scholarly journals New data on the dolines of Velebit Mountain: An evaluation of their sedimentary archive potential in the reconstruction of landscape evolution

2012 ◽  
Vol 41 (1) ◽  
Author(s):  
Christèle Ballut ◽  
Sanja Faivre
Keyword(s):  
Environmental Changes ◽  
Sediment Cores ◽  
Soil Formation ◽  
Soil Nutrient ◽  
Nutrient Content ◽  
Middle Part ◽  
Land Occupation ◽  
Physical Environments ◽  
First Results ◽  
Physical And Chemical

The first approach to the relationships between societies and physical environments on Velebit Mountain shows narrow correlations between spatial distribution of dolines, soil formation, hydric resources, vegetation and land occupation. In 2002, sediment cores have been obtained from different dolines of Velebit Mountain to evaluate the potential of their sedimentary archives in order to reconstruct the landscape history. On the littoral slopes and on the top parts of the mountain, the dolines were difficult to dig due to the presence of rocks in depth. Nevertheless, the cores have been sampled and soil analyses have been made (physical and chemical analyses: colour, grain size, pH, CaCO3, C, N, P, K, Mg, CEC). No dating materials were found. The first results attest to rather homogeneous pedologic processes in each area studied (Kamenica, Stinica, Baške Oštarije and Bilensko Mirevo), but they also indicate colluvial contributions. These contributions differ from one doline to another according to their location and morphology. Dolines reveal themselves to be not very good traps, as the representative nature of their sedimentary archives could be very local. However, the best profile has been obtained at Bilensko Mirevo, which shows a change in the soil nutrient content from an impoverishment in its middle part toward an increase of the soil nutrients in recent parts. Those environmental changes could not be precisely dated, but could be correlated with the 17th to 20th century phase of strong human impact on the Velebit environment and with the rural depopulation observed since the second half of the 20th century.Keywords: karst, dolines, Mediterranean soils, Velebit Mountain,Dinarides, Croatia.

scholarly journals Effects of Elevation and Distance from Highway on the Abundance and Community Structure of Bacteria in Soil along Qinghai-Tibet Highway

2021 ◽  
Vol 18 (24) ◽  
pp. 13137
Author(s):  
Zhuocheng Liu ◽  
Yangang Yang ◽  
Shuangxuan Ji ◽  
Di Dong ◽  
Yinruizhi Li ◽  
...  
Keyword(s):  
Community Structure ◽  
Soil Bacteria ◽  
Environmental Changes ◽  
Chemical Properties ◽  
Soil Nutrient ◽  
Nutrient Content ◽  
Tibet Plateau ◽  
Nitrifying Bacteria ◽  
Ecological Environment ◽  
The Impact

In recent years, highway construction in the Qinghai-Tibet Plateau (QTP) has developed rapidly. When the highway passes through grassland, the soil, vegetation, and ecological environment along the line are disturbed. However, the impact on soil bacteria is still unclear. Soil bacteria play an important role in the ecological environment. The Qinghai-Tibet Highway (QTH) was selected as the research object to explore the changes in bacterial community structure, vegetation, soil, and other indicators. The results showed that the highway-related activities increased the degradation of vegetation along the road, significantly changed the physical and chemical properties of soil, and caused heavy metal pollution. These environmental factors affected the diversity and community structure of soil bacteria. This kind of disturbance shows a trend of gradually increasing from near to far from the highway. Gemmatimonas, Terrimonas, Nitrospira and Bacillus are more tolerant to environmental changes along the highway, while Barnesiella, and Blastococcus are more sensitive. The content of nitrate decreased and the content of ammonium nitrogen increased in the disturbed area, increasing the abundance of nitrifying bacteria. Therefore, the main factor of the disturbance of the QTH on the grassland is the decline of soil nutrient content, and the supplement of soil nutrients such as carbon and nitrogen should be taken into account in the process of ecological restoration of grassland along the line.

