Holocene History of Desertification along the Woodland-Steppe Border in Northern China

2002 ◽  
Vol 57 (2) ◽  
pp. 259-270 ◽  
Author(s):  
Hongyan Liu ◽  
Lihong Xu ◽  
Haiting Cui
Keyword(s):  
Northern China ◽  
Mongolian Plateau ◽  
Dry Period ◽  
Physical Chemical ◽  
The Pacific ◽  
Aeolian Activity ◽  
Winter Temperatures ◽  
History Of ◽  
Moisture Conditions ◽  
Humid Period

AbstractThe woodland-steppe ecotone of the southeastern Inner Mongolian Plateau in northern China is located at the northwestern limit of the Pacific monsoon influence, where the landscape may have been a sensitive recorder of past climatic changes. Physical, chemical, and biological analyses of AMS 14C-dated sediment sequences from two lakes of this region were used to reconstruct the Holocene vegetation and desertification history and distinguish four periods: (1) a cold and humid period from 10000 to 8000 14C yr B.P., (2) a warm and humid period from 8000 to 5900 14C yr B.P., (3) a warm and dry period from 5900 to 2900 14C yr B.P., and (4) a cool and dry period from 2900 14C yr B.P. to the present. The increased aridity during the middle Holocene was likely caused by increased winter temperatures and enhanced winter evaporation. The transition from a humid to an arid climate after ∼5900 14C yr B.P. coincided with enhanced aeolian activity, and deciduous woodlands were replaced by pine woodlands and then by steppes in response to the climatic deterioration. These transitions led to the present desertification. The records suggest that a simple association of thermal and moisture conditions, such as warm/wet or cold/dry, may be misleading.

scholarly journals Tree-ring history of Swiss needle cast impact on Douglas-fir growth in Western Oregon: correlations with climatic variables

2021 ◽  
Vol 5 (3) ◽  
pp. 076-087
Author(s):  
Lee E Henry ◽  
Beedlow Peter A ◽  
Waschmann Ronald S ◽  
Cline Steve ◽  
Bollman Michael ◽  
...  
Keyword(s):  
Tree Ring ◽  
Summer Precipitation ◽  
Douglas Fir ◽  
Coast Range ◽  
The West ◽  
The Pacific ◽  
Winter Temperatures ◽  
Coastal Fog ◽  
Swiss Needle Cast ◽  
History Of

The fungal pathogen, Nothophaeocryptopus gaeumannii, occurs wherever Douglas-fir is found but disease damage is believed to be limited to the Coast Range and is of no concern outside the coastal fog zone (Shaw, et al., 2011). However, knowledge remains limited on the history and spatial distribution of Swiss Needle Cast (SNC) impacts in the Pacific Northwest (PNW). We reconstructed the history of SNC impacts on mature Douglas-fir trees based on tree ringwidth chronologies from the west slope of the Coast Range to the high Cascades of Oregon. Our findings show that SNC impacts on growth occur wherever Douglas-fir is found in western Oregon and is not limited to the coastal fog zone. The spatiotemporal patterns of growth impact from SNC disease were synchronous across the region, displayed periodicities of 25-30 years, strongly correlated with winter and summer temperatures and summer precipitation, and matched the patterns of enriched cellulosic stable carbon isotope indicative of physiological stress. While winter and summer temperature and summer precipitation influenced pathogen dynamics at all sites, the primary climatic factor of these three limiting factors varied spatially by location, topography, and elevation. In the 20th century, SNC impacts at low- to mid-elevations were least severe during the warm phase of the Pacific Decadal Oscillation (PDO, 1924-1945) and most severe in 1984-1986, following the cool phase of the PDO (1945-1977). At high elevations on the west slope of the Cascade Mountains, SNC impacts were the greatest in the 1990s and 2000s, a period of warmer winter temperatures associated with climate change. Warmer winters will likely continue to increase SNC severity at higher elevations, north along the coast from northern Oregon to British Columbia, and inland where low winter temperatures currently limit growth of the pathogen. Surprisingly, tree-ring records of ancient Douglas-fir logs dated ~53K radioactive years B.P. from Eddyville, OR displayed 7.5- and 20-year periodicities of low growth, similar to those found in modern day coastal Douglas-fir tree-ring records which we interpret as being due to cyclic fluctuations in SNC severity. Our findings indicate that SNC has persisted for as long as its host, and as a result of changing climate, may become a significant forest health problem in areas of the PNW beyond the coastal fog zone.

A Short history of the post-graduate surgical training in Fiji - where to from here?

2018 ◽  
Vol 21 (2) ◽  
pp. 103-107 ◽  
Author(s):  
Jitoko Kelepi Cama ◽  
Sonal Singh Nagra
Keyword(s):  
Surgical Training ◽  
Training Programme ◽  
Post Graduate ◽  
School Of Medicine ◽  
Postgraduate Training Programme ◽  
The Pacific ◽  
National University ◽  
History Of ◽  
Training Of Surgeons ◽  
Pacific Island Nations

Post-graduate surgical training at the Fiji National University (FNU), previously known as the Fiji School of Medicine) has recently been updated by incorporating elements from the Royal Australasian College of Surgeons (RACS) training curriculum. The revised curriculum maintains strong contextual relevance to the needs and pathologies of the Pacific Island nations.  This paper outlines why the FNU surgical postgraduate training programme should be applauded as a successful programme in the training of surgeons for the region.

