scholarly journals Stability of the vegetation–atmosphere system in the early Eocene climate

2015 ◽  
Vol 11 (3) ◽  
pp. 1551-1578
Author(s):  
U. Port ◽  
M. Claussen

Abstract. We explore the stability of the atmosphere–vegetation system in the warm, almost ice-free early Eocene climate and in the interglacial, pre-industrial climate by analysing the dependence of the system on the initial vegetation cover. The Earth system model of the Max Planck Institute for Meteorology is initialised with either dense forests or bare deserts on all continents. Starting with desert continents, an extended desert remains in Central Asia in early Eocene climate. Starting with dense forest coverage, this desert is much smaller because the initially dense vegetation cover enhances water recycling in Central Asia relative to the simulation with initial deserts. With a smaller Asian desert, the Asian monsoon is stronger than in the case with a larger desert. The stronger Asian monsoon shifts the global tropical circulation leading to coastal subtropical deserts in North and South America which are significantly larger than with a large Asian desert. This result indicates a global teleconnection of the vegetation cover in several regions. In present-day climate, a bi-stability of the atmosphere–vegetation system is found for Northern Africa only. A global teleconnection of bi-stabilities in several regions is absent highlighting that the stability of the vegetation–atmosphere system depends on climatic and tectonic boundary conditions.

2015 ◽  
Vol 11 (11) ◽  
pp. 1563-1574 ◽  
Author(s):  
U. Port ◽  
M. Claussen

Abstract. To date, the transitivity of the global system has been analysed for late Quaternary (glacial, interglacial, and present-day) climate. Here, we extend this analysis to a warm, almost ice-free climate with a different configuration of continents. We use the Earth system model of the Max Planck Institute for Meteorology to analyse the stability of the climate system under early Eocene and pre-industrial conditions. We initialize the simulations by prescribing either dense forests or bare deserts on all continents. Starting with desert continents, an extended desert remains in central Asia in the early Eocene climate. Starting with dense forest coverage, the Asian desert is much smaller, while coastal deserts develop in the Americas which appear to be larger than in the simulations with initially bare continents. These differences can be attributed to differences in the large-scale tropical circulation. With initially forested continents, a stronger dipole in the 200 hPa velocity potential develops than in the simulation with initially bare continents. This difference prevails when vegetation is allowed to adjust to and interact with climate. Further simulations with initial surface conditions that differ in the region of the Asian desert only indicate that local feedback processes are less important in the development of multiple states. In the interglacial, pre-industrial climate, multiple states develop only in the Sahel region. There, local climate–vegetation interaction seems to dominate.


Author(s):  
B.O. Berdiyev ◽  

The article is devoted to the issues of interethnic relations in Central Asia, the need for integration and cooperation between states, external influences, information impacts on the peoples of the region, border issues, overpopulation, ethnic issues and their impact on the stability of the region.


1983 ◽  
Vol 20 (9) ◽  
pp. 1389-1408 ◽  
Author(s):  
Philippe Erdmer ◽  
Herwart Helmstaedt

Eclogite occurring in central Yukon, at Faro and near Last Peak, as lenses interleaved with muscovite–quartz blastomylonite has the chemical and field characteristics of group C rocks. From sigmoidal inclusion trails in garnet, from geothermometry and geobarometry, and from mineral parageneses, the eclogite is inferred to have a crustal protolith and to have followed a hysteretic, subduction-cycle P–T trajectory. Transformation of basic igneous rock into schist was followed by eclogite metamorphism during which pressure was at least 1000 MPa and temperature was between 600 and 700 °C. Uplifting involved passage through the stability field of glaucophane; the eclogite and its host rocks were then subjected to greenschist fades metamorphism and deformation, with temperature at approximately 400 °C. The rocks were emplaced as thrust sheets against or onto the western North American cratonal margin. The tectonic boundary ranges from nearly vertical, where it is outlined by a zone of steeply dipping mélange, to nearly horizontal beneath klippen of cataclastic rocks that lie on North American miogeoclinal strata. Together with occurrences of eclogite on strike, in Yukon, near Fairbanks (Alaska), and near Pinchi Lake (British Columbia), eclogite at Faro and near Last Peak implies that the Yukon Cataclastic Complex is a deeply eroded collision mélange that borders over 1000 km of the ancient continental margin.


