On the multiple ecological roles of water in river networks

The distribution and movement of water can influence the state and dynamics of terrestrial and aquatic ecosystems through a diversity of mechanisms. These mechanisms can be organized into three general categories wherein water acts as (1) a resource or habitat for biota, (2) a vector for connectivity and exchange of energy, materials, and organisms, and (3) as an agent of geomorphic change and disturbance. These latter two roles are highlighted in current models, which emphasize hydrologic connectivity and geomorphic change as determinants of the spatial and temporal distributions of species and processes in river systems. Water availability, on the other hand, has received less attention as a driver of ecological pattern, despite the prevalence of intermittent streams, and strong potential for environmental change to alter the spatial extent of drying in many regions. Here we summarize long-term research from a Sonoran Desert watershed to illustrate how spatial patterns of ecosystem structure and functioning reflect shifts in the relative importance of different 'roles of water' across scales of drainage size. These roles are distributed and interact hierarchically in the landscape, and for the bulk of the drainage network it is the duration of water availability that represents the primary determinant of ecological processes. Only for the largest catchments, with the most permanent flow regimes, do flood-associated disturbances and hydrologic exchange emerge as important drivers of local dynamics. While desert basins represent an extreme case, the diversity of mechanisms by which the availability and flow of water influence ecosystem structure and functioning are general. Predicting how river ecosystems may respond to future environmental pressures will require clear understanding of how changes in the spatial extent and relative overlap of these different roles of water shape ecological patterns. © 2013 Sponseller et al.

Convergent Surface Water Distributions in U.S. Cities

Earth's surface is rapidly urbanizing, resulting in dramatic changes in the abundance, distribution and character of surface water features in urban landscapes. However, the scope and consequences of surface water redistribution at broad spatial scales are not well understood. We hypothesized that urbanization would lead to convergent surface water abundance and distribution: in other words, cities will gain or lose water such that they become more similar to each other than are their surrounding natural landscapes. Using a database of more than 1 million water bodies and 1 million km of streams, we compared the surface water of 100 US cities with their surrounding undeveloped land. We evaluated differences in areal (A WB) and numeric densities (N WB) of water bodies (lakes, wetlands, and so on), the morphological characteristics of water bodies (size), and the density (D C) of surface flow channels (that is, streams and rivers). The variance of urban A WB, N WB, and D C across the 100 MSAs decreased, by 89, 25, and 71%, respectively, compared to undeveloped land. These data show that many cities are surface water poor relative to undeveloped land; however, in drier landscapes urbanization increases the occurrence of surface water. This convergence pattern strengthened with development intensity, such that high intensity urban development had an areal water body density 98% less than undeveloped lands. Urbanization appears to drive the convergence of hydrological features across the US, such that surface water distributions of cities are more similar to each other than to their surrounding landscapes. © 2014 The Author(s).

Evidence for GC-biased gene conversion as a driver of between-lineage differences in avian base composition.

BACKGROUND: While effective population size (Ne) and life history traits such as generation time are known to impact substitution rates, their potential effects on base composition evolution are less well understood. GC content increases with decreasing body mass in mammals, consistent with recombination-associated GC biased gene conversion (gBGC) more strongly impacting these lineages. However, shifts in chromosomal architecture and recombination landscapes between species may complicate the interpretation of these results. In birds, interchromosomal rearrangements are rare and the recombination landscape is conserved, suggesting that this group is well suited to assess the impact of life history on base composition. RESULTS: Employing data from 45 newly and 3 previously sequenced avian genomes covering a broad range of taxa, we found that lineages with large populations and short generations exhibit higher GC content. The effect extends to both coding and non-coding sites, indicating that it is not due to selection on codon usage. Consistent with recombination driving base composition, GC content and heterogeneity were positively correlated with the rate of recombination. Moreover, we observed ongoing increases in GC in the majority of lineages. CONCLUSIONS: Our results provide evidence that gBGC may drive patterns of nucleotide composition in avian genomes and are consistent with more effective gBGC in large populations and a greater number of meioses per unit time; that is, a shorter generation time. Thus, in accord with theoretical predictions, base composition evolution is substantially modulated by species life history.

