Holocene Vegetation History from Fossil Rodent Middens near Arequipa, Peru

2001 ◽  
Vol 56 (2) ◽  
pp. 242-251 ◽  
Author(s):  
Camille A. Holmgren ◽  
Julio L. Betancourt ◽  
Kate Aasen Rylander ◽  
Jose Roque ◽  
Oscar Tovar ◽  
...  
Keyword(s):  
Vegetation History ◽  
Southern Oscillation ◽  
Atacama Desert ◽  
Summer Rainfall ◽  
Plant Macrofossils ◽  
Poor Correlation ◽  
Apparent Difference ◽  
The Holocene ◽  
Middle Holocene ◽  
The Pacific

AbstractRodent (Abrocoma, Lagidium, Phyllotis) middens collected from 2350 to 2750 m elevation near Arequipa, Peru (16°S), provide an ∼9600-yr vegetation history of the northern Atacama Desert, based on identification of >50 species of plant macrofossils. These midden floras show considerable stability throughout the Holocene, with slightly more mesophytic plant assemblages in the middle Holocene. Unlike the southwestern United States, rodent middens of mid-Holocene age are common. In the Arequipa area, the midden record does not reflect any effects of a mid-Holocene mega drought proposed from the extreme lowstand (100 m below modern levels, >6000 to 3500 yr B.P.) of Lake Titicaca, only 200 km east of Arequipa. This is perhaps not surprising, given other evidence for wetter summers on the Pacific slope of the Andes during the middle Holocene as well as the poor correlation of summer rainfall among modern weather stations in the central Andes-Atacama Desert. The apparent difference in paleoclimatic reconstructions suggests that it is premature to relate changes observed during the Holocene to changes in El Niño Southern Oscillation modes.

Vegetation history along the eastern, desert escarpment of the Sierra San Pedro Mártir, Baja California, Mexico

2011 ◽  
Vol 75 (3) ◽  
pp. 647-657 ◽  
Author(s):  
Camille A. Holmgren ◽  
Julio L. Betancourt ◽  
Kate A. Rylander
Keyword(s):  
Lake Sediments ◽  
Marine Sediments ◽  
Baja California ◽  
Vegetation History ◽  
Summer Rainfall ◽  
Plant Macrofossils ◽  
Eastern Desert ◽  
Pollen Stratigraphy ◽  
San Pedro ◽  
Sierra San Pedro Martir

AbstractPlant macrofossils from 38 packrat middens spanning the last ~ 33,000 cal yr BP record vegetation between ~ 650 and 900 m elevation along the eastern escarpment of the Sierra San Pedro Mártir, northern Baja California. The middens span most of the Holocene, with a gap between ~ 4600 and 1800 cal yr BP, but coverage in the Pleistocene is uneven with a larger hiatus between 23,100 and 14,400 cal yr BP. The midden flora is relatively stable from the Pleistocene to Holocene. Exceptions include Pinus californiarum, Juniperus californica and other chaparral elements that were most abundant > 23,100 cal yr BP and declined after 14,400 cal yr BP. Despite being near the chaparral/woodland-desertscrub ecotone during glacial times, the midden assemblages reflect none of the climatic reversals evident in the glacial or marine record, and this is corroborated by a nearby semi-continuous pollen stratigraphy from lake sediments. Regular appearance of C4 grasses and summer-flowering annuals since 13,600 cal yr BP indicates occurrence of summer rainfall equivalent to modern (JAS average of ~ 80–90 mm). This casts doubt on the claim, based on temperature proxies from marine sediments in the Guaymas Basin, that monsoonal development in the northern Gulf and Arizona was delayed until after 6200 cal yr BP.

Holocene hydroclimate reconstruction based on pollen, XRF, and grain-size analyses and its implications for past societies of the Korean Peninsula

The Holocene ◽  
2021 ◽  
pp. 095968362110191
Author(s):  
Jinheum Park ◽  
Jungjae Park ◽  
Sangheon Yi ◽  
Jaesoo Lim ◽  
Jin Cheul Kim ◽  
...  
Keyword(s):  
Grain Size ◽  
Korean Peninsula ◽  
Southern Oscillation ◽  
Asian Summer Monsoon ◽  
Underlying Mechanism ◽  
Kuroshio Current ◽  
The Holocene ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Asian Summer

