The Holocene record of Alberca de Tacámbaro, a tropical lake in western Mexico: evidence of orbital and millennial‐scale climatic variability

2021 ◽  
Author(s):  
Beatriz Ortega‐Guerrero ◽  
Margarita Caballero ◽  
Isabel Israde‐AlcáNtara
Keyword(s):  
Climatic Variability ◽  
Tropical Lake ◽  
The Holocene ◽  
Western Mexico ◽  
Holocene Record ◽  
Millennial Scale

scholarly journals The Holocene Cedrus pollen record from Sierra Nevada (S Spain), a proxy for climate change in N Africa

2020 ◽  
Author(s):  
Gonzalo Jiménez-Moreno ◽  
R. Scott Anderson ◽  
María J. Ramos-Román ◽  
Jon Camuera ◽  
Jose Manuel Mesa-Fernández ◽  
...  
Keyword(s):  
Sierra Nevada ◽  
Climatic Variability ◽  
Mediterranean Area ◽  
Western Mediterranean ◽  
Northern Africa ◽  
Pollen Record ◽  
North African ◽  
The Holocene ◽  
Middle And Late Holocene ◽  
Millennial Scale

<p>In this study, we synthesized pollen data from seven sites from the Sierra Nevada in southern Spain to investigate the response of forests in the western Mediterranean area to centennial- and millennial-scale climate changes and to human impact during the Holocene. In particular, here we focused in <em>Cedrus</em> pollen abundances, which most-likely originated from Northern Africa and were carried to Sierra Nevada by wind. Although <em>Cedrus</em> abundances are generally lower than 1% in the studied pollen samples, a comparison with North African pollen records shows similar trends at long- and short-term time-scales. Therefore, this record could be used as a proxy for changes in this forest species in North Africa. A Middle and Late Holocene <em>Cedrus</em> pollen increasing trend has been observed in the Sierra Nevada synthetic record, which seems to be the result of decreasing summer insolation. This would have produced overall cooler annual temperatures in Northern Africa (Atlas and Rif Mountains), benefiting the growth of this cool-adapted montane tree species, and lower summer evaporation, increasing available moisture during the summer, which is critical for this water-demanding species. Millennial- and centennial-scale variability also characterize the Sierra Nevada <em>Cedrus</em> synthetic record. <em>Cedrus</em> abundance oscillations could have been produced by well-known millennial-scale climatic variability that controlled cedar abundance in montane areas of N Africa.  </p>

The sensitivity of Neotoma to climate change and biodiversity loss over the late Quaternary

2021 ◽  
pp. 1-15
Author(s):  
Catalina P. Tomé ◽  
S. Kathleen Lyons ◽  
Seth D. Newsome ◽  
Felisa A. Smith
Keyword(s):  
Body Size ◽  
Late Quaternary ◽  
Climatic Variability ◽  
Isotope Analysis ◽  
Biodiversity Loss ◽  
Bone Collagen ◽  
Cam Plants ◽  
The Holocene ◽  
Carbon And Nitrogen ◽  
Terminal Pleistocene

Abstract The late Quaternary in North America was marked by highly variable climate and considerable biodiversity loss including a megafaunal extinction event at the terminal Pleistocene. Here, we focus on changes in body size and diet in Neotoma (woodrats) in response to these ecological perturbations using the fossil record from the Edwards Plateau (Texas) across the past 20,000 years. Body mass was estimated using measurements of fossil teeth and diet was quantified using stable isotope analysis of carbon and nitrogen from fossil bone collagen. Prior to ca. 7000 cal yr BP, maximum mass was positively correlated to precipitation and negatively correlated to temperature. Independently, mass was negatively correlated to community composition, becoming more similar to modern over time. Neotoma diet in the Pleistocene was primarily sourced from C3 plants, but became progressively more reliant on C4 (and potentially CAM) plants through the Holocene. Decreasing population mass and higher C4/CAM consumption was associated with a transition from a mesic to xeric landscape. Our results suggest that Neotoma responded to climatic variability during the terminal Pleistocene through changes in body size, while changes in resource availability during the Holocene likely led to shifts in the relative abundance of different Neotoma species in the community.

scholarly journals Global sea-level control on local parasequence architecture from the Holocene record of the Po Plain, Italy

