Fire and vegetation shifts in the Americas at the vanguard of Paleoindian migration     

Nicholas Pinter  Stuart Fiedel  Jon E. Keeley 《Quaternary Science Reviews》2011,30(3-4):269-272

Across North and South America, the final millennia of the Pleistocene saw dramatic changes in climate, vegetation, fauna, fire regime, and other local and regional paleo-environmental characteristics. Rapid climate shifts following the Last Glacial Maximum (LGM) exerted a first-order influence, but abrupt post-glacial shifts in vegetation composition, vegetation structure, and fire regime also coincided with human arrival and transformative faunal extinctions in the Americas. We propose a model of post-glacial vegetation change in response to climatic drivers, punctuated by local fire regime shifts in response to megaherbivore-driven fuel changes and anthropogenic ignitions. The abrupt appearance of humans, disappearance of megaherbivores, and resulting changes in New World fire systems were transformative events that should not be dismissed in favor of climate-only interpretations of post-glacial paleo-environmental shifts in the Americas. Fire is a mechanism by which small human populations can have broad impacts, and growing evidence suggests that early anthropogenic influences on regional, even global, paleo-environments should be tested alongside other potential causal mechanisms.  相似文献   

Dams on the Mekong River: Lost fish protein and the implications for land and water resources     

Stuart Orr  Jamie Pittock  Ashok Chapagain  David Dumaresq 《Global Environmental Change》2012,22(4):925-932

Proposed dam construction in the Lower Mekong Basin will considerably reduce fish catch and place heightened demands on the resources necessary to replace lost protein and calories. Additional land and water required to replace lost fish protein with livestock products are modelled using land and water footprint methods. Two main scenarios cover projections of these increased demands and enable the specific impact from the main stem dam proposals to be considered in the context of basin-wide hydropower development. Scenario 1 models 11 main stem dams and estimates a 4–7% increase overall in water use for food production, with much higher estimations for countries entirely within the Basin: Cambodia (29–64%) and Laos (12–24%). Land increases run to a 13–27% increase. In scenario 2, covering another 77 dams planned in the Basin by 2030 and reservoir fisheries, projections are much higher: 6–17% for water, and 19–63% for land. These are first estimates of impacts of dam development on fisheries and will be strongly mediated by cultural and economic factors. The results suggest that basic food security is potentially at a high risk of disruption and therefore basin stakeholders should be fully engaged in strategies to offset these impacts.  相似文献   

Modelling tropical cyclone risks for present and future climate change scenarios using geospatial techniques     

Muhammad Al-Amin Hoque  Stuart Phinn  Chris Roelfsema  Iraphne Childs 《International Journal of Digital Earth》2018,11(3):246-263

Tropical cyclones and their devastating impacts are of great concern to coastal communities globally. An appropriate approach integrating climate change scenarios at local scales is essential for producing detailed risk models to support cyclone mitigation measures. This study developed a simple cyclone risk-modelling approach under present and future climate change scenarios using geospatial techniques at local scales, and tested using a case study in Sarankhola Upazila from coastal Bangladesh. Linear storm-surge models were developed up to 100-year return periods. A local sea level rise scenario of 0.34?m for the year 2050 was integrated with surge models to assess the climate change impact. The resultant storm-surge models were used in the risk-modelling procedures. The developed risk models successfully identified the spatial extent and levels of risk that match with actual extent and levels within an acceptable limit of deviation. The result showed that cyclone risk areas increased with the increase of return period. The study also revealed that climate change scenario intensified the cyclone risk area by 5–10% in every return period. The findings indicate this approach has the potential to model cyclone risk in other similar coastal environments for developing mitigation plans and strategies.  相似文献   

Geophysical surveys of the sediments of Loch Ness,Scotland: implications for the deglaciation of the Moray Firth Ice Stream,British–Irish Ice Sheet     

Andrew J. Turner  John Woodward  Stuart A. Dunning  Adrian J. Shine  Chris R. Stokes  Colm Ó Cofaigh 《第四纪科学杂志》2012,27(2):221-232

