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21.
How much water do Chilean forests use? A review of interception losses in forest plot studies 下载免费PDF全文
After several years of decreased annual rainfall and water shortages, the Chilean society is demanding that forest plantations take accountability of their role in consuming scarce water resources. Evidence has shown that interception losses are considerable when determining water production in watersheds. The aim of this study was to determine if site and stand variables explain interception losses by Chilean forests for the development of an empirical model that could predict the potential impacts of forest management practices and land‐use change. A total of 127 data from annual water balance plot studies in Chile were compiled to derive relationships between interception and precipitation, species composition, plantation age and other stand and site variables. The reviewed data indicated that annual interception losses are mainly explained by annual rainfall and basal area of the forest stands, with a clear difference between the northern (dryer) and southern (wetter) regions of Chile. For a wide latitudinal gradient, forest composition and age, annual interception accounted for approximately 21% of incoming precipitations. Broadleaved forest stands (including native broadleaved and eucalypt forests) generally presented higher interception losses than conifers. Interception was higher in northern zones, indicating that forests have greater impacts on water resources in dryer regions. Our results were compiled in empirical models, which can be used to estimate forest interception in a latitudinal gradient in Chile and to support policy making. These results are also proposed as an approximate analogue of the changes in forest interception losses, which may occur as vegetation belts shift latitudinally as a result of the impact of climate change. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
22.
Sylvia E. Berg Valentin R. Troll Steffi Burchardt Morten S. Riishuus Michael Krumbholz Ludvik E. Gústafsson 《Geology Today》2014,30(2):54-60
The ‘forgotten fjords’ and ‘deserted inlets’ of NE‐Iceland, in the region between Borgarfjörður Eystri and Loðmundarfjörður, are not only prominent because of their pristine landscape, their alleged elfin settlements, and the puffins that breed in the harbour, but also for their magnificent geology. From a geological point of view, the area may hold Iceland's best kept geological secret. The greater Borgarfjörður Eystri area hosts mountain chains that consist of voluminous and colourful silicic rocks that are concentrated within a surprisingly small area (Fig. 1 ), and that represent the second‐most voluminous occurrence of silicic rocks in the whole of Iceland. In particular, the presence of unusually large volumes of ignimbrite sheets documents extremely violent eruptions during the Neogene, which is atypical for this geotectonic setting. As a group of geoscientists from Uppsala University (Sweden) and the Nordic Volcanological Center (NordVulk, Iceland) we set out to explore this remote place, with the aim of collecting material that may allow us to unravel the petrogenesis of these large volumes of silicic rocks. This effort could provide an answer to a long‐standing petrological dilemma; the question of how silicic continental crust is initially created. Here we document on our geological journey, our field strategy, and describe our field work in the remote valleys of NE‐Iceland. 相似文献
23.
Simon A. Parfitt G. Russell Coope Sylvia M. Peglar John E. Whittaker 《Proceedings of the Geologists' Association. Geologists' Association》2010,121(1):55-52
At three sites along the North Norfolk coast, freshwater sediments containing arctic plants have been reported to occur immediately beneath the glacial deposits. The sections at Mundesley and Beeston are no longer visible but a small exposure of this ‘Arctic Fresh-water Bed’ has recently been rediscovered at Ostend near Bacton. The fossils from this deposit are distinctly high boreal/arctic in character, indicating a small, possibly ephemeral, pool in a generally open landscape supporting some dwarf shrubs and conifers. Noteworthy records include three beetle species (Pterostichus brevicornis, P. middendorffi and Helophorus obscurellus) that today have their closest occurrences on either the Kanin or Kola peninsulas in arctic Russia. A Mutual Climatic Range reconstruction on the limited beetle fauna suggests that the mean temperatures of the warmest and coldest months were between 9 °C and 11 °C and between −36 °C and −10 °C, respectively. Other noteworthy occurrences include the aquatic pulmonate gastropod Gyraulus rossmaessleri (second and earliest British record), the ostracod Amplocypris tonnensis (earliest British record), ground squirrel (Spermophilus sp.) and the first record of arctic lemming (Dicrostonyx sp.) from the Cromer Forest-bed Formation (CF-bF). The ‘Arctic Fresh-water Bed’ has been assigned to the Bacton Member of the CF-bF and formed during the early Anglian, correlated with Marine Isotope Stage (MIS) 12 of the deep sea record. The Ostend assemblage is therefore important in providing a glimpse of conditions that occurred during a major cold stage in the early Middle Pleistocene. 相似文献
24.
