Survey of the terrestrial habitats and vegetation of Shetland, 1974 – a framework for long-term ecological monitoring

A survey of the natural environment was undertaken in Shetland in 1974, after concern was expressed that large-scale development from the new oil industry could threaten the natural features of the islands. A framework was constructed by the Institute of Terrestrial Ecology on which to select samples for the survey. The vegetation and habitat data that were collected, along with the sampling framework, have recently been made public via the following doi:10.5285/06fc0b8c-cc4a-4ea8-b4be-f8bd7ee25342 (Terrestrial habitat, vegetation and soil data from Shetland, 1974) and doi:10.5285/f1b3179e-b446-473d-a5fb-4166668da146 (Land Classification of Shetland 1974). In addition to providing valuable information about the state of the natural environment of Shetland, the repeatable and statistically robust methods developed in the survey were used to underpin the Countryside Survey, Great Britain's national long-term integrated environmental monitoring programme. The demonstration of the effectiveness of the methodology indicates that a repeat of the Shetland survey would yield statistics about ecological changes in the islands, such as those arising from the impacts of the oil industry, a range of socio-economic impacts, and perhaps climate change. Currently no such figures are available, although there is much information on the sociological impacts, as well as changes in agriculture

Ecological survey of the native pinewoods of Scotland 1971

In 1971, a comprehensive ecological survey of the native pinewoods of Scotland was carried out by the Institute of Terrestrial Ecology. The survey was initiated as a consequence of growing concern about the status of the pinewood resource. Since the Twentieth Century, this unique habitat is widely recognised, not only by ecologists for its inherent biodiversity, but also by the general public for its cultural and amenity value. The survey, utilising demonstrably repeatable methods, collected information on ground flora, soils, forest structure and also general site information from the major 27 sites of the 35 sites identified as truly native pinewoods in Scotland. The results from the survey prompted the organisation of an International Symposium in 1975, which set the conservation agenda for the Old Caledonian Pinewoods. The data collected during the 1971 survey are now publicly available via the following DOI: http://doi.org/10/7xb (Habitat, vegetation, tree and soil data from Native Pinewoods in Scotland, 1971). Although the data are now 44 years old, the repeatable methods will allow for a resurvey to take place, in order to assess changes in the vegetation, habitats and tree composition in statistically robust manner

Temperature effects on the electrohydrodynamic and electrokinetic behaviour of ion-selective nanochannels

A non-isothermal formulation of the Poisson–Nernst–Planck with Navier–Stokes equations is used to study the influence of heating effects in the form of Joule heating and viscous dissipation and imposed temperature gradients on a microchannel/nanochannel system. The system is solved numerically under various cases in order to determine the influence of temperature-related effects on ion-selectivity, flux and fluid flow profiles, as well as coupling between these phenomena. It is demonstrated that for a larger reservoir system, the effects of Joule heating and viscous dissipation only become relevant for higher salt concentrations and electric field strengths than are compatible with ion-selectivity due to Debye layer overlap. More interestingly, it is shown that using different temperature reservoirs can have a strong influence on ion-selectivity, as well as the induced electrohydrodynamic flows

Enhanced ion transport using geometrically structured charge selective interfaces

A microfluidic platform containing charged hydrogels is used to investigate the effect of geometry on charge transport in electrodialysis applications. The influence of heterogeneity on ion transport is determined by electrical characterization and fluorescence microscopy of three different hydrogel geometries. We found that electroosmotic transport of ions towards the hydrogel is enhanced in heterogeneous geometries, as a result of the inhomogeneous electric field in these systems. This yields higher ionic currents for equal applied potentials when compared to homogeneous geometries. The contribution of electroosmotic transport is present in all current regimes, including the Ohmic regime. We also found that the onset of the overlimiting current occurs at lower potentials due to the increased heterogeneity in hydrogel shape, owing to the non-uniform electric field distribution in these systems. Pinning of ion depletion and enrichment zones is observed in the heterogeneous hydrogel systems, due to electroosmotic flows and electrokinetic instabilities. Our platform is highly versatile for the rapid investigation of the effects of membrane topology on general electrodialysis characteristics, including the formation of ion depletion zones on the micro-scale and the onset of the overlimiting current