The dynamics of the East Asian Summer Monsoon (EASM) and their link to past societies during the Holocene are topics of growing interest. In this study, we present results of pollen, geochemistry, and grain-size analyses from the STP18-03 core sampled from Miryang in the Korean Peninsula, which spans ca. 8.3–2.3 ka BP. In-phase relationships of these proxies revealed an imprint of the Holocene Climate Optimum (HCO) during the early to mid-Holocene and subsequent drying toward the late-Holocene in accordance with decreasing solar insolation. At centennial timescales, our study indicates drier climate during ca. 7.5–7.1, 6.4–6.0, and 4.8–3.6 ka BP. Notably, our finding for ca. 6.4–6.0 ka BP contributes further evidence of a drying event in the Korean Peninsula during this period. We suggest that the Pacific Ocean played a role in the underlying mechanism of hydroclimate change in the region. A strong Kuroshio Current (KC) and long-term El Niño–Southern Oscillation (ENSO)-like variability in the Western Tropical Pacific (WTP) were closely linked to the influence of the EASM over the Korean Peninsula. In particular, dry phases during ca. 4.8–3.6 and 2.8–2.3 ka BP, which were synchronous with a more active ENSO, closely corresponded to lower population levels indicated by a summed probability distribution (SPD) of archaeological records previously assembled in the Korean Peninsula. This finding implies that past human societies of Korea were highly vulnerable to climate deterioration caused by precipitation deficits.

scholarly journals Holocene vegetation dynamics in response to climate change and hydrological processes in the Bohai region

2020 ◽  
Vol 16 (6) ◽  
pp. 2509-2531
Author(s):  
Chen Jinxia ◽  
Shi Xuefa ◽  
Liu Yanguang ◽  
Qiao Shuqing ◽  
Yang Shixiong ◽  
...  
Keyword(s):  
Climate Change ◽  
Vegetation Dynamics ◽  
Southern Oscillation ◽  
Coastal Vegetation ◽  
Intertidal Mudflat ◽  
Pollen Record ◽  
Lateral Migration ◽  
Sediment Grain Size ◽  
The Holocene ◽  
Middle Holocene

Abstract. Coastal vegetation both mitigates the damage inflicted by marine disasters on coastal areas and plays an important role in the global carbon cycle (i.e., blue carbon). Nevertheless, detailed records of changes in coastal vegetation composition and diversity in the Holocene, coupled with climate change and river evolution, remain unclear. To explore vegetation dynamics and their influencing factors on the coastal area of the Bohai Sea (BS) during the Holocene, we present high-resolution pollen and sediment grain size data obtained from a sediment core of the BS. The results reveal that two rapid and abrupt changes in salt marsh vegetation are linked with the river system changes. Within each event, a recurring pattern – starting with a decline in Cyperaceae, followed by an increase in Artemisia and Chenopodiaceae – suggests a successional process that is determined by the close relationship between Yellow River (YR) channel shifts and the wetland community dynamics. The phreatophyte Cyperaceae at the base of each sequence indicate lower saline conditions. Unchannelized river flow characterized the onset of the YR channel shift, caused a huge river-derived sediment accumulation in the floodplain and destroyed the sedges in the coastal depression. Along with the formation of a new channel, lateral migration of the lower channel stopped, and a new intertidal mudflat was formed. Pioneer species (Chenopodiaceae, Artemisia) were the first to colonize the bare zones of the lower and middle marsh areas. In addition, the pollen results revealed that the vegetation of the BS land area was dominated by broadleaved forests during the Early Holocene (8500–6500 BP) and by conifer and broadleaved forests in the Middle Holocene (6500–3500 BP), which was followed by an expansion of broadleaved trees (after 3500 BP). The pollen record indicated that a warmer Early and Late Holocene and colder Middle Holocene were consistent with previously reported temperature records for East Asia. The main driving factors of temperature variation in this region are insolation, the El Niño–Southern Oscillation and greenhouse gases forcing.