The way that the media reports and comments on key events in the fragmented global climate governance landscape is one important route to strengthening public accountability of such governance. Editorials and other opinion pieces provide key contributions to the public sphere, but have been almost entirely neglected in media research on climate change. Another understudied aspect in such research is the reporting on the fragmentation of global climate governance across numerous forums. This article provides an exploratory approach to address these two research gaps. It presents a quantitative analysis of how often leading newspapers in seven countries (Finland, India, Laos, Norway, South Africa, UK and USA) wrote about 18 meetings in six different global climate governance forums between 2004–2009 and whether they provided commentaries about them. The study shows that media coverage (articles and opinion pieces) is limited or absent for many meetings that are not attended by heads of state, are the launch of a new process or do not have the convening power of the United Nations Framework Convention on Climate Change. The pattern of coverage differs significantly among individual newspapers and there is no clear distinction between developed and developing country newspapers. The article concludes that overall news coverage, and editorial commentary in particular, of global climate meetings in the selected newspapers is too low and too patchy to significantly support domestic publics to hold their own (and indirectly other) governments accountable with regard to fragmented global climate governance.Policy relevanceThis study is instructive for the media and civil society, who should both act as accountholders of governments with regard to how they act in global climate governance and its implementation. Reporting and commentaries need to reflect the overarching process, not only sporadic coverage of high-level meetings, but also critical analysis of what is achieved. They should also take a broader scope in terms of the kinds of meetings and processes in global governance that they cover. Civil society should encourage the media to increase coverage along these lines, e.g. by adequate monitoring of government actions (or lack thereof) and share this with the media. 相似文献
25.
Observations of the Hudson River plume were taken in the spring of 2006 in conjunction with the Lagrangian Transport and Transformation
Experiment using mooring arrays, shipboard observations, and satellite data. During this time period, the plume was subjected
to a variety of wind, buoyant, and shelf forcings, which yield vastly different responses in plume structure including a downstream
recirculating eddy. During weak and downwelling winds, the plume formed a narrow buoyant coastal current that propagated downstream
near the internal wave speed. Freshwater transport during periods when the downwelling wind was closely aligned with the coast
was near the river discharge values. During periods with a cross-shore component to the wind, freshwater transport in the
coastal current estimated by the mooring array is less than the river discharge due to a widening of the plume that leads
to the internal Rossby radius scaling for the plume width to be invalid. The offshore detachment of plume and formation of
a downstream eddy that is observed surprisingly persisted for 2 weeks under a variety of wind forcing conditions. Comparison
between mooring, shipboard, and satellite data reveal the downstream eddy is steady in time. Shipboard transects yield a freshwater
content equal to the previous 3 days of river discharge. The feature itself was formed due to a large discharge following
a strong onshore wind. The plume was then further modified by a brief upwelling wind and currents influenced by the Hudson
Shelf Valley. The duration of the detachment and downstream eddy can be explained using a Wedderburn number which is largely
consistent with the wind strength index described by Whitney and Garvine (J Geophys Res 110:C03014 1997). 相似文献
26.
27.