Heritage

This article examines the concepts, definitions, policies, and practices of heritage in a contemporary context. Within recent years, there have been significant shifts in our understandings and applications of heritage concepts and policies in the modern world. ‘Heritage’ emerged as a buzz word in international policy arenas in the 1980s and early 1990s, and has since weathered the vagaries of turbulent definitional and governance–nomenclature storms, as traditional debates about ‘what it is and what it is not’ reverberate around academia and state agencies alike. Policy and funding structures for heritage are determined by the classifications used to define them in various countries. Typically, reference is made to ‘built heritage’, ‘natural heritage’, and ‘intangible heritage’, loosely reflecting buildings, landscapes, and culture. Aspects of heritage are used by the cultural and tourism industries to add economic value, through heritage tourism sites, museums, and other activities. The cultural tourism product is often anchored around notions of heritage, and in postmodern, post-tourist societies, boundaries between culture, (travel) space, and identities are increasingly blurred. Issues of authenticity become important in the representation of heritage, and questions are asked about the validity of nostalgia versus realism. The role of heritage is examined in the context of identity formulation at individual and nation-state levels, and the political aspects of this are also discussed. Finally, heritage conservation is assessed through an examination of UNESCO’s World Heritage Site listing and protection strategy. In a changing world, new constructs of heritage, identity, authenticity, and representation will continue to emerge as meanings are constantly renegotiated over time and space.

Rats, floods and flowers: London's Gothicized nature

AUTHOR's OVERVIEW This chapter attempts a definition of London eco-gothic, beginning with an ecocritical reading of the ubiquitous London rat. Following Dracula, popular London gothic has been overrun, from the blunt horror-schlock of James Herbert’s 1970s Rats series to China Miéville’s King Rat. Maud Ellman’s elegant discussion of the modernist rat as a protean figure associated with a ‘panoply of fears and fetishes’, underlines how the rat has always featured in anti-urban discourse: as part of racist representations of immigration; as an expression of fear of disease and poverty; or through a quasi-supernatural anxiety about their indestructible and illimitable nature which makes them a staple feature of post-apocalyptic landscapes. Even so, the London rat is a rather more mundane manifestation of urban eco-gothic than the ‘city wilderness’ metaphors common to representations of New York or Los Angles as identified by eco-critic Andrew White. London’s gothic noses its way out through cracks in the pavements, grows from seeds in suburban gardens or accumulates through the steady drip of rainwater. However, I will suggest, in texts such as Maggie Gee’s The Flood and P. D. James’ Children of Men, London eco-gothic becomes less local and familiar as it responds to global environmental crisis with more dramatic tales of minatorial nature.

Unterstützungssysteme im Kontext von Regionalisierungsprozessen. Eine theoretische und empirische Annäherung

In Fragen der Schulentwicklung allgemein, aber auch im Zuge der aktuellen Regionalisierungstendenzen im Schul- und Bildungswesen, wird Unterstützungssystemen für die Einzelschule eine wachsende Bedeutung zugeschrieben. Dennoch finden sich bislang erst wenige Arbeiten im Diskurs, die Unterstützungssysteme im Zusammenhang mit Regionalisierungsprozessen beleuchten und robuste Analyseinstrumente vorstellen, mit deren Hilfe Unterstützung im Zusammenhang von Regionalisierung gefasst werden kann. Dieses Desiderat wird im vorliegenden Beitrag aufgegriffen, indem unter anderem auf Grundlage von governance- sowie motivationstheoretischen Überlegungen Kategorien für eine Heuristik erarbeitet werden, die es erlauben, Unterstützungssysteme allgemein und im Kontext von Schul- und Bildungslandschaften entlang verschiedener Dimensionen zu betrachten. Mittels Interviews, die im Rahmen des Projektes ,Schulen im Team – Übergänge gemeinsam gestalten‘ durchgeführt wurden, wird die Heuristik auf den Forschungskontext zu Regionalen Bildungsbüros inhaltsanalytisch angewendet. Erste Befunde weisen darauf hin, dass sich die Heuristik zur Untersuchung von Unterstützungssystemen für einen regionalen Kontext plausibilisieren lässt. (DIPF/Orig.)

