Fish Lake is located at 2700 m (a.s.l.) on the boundary of the Colorado Plateau and Great Basin geologic provinces in western North America. Climate forecast models suggest that this region will become warmer and drier during the 21st Century, which will likely intensify fire regimes and threaten biodiversity in this region, including the ancient Pando aspen clone located next to Fish Lake. Here we present a paleoenvironmental reconstruction from an 80-meter lake sediment core spanning the last 60,000 years. At the Last Glacial Maximum (LGM), the upland areas near Fish Lake (3200-3500 m asl) were heavily glaciated and plant communities were open and dominated mainly by herbs and conifers, such as grasses (Poaceae) and spruce (Picea spp.). During the LGM fire activity was low due to cold temperatures, low woody fuel abundance and connectivity, and the presence of megaherbivores (e.g., Mammuthus) as reconstructed from nearby fossil sites and the presence of coprophilous fungal spores (Sporormiella) in the Fish Lake sediments. In the Late Glacial Period, the demise of upland glaciers and megaherbivores was accompanied by a ‘release’ in woody vegetation, especially spruce and pine (Pinus spp.) and a rise in charcoal accumulation. During the Early Holocene, this rise in burning sustained and was likely enhanced by warming temperatures and the establishment of closed-canopy forests similar to modern composed of Engelmann spruce (Picea engelmannii), aspen (Populus tremuloides), and subalpine fir (Abies lasiocarpa). Fire activity in the Middle Holocene remained high, with a stepwise increase observed during the Late Holocene that occurred with increasing evidence of human activities and amplification of El Nino-Southern Oscillation (ENSO). Throughout the 60,000 record, aspen pollen is consistently present. While pollen alone does not provide direct evidence of the long-lived Pando aspen clone, this record does confer the presence of aspen growing near Fish Lake through contrasting climate periods and fire regimes. This long-term reconstruction offers new insights into the interactions of climate, vegetation, and herbivory in shaping wildfire in western North America to help support land management policies.

Using Alaskan lake sediment oxygen isotope records (δ 18 O), which trace the δ 18 O of precipitation, we establish that abrupt atmospheric shifts occurred during the last deglacial period in the North Pacific-Arctic. The robust lake δ 18 O chronologies confidently correlate Younger-Dryas (YD) atmospheric adjustments in Alaska with Greenland ice-core records and their seasonal sensitivity are consistent with cooling during winter. In contrast, abrupt δ 18 O decreases during the late Holocene observed in our records, of similar magnitude as the YD, are best explained by atmospheric modes involving long-distance transport of sub-tropical Pacific moisture. Our sediment cores are among the most reliably dated records yet produced in the circum-Arctic and show that similar decreases in δ 18 O of winter precipitation during the YD and late Holocene were driven by different atmospheric teleconnections. These results underscore major roles for seasonality and atmospheric patterns in the conceptual understanding of global scale climate oscillations, both past and future.

Bering Land Bridge (BLB) climate and vegetation during the Last Glacial Maximum (LGM) remains largely understudied, given challenges associated with collecting records from the submerged BLB. Previous records, confined to the margins of the modern land area and adjacent shelf, reveal conflicting interpretations of Beringian vegetation during the LGM. Here, we reconstruct LGM vegetation, sedimentology, and stable isotopes from a central BLB paleo-lake (Lake Knebel, LK) and compare it with a Holocene peat record from nearby St. Matthew Island (SMI). Results show strong similarities between LGM and late Holocene pollen assemblages, although with differences in relative taxonomic abundance. LGM communities are consistent with a cold and dry steppe or herb tundra environment but suggest the possibility of localized Betula presence in low-lying areas. LK's bedded lacustrine stratigraphy transitions into undisturbed marine sediments by similar to 19 ka, providing a maximum limiting age of the transgression. Shrub absence on SMI today and during the Holocene is consistent with island isolation before similar to 14 to 15 ka, when Betula expanded rapidly at most sites with Bolling-Allerod warming. The combined vegetation evidence indicates preservation of LGM tundra and steppe vegetation assemblages on SMI, suggesting that island vegetation communities may provide additional constraints on the timing of sea level transgression.

