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Long-term Grazing Experiment (long-term + grazing_experiment)
Selected AbstractsStudying spatial and temporal dynamics of sward structure at low stocking densities: the use of an extended rising-plate-meter methodGRASS & FORAGE SCIENCE, Issue 4 2003O. Correll Abstract An extended rising-plate-meter method was used to study the spatial and temporal variability of the sward structure of extensively managed pastures over a grazing season. Two treatments of a long-term grazing experiment with heifers were investigated: extensive continuous grazing (EG) with a target sward height of 10 cm and intensive continuous grazing (IG) with a target sward height of 5 cm. Compressed sward height and related herbage mass (HM), dominant plant species and stage of development of phenology were determined at weekly or twice weekly intervals at fixed measuring points. The results demonstrated a strong variability in sward height and HM, especially on the EG treatment. The botanical composition of the standing herbage differed between treatments and between patches of different heights within the same treatment. In areas with a short sward, the herbage was predominantly composed of Agrostis capillaris, Festuca rubra and Trifolium repens. It was more evenly composed and also included taller growing species, such as Alopecurus pratensis and Galium mollugo, in areas with a tall sward. The area potentially available for reproductive development was high in the EG treatment and low in the IG treatment. The method employed proved suitable to provide a detailed description of the dynamics of the sward structure. [source] Seasonal differences in the adaptability of herbage species to environmental variations in a long-term grazing experimentGRASSLAND SCIENCE, Issue 1 2007Yiruhan Abstract Mixtures of orchardgrass, perennial ryegrass, tall fescue, redtop, Kentucky bluegrass, and white clover were sown in autumn 1973. Two 8-year grazing experiments were conducted at the National Grassland Research Institute (Nasushiobara, Japan) to determine the effects of grazing intensity and nitrogen levels on pasture ecosystems. These experiments involved two different grazing intensities (1974,1981) and two different nitrogen levels (1982,1989). Large spatiotemporal variations in phytomass due to environmental variations were observed in both experiments. Finlay,Wilkinson analysis was applied to clarify seasonal (monthly) differences in the adaptability of the herbage species, as measured by phytomass, to environmental variations by year and treatments in the two experiments. Seasonality in the adaptability to environments differed greatly among species. In this paper, we examined from livestock farmers' standpoint whether seasonality in adaptability of herbage species in the grazing pasture could be satisfied. A significantly high adaptability was shown for: orchardgrass from May to July and November; tall fescue in April, June and July, and November; redtop and Kentucky bluegrass in April; and Zoysia japonica in September and October. In contrast, perennial ryegrass and white clover exhibited very low adaptability in any season. Z. japonica and weeds such as Pennisetum alopecuroides, Eragrostis ferruginea and Digitaria adscendens, which had invaded from surrounding areas, showed low adaptability, except in autumn, when they showed moderate adaptability. [source] Evaluating the adaptability of herbage species to environmental variation through a long-term grazing experimentGRASSLAND SCIENCE, Issue 4 2005Yiruhan Abstract Mixtures of orchard grass, perennial ryegrass, tall fescue, redtop, Kentucky bluegrass and white clover were sown in the autumn of 1973. Two 8-year grazing experiments were carried out at the National Grassland Research Institute (Nasushiobara, Tochigi, Japan) to determine the effects of grazing intensity and nitrogen levels on the pasture ecosystem: two different grazing intensities (1974,1981) and two different nitrogen levels (1982,1989). Large temporal and spatial variations in phytomass were observed in both experiments. To clarify the adaptability of the phytomass of the herbage species to environmental variations in year, season and treatments, we re-examined the data obtained in these two experiments using a Finlay-Wilkinson analysis. Orchard grass and tall fescue achieved significantly higher phytomass in a more fertile environment in that they showed a high adaptability to environmental variation. Redtop and Kentucky bluegrass showed an increase in phytomass proportional to environmental improvement. The phytomass performances of perennial ryegrass and white clover were almost independent of environmental variation in that their adaptability was low. Finally, Zoysia japonica and weeds such as Pennisetum alopecuroides and Digitaria adscendens, which were invaders from the surrounding areas to the experimental site, were not observed in the pasture during the first 8-year period; during the second 8-year period, they showed moderate adaptability. [source] Grasslands, grazing and biodiversity: editors' introductionJOURNAL OF APPLIED ECOLOGY, Issue 2 2001Watkinson A.R. Summary 1Natural, semi-natural and artificial grasslands occur extensively around the globe, but successful management for production and biodiversity poses several dilemmas for conservationists and farmland managers. Deriving from three continents (Africa, Australia and Europe), papers in this Special Profile interface three specific issues: plant responses to grazing, plant invasions and the responses to management of valued grassland biota. 2Although pivotal in grassland management, plant responses to grazing are sometimes difficult to predict. Two alternative approaches are presented here. The first uses natural variations in sheep grazing around a water hole to model the dynamic population response of a chenopod shrub. The second analyses a long-term grazing experiment to investigate the links between plant traits and grazing response. 3Linked often crucially with grazing, but also driven sometimes by extrinsic factors, invasions are often cause for concern in grassland management. The invasions of grasslands by woody plants threatens grassland habitats while the invasions of pastures by alien weeds reduces pasture productivity. The papers in this section highlight how a complementary range of management activities can reduce the abundance of invaders. A final paper highlights how global environmental change is presenting new circumstances in which grassland invasion can occur. 4The impact of grassland management on biodiversity is explored in this Special Profile with specific reference to invertebrates, increasingly recognized both for the intrinsic conservation value of many groups and for their role in ecosystem processes. The potential for manipulating flooding in wet grasslands to increase the soil invertebrate prey of wading birds is illustrated, together with the roles of management and landscape structure in enhancing insect diversity. 5In the face of climate change and growing demands for agricultural productivity, future pressures on grassland ecosystems will intensify. In this system in which productivity and conservation are so closely bound, there is a need both to raise the profile of the issues involved, and to improve our understanding of the applied ecology required for successful management. [source] | ||||||||||