Postglacial flooding and vegetation history on the Ob River terrace, central Western Siberia based on the palaeoecological record from Lake Svetlenkoye

The Holocene ◽  
2020 ◽  
Vol 30 (5) ◽  
pp. 618-631
Author(s):  
Leeli Amon ◽  
Ansis Blaus ◽  
Tiiu Alliksaar ◽  
Atko Heinsalu ◽  
Elena Lapshina ◽  
...  
Keyword(s):  
Lake Water ◽  
Aquatic Vegetation ◽  
Vegetation History ◽  
Accumulation Rate ◽  
Plant Macrofossils ◽  
West Siberian Plain ◽  
Climatic Fluctuations ◽  
The Holocene ◽  
Ob River ◽  
Water Ph

The hemispheric-scale climatic fluctuations during the Holocene have probably influenced the large Siberian rivers. However, detailed studies of the West Siberian Plain postglacial environmental change are scarce and the records of millennial-scale palaeohydrology are nearly absent. This paper presents the Holocene palaeoecological reconstruction based on the sedimentary record of Lake Svetlenkoye, located near the confluence of major Siberian rivers Ob and Irtysh. Postglacial history of flooding, dynamics of regional and local vegetation, sedimentation regime, geochemical changes and lake water pH were reconstructed based on multi-proxy studies. We used palaeobotanical (plant macrofossils, pollen, diatoms), geochemical (organic matter, total organic carbon and nitrogen content, carbon/nitrogen ratio) and chronological (14C dates, spheroidal fly-ash particle counts) methods. The studied sediment section started to accumulate ~11,400 cal. yr BP. The initial shallow water body was flooded by Ob River waters ~8100–8000 cal. yr BP as confirmed by a remarkable increase in the sedimentation rate and the accumulation rate of the aquatic vegetation proxies. The period of flooding coincides with the high humidity periods reconstructed from regional palaeobotanical records. About 6800–6700 cal. yr BP, the study site became isolated from the Ob River floodplain and remained a small lake until present. The diatom-based lake water pH estimates suggest fluctuations in the pH values during the Holocene, the recent decrease since 1960s being the most notable. The vegetation record revealed constant postglacial presence of tree taxa – Betula, Pinus and Picea – although in different pollen ratios and accumulation rates through time. The paludification of the surroundings occurred since ca. 8500 cal. yr BP.

scholarly journals The evolving response of mesopelagic fishes to declining midwater oxygen concentrations in the southern and central California Current

2018 ◽  
Vol 76 (3) ◽  
pp. 626-638 ◽  
Author(s):  
J Anthony Koslow ◽  
Pete Davison ◽  
Erica Ferrer ◽  
S Patricia A Jiménez Rosenberg ◽  
Gerardo Aceves-Medina ◽  
...  
Keyword(s):  
Baja California ◽  
Southern Oscillation ◽  
Global Climate ◽  
California Current ◽  
Deep Ocean ◽  
Near Surface ◽  
Oxygen Minimum Zones ◽  
The North ◽  
The Pacific ◽  
Oxygen Concentrations

Abstract Declining oxygen concentrations in the deep ocean, particularly in areas with pronounced oxygen minimum zones (OMZs), are a growing global concern related to global climate change. Its potential impacts on marine life remain poorly understood. A previous study suggested that the abundance of a diverse suite of mesopelagic fishes off southern California was closely linked to trends in midwater oxygen concentration. This study expands the spatial and temporal scale of that analysis to examine how mesopelagic fishes are responding to declining oxygen levels in the California Current (CC) off central, southern, and Baja California. Several warm-water mesopelagic species, apparently adapted to the shallower, more intense OMZ off Baja California, are shown to be increasing despite declining midwater oxygen concentrations and becoming increasingly dominant, initially off Baja California and subsequently in the CC region to the north. Their increased abundance is associated with warming near-surface ocean temperature, the warm phase of the Pacific Decadal oscillation and Multivariate El Niño-Southern Oscillation Index, and the increased flux of Pacific Equatorial Water into the southern CC.

Development and degradation of a submontane forest in the Beskid Wyspowy Mountains (Polish Western Carpathians) during the Holocene

The Holocene ◽  
2021 ◽  
pp. 095968362110332
Author(s):  
Piotr Kołaczek ◽  
Krzysztof Buczek ◽  
Włodzimierz Margielewski ◽  
Mariusz Gałka ◽  
Aleksandra Rycerz ◽  
...  
Keyword(s):  
Size Fraction ◽  
Abies Alba ◽  
Plant Macrofossils ◽  
Western Carpathians ◽  
Substantial Contribution ◽  
Forest Belt ◽  
The Holocene ◽  
Parasitic Fungi ◽  
Carpathian Region ◽  
Fire Activity