2017 ◽  
Vol 87 ◽  
pp. 99-111 ◽  
Author(s):  
Alessandro Amorosi ◽  
Luigi Bruno ◽  
Bruno Campo ◽  
Agnese Morelli ◽  
Veronica Rossi ◽  
...  
Keyword(s):  
Sea Level ◽  
Level Control ◽  
Po Plain ◽  
The Holocene ◽  
Holocene Record ◽  
Global Sea Level

scholarly journals Climatic variability and human impact during the last 2000 years in western Mesoamerica: evidence of late Classic (AD 600–900) and Little Ice Age drought events

2015 ◽  
Vol 11 (9) ◽  
pp. 1239-1248 ◽  
Author(s):  
A. Rodríguez-Ramírez ◽  
M. Caballero ◽  
P. Roy ◽  
B. Ortega ◽  
G. Vázquez-Castro ◽  
...  
Keyword(s):  
Human Impact ◽  
Little Ice Age ◽  
Climatic Variability ◽  
Seasonal Migration ◽  
Ice Age ◽  
Cultural Tradition ◽  
Late Classic ◽  
High Pressure Cell ◽  
Western Mexico ◽  
The North

Abstract. We present results of analysis of biological (diatoms and ostracodes) and non-biological (Ti, Ca / Ti, total inorganic carbon, magnetic susceptibility) variables from an 8.8 m long, high-resolution (~ 20 yr sample−1) laminated sediment sequence from Lake Santa María del Oro (SMO), western Mexico. This lake lies at a sensitive location between the dry climates of northern Mexico, under the influence of the North Pacific subtropical high-pressure cell and the moister climates of central Mexico, under the influence of the seasonal migration of the intertropical convergence zone and the North American monsoon (NAM). The sequence covers the last 2000 years and provides evidence of two periods of human impact in the catchment, shown by increases in the diatom Achnanthidium minutissimum. The first from AD 100 to 400 (Early Classic) is related to the shaft and chamber tombs cultural tradition in western Mexico, and the second is related to Post-Classic occupation from AD 1100 to 1300. Both periods correspond to relatively wet conditions. Three dry intervals are identified from increased carbonate and the presence of ostracodes and aerophilous Eolimna minima. The first, from AD 500 to 1000 (most intense during the late Classic, from AD 600 to 800), correlates with the end of the shaft and chamber tradition in western Mexico after ca. AD 600. This late Classic dry period is the most important climatic signal in the Mesoamerican region during the last 2000 years, and has been recorded at several sites from Yucatan to the Pacific coast. In the Yucatan area, this dry interval has been related with the demise of the Maya culture at the end of the Classic (AD 850 to 950). The last two dry events (AD 1400 to 1550 and 1690 to 1770) correspond with the onset of, and the late, Little Ice Age, and follow largely the Spörer and Maunder minima in solar radiation. The first of these intervals (AD 1400 to 1550) shows the most intense signal over western Mexico; however this pattern is different at other sites. Dry/wet intervals in the SMO record are related with lower/higher intensity of the NAM over this region, respectively.

scholarly journals Holocene Records of Nebraska Mammals

2021 ◽  
Author(s):  
Hugh Genoways
Keyword(s):  
Native Americans ◽  
Fossil Record ◽  
The State ◽  
Additional Species ◽  
The Holocene ◽  
Sand Hills ◽  
Food Species ◽  
Main Portion ◽  
Holocene Record ◽  
Harlan County

A survey of the archeological and paleontological literature allowed a compilation of Holocene records of mammals in Nebraska. This survey identified Holocene records from 338 sites in 62 of the 93 Nebraska counties. These counties were located throughout state, but there was a concentration of sites in southwestern Nebraska where there were 27 fossil sites in Frontier County and 22 in Harlan County. Fossils sites were underrepresented in the Sand Hills region. Records of fossil mammals covered the entire Holocene period from 13,000 years ago until AD 1850. A minimum of 57 species (with eight additional species potentially present) representing six orders of mammals were represented in the compilation—four species of Lagomorpha, four species of Soricomorpha, 17 species of Carnivora (with three additional species potentially present), one species of Perissodactyla, six species of Artiodactyla, and 25 species of Rodentia (with five additional species potentially present). The remains of bison were found at 276 sites, which was more than for any other species in the state. Additional species that formed the main portion of the diet of Native Americans were the next most abundant in the fossil record—deer, pronghorn, and wapiti. That these food species dominated in the Holocene record was to be expected because fossils were recovered primarily from archeological sites.

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