Multi-proxy records of Holocene hydroclimatic and environmental changes on the southern coast of South Korea

2020 ◽  
Vol 545 ◽  
pp. 109642 ◽  
Author(s):  
Eunmi Lee ◽  
Sangheon Yi ◽  
Jaesoo Lim ◽  
Yongmi Kim ◽  
Kyoung-nam Jo ◽  
...  
Keyword(s):  
South Korea ◽  
Environmental Changes ◽  
Southern Coast ◽  
Proxy Records

scholarly journals Distribution Patterns of Odonate Assemblages in Relation to Environmental Variables in Streams of South Korea

Insects ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 152 ◽  
Author(s):  
Da-Yeong Lee ◽  
Dae-Seong Lee ◽  
Mi-Jung Bae ◽  
Soon-Jin Hwang ◽  
Seong-Yu Noh ◽  
...  
Keyword(s):  
Land Use ◽  
Ecosystem Services ◽  
Environmental Factors ◽  
South Korea ◽  
Habitat Heterogeneity ◽  
Environmental Variables ◽  
Environmental Changes ◽  
Distribution Patterns ◽  
Self Organizing Map ◽  
Factors Affecting

Odonata species are sensitive to environmental changes, particularly those caused by humans, and provide valuable ecosystem services as intermediate predators in food webs. We aimed: (i) to investigate the distribution patterns of Odonata in streams on a nationwide scale across South Korea; (ii) to evaluate the relationships between the distribution patterns of odonates and their environmental conditions; and (iii) to identify indicator species and the most significant environmental factors affecting their distributions. Samples were collected from 965 sampling sites in streams across South Korea. We also measured 34 environmental variables grouped into six categories: geography, meteorology, land use, substrate composition, hydrology, and physicochemistry. A total of 83 taxa belonging to 10 families of Odonata were recorded in the dataset. Among them, eight species displayed high abundances and incidences. Self-organizing map (SOM) classified sampling sites into seven clusters (A–G) which could be divided into two distinct groups (A–C and D–G) according to the similarities of their odonate assemblages. Clusters A–C were characterized by members of the suborder Anisoptera, whereas clusters D–G were characterized by the suborder Zygoptera. Non-metric multidimensional scaling (NMDS) identified forest (%), altitude, and cobble (%) in substrata as the most influential environmental factors determining odonate assemblage compositions. Our results emphasize the importance of habitat heterogeneity by demonstrating its effect on odonate assemblages.

scholarly journals Eastern Andean environmental and climate synthesis for the last 2000 years BP from terrestrial pollen and charcoal records of Patagonia

2015 ◽  
Vol 11 (3) ◽  
pp. 2121-2157 ◽  
Author(s):  
G. D. Sottile ◽  
M. E. Echeverria ◽  
M. V. Mancini ◽  
M. M. Bianchi ◽  
M. A. Marcos ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Environmental Changes ◽  
Fire Regime ◽  
Ice Age ◽  
Circulation System ◽  
Forest Steppe ◽  
Proxy Records ◽  
The Andes ◽  
Precipitation Regimes ◽  
Southern Patagonia

Abstract. The Southern Hemisphere Westerly Winds (SWW) constitute an important zonal circulation system that dominates the dynamics of Southern Hemisphere mid-latitude climate. Little is known about climatic changes in the Southern South America in comparison to the Northern Hemisphere due to the low density of proxy records, and adequate chronology and sampling resolution to address environmental changes of the last 2000 years. Since 2009, new pollen and charcoal records from bog and lakes in northern and southern Patagonia at the east side of the Andes have been published with an adequate calibration of pollen assemblages related to modern vegetation and ecological behaviour. In this work we improve the chronological control of some eastern Andean previously published sequences and integrate pollen and charcoal dataset available east of the Andes to interpret possible environmental and SWW variability at centennial time scales. Through the analysis of modern and past hydric balance dynamics we compare these scenarios with other western Andean SWW sensitive proxy records for the last 2000 years. Due to the distinct precipitation regimes that exist between Northern (40–45° S) and Southern Patagonia (48–52° S) pollen sites locations, shifts on latitudinal and strength of the SWW results in large changes on hydric availability on forest and steppe communities. Therefore, we can interpret fossil pollen dataset as changes on paleohydric balance at every single site by the construction of paleohydric indices and comparison to charcoal records during the last 2000 cal yrs BP. Our composite pollen-based Northern and Southern Patagonia indices can be interpreted as changes in latitudinal variation and intensity of the SWW respectively. Dataset integration suggest poleward SWW between 2000 and 750 cal yrs BP and northward-weaker SWW during the Little Ice Age (750–200 cal yrs BP). These SWW variations are synchronous to Patagonian fire activity major shifts. We found an in phase fire regime (in terms of timing of biomass burning) between northern Patagonia Monte shrubland and Southern Patagonia steppe environments. Conversely, there is an antiphase fire regime between Northern and Southern Patagonia forest and forest-steppe ecotone environments. SWW variability may be associated to ENSO variability especially during the last millennia. For the last 200 cal yrs BP we can concluded that the SWW belt were more intense and poleward than the previous interval. Our composite pollen-based SWW indices show the potential of pollen dataset integration to improve the understanding of paleohydric variability especially for the last 2000 millennial in Patagonia.