2018 ◽  
Vol 22 (03) ◽  
pp. 89-95
Author(s):  
Lkhamsuren B ◽  
Odgerel B ◽  
Purevsuren Sh

The study aims to investigate changes in the physical properties of soil depending on the utilization conditions of the Special Protected National Park compared to the area fenced for more than 10 years. The stability and stabilization of the stabilized mountain meadow soil stabilization and physical properties of soil in the Gorkhi-Terelj National Park (GTNP) resort and limited concentration of tourism. As a result of the study, the stability of the soil structure was 2.8 points in the area of vegetation cover 0-3 cm outside the fence, while the 2.6 layered soil layers above the soils of the vegetation cover. However, the area with vegetation cover within the fence is 4.2 points in soil 0-3 cm and 4 leaves in soil without vegetation cover.


Author(s):  
Pulatov Abrorjon Masutovich ◽  

The article examines modern socio-political relations, the rapid development of communication and information technologies, the expansion of ideological influence, impulses to improve methods and means of communication, as well as criminal threats to society. The study notes that the minds and hearts of people in different parts of the world turn into a training ground for testing various ideas, in other words, an ideological training ground for training. It is also clear that the activities of fanatical political Islamists and religious extremist movements that try to disguise religion and undermine religious values are one of the factors that threaten the spirituality of our children. Despite its growing role in the global geopolitical arena in Central Asia, it is important to protect our country, which is a key player in the region in terms of population and territory, from stereotypes of religious fanaticism, to create conditions for citizens so that they can practice their beliefs, tolerance and views on interethnic harmony, further strengthening the centuries-old traditions and customs of our people.


2008 ◽  
Vol 4 (6) ◽  
pp. 1265-1287 ◽  
Author(s):  
L. Jin ◽  
Y. Peng ◽  
F. Chen ◽  
A. Ganopolski

Abstract. The impacts of various scenarios of snow and glaciers developing over the Tibetan Plateau on climate change in Afro-Asian monsoon region and other regions during the Holocene (9 kyr BP–0 kyr BP) are studied by using the coupled climate model of intermediate complexity, CLIMBER-2. The simulations show that the imposed snow and glaciers over the Tibetan Plateau in the mid-Holocene induce global summer temperature decreases, especially in the northern parts of Europe, Asia, and North America. At the same time, with the imposed snow and glaciers, summer precipitation decreases strongly in North Africa and South Asia as well as northeastern China, while it increases in Southeast Asia and the Mediterranean. For the whole period of Holocene (9 kyr BP–0 kyr BP), the response of vegetation cover to the imposed snow and glaciers cover over the Tibetan Plateau is not synchronous in South Asia and in North Africa, showing an earlier and a more rapid decrease in vegetation cover in North Africa from 9 to 6 kyr BP while it has only minor influence on that in South Asia until 5 kyr BP. Imposed gradually increased snow and glacier cover over the Tibetan Plateau causes temperature increases in South Asia and it decreases in North Africa and Southeast Asia during 6 kyr BP to 0 kyr BP. The precipitation decreases rapidly in North Africa and South Asia while it decreases slowly or unchanged during 6 kyr BP to 0 kyr BP with imposed snow and glacier cover over the Tibetan Plateau. The different scenarios of snow and glacier developing over the Tibetan Plateau would result in differences in variation of temperature, precipitation and vegetation cover in North Africa, South Asia and Southeast Asia. The model results show that the response of climate change in African-Asian monsoon region to snow and glacier cover over the Tibetan Plateau is in the way that the snow and glaciers amplify the effect of vegetation feedback and, hence, further amplify orbital forcing.


2020 ◽  
Author(s):  
Phillipe Gauvin-Bourdon ◽  
James King ◽  
Liliana Perez

Abstract. Arid environments are characterized by the complex interaction between vegetation cover, surface soil properties, and the climate. The dynamic balance between these components makes arid environments highly susceptible to swift changes in vegetation cover and in surface morphology in response to climate change. Furthermore, arid environments often support grazing activities, which influence other ecogeomorphic processes and alter the stability of vegetation cover in these environments. Despite the growing knowledge and the parallel modelling advances to simulate the sediment transport, vegetation distribution, and grazing, in arid environments, relatively little progress has been accomplished on the interaction between all these components in combination. Here we present an adaptation of an already established sediment transport-vegetation cellular automata model (Vegetation and Sediment TrAnsport or ViSTA) that represents landscape dynamics, with an agent-based model (GrAM) representing the activity of grazers on the landscape. In this study our resulting model, ViSTA_GrAM, is subjected to a series of 100-year long tests that aim to highlight the capacity of the model to represent ecogeomorphic processes linked to vegetation composition, rainfall, windspeed, and grazing pressure. The new model provides an improved representation of the feedback complexities between grazers and the vegetation, in addition to providing insight on the vegetation and wind shear sensitivity of the original model. The simulations reinforce our current knowledge on the resilience of grass-based landscapes to foraging activities and highlights the need to identify growth response rates at the species level to fully understand the complexity of the interactions between individual components within arid environments. Overall, the ViSTA_GrAM model represents an important improvement for managing arid landscapes over the previously available tools.


