The droughts of 1997 and 2005 in Amazonia: floodplain hydrology and its potential ecological and human impacts     

Javier Tomasella  Patrícia F. Pinho  Laura S. Borma  José A. Marengo  Carlos A. Nobre  Olga R. F. O. Bittencourt  Maria C. R. Prado  Daniel A. Rodriguez  Luz A. Cuartas 《Climatic change》2013,116(3-4):723-746

It is well known that most of the severe droughts in Amazonia, such as that of 1997, are El Niño-related. However, in 2005, the Amazon was affected by a severe drought that was not El Niño-related, as most of the rainfall anomalies that have happened in southwestern Amazonia are driven by sea surface temperature anomalies in the tropical North Atlantic. Earlier studies have analyzed both droughts in terms of their meteorological causes and impacts in terra firme (non-flooded) forests. This study compares the hydrological effects of both droughts on the Amazonian floodplain and discusses their potential ecological and human impacts based on an extensive literature review. The results revealed that the effects of the 2005 drought were exacerbated because rainfall was lower and evaporation rates were higher at the peak of the dry season compared to the 1997 drought. This induced a more acute depletion of water levels in floodplain lakes and was most likely associated with higher fish mortality rates. Based on the fact that the stem growth of many floodplain species is related to the length of the non-flooded period, it is hypothesized that the 1997 drought had more positive effects on floodplain forest growth than the 2005 drought. The fishing community of Silves in central Amazonia considered both droughts to have been equally severe. However, the 2005 drought was widely broadcasted by the press; therefore, the governmental mitigation efforts were more comprehensive. It is suggested that the availability of new communication technology and greater public awareness regarding environmental issues, combined with the new legal framework for assessing the severity of calamities in Brazil, are among the primary factors that explain the difference in societal response between the two droughts.  相似文献   

Hydrologic,geomorphic and climatic processes controlling willow establishment in a montane ecosystem     

David J. Cooper  Joyce Dickens  N. Thompson Hobbs  Lindsey Christensen  Laura Landrum 《水文研究》2006,20(8):1845-1864

Willow communities dominate mid‐elevation riparian areas throughout the Rocky Mountains of North America. However, many willow stands are rapidly declining in aerial cover and individual plants in stature. A poor understanding of the processes that control willow establishment hinders identifying the causes of this decline. We analysed the processes that have facilitated or limited willow establishment over the last half of the 20th century on two large floodplains in Rocky Mountain National Park in Colorado by addressing two questions: (1) How does hydrologic regime control willow establishment on different fluvial landforms? (2) How might climate‐driven variations in hydrologic regime affect future willow establishment? We precisely aged willows on the three most common fluvial landforms, stream point bars, drained beaver ponds, and abandoned channels, and statistically related establishment dates to patterns of annual stream peak flow. The role of peak flow on willow establishment varied significantly by landform. Willow recruitment had occurred nearly every year on point bars. In former beaver complexes, most willows had established following dam breaches, whereas willows had established on abandoned channels for several years following channel avulsion. Establishment on point bars and abandoned channels was driven by peak flows of 2‐ to 5‐year return intervals, whereas in abandoned beaver ponds most establishment was associated with flow events of >5‐year return interval. Models of climate change suggest that temperatures will increase and precipitation seasonality will shift over the coming decades in the Rocky Mountains, leading to earlier spring runoff, lower summer and fall flows, decreased snowpack and decreased soil moisture. Such changes are likely to diminish opportunities for willow establishment. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

The interaction of 3C 401 with the surrounding intracluster medium     

Christopher S. Reynolds  Laura W. Brenneman  John T. Stocke 《Monthly notices of the Royal Astronomical Society》2005,357(1):381-386

  相似文献   

Anisotropy in the distribution of satellites around primary galaxies in the 2dF Galaxy Redshift Survey: the Holmberg effect   总被引：1，自引：0，他引：1  

Laura Sales  Diego G. Lambas†‡ 《Monthly notices of the Royal Astronomical Society》2004,348(4):1236-1240

  相似文献   

Satellites of simulated galaxies: survival, merging and their relationto the dark and stellar haloes     

Laura V. Sales  Julio F. Navarro †  Mario G. Abadi  Matthias Steinmetz 《Monthly notices of the Royal Astronomical Society》2007,379(4):1464-1474

  相似文献   

The Behavior of Sandwich Structures of Isotropic and Composite Materials: by Jack R. Vinson; 1999, TECHNOMIC Publishing Company, Inc., Lancaster, PA, USA, 378 pp.     

