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31.
32.
Conservation Implications of Introduced Game Birds in High-Elevation Hawaiian Shrubland 总被引:1,自引:0,他引:1
F. Russell Cole Lloyd L. Loope Arthur C. Medeiros Jane A. Raikes Cynthia S. Wood 《Conservation biology》1995,9(2):306-313
The Ring-necked Pheasant ( Phasianus colchicus ) and the Chukar ( Alectoris chukar ) are the dominant avifauna in high-elevation shrubland (2070–3000 m) of Haleakala National Park, Maui, Hawaii. We studied the food habits, ecological niche, and effects of these alien game birds on the native biota in this Hawaiian ecosystem. Analyses of crop contents indicated that pheasant and Chukar consumed predominantly fruits of native, woody dicots (39% and 47% respectively) and leaves (29% and 24% respectively) and flower parts (12% and 17% respectively) of alien, herbaceous dicots. Both species generally selected food items according to their relative availability, although other factors influenced choice of certain items. Invertebrates were a minor component of the game-bird diet, suggesting that their impact on native invertebrate populations is minimal. Pheasant and Chukar occupy, at least partially, an ecological niche once held by now-extinct or rare birds, and they appear not to be significant competitors with the endangered Nene. The role of these alien birds in facilitating seed dispersal and germination of native plant species is beneficial in restoring degraded ecosystems. 相似文献
33.
We report a child with a subarachnoid cyst with hydrocephalus following a mid-trimester amniocentesis. Although fetal trauma is a rare complication, it is important to stress the need to perform amniocentesis under ultrasound control. Children with neurological disease or convulsions of unknown origin in early infancy who are born to mothers who have had midtrimester amniocentesis should have a CT scan as part of the investigations to exclude this rare but nevertheless important complication. 相似文献
34.
Philip J. Lloyd 《Atmospheric environment (Oxford, England : 1994)》2010,44(26):3196-3206
Data on wet-only precipitation from the National Atmospheric Deposition Program/National Trends Network were analysed for trends in the sodium and chloride fluxes over the United States between 1 January 1984 and 31 December 2006. The data were first checked for consistency and for ionic balance. It was necessary to correct for changes in bicarbonate due to changes in atmospheric CO2 levels over the study period, in order to obtain a balance. The fluxes were calculated and the trends determined by linear regression in the log domain. The significance of the trends was checked using both F- and t-tests. At 154 sites having reasonably continuous records over the assessment period, the sodium flux fell significantly at 139 and increased significantly at only one. The chloride flux similarly fell significantly at 140 and increased significantly at the same one as the sodium flux increased. At coastal sites the chloride to sodium ratio was the same as that in sea water, within experimental limits. Further from the coast the ratio changed apparently due to changes in the entire aerosol chemistry. The findings are discussed in terms of the simplicity and robustness of the methodology employed to determine the trends; the oceanic origin of most observable sodium even in the interior of the continent, probably because it occurs as a fine (<1 micron) aerosol which is poorly scavenged by precipitation; and the possibility that the drop in sodium and chloride fluxes might be driven by climate change. 相似文献
35.
Donald R. Rowe William G. Lloyd 《Journal of the Air & Waste Management Association (1995)》2013,63(3):253-255
A comparative study was performed in order to determine the relative accuracy of a gaussian dispersion model. The U.S. EPA’s RAM (Urban) model was chosen to estimate 24-hour average sulfur dioxide concentrations in the Cleveland, Ohio area. Point and area source emissions, along with a background concentration were included in the modeling effort. Projections from the model made at the ambient air stations were compared to measured sulfur dioxide concentrations. A total of 3020 comparisons were performed at 33 monitoring sites. An analysis of the results illustrates that, on a daily basis, the predictions of the model did not reflect actual air quality. The correlation coefficients of the 24-hour comparisons at the monitoring sites varied from a low of —0.121 to a high of 0.541. When the highest and second highest modeled concentrations were evaluated with respect to the highest and second highest measured concentrations, over a period of a year, a more favorable comparison was observed. 相似文献
36.
Lloyd L. Schulman Steven R. Hanna 《Journal of the Air & Waste Management Association (1995)》2013,63(3):258-264
The Industrial Source Complex (ISC) model has been modified to account for Improved understanding of plume rise and downwash around buildings. Two sets of observations are used to compare the modified and the original ISC models, showing that the new model better simulates the observed concentrations during high-wind conditions when downwash usually occurs. 相似文献
37.
The effects of landscape fragmentation on nest predation and brood parasitism, the two primary causes of avian reproductive failure, have been difficult to generalize across landscapes, yet few studies have clearly considered the context and spatial scale of fragmentation. Working in two river systems fragmented by agricultural and rural-housing development, we tracked nesting success and brood parasitism in > 2500 bird nests in 38 patches of deciduous riparian woodland. Patches on both river systems were embedded in one of two local contexts (buffered from agriculture by coniferous forest, or adjacent to agriculture), but the abundance of agriculture and human habitation within 1 km of each patch was highly variable. We examined evidence for three models of landscape effects on nest predation based on (1) the relative importance of generalist agricultural nest predators, (2) predators associated with the natural habitats typically removed by agricultural development, or (3) an additive combination of these two predator communities. We found strong support for an additive predation model in which landscape features affect nest predation differently at different spatial scales. Riparian habitat with forest buffers had higher nest predation rates than sites adjacent to agriculture, but nest predation also increased with increasing agriculture in the larger landscape surrounding each site. These results suggest that predators living in remnant woodland buffers, as well as generalist nest predators associated with agriculture, affect nest predation rates, but they appear to respond at different spatial scales. Brood parasitism, in contrast, was unrelated to agricultural abundance on the landscape, but showed a strong nonlinear relationship with farm and house density, indicating a critical point at which increased human habitat causes increased brood parasitism. Accurate predictions regarding landscape effects on nest predation and brood parasitism will require an increased appreciation of the multiple scales at which landscape components influence predator and parasite behavior. 相似文献
38.
39.
Lloyd C. Irland 《Environmental management》1980,4(5):381-389
The eastern spruce budworm is a major forest pest over the continental range of the spruce-fir forest ecosystem and its southern ecotonal fringes in Canada and the northeastern United States. The current budworm outbreak illustrates the difficulty of arriving at economically sound and publicly acceptable forest pest control policies. Policies ranging from no use of chemical control to annual widespread crop protection have been adopted. There is no single all-around best policy for spruce budworm control. Chemical spray programs have demonstrably slowed the normal progress of mortality due to budworm, but have not eradicated the pest. Where industry remains heavily dependent on a fully utilized spruce-fir forest, no easy, low-cost solutions to the budworm problem exist. Reliance on spraying will have to be reduced and plans made to utilize higher levels of tree mortality and to manage the forest for lower future vulnerability. 相似文献
40.
Bruce Lloyd 《Resources Policy》1975,1(6):326-342
This paper discusses the present position and future prospects of mineral exploration and exploitation in Indonesia. It places the industry within the economic and political context of the country as a whole and considers the development of government policy towards the sector. Although the mineral resources of Indonesia are believed to be vast, the performance of the industry in the past has been erratic. The relative political stability of the last few years, combined with rising prices, has encouraged the opening up of new mines, and has also emphasised the need for more local processing of those minerals that are produced. At present, income from oil provides most of the government revenue and consequently the prospects of this sector are critically important for the nation's future. Increased diversification can, however, be expected in the next few years as the resources of tin, bauxite, nickel, copper, coal and many other products are developed. Given a favourable political and economic climate, Indonesia could be one of the world's major mineral producers by the end of the century. 相似文献