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21.
William Pepper Wiley Barbour Alexei Sankovski Barbara BraatzAuthor vitae 《Environmental Science & Policy》1998,1(4):289-311
A new set of no-policy global greenhouse gas (GHG) emission scenarios was developed using the atmospheric stabilization framework, the same modeling tool that was used to generate the IS92 emission scenarios for the Intergovernmental Panel on Climate Change. Revised assumptions about population and economic growth, combined with updated information on changes in renewable energy supply, the efficiency of energy generation and other factors resulted in changes in GHG emission profiles over the next century, which led to an increase in the estimated global average temperature change as compared to the IS92 scenarios. Model results indicate that the largest increase in emissions, which led to a temperature increase of about 3.4°C by 2100 (relative to 1990), can be expected when a rapid increase in the GNP per capita levels of the non-OECD countries is combined with a low availability of solar/wind and biomass energy resources and slow energy efficiency improvements. The smallest increase in emissions and temperature by 2100 (about 2.5°C) occurred when a relatively slow increase in the GNP per capita in the non-OECD countries was combined with a high availability of renewable energy resources and rapid energy efficiency improvements. 相似文献
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Pepper W. Trail 《Behavioral ecology and sociobiology》1980,7(2):83-92
Summary Acorn woodpeckers (Melanerpes formicivorus) were studied during the summers of 1976 and 1977 in the Chiricahua Mountains of Arizona to determine the ecological correlates of variations in unit size, storage behavior, and home range. Unit size varied from two to five adults, acorn storage capacity varied from 0 to 5,000 individual holes per unit, and home range size varied from 5.2 to 51.2 ha.There was a consistent but nonsignificant trend for units inhabiting pine-oak woodland to be larger and to maintain more food storage holes than units in oak-juniper or oak woodland. Pine-oak woodland had the highest oak species number, density, and basal area of any community in the study area, and showed the least annual variation in percent of oaks producing acorns during the study. However, pineoak woodland also had the lowest acorn productivity per hectare.More than four times as many oak trees produced acorns in 1977 than in 1976. Following the poor 1976 crop, unit home range size increased so that the mean number of oaks contained per home range size increased more than three and a half times in 1977. The number of woodpecker units containing nonbreeding adults decreased from 90% in 1976 to 20% in 1977. These data suggest that the size and reliability of acorn crops control the composition of acorn woodpecker social units.A comparison of acorn woodpecker population parameters in the Chiricahua Mountains and at the Hastings Reservation, California, was made, using data of MacRoberts and MacRoberts (1976). The California population was significantly more dense and maintained more storage trees and more individual storage holes per unit, but there was no evidence that more California units contained nonbreeding adults than did Chiricahua units.A model is presented that emphasizes the importance of acorn crop reliability as the major determinant of acorn woodpecker social organization (Fig. 2). Annual crop fluctuations affect the winter survival and dispersion of woodpecker units, and the density of the population in the following spring. Bad acorn years will result in decreased saturation of woodpecker nesting habitat by established groups. The model predicts a corresponding decrease in the frequency of units with helpers, as young adults take advantage of opportunities to breed on their own. Longer-term crop reliability determines the benefitcost ratio for establishing and maintaining food storage facilities. The observed geographic variation in storage behavior between California and Arizona populations is suggested to reflect differences in the long-term return on investment in expensive storage facilities. 相似文献
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David Pepper Sally Eden Gordon Walker Susie Ohlenschlager Bob Roper Mary Blake 《Local Environment》2013,18(2):231-244
Making Cities Work: the role of local government in the urban environment. Richard Gilbert, Don Stevenson, Herbert Girardet &; Richard Stren, 1996, London, Earthscan, 203pp. ISBN 1 85383 354 1, £13.95 pbk Environmental Policy in an International Context, Vols 1–3: Perspectives, Conflicts and Prospects. P. Glasbergen &; A. Blowers (Series Eds) London, Arnold Rhetoric and Reality in Environmental Policy. M. Wintle &; R. Reeve (Eds), 1994, Aldershot, Avebury Studies in Green Research, 154 pp. ISBN 1 85628 927 3 FutureNatural: Nature, Science, Culture. G. Roberston et al. (Eds) 1996, London, Routledge, ISBN 0415 070139, £40.00 hbk Environmental Policy with Political Integration: the European Union and the United States. New horizons in environmental economics. John B. Braden, Henk Folmer &; Thomas S. Ulen (Eds), 1996, Cheltenham, Elgar Publishing, 477 pp. ISBN 1 85898 217 0 相似文献