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51.
Holocene fire history from the Greater Blue Mountains World Heritage Area, New South Wales, Australia: the climate, humans and fire nexus 总被引:1,自引:1,他引:1
This study presents a reconstruction of the fire activity of the last ~14,200 cal. years BP (before AD 1950) from Gooches Crater Right, located on the Newnes Plateau, approximately 150 km to the west of Sydney (~33°27′S, 150°16′E)
within the Blue Mountains National Park. Charcoal analysis and palynology were undertaken with the aim of untangling any inter-relationship
between climate, humans and fire. A chronology of the site was provided by radiocarbon dating. The dominant control on fire
in this environment during the Holocene appears to be climate. Periods of climate change, identified in previous studies,
are associated with higher levels of fire activity. Fire was less ubiquitous between ~9,000 and 6,000 years BP, a period normally
described as having a higher effective moisture in south-eastern Australia. The mid-Holocene fluctuations in charcoal may
reflect anthropogenic fire, climate forcing or alternatively human responses to any climate change. Coeval changes in palaeoclimatic
sequences elsewhere and palynology at the site support a climatic explanation or that Aboriginal people used fire within a
climatic framework. 相似文献
52.
珠三角秋冬季节长时间灰霾污染特性与成因 总被引:1,自引:6,他引:1
利用珠三角大气超级站2012年10月与2013年1月能见度、不同粒径颗粒物与BC质量浓度、气溶胶光散射系数、O3、相对湿度等在线监测数据,分析秋冬季节2次持续时间超过10 d的长时间灰霾过程污染特性与成因。结果表明,冬季灰霾过程中气溶胶吸光系数和光散射系数对大气总消光系数的贡献分别为13%和67%;PM2.5、PM1占PM10质量浓度分别为66%和39%;较高的PM2.5与BC日均浓度相关系数(R2=0.88)体现了一次排放对颗粒物质量浓度及能见度的显著影响。秋季灰霾过程中气溶胶吸光系数和光散射系数对大气总消光系数的贡献分别为11%和69%,由BC导致的吸光效应较冬季下降了约20%;PM2.5和PM1占PM10质量浓度比例分别为68%和45%,均高于冬季;O3浓度日最大小时值的平均值接近冬季的2倍;二次来源对PM2.5浓度升高和能见度下降起主导作用。来自不同方向的2种气团在珠三角僵持,大气扩散条件差是导致这2次灰霾过程的重要外在条件,应成为灰霾预报预警的重点关注对象。 相似文献
53.
Ammophila arenaria (marram grass) was introduced to South Africa from Europe as a means of stabilizing the Cape Flats in the 1870s, but was
only successfully established in the 1890s as it was found that seeds from the first introductions did not readily germinate.
By the end of the last century, it was successfully used as a dune stabilizing grass. It is now widely used in stabilization
projects along the Cape coastline, being established by planting cuttings or whole plants. Because of problems experienced
of marram becoming invasive, especially on the west coast of North America, and the fact that we have many invasive species
which threaten our indigenous dune fields, studies have been initiated on this plant in South Africa. Most work to date has
involved investigating the methods used to establish the plant in stabilization sites, and very little has been done on the
biology of the species in this country. Marram is generally thought not to seed in South Africa, and thus its spread has been
limited.
However, in the light of recent reports of successful germination of the seed, detailed studies on the phenology of seed production
and establishment in natural areas will be undertaken. Studies on the natural control by fungal species and nematodes will
be carried out in conjunction with work done in the Netherlands, so that a comparison of the biology of the species in South
Africa can be made with that in Europe, where it is used extensively to stabilize dunes. 相似文献
54.
南岳自然保护区素为天下名山,层峦叠翠,风光旖旎,灵动俊秀的自然景观,源远流长的宗教文化,古朴神奇的历史遗迹,形成了博大精深的旅游资源.我国加入WTO后,随着世界旅游业的蓬勃发展,一个全新的旅游分支文化旅游正呈现出迅猛的发展势头.南岳作为素有文明奥区之称,进行文化资源的调查,构筑系统的旅游文化体系,开拓旅游市场,提升旅游品位,做好保护与利用旅游资源这篇文章有着重要意义. 相似文献
55.
Leo W. Bruinzeel 《Behavioral ecology and sociobiology》2007,61(4):551-556
Intermittent breeding (skipping a breeding season) can be the result of an adaptive decision by a focal individual, trading
current reproductive success in favour of future reproductive success (residual reproductive value hypothesis). In contrast,
an individual can also be forced by conspecifics to abandon the familiar breeding site and refrain from breeding due to lack
of suitable alternative breeding sites or mates (competition hypothesis). I studied intermittent breeding in the territorial
and site-faithful Eurasian oystercatcher Haematopus ostralegus, using a dataset covering 20 years. Intermittent breeding (in total 86 cases) occurred among breeders that formerly bred
in high- as well as low-quality territories. The main factor associated with intermittent breeding in high-quality sites was
death of a mate, while in low quality sites divorce was the most prominent factor. In 93% of the cases birds were forced to
cease breeding due to pressure from conspecifics consistent with the competition hypothesis. There was no association between
intermittent breeding and promotion to a territory of better quality. Instead, oystercatchers returned to breeding habitat
of similar quality and at a very close distance (median distance 128 m) from the previous breeding location. Breeding absences
lasted on average 2.4 years, with a maximum of 9 years, and the quality of the territory obtained after the absence varied
with the duration of it. Birds who re-bred in a high-quality territory acquired this on average faster than those that re-bred
in a low-quality territory, indicating that birds in high-quality sites are better competitors. 相似文献
56.