Contributions to the Knowledge of Sandy Soils from Oltenia Plain

2020 ◽  
Vol 71 (1) ◽  
pp. 192-200
Author(s):  
Anca-Luiza Stanila ◽  
Catalin Cristian Simota ◽  
Mihail Dumitru
Keyword(s):  
Chemical Properties ◽  
Soil Formation ◽  
Sandy Soils ◽  
Physical Geography ◽  
Parent Material ◽  
Negative Effects ◽  
Small Water ◽  
Wind Characteristic ◽  
The One ◽  
Physical And Chemical

Highlighting the sandy soil of Oltenia Plain calls for a better knowledge of their variability their correlation with major natural factors from each physical geography. Pedogenetic processes specific sandy soils are strongly influenced by nature parent material. This leads, on the one hand, climate aridity of the soil due to strong heating and accumulation of small water reserves, consequences emphasizing the moisture deficit in the development of the vegetation and favoring weak deflation, and on the other hand, an increase in mineralization organic matter. Relief under wind characteristic sandy land, soil formation and distribution has some particularly of flat land with the land formed on the loess. The dune ridges are less evolved soils, profile underdeveloped and poorly supplied with nutrients compared to those on the slopes of the dunes and the interdune, whose physical and chemical properties are more favorable to plant growth.Both Romanati Plain and the Blahnita (Mehedinti) Plain and Bailesti Plain, sand wind shaped covering a finer material, loamy sand and even loess (containing up to 26% clay), also rippled with negative effects in terms of overall drainage. Depending on the pedogenetic physical and geographical factors that have contributed to soil cover, in the researched were identified following classes of soils: protisols, cernisols, cambisols, luvisols, hidrisols and antrosols.Obtaining appropriate agricultural production requires some land improvement works (especially fitting for irrigation) and agropedoameliorative works. Particular attention should be paid to preventing and combating wind erosion.

An Assessment of Environmental Changes in Three Lakes from King's County (Nova Scotia, Canada) Using Diatom-Based Paleolimnological Techniques

2008 ◽  
Vol 43 (2-3) ◽  
pp. 85-98 ◽  
Author(s):  
Joshua R. Thienpont ◽  
Brian K. Ginn ◽  
Brian F. Cumming ◽  
John P. Smol
Keyword(s):  
Nova Scotia ◽  
Environmental Changes ◽  
Sediment Cores ◽  
Lake Management ◽  
River System ◽  
210Pb Dating ◽  
Hydroelectric Power ◽  
Diatom Assemblages ◽  
Shoreline Development ◽  
Before And After

Abstract Paleolimnological approaches using sedimentary diatom assemblages were used to assess water quality changes over the last approximately 200 years in three lakes from King's County, Nova Scotia. In particular, the role of recent shoreline development in accelerating eutrophication in these systems was assessed. Sediment cores collected from each lake were analyzed for their diatom assemblages at approximately 5-year intervals, as determined by 210Pb dating. Analyses showed that each system has changed, but tracked different ecosystem changes. Tupper and George lakes recorded shifts, which are likely primarily related to climatic warming, with diatom assemblages changing from a preindustrial dominance by Aulacoseira spp. to present-day dominance by Cyclotella stelligera. In addition to the recent climatic-related changes, further diatom changes in the Tupper Lake core between approximately 1820 and 1970 were coincident with watershed disturbances (farming, forestry, and construction of hydroelectric power infrastructure). Black River Lake has recorded an increase in diatom-inferred total phosphorus since about 1950, likely due to impoundment of the Black River system for hydroelectric generation and subsequent changes in land runoff. Before-and-after (i.e., top-bottom) sediment analyses of six other lakes from King's County provided further evidence that the region is being influenced by climatic change (decreases in Aulacoseira spp., increases in planktonic diatom taxa), as well as showing other environmental stressors (e.g., acidification). However, we recorded no marked increase in diatom-inferred nutrient levels coincident with shoreline cottage development in any of the nine study lakes. Paleolimnological studies such as these allow lake managers to place the current limnological conditions into a long-term context, and thereby provide important background data for effective lake management.

scholarly journals Biofilm Formation in Xanthomonas arboricola pv. pruni: Structure and Development

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 546
Author(s):  
Pilar Sabuquillo ◽  
Jaime Cubero
Keyword(s):  
Biofilm Formation ◽  
Extracellular Polymeric Substances ◽  
Environmental Changes ◽  
Nutrient Content ◽  
Infection Process ◽  
Bacterial Attachment ◽  
Key Factors ◽  
Cell Structures ◽  
Microscopy Techniques

