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Bethanie Francis on Twitter: "Absolutely over the moon to have been awarded runner up for best presentation at #MBA18! @MBAconference18 @thembauk @BangorUni @CNSpostgrads @ENVISIONDTP… https://t.co...

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The resilience of postglacial hunter-gatherers to abrupt climate change

The resilience of postglacial hunter-gatherers to abrupt climate change | Envision DTP - Developing next generation leaders in environmental science | Scoop.it
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Fossils, phylogenies and the evolving climate niche | Nature Ecology & Evolution

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Simon Tarr's first 'News & Views' article with Adam Algar!
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Tidal conversion and mixing poleward of the critical latitude (an Arctic case study)

Tidal conversion and mixing poleward of the critical latitude (an Arctic case study) | Envision DTP - Developing next generation leaders in environmental science | Scoop.it

The tides are a major source of the kinetic energy supporting turbulent mixing in the global oceans. The prime mechanism for the transfer of tidal energy to turbulent mixing results from the interaction between topography and stratified tidal flow, leading to the generation of freely propagating internal waves at the period of the forcing tide. However, poleward of the critical latitude (where the period of the principal tidal constituent exceeds the local inertial period), the action of the Coriolis force precludes the development of freely propagating linear internal tides. Here we focus on a region of sloping topography, poleward of the critical latitude, where there is significant conversion of tidal energy and the flow is supercritical (Froude number, Fr > 1). A high-resolution non-linear modelling study demonstrates the key role of tidally generated lee waves and super-critical flow in the transfer of energy from the barotropic tide to internal waves in these high latitude regions. Time series of flow and water column structure from the region of interest show internal waves with characteristics consistent with those predicted by the model, and concurrent microstructure dissipation measurements show significant levels of mixing associated with these internal waves. The results suggest that tidally generated lee-waves are a key mechanism for the transfer of energy from the tide to turbulence poleward of the critical latitude.

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ScienceDirect

Root exudates represent a large and labile carbon input in tropical peatlands, but their contribution to carbon dioxide (CO2) and methane (CH4) production remains poorly understood. Changes in species composition and productivity of peatland plant communities in response to global change could alter both inputs of exudates and associated greenhouse gas emissions. We used manipulative laboratory incubations to assess the extent to which root exudate quantity and chemical composition drives greenhouse gas emissions from tropical peatlands. Peat was sampled from beneath canopy palms (Raphia taedigera) and broadleaved evergreen trees (Campnosperma panamensis) in an ombrotrophic wetland in Panama. Root exudate analogues comprising a mixture of sugars and organic acids were added in solution to peats derived from both species, with CO2 and CH4 measured over time. CO2 and CH4 production increased under most treatments, but the magnitude and duration of the response depended on the composition of the added labile carbon mixture rather than the quantity of carbon added or the botanical origin of the peat. Treatments containing organic acids increased soil pH and altered other soil properties including redox potential but did not affect the activities of extracellular hydrolytic enzymes. CO2 but not CH4 production was found to be linearly related to microbial activity and redox potential. Our findings demonstrate the importance of root exudate composition in regulating greenhouse gas fluxes and propose that in situ plant species changes, particularly those associated with land use change, may account for small scale spatial variation in CO2 and CH4 fluxes due to species specific root exudate compositions.
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Geophysical characterisation of the groundwater-surface water interface

Interactions between groundwater (GW) and surface water (SW) have important implications for water quantity, water quality, and ecological health. The subsurface region proximal to SW bodies, the GW–SW interface, is crucial as it actively regulates the transfer of nutrients, contaminants, and water between GW systems and SW environments. However, geological, hydrological, and biogeochemical heterogeneity in the GW–SW interface makes it difficult to characterise with direct observations. Over the past two decades geophysics has been increasingly used to characterise spatial and temporal variability throughout the GW–SW interface. Geophysics is a powerful tool in evaluating structural heterogeneity, revealing zones of GW discharge, and monitoring hydrological processes. Geophysics should be used alongside traditional hydrological and biogeochemical methods to provide additional information about the subsurface. Further integration of commonly used geophysical techniques, and adoption of emerging techniques, has the potential to improve understanding of the properties and processes of the GW–SW interface, and ultimately the implications for water quality and environmental health.
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Postglacial Human resilience and susceptibility to abrupt climate change new insights from Star Carr

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Zoo elephants help their wild counterparts in Kruger National Park...by Fiona Sach

Zoo elephants help their wild counterparts in Kruger National Park...by Fiona Sach | Envision DTP - Developing next generation leaders in environmental science | Scoop.it
Fiona feeding lemurs. Eight zoo elephants from Knowsley Safari Park and Twycross Zoo have been contributing to work that is bein
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Remote Sensing | Free Full-Text | Tropical Peatland Vegetation Structure and Biomass: Optimal Exploitation of Airborne Laser Scanning