2018 ◽  
pp. 137-148
Author(s):  
E. I. Rachkovskaya ◽  
Z. V. Karamysheva ◽  
N. P. Litvinova ◽  
I. Yu. Sumerina ◽  
V. N. Khramtsov ◽  
...  

On May 3, 2018 Elena Anatolievna Volkova ce­lebrates her anniversary. She is a highly qualified phytogeographer, thoughtful field researcher, expert in mountain vegetation of Asia, tireless traveler. The field of her scientific interests is the regularity of vegetation cover, small- and large-scale mapping of vegetation in different regions of Eurasia. She has made a great contribution to the study of the composition and structure of vegetation cover of complex and inaccessible arid and subarid mountain areas of Central Asia. E. Volkova began to work in deserts and steppes of Kazakhstan, and then 15 years studied arid plain and mountain regions of Mongolia. In Joint Soviet-Mongolian complex biological expedition of Academies of sciences of USSR and Mongolian People’s Republic E. Volkova investigated the deserts of Alashan Gobi, Trans-Altai Gobi and Dzhungarian Gobi. The result of these field works was a publication on the study of the relationship between the composition and structure of plant communities with the petrographic composition of rocks in melkosopochniks in different subzones and provinces of Gobi (Volkova, 1976); together with E. I. Rachkovskaya original vegetation maps of these extra-arid territories were created (Rachkovskaya, Volkova, 1977, 1980, etc.). The collected data on mountain vegetation were used to produce the vegetation map of Mongolia in the National Atlas (Karta..., 1990) and the monograph “Botanical geography of Mongolian and Gobi Altai” (Volkova, 1994). E. Volkova has made two vegetation maps: of Asia in atlas “Our Earth” (Волкова, 1996) and (together with I. Fedorova) of the World (scale 1: 60 000 000) for “Resources and Environment: World Atlas” (Volkova, Fedorova, 1998). In 2003 the monograph “Botanical geography of Kazakhstan and Central Asia (within the desert area)” was published in which E. Volkova is the author of a large section “Vegetation cover of mountains” and sub-section “Mountain provinces” in the section “Principles and basic units of regionalization” (Volkova, 2003a, b). After the collapse of the Soviet Union, most of the arid areas of the country became inaccessible for research, and E. Volkova’ interests have turned to the vegetation of the Northwest of European Russia (Le­ningrad Region). The Botanical Institute of Russian Academy of sciences organized complex researches for the purpose of inventory of natural complexes and their components in territories valuable for nature protection, and also of areas of economic importance. The result of this work was the organization of natural protected areas in the Leningrad Region and Saint Petersburg and the publication of the “Atlas of natural protected areas of St. Petersburg” (Atlas..., 2013, 2016) and 11 collective monographs (2001–2017) in which E.Volkova is the constant co-editor and author of the sections on vegetation. E. A. Volkova has published about 190 works, including articles in the journals “Proceedings of theRussianGeographical Society”, “Botanical journal”, “Vegetation of Russia”, “Biosphere”, the “Geobotanical mapping” (Volkova, Khramtsov 2018). She conti­nues to be an active field researcher and preparing new articles and monographs.


2021 ◽  
Vol 17 (6) ◽  
pp. 20210185
Author(s):  
Matthew F. Jones ◽  
Qiang Li ◽  
Xijun Ni ◽  
K. Christopher Beard

Bats dispersed widely after evolving the capacity for powered flight, and fossil bats are known from the early Eocene of most continents. Until now, however, bats have been conspicuously absent from the early Eocene of mainland Asia. Here, we report two teeth from the Junggar Basin of northern Xinjiang, China belonging to the first known early Eocene bats from Asia, representing arguably the most plesiomorphic bat molars currently recognized. These teeth combine certain bat synapomorphies with primitive traits found in other placental mammals, thereby potentially illuminating dental evolution among stem bats. The Junggar Basin teeth suggest that the dentition of the stem chiropteran family Onychonycteridae is surprisingly derived, although their postcranial anatomy is more primitive than that of any other Eocene bats. Additional comparisons with stem bat families Icaronycteridae and Archaeonycteridae fail to identify unambiguous synapomorphies for the latter taxa, raising the possibility that neither is monophyletic as currently recognized. The presence of highly plesiomorphic bats in the early Eocene of central Asia suggests that this region was an important locus for the earliest, transitional phases of bat evolution, as has been demonstrated for other placental mammal orders including Lagomorpha and Rodentia.


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