Small-scale vegetation dynamics in semi-arid steppe in Inner Mongolia

Small-scale vegetation dynamics were followed for ecotones and in uniform stands inArtemisia-dominated steppe vegetation under grazing and when recovering from heavy grazing. Species composition was followed annually for 5 years in 1 m²and 0·25 m²plots for (1) presence–absence; (2) density; and (3) biomass.More rapid vegetation dynamics, in terms of change of type of vegetation and distance moved in DCA species space between sampling occasions, were observed in smaller plots and in early seral stages, where species were few and alpha diversity low. Only the plots recently protected from grazing showed a directional vegetation change; those protected for more than 3 years and those under continued grazing showed, at this scale, non-directional dynamics.     

Oceanic origin of southeast tropical Atlantic biases

Most coupled general circulation models suffer from a prominent warm sea surface temperature bias in the southeast tropical Atlantic Ocean off the coast of Africa. The origin of the bias is not understood and remains highly controversial. Previous studies suggest that the origin of the bias stems from systematic errors of atmospheric models in simulating surface heat flux and coastal wind, or poorly simulated coastal upwelling. In this study, we show, using different reanalysis and observational data sets combined with a set of eddy-resolving regional ocean model simulations, that systematic errors in ocean models also make a significant contribution to the bias problem. In particular (1) the strong warm bias at the Angola-Benguela front that is maintained by the local wind and the convergence of Angola and Benguela Currents is caused by an overshooting of the Angola Current in ocean models and (2) the alongshore warm bias to the south of the front is caused by ocean model deficiencies in simulating the sharp thermocline along the Angola coast, which is linked to biases in the equatorial thermocline, and the complex circulation system within the Benguela upwelling zone.     

Refining the ice flow chronology and subglacial dynamics across the migrating Labrador Divide of the Laurentide Ice Sheet with age constraints on deglaciation

The Laurentide Ice Sheet was characterized by a dynamic polythermal base. However, important data and knowledge gaps have led to contrasting reconstructions in areas such as the Labrador Ice Divide. In this study, detailed fieldwork was conducted at the southeastern edge of a major landform boundary to resolve the relative ice flow chronology and constrain the evolution of the subglacial dynamics, including the migration and collapse of the Labrador Ice Divide. Surficial mapping and analysis of 94 outcrop‐scale ice flow indicators were used to develop a relative ice flow chronology. ¹⁰Be exposure ages were used with optical ages to confine the timing of deglaciation within the study area. Four phases of ice flow were identified. Flow 1 was a northeasterly ice flow preserved under non‐erosive subglacial conditions associated with the development of an ice divide. Flow 2 was a northwest ice flow, which we correlate to the Ungava Bay Ice Stream and led to a westward migration of the ice divide, preserving Flow 2 features and resulting in Flow 3's eastward‐trending indicators. Flow 4 is limited to sparse fine striations within and around the regional uplands. The new optical ages and ¹⁰Be exposure ages add to the regional geochronology dataset, which further constrains the timing of ice margin retreat in the area to around 8.0 ka. Copyright © 2019 The Authors. Journal of Quaternary Science Published by John Wiley & Sons Ltd.     

http://www.sciencedirect.com/science/article/pii/S1674987111001290

The Three Gorges Dam(TGD) of the Yangtze River.China,is one of the largest irrigation and hydroelectric engineering projects in the world.The effects of huge man-made projects like TGD on fauna and macrophyte are obvious,mainly through changes of water dynamics and flow pattern;however, it is less clear how microorganisms respond to such changes.This research was aimed to examine differences in microbial diversity at different seasons and locations(in front of and behind the TGD).In addition, differences between particle-attached and free-living communities were also examined.The community structures of total and potentially active microorganisms in the water columns behind and in front of the TGD were analyzed with the DNA- and RNA-based 16S rRNA gene phylogenetic approaches over three different seasons.Clone libraries of 16S rRNA genes were prepared after amplification from extracted DNA and.for some samples,after preparing cDNA from extracted rRNA.Differences were observed between sites at different seasons and between free-living and particle-attached communities.Both bacterial and archaeal communities were more diverse in summer than in winter, due to higher nutrient levels and warmer temperature in summer than in winter.Particle-attached microorganisms were more diverse than free-living communities,possibly because of higher nutrient levels and heterogeneous geochemical micro-environments in particles.Spatial variations in bacterial community structure were observed,i.e..the water reservoir behind the TGD(upstream) hosted more diverse bacterial populations than in front of the dam(downstream),because of diverse sources of sediments and waters from upstream to the reservoir.These results have important implications for our understanding of responses of microbial communities to environmental changes in river ecosystems affected by dam construction.     

On the geologic structure of the Explora Escarpment (Weddell Sea,Antarctica) revealed by satellite and Shipboard data evaluation

Bathymetric, gravity, and magnetic data from Antarctic expeditions with RV POLARSTERN and satellite altimeter data from the Geosat Geodetic Mission are analysed using methods from geostatistics and geophysical inverse theory.The Explora Escarpment represents the edge between the Antarctic Continental Shelf and the Weddell Abyssal Plain. It is an important link in the reconstruction of Gondwana breakup, but a feature as large as the 2000 m deep Wegener Canyon was only discovered in 1984, when extensive bathymetric, gravimetric, and magnetic surveys with RV POLARSTERN began.Geostatistics, the theory of regionalized variables, is applied to integrate dense surveys of Wegener Canyon and sparse observations in adjacent areas into maps with full coverage of the 230 km by 330 km area at 10°–20° W/70°–72° S. The resultant highresolution bathymetric and gravity maps reveal detailed structures of the Explora Escarpment. Using geophysical inversion, the gravity terrain effect is calculated. Satellite data are used for their better coverage, but have much lower resolution. Nevertheless, the structures of Wegener Canyon and other more prominent features appear with surprisingly good correlation also in the Geosat altimeter data. While it was initially supposed that Wegener Canyon is purely an erosional structure, the magnetic map now provides evidence of the canyon's tectonic origin.     