南岳宗教文化历史悠久,最早进入南岳的宗教是中国土生土长的道教,据史载,西汉时道家就在南岳活动,到东汉时道教天师张道陵从天目山来南岳谒青玉坛和祭祀祝融神后,道教正式进入南岳活动,约在两晋南北朝时期,佛道传入南岳,至今已有1700年历史;佛道两家虽然信仰不同,追求各异,但友好相处,佛、道共存一山,共荣一庙(南岳庙),佛道共荣的宗教文化尤为国内外宗教名山所罕见,极盛时期,有宫观41所,佛寺150所;基督教于清末传入南岳,也有一定影响,南岳宗教文化的表现形式有:香期、庙会. 相似文献
57.
Ammophila arenaria (marram grass) was introduced to South Africa from Europe as a means of stabilizing the Cape Flats in the 1870s, but was
only successfully established in the 1890s as it was found that seeds from the first introductions did not readily germinate.
By the end of the last century, it was successfully used as a dune stabilizing grass. It is now widely used in stabilization
projects along the Cape coastline, being established by planting cuttings or whole plants. Because of problems experienced
of marram becoming invasive, especially on the west coast of North America, and the fact that we have many invasive species
which threaten our indigenous dune fields, studies have been initiated on this plant in South Africa. Most work to date has
involved investigating the methods used to establish the plant in stabilization sites, and very little has been done on the
biology of the species in this country. Marram is generally thought not to seed in South Africa, and thus its spread has been
limited.
However, in the light of recent reports of successful germination of the seed, detailed studies on the phenology of seed production
and establishment in natural areas will be undertaken. Studies on the natural control by fungal species and nematodes will
be carried out in conjunction with work done in the Netherlands, so that a comparison of the biology of the species in South
Africa can be made with that in Europe, where it is used extensively to stabilize dunes.
Nomenclature: Arnold & de Wet (1993) for vascular plants. 相似文献
58.
Mark R. L. Forbes Robert G. Clark Patrik J. Weatherhead Terry Armstrong 《Behavioral ecology and sociobiology》1994,34(2):79-85
We tested several predictions of nest defense theory by observing variation in flushing distance and probability of nest abandonment within and between six species of waterfowl. In these species, only the females incubate eggs and attend offspring. First, we examined whether flushing distance by females varied in relation to clutch size, stage of incubation, and time of season, after controlling for the number of visits made to nests by observers. Revisits by observers appeared to affect flushing distance by females for reasons unrelated to the relative value of the current clutch. We found that as incubation progressed, females allowed observers to approach more closely before flushing from the nest. In some species, females with larger clutches allowed closer approaches to nests before flushing which was also consistent with nest defense theory. In contrast, time of season (Julian date) did not relate to flushing distance for any species. When species were compared, we found that species with moderate to high yearly mortality and high reproductive output per breeding attempt (e.g., northern shoveler and blue-winged teal) were less likely to abandon nesting attempts and exhibited riskier behavior (remained at nests when approached closely by observers) than species that had lower yearly mortality (e.g., mallard). Our results show that flushing distance and patterns of nest abandonment by female ducks conform to several predictions of nest defense theory.Correspondence to: M.R.L. Forbes 相似文献
59.
PROBLEM: The purpose of this study is to understand the reasons behind older women's driving cessation by comparing the driving histories of Finnish women who either gave up or renewed their drivers license at the age of 70. METHOD: A mail survey was sent to all Finnish women born in 1927 who gave up their license in 1997 (N=1,476) and to a corresponding random sample of women who renewed their license (N=1,494). The total response rate was 42.1%. RESULTS: The length and level of activity of personal driving history were strongly associated with driving cessation and continuation. Ex-drivers tended to have an inactive driving career behind them, whereas drivers had a more active personal driving history. In addition, those women with an active, "male-like" driving history who had decided to stop driving gave reasons for driving cessation that were similar to what is known about older men's reasons to give up driving. The results suggest that the decision to stop driving is related to driving habits rather than gender. 相似文献
60.
Group sizes are often considered to be the result of a trade-off between predation risk and the costs of feeding competition. We develop a model to explore the interaction between different ecological constraints on group sizes, using a primate (baboons) case study. The model uses climatic correlates of time budgets to predict maximum ecologically tolerable group size, and climatic predictors of predation risk (reflected mainly in predator density and female body mass) to predict minimum tolerable group size for any given habitat. As well as defining the range of sustainable group sizes for a given habitat, the model also allows us to reliably predict our exemplar taxon's biogeographical distribution across Africa. We also explore the life history implications of the model to ask whether baboons form group sizes which maximise survival or fecundity in the classic trade off between these two key life history variables. Our results indicate that, within the range of study sites in our sample, baboons prefer to maximise fecundity. However, the data indicate that in higher predation risk habitats they would switch to maximising survival at the expense of fecundity. We argue that this is due to the fact that interbirth interval and developmental rates have a ceiling that cannot be breached. Thus, while females can shorten interbirth intervals to compensate for increased predation risk, there is a limit to how much these life history variables can be altered, and when this is reached the best strategy is to maximise survivorship. 相似文献