Literature type: Scientific
Journal: Journal of Ornithology
, Pages: online June 2013.
Full reference: Wang, X., Zhang, Y., Zhao, M. Cao, L. & Fox, A.D. 2013. The benefits of being big: effects of body size on energy budgets of three wintering goose species grazing Carex beds in the Yangtze River floodplain, China. Journal of Ornithology : online June 2013. https://www.dx.doi.org/10.1007/s10336-013-0979-7
Herbivores of different body size vary in food selection because of their different metabolic requirements and abilities to harvest and digest food. Compared with smaller grazers, larger ones require higher food quantity but can tolerate poorer quality. This divergence may also explain habitat partitioning in the distribution of closely related species. By estimating daily energy expenditure (based on observed activity budgets) and energy intake (using the indigestible marker method in food and faeces), we compared the field energy budgets of three wintering herbivorous goose species differing in body size feeding on the same Carex meadows. Throughout the winter, the larger Bean Geese Anser fabalis serrirostris and Greater White-fronted Geese Anser albifrons maintained positive energy budgets grazing lower quality Carex, in contrast to the smaller Lesser White-fronted Geese Anser erythropus which failed to do so and could only maintain positive energy budgets by grazing high-quality Alopecurus, Cynodon and Eleocharis. However, all three species failed to maintain positive energy balance and lost mass in midwinter. These results have important implications for explaining the divergent distribution patterns of these species on their wintering grounds in China.
Literature type: Thesis
Full reference: Niemelä, M. 2009. Biotic interactions and vegetation management on coastal meadows. , Acta Universitatis Ouluensis. A Scientiae Rerum Naturalium 360. Faculty of Science, University of Oulu, Finland.
Conservation of rare habitats and species are central elements in the management of semi-natural grasslands of high biodiversity. Understanding the impacts of various abiotic and biotic interactions and management methods on threatened species is fundamental to their conservation. In the present study, effects of competition, plant parasitism, grazing and mowing were studied at the community level in Bothnian Bay coastal meadows and in greenhouse. This was the first time when the impacts of various biotic interactions on the critically endangered creeping alkali grass (Puccinellia phryganodes) have been explored in detail in one of its rare occurrences in the boreal vegetation zone in Europe. In addition, questions related to ecological and economical sustainability of cattle grazing on coastal meadows were examined. Puccinellia phryganodes was found to suffer severely from competition with taller graminoids. Simulated and actual grazing by greylag goose, Anser anser, as well as infection by a hemiparasitic plant, Odontites litoralis, were found to indirectly benefit P. phryganodes by decreasing the competitive advantage of its competitors. In spite of the relatively intensive grazing by greylag goose in the field, P. phryganodes experienced a drastic decrease during four years in the grazed experimental quadrats and simultaneously the proportion of the taller graminoids increased substantially. Primary succession of coastal meadow vegetation was found to progress rapidly and continuous formation of suitable open habitats is therefore crucial for the subordinate species. Mowing was found to be an effective management method for some threatened plant species in coastal meadows, but not for P. phryganodes, which would probably benefit more, for example, from livestock grazing. Both lightly and rather intensively managed large open meadows could provide optimal habitats for the critically endangered lesser white fronted goose (Anser erythropus) as well as for the greylag goose. The relatively low and variable yield of the coastal meadow vegetation compared to that of cultivated grasslands sets limits how management by cattle grazing can be implemented. Key factors for both the biodiversity management and livestock production in coastal meadows are timing of the grazing season, intensity of grazing and selection of suitable types of animals.
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