scholarly journals Changes in Pleistocene vegetation and climate of Ukraine in the range of 1.8-0.4 million years

2019 ◽  
Vol 28 (2) ◽  
pp. 355-366
Author(s):  
O. A. Sirenko
Keyword(s):  
Vegetation Cover ◽  
Climatic Factors ◽  
Climatic Conditions ◽  
Vegetation Changes ◽  
Vegetation Composition ◽  
Geological Time ◽  
Nature Development ◽  
Climatic Characteristics ◽  
Vegetation And Climate ◽  
Dynamics Of Vegetation

On the basis of the analysis of the results of detailed palynological studies of Pleistocene deposits in Ukraine, the correlation between climatic changes and vegetation dynamics was retraced in the range of 1.8-0.43 million years. The curve of paleoclimate changes was constructed and analyzed. It was shown that certain climatic characteristics were inherent for each stage of the nature development, which was reflected in the composition of vegetation. It was found thattemperature and humidity fluctuations also occurred during each stage. The evidence of this is the reconstructed micro-rhythm in the development of vegetation of each stage. The main features of vegetation composition were determined for four warm and five cold stages of nature development, and a pattern of vegetation changes was retraced during each stage. The dynamics of vegetation cover of the Prydonetska Plain, different parts of the Prydniprovska Lowland, the Prydniprovska Upland, the Near Black Sea Lowland, and the Podil’ska Upland vegetation during the specified geological time was reconstructed. General and regional distinctions of the composition of vegetation cover were revealed, and the influence of the main climatic factors such as temperature and humidity on the character of its changes was retraced. The stages characterized by the warmest and wet climatic conditions and the most cold and dry ones were established. It was substantiated that the climatic conditions of the Sula period were less severe than in the subsequent stages of the fall of temperature. The existence of refugiums of thermophilic flora in the Sula period within separate regions of Ukraine was established. The existence of vegetation zonality was substantiated not only in warm stages, but also in cold periods of the Early Neopleistocene.

scholarly journals Three millennia of vegetation and environmental dynamics in the Lagunas de Mojanda region, northern Ecuador

2017 ◽  
Vol 57 (2) ◽  
pp. 407-421 ◽  
Author(s):  
Andrea Villota ◽  
Hermann Behling ◽  
Susana León-Yánez
Keyword(s):  
Vegetation Type ◽  
Montane Forest ◽  
Climatic Conditions ◽  
Climate Dynamics ◽  
Peat Bog ◽  
Pollen Record ◽  
Vegetation Composition ◽  
Human Occupation ◽  
Vegetation And Climate ◽  
Montane Rainforest

AbstractThe pollen record from Lagunas de Mojanda, located at 3748 m a.s.l. (northern Ecuadorian Andes) reflects the vegetation and climate dynamics for the last ca 3400 cal yr BP. Páramo vegetation has been the main vegetation type since the beginning of the record. At Lagunas de Mojanda, from the last ca 3400 to 2200 cal yr BP, grass páramo was well represented mainly by Poaceae (40%) and the occurrence ofValeriana(5%), while montane forest taxa were poorly represented and subpáramo taxa were rare. The vegetation composition suggests cool and humid conditions. Between ca 2200 and ca 1300 cal yr BP, montane rainforest and subpáramo taxa had a higher presence but páramo taxa remained the main vegetation type in the study area, suggesting cool climatic conditions. From ca 1300 to ca 500 cal yr BP, páramo vegetation remained stable, with higher presence ofPhlegmariurusandIsoetes, suggesting cool and humid conditions. The last ca 500 cal yr BP generally show lower frequency of montane rainforest and subpáramo taxa. Páramo vegetation reached the highest share, with the presence of Poaceae,PlantagoandRanunculussuggesting a trend of peat bog drying. Fires were present during the whole record, perhaps human-caused, but the study area does not show great disturbance except from ca 1300 to 500 cal yr BP, a period of an evident higher influx of charcoal particles coincidentally with nearby ancient human occupation.

scholarly journals Effect of changing vegetation on denudation (part 1): Predicted vegetation composition and cover over the last 21 thousand years along the Coastal Cordillera of Chile

2018 ◽  
Author(s):  
Christian Werner ◽  
Manuel Schmid ◽  
Todd A. Ehlers ◽  
Juan Pablo Fuentes-Espoz ◽  
Jörg Steinkamp ◽  
...  
Keyword(s):  
Vegetation Cover ◽  
General Circulation ◽  
Landscape Evolution ◽  
General Circulation Models ◽  
Sensitivity Study ◽  
Evolution Model ◽  
Vegetation Changes ◽  
Vegetation Composition ◽  
Climate Conditions ◽  
Coastal Cordillera

