scholarly journals Eustatic, Climatic and Tectonic Controls on the Evolution of a Middle to Late Holocene Coastal Dune System in Shimokita, Northeast Japan

Geosciences ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 410
Author(s):  
Koji Minoura ◽  
Norihiro Nakamura
Keyword(s):  
Regional Climate ◽  
Transitional Zone ◽  
Surface Erosion ◽  
Dune System ◽  
Shimokita Peninsula ◽  
The Pacific ◽  
Aeolian Dunes ◽  
Strong Winds ◽  
Coastal Dune System ◽  
Atmospheric Changes

The Pacific coast of the Shimokita Peninsula, Northeast Japan, is occupied by one of the larger dune complexes in Japan. This coastal aeolian dune complex developed during the Holocene in a monsoon-influenced temperate climatic belt. The stratigraphic and sedimentological characteristics of outcrops, exposures and cores indicate that four generation of aeolian dunes are presented. These dunes developed during eustatic regression following the post-glacial sea-level highstand. Seaward shoreline movement, combined with strong winds from the Pacific Ocean, enhanced aeolian grain transport on the beach, resulting in the onset of dune growth and the consequent shrinkage of the coastal forest. Northeast Japan is located in a transitional zone affected largely by monsoonal circulation from Siberia and Southeast Asia. Thus, the regional climate is responsible for atmospheric changes on a hemispheric scale. Intensified monsoons contributed to flooding produced by rains and snow-melt. Steep increases in annual precipitation at 7200–6300, 4700–3600, 3050–2500, 1850–1100, and 550–200 calendar years before present (cal. yr. BP) increased the amount of surface erosion, causing a large volume of sediment discharge toward the coast. Shimokita has experienced frequent earthquakes and tsunamis, which have reduced dune landform relief by sediment displacement.

No evidence for interspecific interactions between plants in the first stage of succession on coastal dunes in subarctic Quebec, Canada

1997 ◽  
Vol 75 (6) ◽  
pp. 902-915 ◽  
Author(s):  
Gilles Houle
Keyword(s):  
Plant Biomass ◽  
Interspecific Interactions ◽  
Regional Climate ◽  
Salt Spray ◽  
Coastal Dunes ◽  
Growing Season ◽  
Coastal Dune ◽  
Dune System ◽  
Abiotic Conditions ◽  
Herbaceous Perennials

Coastal dunes are very dynamic systems, particularly where the coast is rising as a result of isostatic rebound. In those environments, succession proceeds from plants highly tolerant to sand accumulation, salt spray, and low nutrient availability to less disturbance-tolerant and stress-tolerant, more nutrient-demanding, and supposedly more competitive species. In the subarctic, the regional climate exacerbates the stresses imposed by local abiotic conditions on the dunes. I hypothesized that facilitation would be particularly significant on the foredune of subarctic coastal dune systems because of intense stresses (local and regional) and frequent disturbance in the form of sand deposition. Belowground and aboveground plant biomass was sampled at three different periods during the 1990 growing season along transects perpendicular to the shoreline on a coastal dune system in subarctic Quebec (Canada). The three herbaceous perennials found on the foredune (Honckenya peploides, Elymus mollis, and Lathyrus japonicus) were segregated in time during the growing season and in space along the topographical gradient. The biomass of Honckenya, the first species encountered as one progresses from the upper part of the beach towards the foredune ridge, was not correlated to substrate physicochemistry. However, the biomass of Elymus and that of Lathyrus, the next two species to appear along the flank of the foredune, were related to pH, Mg, Na, and Cl (negatively), and to P and Ca (positively). These results suggest variable linkages between substrate physicochemistry and plant species along the foredune, possibly in relation to species-specific tolerance for abiotic conditions and requirements for substrate resources or to microscale influence of the plants themselves on substrate physicochemistry. Removal experiments carried out over 2 years revealed only one significant unidirectional interaction between these three species along the topographical gradient, and little plant control over abiotic variables (e.g., soil temperature, wind velocity, and photosynthetically active radiation). Early primary succession on subarctic coastal dunes (and elsewhere) appears to be under the control of strong limiting abiotic conditions. As plants slowly gain more control over the physical environment, interspecific interactions (positive and negative) may become more significant. Key words: Elymus mollis, facilitation, Honckenya peploides, inhibition, Lathyrus japonicus, removal experiment, succession, tolerance.

Geomophological and vulnerability analysis of a coastal delta under increased hydrological alteration over the past two centuries: Tana River delta, Kenya, East Africa.

