scholarly journals Recent climate-driven ecological changes in tropical montane lakes of Rwenzori Mountains National Park, central Africa

2020 ◽  
Author(s):  
Anson W. Mackay ◽  
Rebecca Lee ◽  
James M. Russell
Keyword(s):  
Twentieth Century ◽  
Organic Carbon ◽  
National Park ◽  
Organic Geochemistry ◽  
Published Data ◽  
Rwenzori Mountains ◽  
High Profile ◽  
The Past ◽  
Low Profile ◽  
Recent Climate

Abstract Rwenzori Mountains National Park, which straddles the border between the Democratic Republic of Congo and Uganda, has experienced rapid glacier loss since the beginning of the twentieth century, yet there has been little investigation of aquatic biodiversity change in the park. This study presents a paleolimnological analysis from Lake Mahoma (2990 m asl), which is situated in the bamboo-forest transition zone. Diatom and organic geochemistry data from a 39-cm-long sediment core with a basal age of c. 1715 CE were compared with new analyses of previously published data from Lakes Bujuku (3891 m asl) and Lower Kitandara (3989 m asl), in the alpine zone. Comparisons were made to determine if aquatic ecosystem changes exhibited similar inter-lake patterns over the past ~ 150 years of climate warming and glacial recession, or if only local change was apparent. The diatom flora of Lake Mahoma is acidophilous, dominated by Aulacoseira ikapoënsis since at least the mid eighteenth century. In recent decades, the obligate nitrogen-heterotroph Nitzschia palea increased in importance, concurrent with declining δ15Norg values. We suggest that these late twentieth century changes were linked to regional warming and increased thermal stratification of Lake Mahoma. Regional comparisons of the Rwenzori lakes were done using existing organic geochemistry records (total organic carbon, C/N and δ13Corg) and through diatom compositional turnover analyses, and categorisation of species into one of four diatom growth morphology traits, or guilds: tychoplanktonic, high-profile, low-profile and motile. Over the past 150 years, all three lakes showed unidirectional, compositional diatom turnover, indicating that deterministic processes had affected diatom communities. Declining turnover at each site is broadly mirrored by an increase in tychoplanktonic taxa, along with concomitant declines in high-profile diatoms at Lake Mahoma, and low-profile diatoms at Lake Bujuku, and at least for the past 60 years, at Lower Kitandara. The interplay between diatom guilds at all sites is mainly a consequence of competition for available resources. Sediment organic carbon at all sites comes from both autochthonous and allochthonous sources, the relative abundances of which are influenced by the time elapsed since lakes had glaciers in their catchment.

The Organic carbon content of gravel bed herring spawning grounds and the impact of herring spawn deposition

1993 ◽  
Vol 73 (4) ◽  
pp. 863-870 ◽  
Author(s):  
Ian R. Napier
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Dry Weight ◽  
Published Data ◽  
Organic Carbon Content ◽  
Spawning Grounds ◽  
The Past ◽  
Benthic Food ◽  
The Impact

The dry weight and organic carbon content of eggs and components of Clyde spring herring eggs were measured at intervals during their development. Comparison with previously published data suggests that an increase has occurred in the weight of these eggs over the past thirty years. It is clear that only a small proportion of the material deposited in the form of herring spawn actually remains attached to the substratum when the larvae hatch and so is available for potential integration into the benthic food web. This was confirmed by the determination at intervals over two years of the organic carbon content of the gravel sediments on spawning grounds of the Clyde spring herring. Although the deposition of herring spawn resulted in an immediate marked increase in the carbon content of the spawning ground sediments, carbon levels quickly returned to pre-spawning levels and there was no evidence of any permanent or long lasting increase. This held true when the spawn died and decayed in situ and even when it was mixed into the sediment by wave action. The rapid decrease in carbon levels is attributed to the strong water movements which frequently occur over the spawning grounds.

““Of Exceptional Importance””: The Origins of the ““Fifty-Year Rule”” in Historic Preservation

2007 ◽  
Vol 29 (2) ◽  
pp. 81-103 ◽  
Author(s):  
JOHN H. SPRINKLE
Keyword(s):  
Twentieth Century ◽  
Historic Preservation ◽  
National Park ◽  
National Park Service ◽  
Historic Site ◽  
Heritage Sites ◽  
The Past ◽  
Park Service ◽  
Site Significance ◽  
National Historic Preservation Act

The ““fifty-year rule”” is one of the most commonly accepted principles within American historic preservation: properties that have achieved significance within the past fifty years are generally not considered eligible for listing in the National Register of Historic places. An often misunderstood chronological threshold, the fifty-year standard was established by National Park Service historians in 1948. Until the advent of the ““new preservation”” with the National Historic Preservation Act in 1966, the standard of exceptional importance had only been applied to presidential and atomic heritage sites. Operating as a filter to ward off potentially controversial decisions about the nature of historic site significance, understanding the origins of the fifty-year rule reveals how Americans have constructed the chronological boundaries of a useable past through historic preservation during the twentieth century.