Abstract. Vegetation is crucial for modulating rates of denudation and landscape evolution as it stabilizes and protects hillslopes and intercepts rainfall. Climate conditions and atmospheric CO2 concentration ([CO2]) influence the establishment and performance of plants and thus have a direct influence on vegetation cover. In addition, vegetation dynamics (competition for space, light, nutrients and water) and stochastic events (mortality and fires) determine the state of vegetation, response times to environmental perturbations, and the successional development. In spite of this, state-of-art reconstructions of past transient vegetation changes have not been accounted for in landscape evolution models. Here, a widely used dynamic vegetation model (LPJ-GUESS) was used to simulate vegetation composition/ cover and surface runoff in Chile for the Last Glacial Maximum (LGM), Mid Holocene (MH) and present day (PD). In addition, we conducted transient vegetation simulations from LGM to PD for four sites of the Coastal Cordillera of Chile at a spatial and temporal resolution adequate for coupling with landscape evolution models. Using a regionally-adapted parametrization, LPJ-GUESS was capable of reproducing present day potential natural vegetation along the strong climatic gradients of Chile and simulated vegetation cover was also in line with satellite-based observations. Simulated vegetation during the LGM differed markedly from PD conditions. Coastal cold temperate rainforests where displaced northward by about 5° and the tree line and vegetation zones were at lower elevations than at PD. Transient vegetation simulations indicate a marked shift in vegetation composition starting with the past-glacial warming that coincides with a rise in [CO2]. Vegetation cover between the sites ranged from 13 % (LGM: 8 %) to 81 % (LGM: 73 %) for the northern Pan de Azúcar and southern Nahuelbuta sites, respectively, but did not vary by more than 10 % over the 21,000 yr simulation. A sensitivity study suggests that [CO2] is an important driver of vegetation changes and, thereby, potentially landscape evolution. Comparisons with other paleoclimate model driver highlight the importance of model input on simulated vegetation. In the near future, we will directly couple LPJ-GUESS to a landscape evolution model (see companion paper) to build a fully-coupled dynamic-vegetation/ landscape evolution model that is forced with paleoclimate data from atmospheric general circulation models.

scholarly journals Effect of changing vegetation and precipitation on denudation – Part 1: Predicted vegetation composition and cover over the last 21 thousand years along the Coastal Cordillera of Chile

2018 ◽  
Vol 6 (4) ◽  
pp. 829-858 ◽  
Author(s):  
Christian Werner ◽  
Manuel Schmid ◽  
Todd A. Ehlers ◽  
Juan Pablo Fuentes-Espoz ◽  
Jörg Steinkamp ◽  
...  
Keyword(s):  
Vegetation Cover ◽  
Vegetation Dynamics ◽  
General Circulation ◽  
Landscape Evolution ◽  
Spatial Scales ◽  
General Circulation Models ◽  
Evolution Model ◽  
Vegetation Changes ◽  
Vegetation Composition ◽  
Coastal Cordillera

Abstract. Vegetation is crucial for modulating rates of denudation and landscape evolution, as it stabilizes and protects hillslopes and intercepts rainfall. Climate conditions and the atmospheric CO2 concentration, hereafter [CO2], influence the establishment and performance of plants; thus, these factors have a direct influence on vegetation cover. In addition, vegetation dynamics (competition for space, light, nutrients, and water) and stochastic events (mortality and fires) determine the state of vegetation, response times to environmental perturbations and successional development. In spite of this, state-of-the-art reconstructions of past transient vegetation changes have not been accounted for in landscape evolution models. Here, a widely used dynamic vegetation model (LPJ-GUESS) was used to simulate vegetation composition/cover and surface runoff in Chile for the Last Glacial Maximum (LGM), the mid-Holocene (MH) and the present day (PD). In addition, transient vegetation simulations were carried out from the LGM to PD for four sites in the Coastal Cordillera of Chile at a spatial and temporal resolution adequate for coupling with landscape evolution models. A new landform mode was introduced to LPJ-GUESS to enable a better simulation of vegetation dynamics and state at a sub-pixel resolution and to allow for future coupling with landscape evolution models operating at different spatial scales. Using a regionally adapted parameterization, LPJ-GUESS was capable of reproducing PD potential natural vegetation along the strong climatic gradients of Chile, and simulated vegetation cover was also in line with satellite-based observations. Simulated vegetation during the LGM differed markedly from PD conditions. Coastal cold temperate rainforests were displaced northward by about 5∘ and the tree line and vegetation zones were at lower elevations than PD. Transient vegetation simulations indicate a marked shift in vegetation composition starting with the past glacial warming that coincides with a rise in [CO2]. Vegetation cover between the sites ranged from 13 % (LGM: 8 %) to 81 % (LGM: 73 %) for the northern Pan de Azúcar and southern Nahuelbuta sites, respectively, but did not vary by more than 10 % over the 21 000 year simulation. A sensitivity study suggests that [CO2] is an important driver of vegetation changes and, thereby, potentially landscape evolution. Comparisons with other paleoclimate model drivers highlight the importance of model input on simulated vegetation. In the near future, we will directly couple LPJ-GUESS to a landscape evolution model (see companion paper) to build a fully coupled dynamic-vegetation/landscape evolution model that is forced with paleoclimate data from atmospheric general circulation models.

