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Matthew J. Labrum 《Ecological modelling》2011,222(5):1205-1207
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能见度的降低与大气污染的关系 总被引:7,自引:0,他引:7
根据重庆十年能见度及气象数据和大气监测数据,作出了不同风向上能见度玫瑰图和多元回归模型.结果显示,水平能见度距离的降低,主要是空气污染引起的. 相似文献
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Waite TA 《Environmental management》2007,40(3):476-480
Bushmeat hunting, a key source of dietary protein, has been implicated as a major extinction threat to tropical vertebrate
species in West Africa. Ideally, any such hunting of wild species should be done sustainably, with off-take levels low enough
to ensure viability of harvested species. Recent work purports to show that a mature bushmeat market in a major city in Ghana
operates sustainably after depletion of vulnerable, slow-reproducing species (Cowlishaw and others 2005). I revisit two aspects of this work. First, I retest the prediction that larger species are transported to the market from
greater distances, as expected if overexploitation depletes large species close to the city. Cowlishaw and others failed to
find a significantly positive relationship between species-specific body mass and distance between capture site and the market.
However, my reanalysis provides evidence for a positive relationship after all, consistent with unsustainable harvesting.
In particular, ungulate species were harvested significantly farther from the market than smaller-bodied rodent species. Second,
I caution that just because species “persist” in the marketplace in no way implies that they can withstand hunting pressure
elsewhere and so should be of little concern to conservationists. I reveal that such species, despite their high intrinsic
rates of population growth, are not robust elsewhere. Several of them have disappeared from a network of protected areas in
Ghana (Brashares and others 2001). I show that faster-reproducing species are not necessarily more likely to persist in protected areas. The mere presence
of fast-reproducing species in a mature bushmeat market should not be construed as generalizable robustness; criteria for
ecological sustainability should ensure viability; and harvested species should be robust, not highly prone to extinction,
in protected areas. 相似文献
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Pascal Godefroit Lina Golovneva Sergei Shchepetov Géraldine Garcia Pavel Alekseev 《Die Naturwissenschaften》2009,96(4):495-501
A latest Cretaceous (68 to 65 million years ago) vertebrate microfossil assemblage discovered at Kakanaut in northeastern
Russia reveals that dinosaurs were still highly diversified in Arctic regions just before the Cretaceous–Tertiary mass extinction
event. Dinosaur eggshell fragments, belonging to hadrosaurids and non-avian theropods, indicate that at least several latest
Cretaceous dinosaur taxa could reproduce in polar region and were probably year-round residents of high latitudes. Palaeobotanical
data suggest that these polar dinosaurs lived in a temperate climate (mean annual temperature about 10°C), but the climate
was apparently too cold for amphibians and ectothermic reptiles. The high diversity of Late Maastrichtian dinosaurs in high
latitudes, where ectotherms are absent, strongly questions hypotheses according to which dinosaur extinction was a result
of temperature decline, caused or not by the Chicxulub impact. 相似文献
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Directly comparable data on the environmental and socio-economic impacts of alien species informs the effective prioritisation of their management. We used two frameworks, the Environmental Impact Classification for Alien Taxa (EICAT) and Socio-Economic Impact Classification for Alien Taxa (SEICAT), to create a unified dataset on the severity and type of impacts caused by alien leporids (rabbits and hares). Literature was reviewed to collate impact data, which was categorised following EICAT and SEICAT guidelines. We aimed to use these data to identify: (1) alien leporid species with severe impacts, (2) their impact mechanisms, (3) the native species and local communities vulnerable to impacts and (4) knowledge gaps. Native species from a range of taxonomic groups were affected by environmental impacts which tended to be more damaging than socio-economic impacts. Indirect environmental impacts were particularly damaging and underreported. No impact data were found for several alien leporid species.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01642-7. 相似文献
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C3H8是液化石油气的主要成分之一,对其湍流燃烧特性的研究对火灾消防等行业具有十分重要的意义。建立了一维湍流模型(ODT)的大规模计算平台并研究在固定雷诺数Re=9800的情况下,丙烷非预混湍流射流火焰中的局部熄火和再燃现象。丙烷火焰的模拟结果显示局部熄火现象主要发生在近场区域。火焰主要自由基OH、O及主要燃烧产物在局部熄火区域都迅速减少,随着之后再燃的发生,这些组分也开始逐渐增多。但是从这些组分增加的量可以看出,丙烷火焰的再燃过程相对比较慢并且没有达到完全再燃。 相似文献
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Two species of butterflies, Euphydryas aurinia and Melitaea phoebe, coexist as two metapopulations in a 38-patch network in Hebei Province, China. A Markovian model, whose transition matrix is the product of two matrices which represent the local extinction and recolonization process respectively, is used to describe the metapopulation dynamics. The application of this model to the metapopulation, consisting of 12 local populations in the northern subregion, shows that the expected life times of E. aurinia and M. phoebe are 160 and 121 years respectively and usually nearly half of the patches are occupied by E. aurinia, while only 1–3 patches are occupied by M. phoebe. We claim that E. aurinia can persist for a long time while M. phoebe faces relatively big extinction risk. By comparing the population dynamics with and without migration, we find M. phoebe benefits much more from migration than E. aurinia. Most patches are occupied mainly by local populations for E. aurinia, while by immigrants from the 8th patch for M. phoebe, meaning that E. aurinia has a classical metapopulation structure while M. phoebe has a source–sink metapopulation structure. 相似文献