Suchergebnisse

Grazing by large herbivores may negatively affect bird populations. This is of great conservation concern in areas with intensive sheep grazing. Sheep management varies substantially between regions, but no study has been performed in less intensively grazed systems. In a fully replicated, landscape scale experiment with three levels of sheep grazing, we tested whether the abundance and diversity of an assemblage of mountain birds were negatively affected by grazing or if grazing facilitated the bird assemblage. Density of birds was higher at high sheep density compared with low sheep density or no sheep by the fourth grazing season, while there was no clear effect on bird diversity. Thus, agricultural traditions and land use politics determining sheep density may change the density of avifauna in either positive or negative directions.

Altres ajuts: Basque Government to E.G (IT1022-16), A.A (IT1365-19), and L.J.R.B. (IT944-16) ; Unidad de excelencia María de Maeztu CEX2019-000940-M ; Pastoral systems face increasing pressure from competing global markets, food sector industrialization, and new policies such as Europe's post-2020 Common Agriculture Policy. This pressure threatens the use of extensive sheep-grazing systems in mountain areas of low productivity but high natural value. Using information gathered at a long-term research setting in a mountainous area of the Basque Country (northern Spain), we assessed the multiple benefits of extensive dairy sheep grazing systems from multiple perspectives using indicators pertaining to ecological, socio-economic, and food quality domains. In this way, we address the benefits that would be lost if sheep grazing abandonment persists in mountain regions. Our results show that the benefits of extensive dairy sheep grazing in the research area include the production of healthy and high-quality foods and multiple ecological benefits including biodiversity conservation. Extensive dairy sheep grazing also contributes to rural development by generating employment and income in marginal, low-productivity lands that can support few economic alternatives. In particular, we found that sheep farmers who produce high-value products, such as cheese, have enhanced their economic profitability and are less dependent on public subsidies. However, careful attention to sustainable practices, support for new generations of farmers, and streamlined supply chains are required. These would contribute to ensure socio-economic benefits for farmers, avoid the ecological costs associated with grazing abandonment, and enhance ecosystem services for the whole society.

This study aimed to assess the morphogenic characteristics and tiller density of Aruana grass managed at different heights under sheep grazing. Aruana grass was managed at four mean heights (12, 15, 20, and 25 cm) distributed in a randomized block design with three replications, totaling 12 paddocks of 250 m² each. Twenty-four crossbred Dorper x Santa Inês lambs, with mean age and weight of 60 ± 15 days and 16.69 ± 2.70 kg, respectively, were randomly distributed in the treatments. Five tillers were demarcated per paddock for measuring morphogenic variables. A representative area in the paddock was used for counting the number of tillers. No differences (P > 0.05) were observed for leaf appearance rate, leaf elongation rate, stem elongation rate, leaf senescence rate, final leaf length, and leaf life span between the assessed heights. Phyllochron was longer at the height of 25 cm when compared to 15 and 20 cm (19.35, 12.11, and 12.75 days, respectively). The number of live leaves was higher at heights of 12, 15, and 20 cm when compared to 25 cm (3.99, 4.35, 4.15, and 2.86, respectively). The number of basal and aerial tillers presented no variation (P > 0.05) between canopy heights. Management heights from 15 to 20 cm allowed a higher number of live leaves and a shorter phyllochron in Aruana grass pastures managed for sheep. Canopy height management did not influence other morphogenic characteristics and tiller density.

10 pages, 5 figures, 4 tables. ; The study was carried out on a continuously stocked grass/white clover pasture, which was maintained at two sward heights: 3.5 cm (low; LSH) and 6.5 cm (high; HSH). Three oesophageal-cannulated and three other rumen-cannulated Merino sheep were allocated to each of the plots (LSH and HSH) in order to study the effects of sward height and advancing grazing season on rumen fermentation in grazing sheep. Three grazing periods (13 days) were considered: mid lune, late July anti early October. During each grazing period and after a preliminary period (7 days), samples of the grazed herbage and of grass hay were incubated in nylon bags in the rumen of each sheep for 0, 3, 6, 12, 24, 48, 72 and 96 h. On days 10 and 12 rumen fluid was sampled at the incubation time (11.00 h) and at 3, 6 and 12 h afterwards and pH, ammonia-nitrogen and volatile fatty acids (VFA) concentrations were determined. Sward height did not affect (P > 0.05) the degradation rate of dry matter (DM) and neutral-detergent fibre (NDF) from grazed herbage in ally of the considered periods. Animals grazing LSH presented higher (P 0.05) observed during October. Sward height did not affect CP < 0.05) grass hay DMED and NDFED during July but during June and October HSH grazing sheep presented higher (P < 0.05) values. In general, DMED and NDFED from grazed herbage increased with advancing season, the lowest ((P < 0.05) value being observed during lune. Rumen ammonia-nitrogen concentrations were higher during October than during lune and July for both sward heights but values were higher than 200 mg/l at any sampling time during all grazing seasons. Rumen pH values were within the range considered adequate for maintaining a normal cellulolytic activity at most of the sampling times, with the exception of sheep grazing LSH during October. Rumen VFA concentrations were within the range reported for other grazing studies and only a few differences between sward heights were found. Differences in rumen parameters are discussed in relation to both chemical composition of grazed herbage and pattern of intake. ; Financial support for this work through a CICYT Project (AGF94.0026) and by a European Union Project (AIR CT92-0646) is gratefully acknowledged. ; Peer reviewed