scholarly journals Paleovegetation in West Africa for 18.000 B.P. and 8.500 B.P.

1997 ◽  
Vol 47 (1) ◽  
pp. 112-119
Author(s):  
Dieter Anhuf
Keyword(s):  
West Africa ◽  
Vegetation Cover ◽  
Temporal Change ◽  
Isotope Analysis ◽  
Climatic Conditions ◽  
West African ◽  
Natural Vegetation ◽  
Tropical Regions ◽  
Climatic Oscillations ◽  
Vegetation And Climate

Abstract. The investigations were concentrated on the reconstruction of former vegetation patterns tor the Sudanian and Guinean savannas as well as tropical semi-evergreen and evergreen rainforests. A numher of research projects concerning changes in the vegetation cover have shown that even tropical regions have been effected by the enormous climatic oscillations of the last 20,000 years. The problem linked to the judgement of a changing vegetation is the increasing effect of human influence on the appearenee of the West African vegetation cover. Thus, all investigations of the temporal change in tropical ecosystems are confronted with the fact that areas which have not been influenced by man can rarely be found. The primary question is which formations of vegetation may allow us to draw conclusions applicable to a nearly natural vegetation. A first step is the estimation of potential forest communities under recent climatic conditions. The derivation of the paleovegetation of West Africa was based on varied published information concerning paleoclimate and paleovegetation. This information is bound to the subjects of archaeology, geomorphology, dendrochronology, palynology, deep-sea-core and isotope analysis. By derivation of the numeric relations between natural vegetation and climate under recent conditions, according models of analogous vegetation climate of palcoclnnatic conditions could be drawn. Presented are paleovegetation maps of West Africa for 18.000 B.P. (glacial climatic pessimum) and 8.500 B.P. (postglacial climatic optimum).

scholarly journals Analysis of the soil and microclimate relationship in two dolines of Carso Huasteco, Mexico

2019 ◽  
Vol 9 ◽  
pp. 25-33
Author(s):  
Joab R. Quintero-Ruiz ◽  
Laura Yáñez-Espinosa ◽  
Joel Flores ◽  
Javier Fortanelli ◽  
Arturo De-Nova ◽  
...  
Keyword(s):  
Climatic Factors ◽  
Climatic Conditions ◽  
Air Humidity ◽  
Tropical Regions ◽  
Abrupt Changes ◽  
Edaphic Properties ◽  
High Concentrations ◽  
Physical And Chemical ◽  
Climatic Characteristics ◽  
Nitrogen Phosphorus

Dolines are karst depressions whose environmental and climatic characteristics in tropical regions are not well known. By measuring and analyzing different components of the microclimate in two dolines located in Tamasopo, Mexico, we aim to contribute to the understanding of the climatic conditions in these formations. The variables analyzed include temperature, solar radiation, soil and air humidity, as well as their relationship to physical and chemical characteristics of the soil such as pH, conductivity, texture, and the content of organic matter, carbon, nitrogen, phosphorus, calcium, potassium, sodium and magnesium. Measurements and soil samples were taken in three strata: bottom, slope and exterior. The results show a gradient in the climatic variables along the three strata, as well as higher concentrations of all elements, except phosphorus, in soil from the dolines, with respect to the exterior. Furthermore, statistical analysis shows a high correlation between the environmental conditions and edaphic properties. The micro climatic factors of the dolines generate a different environment, rich in humidity and with temperatures commonly lower than those present in tropical regions. These conditions cause abrupt changes in the physical and chemical composition of the soil, which present high concentrations of nutrients.