Remote Sensing | Free Full-Text | Tropical Peatland Vegetation Structure and Biomass: Optimal Exploitation of Airborne Laser Scanning | Envision DTP - Developing next generation leaders in environmental science | Scoop.it
Accurate estimation of above ground biomass (AGB) is required to better understand the variability and dynamics of tropical peat swamp forest (PSF) ecosystem function and resilience to disturbance events. The objective of this work is to examine the relationship between tropical PSF AGB and small-footprint airborne Light Detection and Ranging (LiDAR) discrete return (DR) and full waveform (FW) derived metrics, with a view to establishing the optimal use of this technology in this environment. The study was undertaken in North Selangor peat swamp forest (NSPSF) reserve, Peninsular Malaysia. Plot-based multiple regression analysis was performed to established the strongest predictive models of PSF AGB using DR metrics (only), FW metrics (only), and a combination of DR and FW metrics. Overall, the results demonstrate that a Combination-model, coupling the benefits derived from both DR and FW metrics, had the best performance in modelling AGB for tropical PSF (R2 = 0.77, RMSE = 36.4, rRMSE = 10.8%); however, no statistical difference was found between the rRMSE of this model and the best models using only DR and FW metrics. We conclude that the optimal approach to using airborne LiDAR for the estimation of PSF AGB is to use LiDAR metrics that relate to the description of the mid-canopy. This should inform the use of remote sensing in this ecosystem and how innovation in LiDAR-based technology could be usefully deployed.
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Sharks and rays win new protections at global wildlife summit | Environment | The Guardian

Sharks and rays win new protections at global wildlife summit | Environment | The Guardian | Envision DTP - Developing next generation leaders in environmental science | Scoop.it
Cites votes for new measures to control the trade in silky and thresher sharks, hunted for their fins, and devil rays, whose gills are prized as a medicinal ‘cure’
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An Update from the Elephants…by Fiona Sach

An Update from the Elephants…by Fiona Sach | Envision DTP - Developing next generation leaders in environmental science | Scoop.it
Elephants within the Kruger National Park The last year has been an absolute whirlwind of activity involving fieldwork at five UK Zoos
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Correcting Surface Wave Bias in Structure Function Estimates of Turbulent Kinetic Energy Dissipation Rate

The combination of acoustic Doppler current profilers and the structure function methodology provides an attractive approach to making extended time series measurements of oceanic turbulence (the rate of turbulent kinetic energy dissipation) from moorings. However, this study shows that for deployments in the upper part of the water column, estimates of will be biased by the vertical gradient in wave orbital velocities. To remove this bias, a modified structure function methodology is developed that exploits the differing length scale dependencies of the contributions to the structure function resulting from turbulent and wave orbital motions. The success of the modified method is demonstrated through a comparison of estimates based on data from instruments at three depths over a 3-month period under a wide range of conditions, with appropriate scalings for wind stress and convective forcing.
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Contrasting patterns of insect herbivory and predation pressure across a tropical rainfall gradient

Contrasting patterns of insect herbivory and predation pressure across a tropical rainfall gradient | Envision DTP - Developing next generation leaders in environmental science | Scoop.it

One explanation for the extraordinarily high tree diversity of tropical lowland forests is that it is maintained by specialized natural enemies such as insect herbivores, which cause distance and density dependent mortality. Insect herbivory could also explain the positive correlation between tree species richness and rainfall if herbivory increases with rainfall, is higher on locally abundant versus rare species, and is not limited by predation pressure at wet sites. To test these predictions, insect herbivory and predation pressure on insect herbivores were quantified across a Neotropical rainfall and tree species richness gradient, and herbivory was investigated in relation to local tree abundances. Insect herbivory on leaves (folivory) decreased strongly and significantly with rainfall, while predation pressure was significantly higher at the wetter site. Herbivores were more likely to attack abundant tree species, but herbivore damage levels were not related to tree species abundance. Insect folivores might contribute to local tree species coexistence in our system, but seem unlikely to drive the positive correlation between tree species richness and rainfall. The unexpected and contrasting patterns of herbivory and predation we observed support the need for a multi-trophic perspective to understand fully the processes contributing to diversity and ecosystem functioning.

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Reconstructing Past Climate Using Speleothems from Cueva de las Perlas, Northern Spain.

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Frontiers | Emplacing a Cooling-Limited Rhyolite Lava Flow: Similarities with Basaltic Lava Flows | Earth Science

Accurate forecasts of lava flow length rely on estimates of eruption and magma properties and, potentially more challengingly, an understanding of the relative influence of characteristics such as the apparent viscosity, the yield strength of the flow core, or the strength of the surface crust. Consequently, even the most straightforward models of lava advance involve sufficient parameters that constraints can be relatively easily fitted within the uncertainties involved, at the expense of gaining insight. Here, for the first time, we incorporate morphological observations from during and after flow field evolution to improve model constraints and reduce uncertainties. After demonstrating the approach on a basaltic lava flow (Mt. Etna, 2001), we apply it to the 2011-12 Cordón Caulle rhyolite flow, where unprecedented observations and syn-emplacement satellite imagery of an advancing silica-rich lava flow have indicated an important crustal influence on flow emplacement. Our results show that an initial phase of viscosity-controlled advance at Cordón Caulle was followed by later crustal control, accompanied by formation of flow surface folds and large-scale crustal fractures. Where the lava was unconstrained by topography, the cooled crust ultimately halted advance of the main flow and led to the formation of breakouts from the flow front and margins, influencing the footprint of the lava, its advance rate, and the duration of flow advance. Highly similar behaviour occurred in the 2001 Etna basaltic lava flow. The processes controlling the advance of crystal-poor rhyolite and basaltic lava flow therefore appear similar, indicating common controlling mechanisms that transcend profound rheological and compositional differences.
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State of the World’s Plants (SOTWP) Symposium 25-26 May 2017

State of the World’s Plants (SOTWP) Symposium 25-26 May 2017 | Envision DTP - Developing next generation leaders in environmental science | Scoop.it
By Christopher Chandler Last month welcomed the second annual State of the World’s Plants (SOTWP) Symposium – a two day event based at the Royal Botanic Gardens, Kew. The symposium attracted over 250 people from 30 countries around the globe to hear about the latest discoveries and knowledge in plant science. The 2017 SOTWP report…
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