Mountain regions harbour high biodiversity; however, in numerous areas, they are strongly degraded by human activity. Our study reconstructs the development of the submontane forest belt (400 and 650 m a.s.l.) in the Beskid Wyspowy Mountains (Western Carpathians, Central Europe) affected by climate, humans, fire, and parasitic fungi during the Holocene. This forest belt is considered the most transformed by the human in the Carpathian region. Our multi-proxy study included analyses of pollen, non-pollen palynomorphs (NPPs), plant macrofossils, micro- and macrocharcoal (size fraction >100 µm, analysed in contiguous sampling), geochemical, and sedimentological markers. The results revealed that Picea abies dominated on the fen subjected to study at ca. 8510–5010 cal. BP. Tilia cordata was a substantial component of the submontane forest between ca. 8510 and 2970 cal. BP and it survived a probable Kretzschmaria deusta outbreak, as well as a period of increased fire activity (ca. 6000 cal. BP). The final retreat of forests with a substantial contribution of Tilia was induced by the expansion of Abies alba, Fagus sylvatica, and partly Carpinus betulus and was preceded by the period of increased fire activity and erosion. From ca. 900 cal. BP human-induced deforestations and agricultural and pastoral activity increased. The modern presence of woodlands with Pinus sylvestris and Larix decidua, in the submontane zone in the Beskid Wyspowy Mountains, is a result of sub-recent anthropogenic afforestation on overgrazed areas. The example of the Zbludza site reveals that changes related to fire and pathogen infections, if they have low magnitudes and new competitive taxa are absent, may be reversible in a forest composed of fire-intolerant tree taxa as Tilia. Nonetheless, the widespread submontane ecosystem degradation and the introduction of alien species hamper the regeneration of forest vegetation typical of the submontane zone.

scholarly journals Hydroclimate variability in the low-elevation Atacama Desert over the last 2500 yr

2012 ◽  
Vol 8 (1) ◽  
pp. 287-306 ◽  
Author(s):  
E. M. Gayo ◽  
C. Latorre ◽  
C. M. Santoro ◽  
A. Maldonado ◽  
R. De Pol-Holz
Keyword(s):  
Hydrological Cycle ◽  
Atacama Desert ◽  
Plant Macrofossils ◽  
Central Andes ◽  
Tropical Pacific ◽  
Riparian Ecosystems ◽  
Independent Evidence ◽  
Radiocarbon Dates ◽  
Climate Fluctuations ◽  
The Past

Abstract. Paleoclimate reconstructions reveal that Earth system has experienced sub-millennial scale climate changes over the past two millennia in response to internal/external forcing. Although sub-millennial hydroclimate fluctuations have been detected in the central Andes during this interval, the timing, magnitude, extent and direction of change of these events remain poorly defined. Here, we present a reconstruction of hydroclimate variations on the Pacific slope of the central Andes based on exceptionally well-preserved plant macrofossils and associated archaeological remains from a hyperarid drainage (Quebrada Maní, ∼21° S, 1000 m a.s.l.) in the Atacama Desert. During the late Holocene, riparian ecosystems and farming social groups flourished in the hyperarid Atacama core as surface water availability increased throughout this presently sterile landscape. Twenty-six radiocarbon dates indicate that these events occurred between 1050–680, 1615–1350 and 2500–2040 cal yr BP. Regional comparisons with rodent middens and other records suggest that these events were synchronous with pluvial stages detected at higher-elevations in the central Andes over the last 2500 yr. These hydroclimate changes also coincide with periods of pronounced SST gradients in the Tropical Pacific (La Niña-like mode), conditions that are conducive to significantly increased rainfall in the central Andean highlands and flood events in the low-elevation watersheds at inter-annual timescales. Our findings indicate that the positive anomalies in the hyperarid Atacama over the past 2500 yr represent a regional response of the central Andean climate system to changes in the global hydrological cycle at centennial timescales. Furthermore, our results provide support for the role of tropical Pacific sea surface temperature gradient changes as the primary mechanism responsible for climate fluctuations in the central Andes. Finally, our results constitute independent evidence for comprehending the major trends in cultural evolution of prehistoric peoples that inhabited the region.

scholarly journals Role of the Indo-Pacific Interbasin Coupling in Predicting Asymmetric ENSO Transition and Duration

2012 ◽  
Vol 25 (9) ◽  
pp. 3321-3335 ◽  
Author(s):  
Masamichi Ohba ◽  
Masahiro Watanabe
Keyword(s):  
El Niño ◽  
General Circulation ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
La Nina ◽  
The Pacific ◽  
Enso Asymmetry ◽  
Sst Anomalies

