89 resultados para Export competition

em BORIS: Bern Open Repository and Information System - Berna - Suiça


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As the clock is ticking for a positive outcome at the Ninth WTO Ministerial Conference to be held in Bali in December 2013, agricultural negotiators are scrambling to find solutions to issues such as tariff-rate quota (TRQ) administration and export competition in order to improve trade flows. The main issue seems to be whether WTO rules applying to public stockpiles in developing countries need to be changed or temporarily suspended as a means to enhance national food security. This paper is based on a note submitted to the ICTSD-IPC Expert Group “Meeting on Agriculture and Food Security – Policy Options for MC9 and beyond” (Geneva, June 2013). It lists the policy instruments impacting on global, national and (urban and rural) household food security – “The Food Security Tool Box” – and asks which immediate decisions the WTO Ministers might take in this field despite the political difficulties such as continued agro-dumping practices or the “land grab” issue. Three such “deliverables” are outlined: (i) regional and “virtual” food security schemes could be allowed to provide reserves to other countries without violating the obligation to “form an integral part of a food security programme identified in national legislation” (Agreement on Agriculture, Annex II, para 3); (ii) TRQ under-fills could be improved by mandatory enquiries into low fill rate situations; and (iii) World Food Program (WFP) and other non-commercial food purchases could be exempted from export restrictions and prohibitions. High ambitions for Bali seem to be misplaced. A more realistic yet real progress could restore the dwindling credibility of the WTO as a forum for trade negotiations.

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Early developmental conditions have major implications for an individual's fitness. In species where offspring are born simultaneously, the level of sibling competition for food access is intense. In birds, high sibling competition may subject nestlings to decreased growth rate as a result of limited food and increased levels of oxidative stress through high metabolic activity induced by begging behaviors. We manipulated the level of sibling competition in a natural population of great tits and assessed the consequences for nestling body condition and resistance to oxidative stress. In a full factorial design, we both augmented brood size to increase sibling competition and supplemented the male parents with physiological doses of carotenoids thereby doubling the natural carotenoid intake, aiming at increasing the males' investment in current reproduction and thereby decreasing sibling competition. Nestling body mass was reduced by the brood enlargement and enhanced by the carotenoid supplementation of fathers. Nestling resistance to oxidative stress, measured as total antioxidant defenses in whole blood, was not influenced by the treatments. Because nestlings experience high metabolic activities, an absence of an effect of sibling competition on free radicals production seems unlikely. Nestling body mass decreased and resistance to oxidative stress tended to increase with initial brood size, and hence these correlational effects suggest a trade-off between morphological growth and development of the antioxidant system. However, the result of the experimental treatment did not support this trade-off hypothesis. Alternatively, it suggests that nestling developed compensatory mechanisms that were not detected by our antioxidant capacity measure.

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Alpine snowbeds are habitats where the major limiting factors for plant growth are herbivory and a small time window for growth due to late snowmelt. Despite these limitations, snowbed vegetation usually forms a dense carpet of palatable plants due to favourable abiotic conditions for plant growth within the short growing season. These environmental characteristics make snowbeds particularly interesting to study the interplay of facilitation and competition. We hypothesised an interplay between resource competition and facilitation against herbivory. Further, we investigated whether these predicted neighbour effects were species-specific and/or dependent on ontogeny, and whether the balance of positive and negative plant–plant interactions shifted along a snowmelt gradient. We determined the neighbour effects by means of neighbour removal experiments along the snowmelt gradient, and linear mixed model analyses. The results showed that the effects of neighbour removal were weak but generally consistent among species and snowmelt dates, and depended on whether biomass production or survival was considered. Higher total biomass and increased fruiting in removal plots indicated that plants competed for nutrients, water, and light, thereby supporting the hypothesis of prevailing competition for resources in snowbeds. However, the presence of neighbours reduced herbivory and thereby also facilitated survival. For plant growth the facilitative effects against herbivores in snowbeds counterbalanced competition for resources, leading to a weak negative net effect. Overall the neighbour effects were not species-specific and did not change with snowmelt date. Our finding of counterbalancing effects of competition and facilitation within a plant community is of special theoretical value for species distribution models and can explain the success of models that give primary importance to abiotic factors and tend to overlook interrelations between biotic and abiotic effects on plants.