Xanthomonasarboricola pv. pruni (Xap) causes bacterial spot of stone fruit and almond, an important plant disease with a high economic impact. Biofilm formation is one of the mechanisms that microbial communities use to adapt to environmental changes and to survive and colonize plants. Herein, biofilm formation by Xap was analyzed on abiotic and biotic surfaces using different microscopy techniques which allowed characterization of the different biofilm stages compared to the planktonic condition. All Xap strains assayed were able to form real biofilms creating organized structures comprised by viable cells. Xap in biofilms differentiated from free-living bacteria forming complex matrix-encased multicellular structures which become surrounded by a network of extracellular polymeric substances (EPS). Moreover, nutrient content of the environment and bacterial growth have been shown as key factors for biofilm formation and its development. Besides, this is the first work where different cell structures involved in bacterial attachment and aggregation have been identified during Xap biofilm progression. Our findings provide insights regarding different aspects of the biofilm formation of Xap which improve our understanding of the bacterial infection process occurred in Prunus spp and that may help in future disease control approaches.

scholarly journals Late Quaternary paleoenvironment of the Ross Sea continental shelf, Antarctica

1998 ◽  
Vol 27 ◽  
pp. 275-280 ◽  
Author(s):  
Akira Nishimura ◽  
Toru Nakasone ◽  
Chikara Hiramatsu ◽  
Manabu Tanahashi
Keyword(s):  
Organic Carbon ◽  
Marine Environment ◽  
Environmental Changes ◽  
Ross Sea ◽  
Late Quaternary ◽  
Sedimentary Environment ◽  
Sediment Cores ◽  
Ice Sheet ◽  
Ice Shelf ◽  
Accelerator Mass Spectrometer

Based on sedimenlological and micropaleontological work on three sediment cores collected at about 167° Ε in the western Ross Sea, Antarctica, and accelerator mass spectrometer l4C ages of organic carbon, we have reconstructed environmental changes in the area during the late Quaternary. Since 38 ka BP at latest, this area was a marine environment with low productivity. A grounded ice sheet advanced and loaded the sediments before about 30-25 ka BP. After 25 ka BP, the southernmost site (76°46'S) was covered by floating ice (shelf ice), preventing deposition of coarse terrigenous materials and maintaining a supply of diatom tests and organic carbon until 20 ka BP. The northernmost site (74°33'S) was in a marine environment with a moderate productivity influenced by shelf ice/ice sheet after about 20 ka BP. Since about 10 ka BP, a sedimentary environment similar to the present-day one has prevailed over this area.

High-resolution radiocarbon dating to reconstruct last century environmental changes in the pacific island of Espiritu Santo

2021 ◽  
Author(s):  
Giorgia Camperio ◽  
Caroline Welte ◽  
S. Nemiah Ladd ◽  
Matthew Prebble ◽  
Nathalie Dubois
Keyword(s):  
High Resolution ◽  
Radiocarbon Dating ◽  
Environmental Changes ◽  
Accumulation Rate ◽  
Sediment Cores ◽  
Volcanic Eruptions ◽  
High Accumulation ◽  
Sedimentary Records ◽  
The Pacific ◽  
Rapid Accumulation

<p>Espiritu Santo is one of the 82 islands of the archipelago of Vanuatu and is the largest, highest, and most biodiverse of the insular country. Climatic changes linked to El Niño and extreme events such as cyclones and volcanic eruptions are a daily challenge in this remote area. These events can be recorded in sedimentary archives. Here we present a multi-proxy investigation of sediment cores retrieved from two small lakes located on the West coast of Espiritu Santo. Although the records span the last millennium, high-resolution radiocarbon dating of macrofossils reveals a rapid accumulation of sediment in the past 100 years. The high accumulation rate coupled with the high-resolution dating of freshwater sediments allows us to compare the <sup>14</sup>C bomb curve with the biogeochemical proxies of the sedimentary records. The results can then be validated against written and oral historical records linked with the societal perception of recent environmental changes in this vulnerable ecosystem.</p><div> <div title="Translate selected text"></div> <div title="Play"></div> <div title="Copy text to Clipboard"></div> </div>