2021 ◽  
Author(s):  
Peter Gitau ◽  
Stéphanie Duvail ◽  
Dirk Verschuren ◽  
Dominique Guillaud
Keyword(s):  
Sea Level Rise ◽  
East Africa ◽  
Sea Level ◽  
Coastal Dune ◽  
River Delta ◽  
River Channels ◽  
Dune System ◽  
The Past ◽  
Tana River ◽  
Coastal Dune System

<p>Coastal deltas worldwide are under risk of degradation due to the increasing impacts of sea-level rise, and continuous human alterations of river basin hydrology. This research highlights the geomorphological changes that have occurred within the Tana River delta in Kenya, an important deltaic ecosystem of high biodiversity value in East Africa.</p><p>The geomorphological features (river channels, floodplain, coastal dune system) and their evolution over the past two centuries were described. Aerial and satellite imagery was used to assess the magnitude and distribution of coastal changes from the 1960s to present.  Additionally, sediment cores recovered within the mangrove environment were analysed to establish the succession of sedimentation periods and patterns. Finally, we explored the response of the coastal processes of deposition and erosion under anthropogenic alterations of the hydrological system.</p><p>It was established that over the past two centuries Tana River has changed its main channel and outlet to the Indian Ocean on three occasions. A first river avulsion occurred in the 1860s, followed by a second avulsion in the late 1890s that was promoted by human interference through channel expansion and dyke construction. The third change in river course has occurred gradually over the past 20 years, amid human efforts to engineer the river channels.</p><p>From the sediment analysis and radiocarbon dating, it is ascertained that the lower deltaic region developed rapidly over the past ~180 years, facilitated by increased sedimentation from the main Tana River. On the other hand, analysis of the coastline changes indicate that there has been increased erosion of the coastal dune system and mangrove vegetation along the former river outlet, leading to rapid marine intrusion into local subsistence farming areas. By analysing the combined impacts of both natural river dynamics and human alteration we highlight how the integrity of the Tana River delta has increasingly become vulnerable under present sea level rise and continued upstream river alteration.</p>

scholarly journals Northern Hemisphere Stationary Waves in a Changing Climate

2019 ◽  
Vol 5 (4) ◽  
pp. 372-389 ◽  
Author(s):  
Robert C. J. Wills ◽  
Rachel H. White ◽  
Xavier J. Levine
Keyword(s):  
Climate Change ◽  
Atmospheric Circulation ◽  
Northern Hemisphere ◽  
Climate Models ◽  
Regional Climate ◽  
Stationary Wave ◽  
Future Research ◽  
Stationary Waves ◽  
The Pacific ◽  
Longitudinal Variations

Abstract Purpose of Review Stationary waves are planetary-scale longitudinal variations in the time-averaged atmospheric circulation. Here, we consider the projected response of Northern Hemisphere stationary waves to climate change in winter and summer. We discuss how the response varies across different metrics, identify robust responses, and review proposed mechanisms. Recent Findings Climate models project shifts in the prevailing wind patterns, with corresponding impacts on regional precipitation, temperature, and extreme events. Recent work has improved our understanding of the links between stationary waves and regional climate and identified robust stationary wave responses to climate change, which include an increased zonal lengthscale in winter, a poleward shift of the wintertime circulation over the Pacific, a weakening of monsoonal circulations, and an overall weakening of stationary wave circulations, particularly their divergent component and quasi-stationary disturbances. Summary Numerous factors influence Northern Hemisphere stationary waves, and mechanistic theories exist for only a few aspects of the stationary wave response to climate change. Idealized studies have proven useful for understanding the climate responses of particular atmospheric circulation features and should be a continued focus of future research.

scholarly journals Continentality and Oceanity in the Mid and High Latitudes of the Northern Hemisphere and Their Links to Atmospheric Circulation

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Edvinas Stonevicius ◽  
Gintautas Stankunavicius ◽  
Egidijus Rimkus
Keyword(s):  
North America ◽  
Atmospheric Circulation ◽  
Northern Hemisphere ◽  
Regional Climate ◽  
Regional Climate Change ◽  
Climatic Conditions ◽  
High Latitudes ◽  
Teleconnection Patterns ◽  
The Pacific ◽  
The Impact

The climate continentality or oceanity is one of the main characteristics of the local climatic conditions, which varies with global and regional climate change. This paper analyzes indexes of continentality and oceanity, as well as their variations in the middle and high latitudes of the Northern Hemisphere in the period 1950–2015. Climatology and changes in continentality and oceanity are examined using Conrad’s Continentality Index (CCI) and Kerner’s Oceanity Index (KOI). The impact of Northern Hemisphere teleconnection patterns on continentality/oceanity conditions was also evaluated. According to CCI, continentality is more significant in Northeast Siberia and lower along the Pacific coast of North America as well as in coastal areas in the northern part of the Atlantic Ocean. However, according to KOI, areas of high continentality do not precisely correspond with those of low oceanity, appearing to the south and west of those identified by CCI. The spatial patterns of changes in continentality thus seem to be different. According to CCI, a statistically significant increase in continentality has only been found in Northeast Siberia. In contrast, in the western part of North America and the majority of Asia, continentality has weakened. According to KOI, the climate has become increasingly continental in Northern Europe and the majority of North America and East Asia. Oceanity has increased in the Canadian Arctic Archipelago and in some parts of the Mediterranean region. Changes in continentality were primarily related to the increased temperature of the coldest month as a consequence of changes in atmospheric circulation: the positive phase of North Atlantic Oscillation (NAO) and East Atlantic (EA) patterns has dominated in winter in recent decades. Trends in oceanity may be connected with the diminishing extent of seasonal sea ice and an associated increase in sea surface temperature.

