Influence of livestock grazing on meadow pipit foraging behaviour in upland grassland

Changes in grazing management are believed to be responsible for declines in populations of birds breeding in grassland over the last decades. The relationships between grazing management regimes, vegetation structure and composition and the availability of invertebrate food resources to passerine birds remain poorly understood. In this Study, we investigated the foraging site selection of meadow pipits (Anthus pratensis L.) breeding in high intensity sheep-grazed plots or low intensity mixed (i.e. sheep and cattle)-grazed plots. We sampled above-ground invertebrates, measured vegetation height and density and conducted a vegetation survey in areas where meadow pipits were observed to forage and areas that were randomly selected. Birds foraged in areas with a lower vegetation height and density and in areas containing a lower proportion of the dominant, tussock-forming grass species Molinia caerulea. They did not forage in areas with a total higher invertebrate biomass but at areas with preferred vegetation characteristics invertebrate biomass tended to be higher in foraging sites than random sites. The foraging distance of meadow pipits was higher in the intensively grazed plots. Our findings support the hypothesis that resource-independent factors such as food accessibility and forager mobility may determine patch selection and are of more importance as selection criteria than food abundance per se. Food accessibility seems to become an even more important selection criterion under high grazing intensity, where prey abundance and size decrease. In our upland grazing system, a low intensity, mixed grazing regime seems to provide a more suitable combination of sward height, plant diversity, structural heterogeneity and food supply for meadow pipit foraging activity compared to a more intensive grazing regime dominated by sheep. (c) 2009 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.

Optimizing Carbon Storage Within a Spatially Heterogeneous Upland Grassland Through Sheep Grazing Management

Charlotte Vandenberghe

Livestock grazing is known to influence carbon (C) storage in vegetation and soil. Yet, for grazing management to be used to optimize C storage, large scale investigations that take into account the typically heterogeneous distribution of grazers and C across the landscape are required. In a landscape-scale grazing experiment in the Scottish uplands, we quantified C stored in swards dominated by the widespread tussock-forming grass species Molinia caerulea. The impact of three sheep stocking treatments ('commercial' 2.7 ewes ha(-1) y(-1), 'low' 0.9 ewes ha(-1) y(-1) and no livestock) on plant C stocks was determined at three spatial scales; tussock, sward and landscape, and these data were used to predict long-term changes in soil organic carbon (SOC). We found that tussocks were particularly dense C stores (that is, high C mass per unit area) and that grazing reduced their abundance and thus influenced C stocks held in M. caerulea swards across the landscape; C stocks were 3.83, 5.01 and 6.85 Mg C ha(-1) under commercial sheep grazing, low sheep grazing and no grazing, respectively. Measured vegetation C in the three grazing treatments provided annual C inputs to RothC, an organic matter turnover model, to predict changes in SOC over 100 years. RothC predicted SOC to decline under commercial sheep stocking and increase under low sheep grazing and no grazing. Our findings suggest that no sheep and low-intensity sheep grazing are better upland management practices for enhancing plant and soil C sequestration than commercial sheep grazing. This is evaluated in the context of other upland management objectives.

Springer2014

Drought-induced shifts in plants traits, yields and nutritive value under realistic grazing and mowing managements in a mountain grassland

Alexandre Buttler, Claire Emilie Deléglise, Constant Signarbieux, Thomas Spiegelberger

Extreme drought events can dramatically impact grassland ecosystems, causing potential loss of forage production for livestock in temperate grasslands. However, knowledge of drought effects on forage production, nutritive value and plant community stability in the real context of farming management is scarce. For this purpose, the effect of a simulated summer drought was studied under two realistic management types on a semi-natural grassland in the Swiss Jura mountains. The first management ("grazing") consisted in six consecutive utilizations by animals over the growing season, representing a rotational grazing system as regionally conducted. The second management ("mowing") consisted of three harvests, corresponding to the usual mowing frequency of hay meadows. In both managements, drought caused minor short-term modifications of species composition and almost no persistent effects were observed. Besides, important short-term changes were observed in community weighted mean of several key functional traits, reflecting a strong decline in community growth during the drought followed by a partial recovery two months later. Forage yields, and to a lesser extent its nutritive value, thus declined during the drought period. Both were still affected in the following months, but had recovered in spring of the following year. Forage loss was twofold higher in the grazing management, but recovery as well as nutritive value was slightly improved in this management. The results suggest that rotational grazing can amplify negative drought impacts, compared to traditional mowing, and highlight the need to adapt such management in dry years. They also demonstrate that, even under a fairly intensive management, resilience of such mountain grasslands after one extreme drought event can be expected to be high, with no persistent changes in species and trait compositions. (C) 2015 Elsevier B.V. All rights reserved.

Elsevier2015

Effect of dung deposition on small-scale patch structure and seasonal vegetation dynamics in mountain pastures

Alexandre Buttler, François Gillet, Charlotte Vandenberghe

Cattle activity greatly influences plant species composition and biomass production of grassland ecosystems. Dung deposition by cattle together with grazing and trampling can be considered as one of the important factors driving vegetation dynamics in pastures. The objective of this study was to investigate at 10-cm and 1-month resolution the plant community dynamics induced by dung deposition in two plant communities (a mesotrophic and an oligotrophic grassland) in a pasture of the Swiss Jura Mountains. Vegetation was sampled four or three times during the vegetation period in contiguous 10 cm x 10 cm quadrats from the centre of the dung pat to a distance of 60 cm. A lower grazing intensity near the dung pat was recorded for all observation periods. In the mesotrophic grassland the canopy was higher near the dung pat already one week after dung deposition. Vegetation around dung pats was submitted to two opposite fertilizing and grazing gradients, which induced changes in vegetation texture and structure at fine scale and short term. We observed a positive rank correlation between species turnover and distance to the dung for both communities, suggesting a seasonal stabilizing effect of dung on the plant composition of their direct surroundings (0-10 cm) likely due to cattle avoidance. Since dung pats are dropped every year in different locations, they create in the pasture a shifting mosaic of nutrient availability and grazing intensity inducing at seasonal scale micro-successions in plant communities. (c) 2009 Elsevier B.V. All rights reserved.

Elsevier2010

Drought-induced shifts in plants traits, yields and nutritive value under realistic grazing and mowing managements in a mountain grassland

Alexandre Buttler, Claire Emilie Deléglise, Constant Signarbieux, Thomas Spiegelberger

Elsevier2015