Influence of temperature gradients on mono- and divalent ion transport in electrodialysis at limiting currents

Temperature gradients in electrodialysis (ED) stacks can potentially enhance the efficiency of charge separation and the selective transport of ions. We have previously investigated temperature gradients in the Ohmic regime but not in the limiting current regime, where diffusion of ions towards the membrane determines the transport rate and temperature gradients potentially have the largest influence. In this research, commercial ion exchange membranes (FAS and FKS, FUMATECH, Germany) are used for the investigation of temperature gradients in the limiting current regime. In contrast to the Ohmic regime, we find that heating the diluted stream increases the current obtained (at a constant applied potential) when compared to heating the concentrate stream in systems containing monovalent KCl and NaCl solutions. For mixtures of mono- and divalent ions, the temperature gradient has a larger influence on the selectivity of the separation. If the desalinated stream is heated, divalent Mg2+ ions show a higher transport than the monovalent K+ and Na+ ions. This is due to the enhanced competitive transport of the mono- and divalent ions under the application of a temperature gradient. These results show the potential application and relevance of temperature gradients to enhance the selective separation of mono- and divalent ions

Influence of temperature gradients on charge transport in asymmetric nanochannels

Charge selective asymmetric nanochannels are used for a variety of applications, such as nanofluidic sensing devices and energy conversion applications. In this paper, we numerically investigate the influence of an applied temperature difference over tapered nanochannels on the resulting charge transport and flow behavior. Using a temperature-dependent formulation of the coupled Poisson-Nernst-Planck and Navier-Stokes equations, various nanochannel geometries are investigated. Temperature has a large influence on the total ion transport, as the diffusivity of ions and viscosity of the solution are strongly affected by temperature. We find that the selectivity of the nanochannels is enhanced with increasing asymmetry ratios, while the total current is reduced at higher asymmetry cases. Most interestingly, we find that applying a temperature gradient along the electric field and along the asymmetry direction of the nanochannel enhances the selectivity of the tapered channels even further, while a temperature gradient countering the electric field reduces the selectivity of the nanochannel. Current rectification is enhanced in asymmetric nanochannels if a temperature gradient is applied, independent of the direction of the temperature difference. However, the degree of rectification is dependent on the direction of the temperature gradient with respect to the channel geometry and the electric field direction. The enhanced selectivity of nanochannels due to applied temperature gradients could result in more efficient operation in energy harvesting or desalination applications, motivating experimental investigations

Liquid-liquid displacement in slippery liquid-infused membranes (SLIMs)

Liquid-infused membranes inspired by slippery liquid-infused porous surfaces (SLIPS) have been recently introduced to membrane technology. The gating mechanism of these membranes is expected to give rise to anti-fouling properties and multi-phase transport capabilities. However, the long-term retention of the infusion liquid has not yet been explored. To address this issue, we investigate the retention of the infusion liquid in slippery liquid-infused membranes (SLIMs) via liquid-liquid displacement porometry (LLDP) experiments combined with microscopic observations of the displacement mechanism. Our results reveal that pores will be opened corresponding to the capillary pressure, leading to preferential flow pathways for water transport. The LLDP results further suggest the presence of liquid-lined pores in SLIM. This hypothesis is analyzed theoretically using an interfacial pore flow model. We find that the displacement patterns correspond to capillary fingering in immiscible displacement in porous media. The related physics regarding two-phase flow in porous media is used to confirm the permeation mechanism appearing in SLIMs. In order to experimentally observe liquid-liquid displacement, a microfluidic chip mimicking a porous medium is designed and a highly ramified structure with trapped infusion liquid is observed. The remaining infusion liquid is retained as pools, bridges and thin films around pillar structures in the chip, which further confirms liquid-lining. Fractal dimension analysis, along with evaluation of the fluid (non-wetting phase) saturation, further confirms that the fractal patterns correspond to capillary fingering, which is consistent with an invasion percolation with trapping (IPT) model

Land cover and vegetation data from an ecological survey of `key habitat' landscapes in England, 1992-1993