Ecological succession as an aspect of structure in fossil communities

Paleobiology ◽  
1975 ◽  
Vol 1 (3) ◽  
pp. 238-257 ◽  
Author(s):  
Kenneth R. Walker ◽  
Leonard P. Alberstadt
Keyword(s):  
Environmental Changes ◽  
Food Chains ◽  
Short Term ◽  
Niche Specialization ◽  
Pattern Diversity ◽  
Physical Environments ◽  
Autogenic Succession ◽  
Succession Stage ◽  
Stratigraphic Sequences

Succession involves changes in a community through time, whether internally or externally controlled. As succession progresses, niche specialization, species diversity (variety and equitability), complexity of food chains, and pattern diversity increase; net production and species growth rate decrease. We apply the succession concept to three types of ancient community sequences: 1) fossil reefs (Ordovician—Cretaceous in age), 2) short-term successions occurring through thin stratigraphic intervals, and 3) long-term successions occurring through thicker stratigraphic intervals. Ancient reefs show four vertical zones: (1) a basal stabilization zone (autogenic), 2) the overlying colonization zone (autogenic, pioneer stage), 3) the diversification zone, the bulk of most reefs (diversification culminating in climax), and 4) the uppermost domination zone. The first three zones represent autogenic succession but the final stage may involve allogenic succession. Short-term succession usually occurs where periodic allogenic catastrophes wipe out the community which is rebuilt through autogenic succession. Opportunistic pioneer species are important and in our examples (Ordovician, Silurian, and Cretaceous) are species which pave soft substrata. Paleozoic strophomenid brachiopods filled this role, and inoceramid pelecypods served the function in the Mesozoic. The succession which begins with opportunists progresses to a climax community of equilibrists. Repetition of catastrophe-succession couplets produces a cyclic stratigraphic record. Long-term successions are recorded in thicker stratigraphic sequences, and are of two types: 1) autogenic succession in unchanging physical environments and 2) allogenic succession in changing physical environments. Our examples of these are from the Devonian Haragan-Bois D'Arc formations of Oklahoma and the Lime Creek Formation of Iowa. This type of succession represents a temporal-spatial mosaic. The Haragan data (unchanging environments) indicate characteristic, intergrading, and ubiquitous species in the brachiopod communities. Most ubiquitous species in the pioneer community were eurytopic opportunists. The Lime Creek data allows testing of the prediction that environmental changes cause regression to an earlier succession stage. The brachiopod communities after environmental changes have more ubiquitous and intergrading eurytopic species. These represent an earlier stage in the succession.

Holocene eolian sand deposition linked to climatic variability, Northern Great Plains, Canada

The Holocene ◽  
2016 ◽  
Vol 27 (4) ◽  
pp. 579-593 ◽  
Author(s):  
Stephen A Wolfe ◽  
Olav B Lian ◽  
Christopher H Hugenholtz ◽  
Justine R Riches
Keyword(s):  
Great Plains ◽  
Climatic Variability ◽  
Sediment Cores ◽  
Soil Formation ◽  
Temporal Variations ◽  
Ice Age ◽  
Northern Great Plains ◽  
Eolian Sand ◽  
Sand Accumulation ◽  
Sand Deposition

The Bigstick and Seward Sand Hills are possibly two of the oldest dune fields within the late Wisconsin glaciated regions of the Northern Great Plains. As with most Northern Great Plains dune fields, source sediments are former proglacial outwash sands. Thus, Holocene dune construction is primarily related to spatial–temporal variations in surface cover and transport capacity, rather than renewed sediment input. However, eolian landscape reconstructions on the Northern Great Plains have been temporally constrained to recent periods of activity, as older episodes of deposition are typically reworked by younger events. In this study, sediment cores from shallow lacustrine basins and interdune areas provide an improved record of Holocene eolian sand deposition. Eolian sand accumulation in the interdunes and basins occurred between 150 and 270 years ago, 1.9 and 3.0 ka, 5.4 and 8.6 ka, and prior to ca. 10.8 ka. These episodes of sand accumulation were bracketed by lacustrine deposition and soil formation, which represented wetter conditions. Other than mid-Holocene dune activity, which may be related to peak warmth and aridity, most periods of eolian sand accumulation coincided with cooler but drier climatic events such as the Younger Dryas, late-Holocene cooling prior to the Medieval Climatic Anomaly, and the ‘Little Ice Age’. These depositional episodes are also spatially represented by other dune fields in the region, providing a broad-scale view of the connections between past climatic events and eolian landscape evolution on the Northern Great Plains.

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