Oceans and Landless Farms: Linking Southern and Northern Shadow Places of Industrial Livestock (1954–1975)

2020 ◽  
Author(s):  
Floor Haalboom
Keyword(s):  
Animal Feed ◽  
Marine Ecosystem ◽  
Global South ◽  
Humboldt Current ◽  
The Public ◽  
The Pacific ◽  
Production And Consumption ◽  
Boom And Bust ◽  
History Of ◽  
Global North

This article argues for more extensive attention by environmental historians to the role of agriculture and animals in twentieth-century industrialisation and globalisation. To contribute to this aim, this article focuses on the animal feed that enabled the rise of ‘factory farming’ and its ‘shadow places’, by analysing the history of fishmeal. The article links the story of feeding fish to pigs and chickens in one country in the global north (the Netherlands), to that of fishmeal producing countries in the global south (Peru, Chile and Angola in particular) from 1954 to 1975. Analysis of new source material about fishmeal consumption from this period shows that it saw a shift to fishmeal production in the global south rather than the global north, and a boom and bust in the global supply of fishmeal in general and its use in Dutch pigs and poultry farms in particular. Moreover, in different ways, the ocean, and production and consumption places of fishmeal functioned as shadow places of this commodity. The public health, ecological and social impacts of fishmeal – which were a consequence of its cheapness as a feed ingredient – were largely invisible on the other side of the world, until changes in the marine ecosystem of the Pacific Humboldt Current and the large fishmeal crisis of 1972–1973 suddenly changed this.

THE TECTONIC HISTORY OF THE PACIFIC OCEAN BASIN SINCE CHRON 34Y (83 MA)

2017 ◽  
Author(s):  
Nicky M. Wright ◽  
◽  
Maria Seton ◽  
Simon E. Williams ◽  
R. Dietmar Müller
Keyword(s):  
Pacific Ocean ◽  
Ocean Basin ◽  
Tectonic History ◽  
The Pacific ◽  
History Of ◽  
The Pacific Ocean

The Relevance of Old World Archaeology to the First Entry of Man into New Worlds: Colonization Seen from the Antipodes

1977 ◽  
Vol 8 (1) ◽  
pp. 128-148 ◽  
Author(s):  
Sylvia J. Hallam
Keyword(s):  
Demographic Data ◽  
Ecological Zones ◽  
The North ◽  
Technological Potential ◽  
The Pacific ◽  
Peopling Of The Americas ◽  
Rapid Spread ◽  
History Of ◽  
Economic Innovation ◽  
Considerable Complexity

Following several discussions in recent numbers of Quaternary Research on the peopling of the Americas, this paper suggests that movements into the New World should be viewed in the wider context of subsistence, technology, and movement around the western littorals of the Pacific, resulting in the colonization not of one but of two new continents by men out of Asia. Specific points which have been raised by these recent papers are reviewed in the light of Australian, Wallacian, and East Asian data.(1) The earliness of watercraft is evidenced by chronology of the human diaspora through Wallacia and Greater Australia.(2) The simplistic nomenclature of chopper-flake traditions masks considerable complexity and technological potential, revealed in detailed Antipodean studies.(3) These traditions also have great potential for adapting to differing ecological zones, evidenced within Greater Australia; and for technological and economic innovation there, through Southeast Asia, and to Japan and the north Asian littoral.(4) The history of discovery and the nature of the evidence from Australia cannot validly be used to controvert early dates in the Americas.(5) Demographic data from Australia suggest that total commitment to a rapid-spread “bowwave” model for the peopling of new continents may be unwise.

scholarly journals Biological Control of Pest Non-Marine Molluscs: A Pacific Perspective on Risks to Non-Target Organisms

Insects ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 583
Author(s):  
Carl C. Christensen ◽  
Robert H. Cowie ◽  
Norine W. Yeung ◽  
Kenneth A. Hayes
Keyword(s):  
Biological Control ◽  
Environmental Impacts ◽  
Pacific Islands ◽  
Generalist Predators ◽  
Snail Species ◽  
Marine Mollusk ◽  
The Pacific ◽  
History Of ◽  
Ecosystem Level ◽  
Scientific Framework

Classic biological control of pest non-marine mollusks has a long history of disastrous outcomes, and despite claims to the contrary, few advances have been made to ensure that contemporary biocontrol efforts targeting mollusks are safe and effective. For more than half a century, malacologists have warned of the dangers in applying practices developed in the field of insect biological control, where biocontrol agents are often highly host-specific, to the use of generalist predators and parasites against non-marine mollusk pests. Unfortunately, many of the lessons that should have been learned from these failed biocontrol programs have not been rigorously applied to contemporary efforts. Here, we briefly review the failures of past non-marine mollusk biocontrol efforts in the Pacific islands and their adverse environmental impacts that continue to reverberate across ecosystems. We highlight the fact that none of these past programs has ever been demonstrated to be effective against targeted species, and at least two (the snails Euglandina spp. and the flatworm Platydemus manokwari) are implicated in the extinction of hundreds of snail species endemic to Pacific islands. We also highlight other recent efforts, including the proposed use of sarcophagid flies and nematodes in the genus Phasmarhabditis, that clearly illustrate the false claims that past bad practices are not being repeated. We are not making the claim that biocontrol programs can never be safe and effective. Instead, we hope that in highlighting the need for robust controls, clear and measurable definitions of success, and a broader understanding of ecosystem level interactions within a rigorous scientific framework are all necessary before claims of success can be made by biocontrol advocates. Without such amendments to contemporary biocontrol programs, it will be impossible to avoid repeating the failures of non-marine mollusk biocontrol programs to date.

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