Nine Centuries of Man

2017 ◽  
Keyword(s):  
Twentieth Century ◽  
Diverse Range ◽  
Gender Expectations ◽  
Court Records ◽  
The Past ◽  
Wide Range ◽  
Police Reports ◽  
Late Twentieth ◽  
Scottish History ◽  
Late Twentieth Century

What did it mean to be a man in Scotland over the past nine centuries? Scotland, with its stereotypes of the kilted warrior and the industrial ‘hard man’, has long been characterised in masculine terms, but there has been little historical exploration of masculinity in a wider context. This interdisciplinary collection examines a diverse range of the multiple and changing forms of masculinities from the late eleventh to the late twentieth century, exploring the ways in which Scottish society through the ages defined expectations for men and their behaviour. How men reacted to those expectations is examined through sources such as documentary materials, medieval seals, romances, poetry, begging letters, police reports and court records, charity records, oral histories and personal correspondence. Focusing upon the wide range of activities and roles undertaken by men – work, fatherhood and play, violence and war, sex and commerce – the book also illustrates the range of masculinities that affected or were internalised by men. Together, the chapters illustrate some of the ways Scotland’s gender expectations have changed over the centuries and how, more generally, masculinities have informed the path of Scottish history

Modernism Under Review: Hugh Kenner's The Pound Era

2010 ◽  
Vol 5 (2) ◽  
pp. 181-194
Author(s):  
Marjorie Perloff
Keyword(s):  
Twentieth Century ◽  
First World War ◽  
World War ◽  
The Past ◽  
The First World War ◽  
Anglo American ◽  
First World

This essay offers a critical re-assessment of Hugh Kenner's The Pound Era. It argues that Kenner's magisterial survey remains important to our understanding of Modernism, despite its frankly partisan viewpoint. Kenner's is an insider's account of the Anglo-American Modernist writing that he takes to have been significant because it sought to invent a new language consonant with the ethos of the twentieth century. The essay suggests that Kenner's impeccable attention to the Modernist renovation of language goes beyond formalism, since, for him, its ‘patterned energies’ (a term derived from Buckminster Fuller's theory of knots) relate Modernism to the larger complex of artefacts within which it functions and, beyond these, to what he takes to be the great works of the past and to the scientific-technological inventions of the present. But the essay also points out that Kenner's is an eccentric canon, which makes no room for Forster, Frost, Lawrence, or Stevens. Furthermore, Kenner's emphasis on the First World War as a great cultural rupture, while plausible, works less well for Joyce and Williams than it does for Pound and Eliot.

Collective Memory: Between Values and Historical Knowledge

2020 ◽  
pp. 124-142
Author(s):  
VICTOR BURLACHUK
Keyword(s):  
Twentieth Century ◽  
Soviet Union ◽  
Collective Memory ◽  
Rapid Change ◽  
Modern Society ◽  
The State ◽  
Main Element ◽  
Rapid Decline ◽  
The Past ◽  
The Future

At the end of the twentieth century, questions of a secondary nature suddenly became topical: what do we remember and who owns the memory? Memory as one of the mental characteristics of an individual’s activity is complemented by the concept of collective memory, which requires a different method of analysis than the activity of a separate individual. In the 1970s, a situation arose that gave rise to the so-called "historical politics" or "memory politics." If philosophical studies of memory problems of the 30’s and 40’s of the twentieth century were focused mainly on the peculiarities of perception of the past in the individual and collective consciousness and did not go beyond scientific discussions, then half a century later the situation has changed dramatically. The problem of memory has found its political sound: historians and sociologists, politicians and representatives of the media have entered the discourse on memory. Modern society, including all social, ethnic and family groups, has undergone a profound change in the traditional attitude towards the past, which has been associated with changes in the structure of government. In connection with the discrediting of the Soviet Union, the rapid decline of the Communist Party and its ideology, there was a collapse of Marxism, which provided for a certain model of time and history. The end of the revolutionary idea, a powerful vector that indicated the direction of historical time into the future, inevitably led to a rapid change in perception of the past. Three models of the future, which, according to Pierre Nora, defined the face of the past (the future as a restoration of the past, the future as progress and the future as a revolution) that existed until recently, have now lost their relevance. Today, absolute uncertainty hangs over the future. The inability to predict the future poses certain challenges to the present. The end of any teleology of history imposes on the present a debt of memory. Features of the life of memory, the specifics of its state and functioning directly affect the state of identity, both personal and collective. Distortion of memory, its incorrect work, and its ideological manipulation can give rise to an identity crisis. The memorial phenomenon is a certain political resource in a situation of severe socio-political breaks and changes. In the conditions of the economic crisis and in the absence of a real and clear program for future development, the state often seeks to turn memory into the main element of national consolidation.