scholarly journals What Do Rain Gauges Tell Us about the Limits of Precipitation Predictability?*

2013 ◽  
Vol 26 (15) ◽  
pp. 5682-5688 ◽  
Author(s):  
Dan Gianotti ◽  
Bruce T. Anderson ◽  
Guido D. Salvucci
Keyword(s):  
Land Surface ◽  
Regional Climate ◽  
Rain Gauge ◽  
Potential Predictability ◽  
Rain Gauge Data ◽  
Rain Gauges ◽  
Climate Forecasting ◽  
The Pacific ◽  
Climate Signals ◽  
Cold Spots

Abstract A generalizable method is presented for establishing the potential predictability for seasonal precipitation occurrence using rain gauge data. This method provides an observationally based upper limit for potential predictability for 774 weather stations in the contiguous United States. It is found that the potentially predictable fraction varies seasonally and spatially, and that on average 30% of year-to-year seasonal variability is potentially explained by predictable climate processes. Potential predictability is generally highest in winter, appears to be enhanced by orography and land surface coupling, and is lowest (stochastic variance is highest) along the Pacific coast. These results depict “hot” spots of climate variability, for use in guiding regional climate forecasting and in uncovering processes driving climate. Identified “cold” spots are equally useful in guiding future studies as predictable climate signals in these areas will likely be undetectable.

Biodiversity responses to vegetation structure in a fragmented landscape: ant communities in a peri-urban coastal dune system

2016 ◽  
Vol 20 (3) ◽  
pp. 485-495 ◽  
Author(s):  
Sophie L. Cross ◽  
Adam T. Cross ◽  
David J. Merritt ◽  
Kingsley W. Dixon ◽  
Alan N. Andersen
Keyword(s):  
Vegetation Structure ◽  
Coastal Dune ◽  
Fragmented Landscape ◽  
Dune System ◽  
Ant Communities ◽  
Coastal Dune System

scholarly journals Understanding the hydrochemical evolution of a coastal dune system in SW England using a multiple tracer technique

2014 ◽  
Vol 45 ◽  
pp. 94-104 ◽  
Author(s):  
Debbie Allen ◽  
W. George Darling ◽  
Peter J. Williams ◽  
Charlie J. Stratford ◽  
Nick S. Robins
Keyword(s):  
Coastal Dune ◽  
Tracer Technique ◽  
Dune System ◽  
Hydrochemical Evolution ◽  
Coastal Dune System

Reproductive biology of the parsley frog, Pelodytes punctatus, at the northernmost part of its range

1993 ◽  
Vol 14 (2) ◽  
pp. 131-147 ◽  
Author(s):  
M. Ohm ◽  
A.G. Toxopeus ◽  
J.W. Arntzen
Keyword(s):  
Reproductive Biology ◽  
Breeding Season ◽  
Adult Population ◽  
First Year ◽  
Adult Size ◽  
Dune System ◽  
Population Size Estimates ◽  
Coastal Dune System ◽  
Source Sink ◽  
Second Period

AbstractThe reproductive biology and population dynamics of Pelodytes punctatus were studied at the breeding season over a three year period in a coastal dune system located at the extreme northwestern border of the species' range. Adult population size estimates ranged from about 100 in the first year to 60 in the third year. Males were remarkably sedentary near the pond under artificially provided shelters. Many were observed during the most of the breeding season which lasted from mid-March or the end of March to the end of April or mid-May. Most spawning took place in the second half of March or early April. In two years out of three a second period of spawning involving fewer animals was observed in the first half of May. Both periods of spawning coincided with, or shortly followed, periods of rising median air temperature. Egg-clutches were deposited in the deepest parts of pond, mainly on submerged vegetation not reaching the surface. An average sized clutch contained approximately 360 eggs. Development of the embryos until hatching took from 4 to 14 days, depending on the ambient temperature. Larval development and growth were fast. Recently metamorphosed froglets at a size of around 18 mm were found from the end of May onwards. Juveniles may reach adult size in the autumn of the year that they were born. Adult frogs did not show a strong fidelity to the breeding pond between years. In the study area the population structure of Pelodytes punctatus seems to be best described by a source - sink model in which flourishing populations in the dunes give rise to short lived satellite populations outside the dunes.

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