Impact of human activities on benthic biotopes and species

Executive Summary 1. The Marine Life Information Network (MarLIN) has been developed since 1998. Defra funding has supported a core part of its work, the Biology and Sensitivity Key Information Sub-programme. This report relates to Biology and Sensitivity work for the period 2001-2004. 2. MarLIN Biology and Sensitivity research takes information on the biology of species to identify the likely effects of changing environmental conditions linked to human activities on those species. In turn, species that are key functional, key structural, dominant, or characteristic in a biotope (the habitat and its associated species) are used to identify biotope sensitivity. Results are displayed over the World Wide Web and can be accessed via a range of search tools that make the information of relevance to environmental management. 3. The first Defra contract enabled the development of criteria and methods of research, database storage methods and the research of a wide range of species. A contract from English Nature and Scottish Natural Heritage enabled biotopes relevant to marine SACs to be researched. 4. Defra funding in 2001-2004 has especially enabled recent developments to be targeted for research. Those developments included the identification of threatened and declining species by the OSPAR Biodiversity Committee, the development of a new approach to defining sensitivity (part of the Review of Marine Nature Conservation), and the opportunity to use Geographical Information Systems (GIS) more effectively to link survey data to MarLIN assessments of sensitivity. 5. The MarLIN database has been developed to provide a resource to 'pick-and-mix' information depending on the questions being asked. Using GIS, survey data that provides locations for species and biotopes has been linked to information researched by MarLIN to map the likely sensitivity of an area to a specified factor. Projects undertaken for the Irish Sea pilot (marine landscapes), in collaboration with CEFAS (fishing impacts) and with the Countryside Council for Wales (oil spill response) have demonstrated the application of MarLIN information linked to survey data in answering, through maps, questions about likely impacts of human activities on seabed ecosystems. 6. GIS applications that use MarLIN sensitivity information give meaningful results when linked to localized and detailed survey information (lists of species and biotopes as point source or mapped extents). However, broad landscape units require further interpretation. 7. A new mapping tool (SEABED map) has been developed to display data on species distributions and survey data according to search terms that might be used by an environmental manager. 8. MarLIN outputs are best viewed on the Web site where the most up-to-date information from live databases is available. The MarLIN Web site receives about 1600 visits a day. 9. The MarLIN approach to assessing sensitivity and its application to environmental management were presented in papers at three international conferences during the current contract and a 'touchstone' paper is to be published in the peer-reviewed journal Hydrobiologia. The utility of MarLIN information for environmental managers, amongst other sorts of information, has been described in an article in Marine Pollution Bulletin. 10. MarLIN information is being used to inform the identification of potential indicator species for implementation of the Water Framework Directive including initiatives by ICES. 11. Non-Defra funding streams are supporting the updating of reviews and increasing the amount of peer review undertaken; both of which are important to the maintenance of the resource. However, whilst MarLIN information is sufficiently wide ranging to be used in an 'operational' way for marine environmental protection and management, new initiatives and the new biotopes classification have introduced additional species and biotopes that will need to be researched in the future. 12. By the end of the contract, the Biology and Sensitivity Key Information database contained full Key Information reviews on 152 priority species and 117 priority biotopes, together with basic information on 412 species; a total of 564 marine benthic species.

Encounter success of free-ranging marine predator movements across a dynamic prey landscape

Movements of wide-ranging top predators can now be studied effectively using satellite and archival telemetry. However, the motivations underlying movements remain difficult to determine because trajectories are seldom related to key biological gradients, such as changing prey distributions. Here, we use a dynamic prey landscape of zooplankton biomass in the north-east Atlantic Ocean to examine active habitat selection in the plankton-feeding basking shark Cetorhinus maximus. The relative success of shark searches across this landscape was examined by comparing prey biomass encountered by sharks with encounters by random-walk simulations of ‘model’ sharks. Movements of transmitter-tagged sharks monitored for 964 days (16754km estimated minimum distance) were concentrated on the European continental shelf in areas characterized by high seasonal productivity and complex prey distributions. We show movements by adult and sub-adult sharks yielded consistently higher prey encounter rates than 90% of random-walk simulations. Behavioural patterns were consistent with basking sharks using search tactics structured across multiple scales to exploit the richest prey areas available in preferred habitats. Simple behavioural rules based on learned responses to previously encountered prey distributions may explain the high performances. This study highlights how dynamic prey landscapes enable active habitat selection in large predators to be investigated from a trophic perspective, an approach that may inform conservation by identifying critical habitat of vulnerable species.