We present results from three geophysical campaigns using high‐resolution sub‐bottom profiling to image sediments deposited in Loch Ness, Scotland. Sonar profiles show distinct packages of sediment, providing insight into the loch's deglacial history. A recessional moraine complex in the north of the loch indicates initial punctuated retreat. Subsequent retreat was rapid before stabilisation at Foyers Rise formed a large stillstand moraine. Here, the calving margin produced significant volumes of laminated sediments in a proglacial fjord‐like environment. Subsequent to this, ice retreated rapidly to the southern end of the loch, where it again deposited a sequence of proglacial laminated sediments. Sediment sequences were then disturbed by the deposition of a thick gravel layer and a large turbidite deposit as a result of a jökulhlaup from the Spean/Roy ice‐dammed lake. These sediments are overlain by a Holocene sheet drape. Data indicate: (i) a former tributary of the Moray Firth Ice Stream migrated back into Loch Ness as a major outlet glacier with a calving margin in a fjord‐like setting; (ii) there was significant sediment supply to the terminus of this outlet glacier in Loch Ness; and (iii) that jökulhlaups are important for sediment supply into proglacial fjord/lake environments and may compose >20% of proglacial sedimentary sequences. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

AGRICULTURAL CHEMICAL NEWS     

Stuart Cohen 《Ground Water Monitoring & Remediation》1988,8(2):38-40

  相似文献   

Early accretional history of the Earth and the Moon-forming event     

Stuart Ross Taylor 《Lithos》1993,30(3-4):207-221

  相似文献   

Agricultural Chemical News     

Stuart Cohen 《Ground Water Monitoring & Remediation》1994,14(2):96-97

  相似文献   

Photosynthesis-irradiance relationships for three species of submersed macrophytes in the tidal freshwater Hudson River     

Michael T. Harley  Stuart Findlay 《Estuaries and Coasts》1994,17(1):200-205

Net photosynthesis under a range of natural light intensities was determined for three common macrophytes of the tidal freshwater Hudson River:Vallisneria americana Michx.,Potamogeton perfoliatus L., andMyriophyllum spicatum L. Light-saturated net photosynthetic rates did not differ among species, nor were there differences among species in the light intensity at which respiration balanced photosynthesis. The initial slope (α) of the photosynthesis-irradiance (P-I) curve was greater forV. americana than the other two species. As a result, maximum photosynthetic rates were reached inV. americana at significantly lower irradiances than those required to saturate photosynthesis inP. perfoliatus andM. spicatum. This characteristic would give this species a competitive advantage under conditions in which growth is limited by light availability. Macrophyte biomass distribution showed no clear correlation with depth.V. americana was the most abundant of the three species, both in frequency of occurrence and absolute biomass. The low irradiance required for the saturation of photosynthesis inV. americana may contribute to its predominance in the turbid Hudson River.  相似文献   

A Preliminary Study of the Self-Directed Photography of Middle-Class,Homeless, and Mobility-Impaired Children*     

Stuart C. Aitken  Joan Wingate 《The Professional geographer》1993,45(1):65-72

Understanding the ways in which children with different life experiences come to terms with day-to-day contexts and constraints has become an important topic of social science research. This study applies the technique of auto-photography to the study of children-environment transactions. How children apprehend their environments is described through a leitmotif analysis and an interpretation of photographs taken by children from middle-class families, homeless children, and children whose mobility is impaired by cerebral palsy. We speculate upon the social and physical contexts of these children based upon the images that they selected to photograph. Although impressionistic, our findings suggest the importance of auto-photography as a method for uncovering children-environment transactions.  相似文献   

A National Evaluation of the Leaching Potential of Aldicarb Part 2. An Evaluation of Ground Water Monitoring Data     

Matthew N. Lorber  Stuart Z. Cohen  George D. DeBuchananne 《Ground Water Monitoring & Remediation》1990,10(1):127-141

  相似文献