Large-scale mapping of the catenas vegetation in Subarctic tundra

1995 ◽  
pp. 3-21
Author(s):  
S. S. Kholod
Keyword(s):  
Spatial Distribution ◽  
Vegetation Cover ◽  
Large Scale ◽  
Block Diagram ◽  
Abiotic Factors ◽  
Ecological Factors ◽  
Spatial Arrangement ◽  
Geological Time ◽  
Ecological Barriers ◽  
Functional Zones

One of the most difficult tasks in large-scale vegetation mapping is the clarification of mechanisms of the internal integration of vegetation cover territorial units. Traditional way of searching such mechanisms is the study of ecological factors controlling the space heterogeneity of vegetation cover. In essence, this is autecological analysis of vegetation. We propose another way of searching the mechanisms of territorial integration of vegetation. It is connected with intracoenotic interrelation, in particular, with the changing role of edificator synusium in a community along the altitudinal gradient. This way of searching is illustrated in the model-plot in subarctic tundra of Central Chukotka. Our further suggestion concerns the way of depicting these mechanisms on large-scale vegetation map. As a model object we chose the catena, that is the landscape formation including all geomorphjc positions of a slope, joint by the process of moving the material down the slope. The process of peneplanation of a mountain system for a long geological time favours to the levelling the lower (accumulative) parts of slopes. The colonization of these parts of the slope by the vegetation variants, corresponding to the lowest part of catena is the result of peneplanation. Vegetation of this part of catena makes a certain biogeocoenotic work which is the levelling of the small infralandscape limits and of the boundaries in vegetation cover. This process we name as the continualization on catena. In this process the variants of vegetation in the lower part of catena are being broken into separate synusiums. This is the process of decumbation of layers described by V. B. Sochava. Up to the slope the edificator power of the shrub synusiums sharply decreases. Moss and herb synusium have "to seek" the habitats similar to those under the shrub canopy. The competition between the synusium arises resulting in arrangement of a certain spatial assemblage of vegetation cover elements. In such assemblage the position of each element is determined by both biotic (interrelation with other coenotic elements) and abiotic (presence of appropriate habitats) factors. Taking into account the biogeocoenotic character of the process of continualization on catena we name such spatial assemblage an exolutionary-biogeocoenotic series. The space within each evolutionary-biogeocoenotic series is divided by ecological barriers into some functional zones. In each of the such zones the struggle between synusiums has its individual expression and direction. In the start zone of catena (extensive pediment) the interrelations of synusiums and layers control the mutual spatial arrangement of these elements at the largest extent. Here, as a rule, there predominate edificator synusiums of low and dwarfshrubs. In the first order limit zone (the bend of pediment to the above part of the slope) one-species herb and moss synusiums, oftenly substituting each other in similar habitats, get prevalence. In the zone of active colonization of slope (denudation slope) the coenotic factor has the least role in the spatial distribution of the vegetation cover elements. In particular, phytocoenotic interactions take place only within separate microcoenoses of herbs, mosses and lichens. In the zone of the attenuation of continualization process (the upper most parts of slope, crests) phytocoenotic interactions are almost absent and the spatial distribution of vegetation cover elements depends exclusively on the abiotic factors. The principal scheme of the distribution of vegetation cover elements and the disposition of functional zones on catena are shown on block-diagram (fig. 1).

Detection and representation of the basic peculiarities of vegetation cover by the mapping method (experience based on a research of goltsy-taiga territories)

2013 ◽  
pp. 32-47
Author(s):  
S. V. Osipov
Keyword(s):  
Vegetation Cover ◽  
Mapping Method ◽  
Vegetation Changes ◽  
Large Classes ◽  
High Rise ◽  
The Third ◽  
Altitudinal Belts ◽  
The One ◽  
Dynamic Series ◽  
River Valleys

Geobotanical mapping of the territory in riverheads Bureya of 4500 sq.km is carried out and the map of a actual vegetation cover of scale 1 : 200 000 is prepared. The legend of the map is presented in the form of the text with three-level hierarchy of classes. At the heart of structure of a legend of the map such regularities of a vegetation cover, as its latitudinal zonality / altitudinal belts, situation in a relief and dynamic series lie. The largest divisions of the legend reflect, first, change of large classes of mesocombinations of vegetation at the level of belts and, secondly, distinction in a boreal - forestry belt between a vegetation cover of tops and slopes of mountains, on the one hand, and the bottoms of river valleys, with another. Divisions of the legend of the second level reflect, first, vegetation changes in the form of high-rise and barrier changes of subbelts, secondly, distinctions of a vegetation cover in different geomorphological conditions (small and average river valleys, northern slopes, etc.). Divisions of the legend of the second level correspond to dynamic series of units of the third level. Essential addition to it are block diagrams of dynamics of a vegetation cover.

scholarly journals Radial Growth Response of European Larch Provenances to Interannual Climate Variation in Poland