Aftershocks

2017 ◽  
Author(s):  
Seva Gunitsky
Keyword(s):  
Twentieth Century ◽  
Regime Change ◽  
International System ◽  
Political Legitimacy ◽  
Great Powers ◽  
Past Century ◽  
The Past ◽  
Sudden Rise ◽  
The World ◽  
National Borders

Over the past century, democracy spread around the world in turbulent bursts of change, sweeping across national borders in dramatic cascades of revolution and reform. This book offers a new global-oriented explanation for this wavelike spread and retreat—not only of democracy but also of its twentieth-century rivals, fascism, and communism. The book argues that waves of regime change are driven by the aftermath of cataclysmic disruptions to the international system. These hegemonic shocks, marked by the sudden rise and fall of great powers, have been essential and often-neglected drivers of domestic transformations. Though rare and fleeting, they not only repeatedly alter the global hierarchy of powerful states but also create unique and powerful opportunities for sweeping national reforms—by triggering military impositions, swiftly changing the incentives of domestic actors, or transforming the basis of political legitimacy itself. As a result, the evolution of modern regimes cannot be fully understood without examining the consequences of clashes between great powers, which repeatedly—and often unsuccessfully—sought to cajole, inspire, and intimidate other states into joining their camps.

Managing rivers for conservation and ecotourism in the Kruger National Park

1995 ◽  
Vol 32 (5-6) ◽  
pp. 227-233 ◽  
Author(s):  
F. J. Venter ◽  
A. R. Deacon
Keyword(s):  
National Park ◽  
Good Condition ◽  
Kruger National Park ◽  
Rapid Expansion ◽  
Natural Environments ◽  
The West ◽  
The Past ◽  
Management Actions ◽  
Flow Through ◽  
Three Rivers

Six major rivers flow through the Kruger National Park (KNP). All these rivers originate outside and to the west of the KNP and are highly utilized. They are crucially important for the conservation of the unique natural environments of the KNP. The human population growth in the Lowveld during the past two decades brought with it the rapid expansion of irrigation farming, exotic afforestation and land grazed by domestic stock, as well as the establishment of large towns, mines, dams and industries. Along with these developments came overgrazing, erosion, over-utilization and pollution of rivers, as well as clearing of indigenous forests from large areas outside the borders of the KNP. Over-utilization of the rivers which ultimately flow through the KNP poses one of the most serious challenges to the KNP's management. This paper gives the background to the development in the catchments and highlights the problems which these have caused for the KNP. Management actions which have been taken as well as their results are discussed and solutions to certain problems proposed. Three rivers, namely the Letaba, Olifants and Sabie are respectively described as examples of an over-utilized river, a polluted river and a river which is still in a fairly good condition.

Introduction

2018 ◽  
Author(s):  
James Tweedie
Keyword(s):  
Twentieth Century ◽  
Cultural Background ◽  
Media Archaeology ◽  
The Past ◽  
The Future ◽  
Late Twentieth ◽  
Heritage Industry ◽  
Late Twentieth Century

This chapter introduces the concept of the “archaeomodern” and its connection to the aging of the quintessential modern medium of film. It sketches the historical and cultural background of the archaeomodern turn in the late twentieth century, including the development of an obsession with the past in the heritage industry and the rise of postmodernism. It then discusses two phenomena from the 1980s and 1990s—a mannerist or baroque revival, and the development of media archaeology—that complicate the habitual association between tradition and the past or modernity and the future. The introduction suggests that archaeomodern cinema was characterized by the return to failed or abandoned modern experiments and other relics from the modern past.

The Obligation to Choose

2018 ◽  
Author(s):  
Rachel Crossland
Keyword(s):  
Twentieth Century ◽  
Close Attention ◽  
The Past ◽  
Light Quanta ◽  
Early Twentieth Century ◽  
Wave Particle Duality ◽  
Night And Day ◽  
Scientific Ideas

Chapter 1 explores Woolf’s writings up to the end of 1925 in relation to scientific ideas on wave-particle duality, providing the ‘retrospect of Woolf’s earlier novels’ which Michael Whitworth has suggested shows that she was working ‘in anticipation of the physicists’. The chapter as a whole challenges this idea of anticipation, showing that Woolf was actually working in parallel with physicists, philosophers, and artists in the early twentieth century, all of whom were starting to question dualistic models and instead beginning to develop complementary ones. A retrospect on wave-particle duality is also provided, making reference to Max Planck’s work on quanta and Albert Einstein’s development of light quanta. This chapter pays close attention to Woolf’s writing of light and her use of conjunctions, suggesting that Woolf was increasingly looking to write ‘both/and’ rather than ‘either/or’. Among other texts, it considers Night and Day, Mrs Dalloway, and ‘Sketch of the Past’.

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