scholarly journals Radiocarbon Analysis Confirms the Annual Nature of Sagebrush Growth Rings

Radiocarbon ◽  
2007 ◽  
Vol 49 (3) ◽  
pp. 1231-1240 ◽  
Author(s):  
Franco Biondi ◽  
Scotty D J Strachan ◽  
Scott Mensing ◽  
Gianluca Piovesan
Keyword(s):  
Great Basin ◽  
Cross Sections ◽  
Environmental Changes ◽  
Spatially Explicit ◽  
Growth Rings ◽  
Ams Radiocarbon Dating ◽  
Big Sagebrush ◽  
Proxy Records ◽  
Annual Resolution ◽  
Wildfire Regimes

In the Great Basin of North America, big sagebrush (Artemisia tridentata Nutt.) growth rings can be used to reconstruct environmental changes with annual resolution in areas where there is otherwise little such information available. We tested the annual nature of big sagebrush wood layers using accelerator mass spectrometry (AMS) radiocarbon dating. Four cross-sections from 3 sagebrush plants were collected near Ely, Nevada, USA, and analyzed using dendrochronological methods. Ten 14C measurements were then used to trace the location of the 1963–64 “bomb spike.” Although the number of rings on each section did not exceed 60, crossdating was possible within a section and between sections. Years assigned to individual wood layers by means of crossdating aligned with their expected 14C values, matching the location of the 14C peak. This result confirmed the annual nature of growth rings formed by big sagebrush, and will facilitate the development of spatially explicit, well-replicated proxy records of environmental change, such as wildfire regimes, in Great Basin valleys.

Reconstructing Climatic and Environmental Changes of the Past 1000 Years: A Reappraisal

2003 ◽  
Vol 14 (2-3) ◽  
pp. 233-296 ◽  
Author(s):  
Willie Soon ◽  
Sallie Baliunas ◽  
Craig Idso ◽  
Sherwood Idso ◽  
David R. Legates
Keyword(s):  
Environmental History ◽  
20Th Century ◽  
Environmental Changes ◽  
Ice Age ◽  
Local Climate ◽  
Proxy Records ◽  
Local Environments ◽  
Climate Indicators ◽  
Climatic Period ◽  
History Of

The 1000-year climatic and environmental history of the Earth contained in various proxy records is examined. As indicators, the proxies duly represent or record aspects of local climate. Questions on the relevance and validity of the locality paradigm for climatological research become sharper as studies of climatic changes on timescales of 50–100 years or longer are pursued. This is because thermal and dynamical constraints imposed by local geography become increasingly important as the air-sea-land interaction and coupling timescales increase. Because the nature of the various proxy climate indicators are so different, the results cannot be combined into a simple hemispheric or global quantitative composite. However, considered as an ensemble of individual observations, an assemblage of the local representations of climate establishes the reality of both the Little Ice Age and the Medieval Warm Period as climatic anomalies with world-wide imprints, extending earlier results by Bryson et al. (1963), Lamb (1965), and numerous other research efforts. Furthermore, these individual proxies are used to determine whether the 20th century is the warmest century of the 2nd Millennium at a variety of globally dispersed locations. Many records reveal that the 20th century is likely not the warmest nor a uniquely extreme climatic period of the last millennium, although it is clear that human activity has significantly impacted some local environments.