Environmental context explains Lévy and Brownian movement patterns of marine predators

An optimal search theory, the so-called Levy-flight foraging hypothesis(1), predicts that predators should adopt search strategies known as Levy flights where prey is sparse and distributed unpredictably, but that Brownian movement is sufficiently efficient for locating abundant prey(2-4). Empirical studies have generated controversy because the accuracy of statistical methods that have been used to identify Levy behaviour has recently been questioned(5,6). Consequently, whether foragers exhibit Levy flights in the wild remains unclear. Crucially, moreover, it has not been tested whether observed movement patterns across natural landscapes having different expected resource distributions conform to the theory's central predictions. Here we use maximum-likelihood methods to test for Levy patterns in relation to environmental gradients in the largest animal movement data set assembled for this purpose. Strong support was found for Levy search patterns across 14 species of open-ocean predatory fish (sharks, tuna, billfish and ocean sunfish), with some individuals switching between Levy and Brownian movement as they traversed different habitat types. We tested the spatial occurrence of these two principal patterns and found Levy behaviour to be associated with less productive waters (sparser prey) and Brownian movements to be associated with productive shelf or convergence-front habitats (abundant prey). These results are consistent with the Levy-flight foraging hypothesis(1,7), supporting the contention(8,9) that organism search strategies naturally evolved in such a way that they exploit optimal Levy patterns.

Placing biodiversity in ecosystem models without getting lost in translation

A key challenge to progressing our understanding of biodiversity’s role in the sustenance of ecosystem function is the extrapolation of the results of two decades of dedicated empirical research to regional, global and future landscapes. Ecosystem models provide a platform for this progression, potentially offering a holistic view of ecosystems where, guided by the mechanistic understanding of processes and their connection to the environment and biota, large-scale questions can be investigated. While the benefits of depicting biodiversity in such models are widely recognized, its application is limited by difficulties in the transfer of knowledge from small process oriented ecology into macro-scale modelling. Here, we build on previous work, breaking down key challenges of that knowledge transfer into a tangible framework, highlighting successful strategies that both modelling and ecology communities have developed to better interact with one another. We use a benthic and a pelagic case-study to illustrate how aspects of the links between biodiversity and ecosystem process have been depicted in marine ecosystem models (ERSEM and MIRO), from data, to conceptualisation and model development. We hope that this framework may help future interactions between biodiversity researchers and model developers by highlighting concrete solutions to common problems, and in this way contribute to the advance of the mechanistic understanding of the role of biodiversity in marine (and terrestrial) ecosystems.

Paisajes para el Medioambiente. Estudio de caso.

Una de las cuencas hidrográficas más importante de la Península es la del río Tajo, por su extensión y por su caudal. Se trata de una fosa tectónica calificable de modélica. Dos moles montañosas, el Sistema central y los Montes de Toledo en sentido amplio, la flanquean al Norte y al Sur. La dovela hundida, formada por idénticos materiales que las Sierras, granitos y gneis, alcanza una gran profundidad. Al Este el Sistema Ibérico castellano, principalmente calizo y mesozoico, cierra Castilla y la cuenca, viniendo a dar vida con el agua de sus nieves a un Tajo niño’. El inicio de su Historia Geológica podemos situarlo en el Paleozoico, tiempo geológico durante el cual los territorios donde hoy se sitúa la Meseta estaban formando grandes cordilleras producto de la Orogenia Herciniana. La última etapa de la formación de los relieves actuales de la cuenca la encontramos en la reactivación de los antiguos macizos arrasados. Se inicia con los materiales de la raña y sus equivalentes en el centro de la Cuenca o Fosa del Tajo, y se caracteriza por una progresiva individualización de los procesos, pasándose de las grandes superficies generalizadas en macizos y cuencas, Sierras y Fosa del Tajo, a las pequeñas llanuras en franja u orla, que quedan localizadas en cada cuenca fluvial a medida que éstas se van consolidando por jerarquización, y partir de un río generatriz o emisario principal, el Tajo. La tectónica, procesos posteriores de captura, reajustes climáticos..., no permiten aún determinar cuál fue el orden de jerarquía en los ríos que hoy conocemos; no obstante, puede aventurarse que Jarama-Henares, Perales-Alberche y Guadarrama serían los primeros y Manzanares, Guadalix, Tajuña, los siguientes, y así sucesivamente. La síntesis de la realidad geológica, litológica y climática va a coadyuvar, frenando o favoreciendo, el desarrollo y la diferenciación entre los paisajes vegetales de las zonas montañosas y los de las depresiones terciarias y penillanuras paleozoicas, en un territorio marcado por el predominio del clima mediterráneo continentalizado, con matices de montaña y áreas de influencia atlántica.

Identidad territorial y paisaje. Evolución morfológica de los núcleos en Castilla y León.