Warm and cold phases of El Niño–Southern Oscillation (ENSO) exhibit a significant asymmetry in their transition/duration such that El Niño tends to shift rapidly to La Niña after the mature phase, whereas La Niña tends to persist for up to 2 yr. The possible role of sea surface temperature (SST) anomalies in the Indian Ocean (IO) in this ENSO asymmetry is investigated using a coupled general circulation model (CGCM). Decoupled-IO experiments are conducted to assess asymmetric IO feedbacks to the ongoing ENSO evolution in the Pacific. Identical-twin forecast experiments show that a coupling of the IO extends the skillful prediction of the ENSO warm phase by about one year, which was about 8 months in the absence of the IO coupling, in which a significant drop of the prediction skill around the boreal spring (known as the spring prediction barrier) is found. The effect of IO coupling on the predictability of the Pacific SST is significantly weaker in the decay phase of La Niña. Warm IO SST anomalies associated with El Niño enhance surface easterlies over the equatorial western Pacific and hence facilitate the El Niño decay. However, this mechanism cannot be applied to cold IO SST anomalies during La Niña. The result of these CGCM experiments estimates that approximately one-half of the ENSO asymmetry arises from the phase-dependent nature of the Indo-Pacific interbasin coupling.

scholarly journals Determination of a New Coastal ENSO Oceanic Index for Northern Peru

Climate ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 71
Author(s):  
Edgard Gonzales ◽  
Eusebio Ingol
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Extreme Rainfall ◽  
Polynomial Equation ◽  
Extreme Rainfall Events ◽  
Emergency Operations Center ◽  
The Pacific ◽  
Northern Portion ◽  
Sequential Generation

In 2017, extreme rainfall events occurred in the northern portion of Peru, causing nearly 100,000 victims, according to the National Emergency Operations Center (COEN). This climatic event was attributed to the occurrence of the El Niño Southern Oscillation (ENSO). Therefore, the main objective of this study was to determine and differentiate between the occurrence of canonical ENSO, with a new type of ENSO called “El Niño Costero” (Coastal El Niño). The polynomial equation method was used to analyze the data from the different types of existing ocean indices to determine the occurrence of ENSO. It was observed that the anomalies of sea surface temperature (SST) 2.5 °C (January 2016) generated the “Modoki El Niño” and that the anomaly of SST −0.3 °C (January 2017) generated the “Modoki La Niña”; this sequential generation generated El Niño Costero. This new knowledge about the sui generis origin of El Niño Costero, based on the observations of this analysis, will allow us to identify and obtain important information regarding the occurrence of this event. A new oceanic index called the Pacific Regional Equatorial Index (PREI) was proposed to follow the periodic evolution and forecast with greater precision a new catastrophic event related to the occurrence of El Niño Costero and to implement prevention programs.

An Updated Climatology of Tropical Cyclone Impacts on the Southwestern United States

2013 ◽  
Vol 141 (12) ◽  
pp. 4322-4336 ◽  
Author(s):  
Kimberly M. Wood ◽  
Elizabeth A. Ritchie
Keyword(s):  
United States ◽  
North Pacific ◽  
General Circulation ◽  
Southern Oscillation ◽  
Eof Analysis ◽  
Southwestern United States ◽  
Oscillation Phenomenon ◽  
The Pacific ◽  
Sea Surface Temperature Anomalies ◽  
Significant Patterns

Abstract A dataset of 167 eastern North Pacific tropical cyclones (TCs) is investigated for potential impacts in the southwestern United States over the period 1989–2009 and evaluated in the context of a 30-yr climatology. The statistically significant patterns from empirical orthogonal function (EOF) analysis demonstrate the prevalence of a midlatitude trough pattern when TC-related rainfall occurs in the southwestern United States. Conversely, the presence of a strong subtropical ridge tends to prevent such events from occurring and limits TC-related rainfall to Mexico. These statistically significant patterns correspond well with previous work. The El Niño–Southern Oscillation phenomenon is shown to have some effect on eastern North Pacific TC impacts on the southwestern United States, as shifts in the general circulation can subsequently influence which regions receive rainfall from TCs or their remnants. The Pacific decadal oscillation may have a greater influence during the period of study as evidenced by EOF analysis of sea surface temperature anomalies.

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