P. A. A. Laura  C. A. Rossit 《Ocean Engineering》2001,28(10):1437

  相似文献   

X-ray, Lyα and Hα emission from simulated disk galaxies     

Jesper Sommer-Larsen  Sune Toft  Jesper Rasmussen  Kristian Pedersen  Martin Götz  Laura Portinari 《Astrophysics and Space Science》2003,284(2):693-696

The X-ray properties of the haloes of disk galaxies formed in fully cosmological, hydro/gravity simulations are discussed. The results are found to be consistent with observational X-ray detections and upper limits. Disk galaxy haloes are predicted to be about an order of magnitude brighter at z ∼ 1 than at z=0. The Lyα and Hα surface brightness of an edge-on, Milky Way like model galaxy has been determined. The emission is found to be quite extended, with a scale height of about 600 pc, neglecting dust corrections. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

What's new with CUASHI?     

Toran L  Hooper R 《Ground water》2004,42(5):638-640

  相似文献   

Biomarkers of exposure and effect in the Brazilian flounder Paralichthys orbignyanus (Teleostei: Paralichthyidae) from the Patos Lagoon estuary (Southern Brazil)     

Amado LL  Robaldo RB  Geracitano L  Monserrat JM  Bianchini A 《Marine pollution bulletin》2006,52(2):207-213

Biomarkers of exposure (liver metallothionein-like proteins content and catalase and glutathione S-transferase activities) and effect (liver lipoperoxidation and blood cell DNA damage) of contaminants were analyzed in the Brazilian flounder Paralichthys orbignyanus from the Patos Lagoon estuary (Southern Brazil). Flounders were collected for a year in two sites: "Coroa do Boi" (polluted site) and "Saco do Justino" (non-polluted site). Results indicated that micronucleated cells frequency was the best biomarker to distinguish flounders from the two sites. Taken together, data from DNA damage analyses (micronucleus test and comet assay) indicated that flounders from the non-polluted site efficiently repaired the DNA breaks, contrary to those from the polluted site, which probably had their DNA repair system inhibited or exhausted. Furthermore, data from enzyme activities (catalase and GST) and lipid peroxidation indicated that flounders from the polluted site were under oxidative stress in summer and autumn.  相似文献   

Entanglement of New Zealand fur seals in man-made debris at Kaikoura, New Zealand     

Boren LJ  Morrissey M  Muller CG  Gemmell NJ 《Marine pollution bulletin》2006,52(4):442-446

New Zealand fur seals in the Kaikoura region breed near a town with expanding tourist and fishing industries and commonly come ashore entangled in nets and plastic debris. However, the rate at which entanglement occurs was previously unknown. A decade of Department of Conservation seal callout data was analysed to determine the level of entanglement in the region and the most common debris type. Monitoring of adult female fur seals released from entanglement provided information on the potential for serious wounds to heal and survivorship of released individuals. Entanglement rates of pinnipeds in Kaikoura are some of the highest reported world-wide (average range: 0.6-2.8%) with green trawl net (42%), and plastic strapping tape (31%) together contributing the most to debris types. Nearly half of the reported entangled seals are successfully released (43%) and post-release monitoring shows that with appropriate intervention the chance of an individual surviving even with a significant entanglement wound is high. Our study demonstrates that while entanglement in the region is high, a successful intervention protocol may help reduce the potential for entanglement-related mortality in the region.  相似文献