An answer to an important controversy and the need for caution when using simple models to predict inelastic earthquake response of buildings with torsion

This paper presents evidence that the extension of conclusions based on the widely used simplified, one story, eccentric systems of the shear‐beam type, to actual, nonsymmetric buildings and consequent assessments of the pertinent code provisions, can be quite erroneous, unless special care is taken to match the basic properties of the simplified models to those of the real buildings. The evidence comes from comparisons of results obtained using three variants of simplified models, with results from the inelastic dynamic response of three‐ and five‐story eccentric buildings computed with detailed MDOF systems, where the members are idealized with the well‐known plastic hinge model. In addition, a convincing answer is provided on a pertinent hanging controversy: For frame‐type buildings, designed in accordance with the dynamic provisions of modern codes (such as EC8 or IBC2000), which allow reduced shears at the stiff edge due to torsion, the frames at the flexible sides are the critical elements in terms of ductility demands. Copyright © 2009 John Wiley & Sons, Ltd.     

Another Typical Day in this Typical Town: place as inspiration for music creation and creative expression

Geographically isolated within its own State as well as from the rest of the country, and with the highest percentage of metropolitan primacy of all Australian States, Perth is a city somewhat uncomfortable with its creative and cultural identity. The city is physically peripheral to networks in the arts and creative industries that operate at the national level. And, symbolically, many in Perth’s cultural sector feel a sense of isolation. Yet, in certain cultural sectors, such as music, Perth demonstrably punches above its weight, consistently generating high-quality cultural exports. This paper unpicks this curious juxtaposition. It examines the influence of Perth—as a geographical location and a site of creative inspiration—on the music created and disseminated by local contemporary musicians who write and perform their own indie pop/rock music. I discuss the nuanced relationship between creative clustering and place, drawing on theories regarding the relationship between music and place, the notion of the music scenes and creativity and creative practices. I explore how living in Perth, a geographically isolated city, with a highly concentrated population and associated music sector, influences creative expressions, desires and inspirations, for a select group of local indie pop/rock musicians who achieved national and international notoriety with their music in the late 1990s and 2000s. Navigating isolation but nevertheless energised by strong social connections and scene participation, Perth musicians catalysed creativity in ways that contribute to evolving debates on the links between place, creativity and music.     

Enhanced data and methods for improving open and free global population grids: putting ‘leaving no one behind’ into practice

ABSTRACT

Data on global population distribution are a strategic resource currently in high demand in an age of new Development Agendas that call for universal inclusiveness of people. However, quality, detail, and age of census data varies significantly by country and suffers from shortcomings that propagate to derived population grids and their applications. In this work, the improved capabilities of recent remote sensing-derived global settlement data to detect and mitigate major discrepancies with census data is explored. Open layers mapping built-up presence were used to revise census units deemed as ‘unpopulated’ and to harmonize population distribution along coastlines. Automated procedures to detect and mitigate these anomalies, while minimizing changes to census geometry, preserving the regional distribution of population, and the overall counts were developed, tested, and applied. The two procedures employed for the detection of deficiencies in global census data obtained high rates of true positives, after verification and validation. Results also show that the targeted anomalies were significantly mitigated and are encouraging for further uses of free and open geospatial data derived from remote sensing in complementing and improving conventional sources of fundamental population statistics.     

Between-Population Differences in Multi-stressor Tolerance During Embryo Development in the American Horseshoe Crab, <Emphasis Type="Italic">Limulus polyphemus</Emphasis>

The American horseshoe crab, Limulus polyphemus, is found along the Atlantic and Gulf of Mexico coasts in genetically isolated populations. Eggs are laid in shoreline beaches that expose developing embryos to combinations of environmental stressors. Whether populations of L. polyphemus differ in multi-stressor tolerance had never been tested. We assessed the multi-stressor tolerance of L. polyphemus embryos from a population in Delaware Bay (DE) and determined whether these differed from the multi-stressor tolerance of embryos from a more southerly Florida Gulf Coast (FGC) population. We monitored the field sediment temperatures and determined multi-stressor tolerance of DE embryos, then compared these to published data for FGC embryos. For multi-stressor tolerance, we assessed development success of embryos in 2-week exposures to 36 full-factorial combinations of temperature (20, 25, 30, 35 °C), salinity (5, 15, and 34 ppt), and ambient O₂ (5, 13, and 21% O₂), followed by 2 weeks in recovery conditions. Sediment temperatures in the DE site ranged from 9.5 to 46 °C, with extended periods exceeding 35 °C. Development success was similar between the DE and FGC populations in 14 of 26 multi-stressor combinations. The DE embryos were generally more successful in conditions that included high temperature or moderate hyposalinity, whereas the FGC embryos were generally more successful in conditions that included extreme hyposalinity. This suggests that although multi-stressor tolerances are generally similar between the two populations, specific differences exist that correlate more with differences in nest microenvironment than latitude.