Since 1978, a series of national surveys (Countryside Survey, CS) have been carried out by the Centre for Ecology and Hydrology (CEH) (formerly the Institute of Terrestrial Ecology, ITE) to gather data on the natural environment in Great Britain (GB). As the sampling framework for these surveys is not optimised to yield data on rarer or more localised habitats, a survey was commissioned by the then Department of the Environment (DOE, now the Department for Environment, Food and Rural Affairs, DEFRA) in the 1990s to carry out additional survey work in English landscapes which contained semi-natural habitats that were perceived to be under threat, or which represented areas of concern to the ministry. The landscapes were lowland heath, chalk and limestone (calcareous) grasslands, coasts and uplands. The information recorded allowed an assessment of the extent and quality of a range of habitats defined during the project, which can now be translated into standard UK broad and priority habitat classes. The survey, known as the "Key Habitat Survey", followed a design which was a series of gridded, stratified, randomly selected 1 km squares taken as representative of each of the four landscape types in England, determined from statistical land classification and geological data ("spatial masks"). The definitions of the landscapes are given in the descriptions of the spatial masks, along with definitions of the surveyed habitats. A total of 213 of the 1 km2 square sample sites were surveyed in the summers of 1992 and 1993, with information being collected on vegetation species, land cover, landscape features and land use, applying standardised repeatable methods. The database contributes additional information and value to the long-term monitoring data gathered by the Countryside Survey and provides a valuable baseline against which future ecological changes may be compared, offering the potential for a repeat survey. The data were analysed and described in a series of contract reports and are summarised in the present paper, showing for example that valuable habitats were restricted in all landscapes, with the majority located within protected areas of countryside according to different UK designations. The dataset provides major potential for analyses, beyond those already published, for example in relation to climate change, agri-environment policies and land management. Precise locations of the plots are restricted, largely for reasons of landowner confidentiality. However, the representative nature of the dataset makes it highly valuable for evaluating the status of ecological elements within the associated landscapes surveyed. Both land cover data and vegetation plot data were collected during the surveys in 1992 and 1993 and are available via the following DOI: https://doi.org/10.5285/7aefe6aa-0760-4b6d-9473-fad8b960abd4. The spatial masks are also available from https://doi.org/10.5285/dc583be3-3649-4df6-b67e-b0f40b4ec895

The ecology of British upland landscapes. II. The influence of policy on the current character of the uplands and the potential for change

The paper demonstrates that the British Uplands have been influenced to a great extent by policy - for example, the planting of almost a million hectares of exotic conifers since the Second World War, and the extent of designated areas. Otherwise, climate change transcends policy and is locally important to coastal and high mountain habitats. The different policies affecting the Uplands, such as the Common Agricultural Policy, are described, as are the wide range of designations such as National Parks, which may have a stabilising effect in times of great change. A new trend has started in Scotland in the last 20 years of local initiatives, such as the community ownership of Eigg, however large landowners still dominate. An impact table is presented of the habitats that make up the Uplands and their links to driving forces, with potential changes described that are likely to take place under future policies such as Brexit. Dwarf shrub heath is the habitat affected by many management drivers, whereas habitats such as Inland Rock, are relatively stable but most likely to be affected by climate change

The ecology of British upland landscapes. I. Composition of landscapes, habitats, vegetation and species

A primary requirement for policy objectives is reliable figures on the composition of any region. Currently there is no comprehensive, definitive set of statistics for the British Uplands, hence the present paper. An overview of the background to the region is first provided, together with some examples of the available figures and a discussion of their limitations. The paper uses a formal structure, with landscapes at the highest level followed by habitats, then vegetation, and finally species, with exact definitions of the categories applied at all levels. The figures are produced from a survey of stratified, random one kilometre squares. The tables give comprehensive figures for Great Britain (GB) as a whole, and also England, Wales and Scotland. The Uplands are shown to cover 38 % of the country. In terms of UK Broad Habitats, Bog is the most common overall (2062 k ha). It is estimated that 41 % of upland vegetation in Britain is grazed by sheep, and Cervus elephus (red deer) are particularly evident in Scotland. Walls (mainly drystone) are the most important linear feature (84 k km) but hedgerows (30 k km) are also widespread. The major vegetation classes are those linked to moorlands and bogs (about 25 %) but those associated with fertile soils are also common (10 %). In terms of species, Potentilla erecta (tormentil) is the most frequent species with four other acid grassland species in the top ten. Calluna vulgaris (ling heather) has the highest cover in Great Britain (14.8 %)