Growing up with rivers? Rivers in London children's worlds 总被引:1,自引:0,他引:1
Susan Tapsell Sylvia Tunstall Margaret House John Whomsley & Phillip Macnaghten 《Area》2001,33(2):177-189
This paper presents the results from exploratory research which set out to investigate London children's perceptions and uses of river environments. Mainly qualitative, multi-method research was carried out in four primary schools with children aged 9–11, focusing on two rivers near to the schools. Rivers were found to be marginal to the children's everyday lives and outdoor play, being perceived as polluted, neglected, and initially dangerous places. However, when experienced on visits observed as part of the research, some of these perceptions changed and rivers were also found to afford many special activities and experiences for the children. The visits were generally seen to have a positive effect on the children's perceptions of rivers, at least in the short term. This suggests that, if managed appropriately, rivers could be potentially rewarding play areas for children. Moreover, children could provide valuable input for river managers in suggesting ways of improving suitable local rivers for increased recreational uses. 相似文献
28.
A Magnetotelluric (MT) sounding was carried out at a site in south-east Queensland, in the Clarence-Moreton Basin. The synoptic recordings were taken over a period of four months at sampling frequencies from 500 Hz to 5 × 10-5 Hz. The resulting data was analysed by the stationary cross-frequency and the Cone kernel time-frequency distribution (TFD) methods of MT analysis. The results were compared as apparent resistivities on a daily basis for frequencies above 1 Hz, as well as over all the available data. The TFD MT apparent-resistivity results were more stable and less noisy on an daily basis than the cross-frequency results. Similarly the TFD analysis gave less noisy results than the cross-frequency analysis when all available data was processed. Application of these new non-stationary analysis techniques to MT processing should decrease the bias error problem of the MT methods and so increase reliability and repeatability of MT soundings. 相似文献
29.
The effect of the stratospheric ozone depletion on the thermal and dynamical structure of the middle atmosphere is assessed using two 5-member ensembles of transient GCM simulations; one including linear trends in ozone, the other not, for the 1980–1999 period. Simulated temperatures and observations are in good agreement in terms of mean values, autocorrelations and cross correlations. Annual-mean and seasonal temperature trends have been calculated using the same statistical analysis. Simulations show that ozone trends are responsible for reduced wave activity in the Arctic lower stratosphere in February and March, confirming both the role of dynamics in controlling March temperatures and a recently proposed mechanism whereby Arctic ozone depletion causes the reduction in wave activity entering the lower stratosphere. Changes in wave activity are consistent with an intensification of the polar vortex at the time of ozone depletion and with a weakened Brewer–Dobson circulation: A decrease of the dynamical warming/cooling associated with the descending/ascending branch of the wintertime mean residual circulation at high/low latitudes has been obtained through the analysis of temperature observations (1980–1999). Ozone is responsible of about one third of the decrease of this dynamical cooling at high latitudes. An increase in the residual mean circulation is seen in the observations for the 1965–1980 period. 相似文献
30.
Heather Dunning Bonnie Janzen Allison Williams Sylvia Abonyi Bonnie Jeffery J. E. Randall Bill Holden Ronald Labonte Nazeem Muhajarine Gerry Klein Tracey Carr 《GeoJournal》2006,65(4):393-407
While many community initiatives have attempted to assess the nature and determinants of their citizens’ quality of life (QOL),
these initiatives have produced little about whether the key determinants of life quality differ by gender. Using both quantitative
and qualitative data from a recent QOL research project in Saskatoon, Saskatchewan, Canada, this study explores whether factors
that predict poor QOL are similar for women and men. The study also examines whether the nature of these gender differences
varies across low, medium and high socio-economic status locales. Results showed that men and women were very similar in:
(1) their QOL ratings, (2) reports of deterioration in neighborhood QOL, and (3) rating particular aspects of their neighborhood.
Few gender differences were also found when analyzing data referring to place characteristics and social cohesion. Multivariate
analysis revealed further similarities: (1) being divorced/widowed was a significant predictor of poor QOL, and (2) a negative
view of community security issues was associated with deterioration in perceived neighborhood quality of life. For women,
however, other variables were important predictors of QOL: being middle aged, being single, and having a poor opinion of the
overall quality of their neighborhood. Qualitative analysis revealed that while men and women shared concern about general
areas such as safety and neighborhood supports, their perceptions of the details around these issues differed. The multi-method
results suggest that urban policy actions should include a gendered discussion of common QOL issues. 相似文献