Introductory Overview

2003 ◽  
Author(s):  
Raymond C. Smith ◽  
Douglas G. Goodin
Keyword(s):  
Ecosystem Function ◽  
Environmental Changes ◽  
Extreme Environment ◽  
Climatic Conditions ◽  
Large Lake ◽  
Proxy Records ◽  
Grassland Ecosystems ◽  
Biological Responses ◽  
Long Term Ecological Research ◽  
Dry Valley

Elias argues (chapter 18, p. 370) that ecosystems are shaped by environmental changes that have occurred over thousands of years so that the century to millennial timescale is of particular significance because “it is on these timescales that ecosystems form, break apart, and reform in new configurations.” Within this context, the authors for the three chapters in part IV evaluate evidence for climate variability since the Last Glacial Maximum (LGM) to the present. They evaluate the biological responses to these longer term changes and highlight the importance of past climatic conditions on current ecosystem function. If we view, as Elias does, glacial climate as a filter through which ecosystems have passed, then variability since the LGM comprises a significant fraction of the biotic history that shaped current ecosystems. This is an overriding theme for this section. Fountain and Lyons (chapter 16), examining a dry valley ecosystem in Antarctica (MCM), evaluate various proxy records to establish the historic context of their landscape. They argue that this historical context is important for a full understanding of ecosystems and that it is especially important for the MCM ecosystem. Providing an excellent example of legacy, the effect of past imprints on current ecosystem function, they present evidence that past climatic variations truly dictate current ecosystem status. During the LGM, ice blocked the current Taylor Valley, forming a lake that contained phytoplankton and algal mats. Subsequent warming eliminated the blockage, drained the large lake, forming several smaller ones, and established the current landscape. The former large lake supplied nutrients to the soil and current lakes. Fountain and Lyons (p. 334) state that “the vital importance of climatic legacy in the dry valleys is due to its extreme environment, low biodiversity, and short food chains.” They also observe a “polar amplification,” whereby the sharp solid/liquid phase transition of water allows small changes in climate to produce relatively large variations in ecosystem response. The Jornada Long-Term Ecological Research site (JRN) is representative of the desert shrubland and desert grassland ecosystems of the southwestern United States. Monger (chapter 17) makes use of a range of biotic (packrat middens, fossil pollen), abiotic (chronological data on lake levels, position of alpine glaciers and rock glaciers) and soil-geomorphic evidence to create a working hypothesis of the bioclimatic changes during the last 20,000 years. There is a remarkable consistency in these proxy estimates given their diversity.

Evidence for Holocene environmental changes in the northern Fertile Crescent provided by pedogenic carbonate coatings

2007 ◽  
Vol 67 (3) ◽  
pp. 315-327 ◽  
Author(s):  
Konstantin Pustovoytov ◽  
Klaus Schmidt ◽  
Heinrich Taubald
Keyword(s):  
Inverse Relationship ◽  
Environmental Changes ◽  
Early Holocene ◽  
Pedogenic Carbonate ◽  
Proxy Records ◽  
Stable Isotopic ◽  
Fertile Crescent ◽  
Coating Formation ◽  
The Mean ◽  
Coating Growth

AbstractHolocene environmental changes in the northern Fertile Crescent remain poorly understood because of the scarcity of local proxy records in the region. In this study we investigated pedogenic (soil-formed) carbonate coatings on stones at the Pre-Pottery Neolithic site Göbekli Tepe as an indicator of local early-mid Holocene environmental changes. The 14C ages and stable isotopic composition of carbon and oxygen in thin (0.2–0.3 mm thick) pedogenic carbonate lamina indicate two main periods of coating formation: the early-Holocene (ca. 10000–6000 cal yr BP) and the mid-Holocene (ca. 6000–4000 cal yr BP). During the first period, there was an inverse relationship between δ13C and δ18O curves: a decrease in δ13C values coincide with an increase in δ18O values. For this period a trend towards higher temperatures is suggested. In the mid-Holocene, the mean rate of coating growth was 2–3 times higher than in the early Holocene. Both δ13C and δ18O reached their maximum values during this time and the direction of changes of the δ13C and δ18O curves became similar. The combination of data suggests that this period was the most humid in the Holocene and on average warmer than the early Holocene. At ca. 4000 cal yr BP secondary accumulation of carbonate ceased, presumably reflecting a shift to a more arid climate.

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