positive effects of cattle grazing on species richness of plants and insects (e. g. Pykälä, 2003;Pöyry et al, 2004;WallisDeVries et al, 2007). Besides, cattle are the farm animals preferred by local farmers for economic reasons (García-Ruiz & Lasanta-Martínez, 1990) and if conservation policies are to be effective they should be based on economically profitable measures.…”

Motives and values in farming local cattle breeds in Europe: a survey on 15 breeds

“…Telenged, 1996;Wright et al, 2002), they are believed to be well suited for conservation grazing projects. However, some comparisons between local versus industrial breeds at low grazing intensities (0.63-1.52 livestock units/ha) have not yet revealed any significant differences in the impact of grazing on biodiversity (Rook et al, 2004;Scimone et al, 2007;WallisDeVries et al, 2007). In these studies, however, no comparisons between industrial and traditional indigenous breeds were made at higher stocking rates, nor did these studies account for the role of the place of origin of the breeds in question, the history of the breeds' existence in or around the study sites, or implications of the use of industrial breeds that were the results of crossbreeding with traditional indigenous breeds.…”