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 334
Author(s):  
Norbert Szymański ◽  
Sławomir Wilczyński
Keyword(s):  
Radial Growth ◽  
Climatic Factors ◽  
Principal Component ◽  
Climatic Conditions ◽  
Growth Responses ◽  
European Larch ◽  
Temperature And Precipitation ◽  
Provenance Trials ◽  
High Precipitation ◽  
Climatic Elements

The present study identified the similarities and differences in the radial growth responses of 20 provenances of 51-year-old European larch (Larix decidua Mill.) trees from Poland to the climatic conditions at three provenance trials situated in the Polish lowlands (Siemianice), uplands (Bliżyn) and mountains (Krynica). A chronology of radial growth indices was developed for each of 60 European larch populations, which highlighted the interannual variations in the climate-mediated radial growth of their trees. With the aid of principal component, correlation and multiple regression analysis, supra-regional climatic elements were identified to which all the larch provenances reacted similarly at all three provenance trials. They increased the radial growth in years with a short, warm and precipitation-rich winter; a cool and humid summer and when high precipitation in late autumn of the previous year was noted. Moreover, other climatic elements were identified to which two groups of the larch provenances reacted differently at each provenance trial. In the lowland climate, the provenances reacted differently to temperature in November to December of the previous year and July and to precipitation in September. In the upland climate, the provenances differed in growth sensitivity to precipitation in October of the previous year and June–September. In the mountain climate, the provenances responded differently to temperature and precipitation in September of the previous year and to precipitation in February, June and September of the year of tree ring formation. The results imply that both climatic factors and origin (genotype), i.e., the genetic factor, mediate the climate–growth relationships of larch provenances.

Impact of climatic conditions on the parameters of failure flow of military vehicles

2021 ◽  
pp. 095440702110202
Author(s):  
Nikolaj Dobrzinskij ◽  
Algimantas Fedaravicius ◽  
Kestutis Pilkauskas ◽  
Egidijus Slizys
Keyword(s):  
Climatic Factors ◽  
Armed Forces ◽  
Climatic Conditions ◽  
Operating Conditions ◽  
Technical Equipment ◽  
Factors Affecting ◽  
Military Vehicles ◽  
Equipment Reliability ◽  
Number Of Factors ◽  
The Impact

Relevance of the article is based on participation of armed forces in various operations and exercises, where reliability of machinery is one of the most important factors. Transportation of soldiers as well as completion of variety of tasks is ensured by properly functioning technical equipment. Reliability of military vehicles – armoured SISU E13TP Finnish built and HMMWV M1025 USA built were selected as the object of the article. Impact of climatic conditions on reliability of the vehicles exploited in southwestern part of the Atlantic continental forest area is researched by a case study of the vehicles exploitation under conditions of the climate of Lithuania. Reliability of military vehicles depends on a number of factors such as properties of the vehicles and external conditions of their operation. Their systems and mechanisms are influenced by a number of factors that cause different failures. Climatic conditions represent one of the factors of operating load which is directly dependent on the climate zone. Therefore, assessment of the reliability is started with the analysis of climatic factors affecting operating conditions of the vehicles. Relationship between the impact of climatic factors and failure flow of the vehicles is presented and discussed.

scholarly journals Improved Rice Technology Adoption: The Role of Spatially-Dependent Risk Preference

Agriculture ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 691
Author(s):  
Omotuyole Isiaka Ambali ◽  
Francisco Jose Areal ◽  
Nikolaos Georgantzis
Keyword(s):  
Field Experiments ◽  
Climatic Factors ◽  
Risk Preferences ◽  
Risk Preference ◽  
Probit Model ◽  
Climatic Conditions ◽  
High Yield ◽  
Risk Attitudes ◽  
Policy Action ◽  
Rice Varieties

This study analyses farmers’ adoption of improved rice technology, taking into account farmers’ risk preferences; the unobserved spatial heterogeneity associated with farmers’ risk preferences; farmers’ household and farm characteristics; farm locations, farmers’ access to information, and their perceptions on the rice improved varieties (i.e., high yield varieties, HYV). The study used data obtained from field experiments and a survey conducted in 2016 in Nigeria. An instrumental-variable probit model was estimated to account for potential endogenous farmers’ risk preference in the adoption decision model. Results show that risk averse (risk avoidant) farmers are less likely to adopt HYV, with the spatial lags of farmers’ risk attitudes found to be a good instrument for spatially unobserved variables (e.g., environmental and climatic factors). We conclude that studies supporting policy action aiming at the diffusion of improved rice varieties need to collect information, if possible, on farmers’ risk attitudes, local environmental and climatic conditions (e.g., climatic, topographic, soil quality, pest incidence) in order to ease the design and evaluation of policy actions on the adoption of improved agricultural technology.

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