Este estudio intenta esclarecer las transformaciones físicas y socioeconómicas de los asentamientos rurales de la región española de Castilla y León, durante la segunda mitad del siglo XX. Se analiza la evolución temporal de la forma urbana a través de un Sistema de Información Geográfico (SIG), calculando unos índices métricos y comparándolos con la información demográfica histórica. Los resultados pretenden mostrar los efectos de la especialización funcional económica, causada por la integración en las jerarquías productivas globales, sobre la estructura urbana. La pérdida gradual de las características tradicionales de los pueblos castellanos, como la compacidad y la integración en el entorno, debido a la pérdida o degradación de la arquitectura popular y la construcción de nuevas edificaciones industriales, supone un riesgo para las futuras políticas de desarrollo local. Se considera necesario preservar la identidad paisajística y evitar la destrucción del patrimonio cultural para poder revitalizar estos territorios.

Hope in the Most Unlikely Spaces: Thawra and the Contemporary Arabic Novel

In the early to mid-twentieth century, many novelists in the Arab world championed Arab nationalism in their literary reflections on the social and political struggles of their countries, depicting these struggles primarily in terms of spatial binaries that pitted the Arab world against the West, even as they imported Western literary models of progress and modernity into their own work. The intense experience of national awakening that infused their writing often placed these authors at a literary disadvantage, for in their literature, all too often the depth and diversity of Arabic cultures and the complexity of socio-political struggles across the Arab world were undermined by restrictive spatial discourses that tended to focus only on particular versions of Arab history and on a seemingly unifying national predicament. Between the Arab defeat of 1967 and the present day, however, an increasing number of Arab authors have turned to less restrictive forms of spatial discourse in search of a language that might offer alternative narratives of hope beyond the predictable, and seemingly thwarted, trajectories of nationalism. This study traces the ways in which contemporary Arab authors from Egypt and the Sudan have endeavoured to re-think and re-define the Arab identity in ever-changing spaces where elements of the local and the global, the traditional and the modern, interact both competitively and harmoniously. I examine the spatial language and the tropes used in three Arabic novels, viewing them through the lens of thawra (revolution) in both its socio-political and artistic manifestations. Linking the manifestations of thawra in each text to different scenes of revolution in the Arab world today, in Chapter Two, I consider how, at a stage when the Sudan of the sixties was both still dealing with colonial withdrawal and struggling to establish itself as a nation-state, the geographical and textual landscapes of Tayeb Salih‟s Season of Migration to the North depict the ongoing dilemma of the Sudanese identity. In Chapter Three, I examine Alaa iii al-Aswany‟s The Yacoubian Building in the context of a socially diseased and politically corrupt Egypt of the nineties: social, political, modern, historical, local, and global elements intertwine in a dizzyingly complex spatial network of associations that sheds light on the complicated reasons behind today‟s Egyptian thawra. In Chapter Four, the final chapter, Gamal al-Ghitani‟s approach to his Egypt in Pyramid Texts drifts far away from Salih‟s anguished Sudan and al-Aswany‟s chaotic Cairo to a realm where thawra manifests itself artistically in a sophisticated spatial language that challenges all forms of spatial hegemony and, consequently, old and new forms of social, political, and cultural oppression in the Arab world.

“Islands” in Holocene forests: implications for forest openness, landscape clearance and “culture-steppe” species

Human activity has undoubtedly had a major impact on Holocene forested ecosystems, with the concurrent expansion of plants and animals associated with cleared landscapes and pasture, also known as 'culture-steppe'. However, this anthropogenic perspective may have underestimated the contribution of autogenic disturbance (e.g. wind-throw, fire), or a mixture of autogenic and anthropogenic processes, within early Holocene forests. Entomologists have long argued that the north European primary forest was probably similar in structure to pasture woodland. This idea has received support from the conservation biologist Frans Vera, who has recently strongly argued that the role of large herbivores in maintaining open forests in the primeval landscapes of Europe has been seriously underestimated. This paper reviews this debate from a fossil invertebrate perspective and looks at several early Holocene insect assemblages. Although wood taxa are indeed important during this period, species typical of open areas and grassland and dung beetles, usually associated with the dung of grazing animals, are persistent presences in many early woodland faunas. We also suggest that fire and other natural disturbance agents appear to have played an important ecological role in some of these forests, maintaining open areas and creating open vegetation islands within these systems. More work, however, is required to ascertain the role of grazing animals, but we conclude that fossil insects have a significant contribution to make to this debate. This evidence has fundamental implications in terms of how the palaeoecological record is interpreted, particularly by environmental archaeologists and palaeoecologists who may be more interested in identifying human-environment interactions rather than the ecological processes which may be preserved within palaeoecological records.