In 8 periods between February 1967 and June 1968, covering a severe drought and subsequent rain, samples of 66 species of dicotyledons and 50 species of monocotyledons were collected from a large paddock in semiarid 'mulga-box' country in south-western Queensland. The mean N content of the dicotyledons ranged from 1.51 to 2.85 g/100 g DM, and that of the monocotyledons from 0.70 to 1.86 g/100 g DM.Stomach or faecal samples were analysed for plant parts. When known plant mixtures were given to 2 grey kangaroos (Macropus giganteus) and two sheep there was no species difference in the digestibility of the different plants or in the size distribution of faecal particles. Comparison of stomach and rectal samples from 5 shot kangaroos and 7 shot sheep showed quite good agreement. Samples of the faeces of sheep, grey kangaroo and a few red kangaroo (Megaleia rufa) were collected from the ground at the same intervals as the plant samples, dried and analysed for N and for plant parts. Detailed results are given. The grey kangaroos consistently ate more grasses than the sheep. The N content of sheep faeces was higher than that of kangaroo faeces, reflecting the higher protein intake of the sheep. The results confirm those of an earlier study (NAR 38, 1829) made in 1963–4 in a period of average rainfall. The authors conclude that competition between sheep and kangaroos is small.

Context
Grazing by domestic stock can potentially influence ecosystems positively or negatively, depending on the grazing regime and intensity. The pygmy bluetongue lizard (Tiliqua adelaidensis) is an endangered species, restricted to fragmented grasslands in the Mid North region of South Australia, predominantly grazed by sheep. These lizards refuge in vertical burrows. They do not dig their own burrows, instead relying on co-existing spiders for this essential resource.

Aims
We investigated how sheep grazing influenced spider burrows, and predicted the following: that grazing sheep might trample and destroy shallow burrows; that burrows in grazed habitat with less vegetative cover would have higher temperatures in summer; and that, by way of compensation, spiders would dig deeper burrows in grazed habitat.

Methods
We monitored 12 30m×30m plots monthly, over two austral spring/summer periods (September–March 2012–14). We recorded the number, depth and occupant of all spider burrows in those plots in each survey. We also measured temperatures inside artificial burrows in grazed and ungrazed habitat over a 3-day period in September 2014.

Key results
Mean burrow depth increased with grazing. This was not because individual burrows became deeper, but because the shallowest burrows were lost where there were sheep. Burrows were significantly hotter in grazed habitat, but lizards consistently chose deeper, cooler burrows. In the subset of burrows that were occupied by lizards, there was no difference in depth between grazed and ungrazed treatments. We detected no difference in spider digging activity between grazed and ungrazed plots.

Conclusions
Sheep grazing can destroy shallow burrows, probably through trampling, and because sheep produce burrow filling debris. However, grazing did not affect deeper burrows occupied by pygmy bluetongue lizards.

Implications
This short study indicated that moderate levels of grazing have low impact on deeper burrows suitable for pygmy bluetongue lizards and for lizard persistence. It explains how sheep and lizards have co-occurred for so long, but leaves open the question of how the loss of shallow burrows affects populations of the burrow-digging spiders that are an essential component of the lizard environment.

The Resilience Assessment Tool (ResAT) builds on broad academic literature that has identified characteristics of resilience-enhancing policies. However, it adds a distinction between policy characteristics that enhance either robustness, adaptability or transformability. This report presents the findings from an application of the Resilience Assessment Tool in eleven case studies across Europe to assess whether and how the current configuration of EU and national policies supports or constrains the capacity of regional farming systems to cope with the range of novel challenges. Understanding the CAP's effects on the resilience of regional farming systems requires an analysis of the interactions between the CAP and various other policies, which occur not only within the sector, but also across sectors and jurisdictional levels. ; ES; en; contact: barbara.soriano@upm.es

National audience ; It is possible to find a way to manage rationally the grazing by sheep of scrub land (with both herbaceous and bushy species), so as to maximize its grazing potential, provided the edible bushy species have not been eradicated previously, for these are often necessary to stabilize a large daily intake. Public policies are encourageing the farmers to graze their flocks, as a contribution to the conservation of biodiversity, especially through the limitation of encroachment by scrub. After having critically analyzed the recommendations for the management of bushy ranges, we have made observations in situ of the feeding behaviour of flocks of ewes grazed on paddocks and used to this kind of environment ; the ewes appreciate a certain form of 'feed biodiversity' : that which stabilizes their daily intake at a relatively high level, while having a large effect on the paddocks under contract of management. This stabilization is possible thanks to a regular utilization, during the meals, of bushy species giving bulky bites. This is at the root of our Grenouille method which we propose to sheep farmers as an aid to decision ; they will thus be able to recognize and adjust on their paddocks all the feed resources useful to their flocks. From the point of view of the ewes, this tends to rehabilitate the scrub lands, still so badly thought of nowadays among sheep farmers. ; Il est possible de raisonner le pâturage ovin afin de tirer un bon profit alimentaire des milieux embroussaillés. à condition de ne pas avoir éliminé préalablement les broussailles comestibles. Ces dernières se révèlent souvent indispensables à la stabilisation d'une ingestion quotidienne importante. Des politiques publiques incitent à faire pâturer les troupeaux afin de conserver la biodiversité, notamment en limitant l'embroussaillement. Après analyse critique des recommandations pour la gestion des milieux embroussaillés, des observations in situ ont été menées sur le comportement alimentaire de troupeaux de brebis conduits en ...