Eastern Beringia (Alaska and western Yukon) is an extensive, high-latitude region of North America that remained largely unglaciated throughout the Quaternary. Consequently, its sedimentary deposits preserve long-term environmental records that have intrigued scientists for nearly a century. Recent advances in palaeoecological proxies and dating methods have proved critical in addressing long-standing questions about regional late Quaternary environmental change. At the same time, they have led to new and sometimes controversial hypotheses. This review covers recent discoveries and unresolved questions focused on the period 57,000–10,000 calendar years before C.E. 1950 (cal yr BP).The middle Wisconsin interstadial (57,000–30,000 cal yr BP) was a period of relative warmth in eastern Beringia, compared with the late Wisconsin (30,000–14,000 cal yr BP). Early in the interstadial occasional Picea woodland was present amongst widespread shrub tundra. Palaeoecological, sedimentary and isotopic data indicate that climate was cooler and drier than the Holocene, with high rates of aeolian activity. Megafauna typically associated with the ‘mammoth steppe’ ecosystem (woolly mammoth [Mammuthus primigenius], horse [Equus] and steppe-bison [Bison priscus]) were present in some abundance.The transition towards late Wisconsin cold-stage conditions (35,000–30,000 cal yr BP) coincided with the establishment of the Bering Land Bridge and featured expansion of spatially varied, herbaceous vegetation, sometimes associated with deep active layers. Sedimentary DNA (sedaDNA) and macrofossil evidence show vegetation was not a prairie-like grassland, and the term “steppe-tundra” is a better descriptor. Permafrost pore-ice isotopic (δ18O) records suggest a step change in one or more climate drivers ca. 30,000 cal yr BP, by which time steppe-tundra was established across eastern Beringia. It remains uncertain whether Picea survived cold-stage conditions within isolated refugia, or whether it recolonized from south of the Laurentide-Cordilleran ice sheets. Genetic data suggest that Picea probably survived in situ; however, there is no definitive fossil evidence to support this.The end-Pleistocene transition from steppe-tundra to shrub tundra began ca. 15,000 cal yr BP and took place within decades at local scales. The expansion of woody taxa coincided with rising sea levels, reduced sea-ice extent and an abrupt shift in atmospheric circulation that enhanced precipitation. During this time, Earth's orbital configuration caused high early-summer temperatures and strong seasonality, creating growing conditions very different from today. The vegetation consisted of Salix and Betula shrub tundra with open areas of herbs and graminoids. During the deglacial warming trend, the Younger Dryas oscillation (12,800–11,700 cal yr BP) was variably expressed. It is generally evident in records affected by adjacent oceans but can be absent at sites in continental areas.These past conditions and paleoenvironmental changes have implications for contemporary issues: hypotheses about Pleistocene mammalian extinction; sensitivity of eastern Beringia to major oceanic reorganizations and high-frequency climate variability; the nature of woody plant expansion with climate warming; grazing, hydroclimate and fire as controls over ecosystems; the efficacy of “Pleistocene rewilding” for carbon capture.

Stable isotopes of water preserved in geologic archives, primarily as oxygen (delta 18O), have proven critical for documenting Earth's climatic and hydrologic systems past and present. However, timescale differences of water isotope inputs to proxy systems and the signal embedded in long paleorecords often confound translation to observed hydroclimatic metrics. Here, a unique 20-year dataset of meteorology, hydrology, and the isotopic composition of weekly meteoric and surface water samples (delta 18O, delta 2H) are combined with paleoclimate delta 18O data from tree-ring cellulose and lake carbonate to better understand proxy signals of Upper Colorado river basin drought. Annual tree-ring cellulose delta 18O from Picea engelmannii growing within a glacier-fed creek and a spring discharge area were used to derive annual source water delta 18O using a cellulose source-water isotope model. Comparisons with the monitoring record indicates that tree-ring cellulose delta 18O tracks variations in wet and dry hydroclimatic extremes. Source water isotopes are shown to reflect the hydroclimate of the current year and some number of previous years as an effective moisture-discharge proxy rather than a precipitation isotope proxy. Results contextualize Holocene lake carbonate delta 18O data. The contemporary-to-paleo comparison identifies changes in seasonal precipitation extremes during recent millennia and several earlier arid and monsoon-dominated Holocene periods that exceed the arid maximum of the calibration period.

Stable isotope data have made pivotal contributions to nearly every discipline of the physical and natural sciences. As the generation and application of stable isotope data continues to grow exponentially, so does the need for a unifying data repository to improve accessibility and promote collaborative engagement. This paper provides an overview of the design, development, and implementation of IsoBank (www.isobank.org), a community-driven initiative to create an open-access repository for stable isotope data implemented online in 2021. A central goal of IsoBank is to provide a web-accessible database supporting interdisciplinary stable isotope research and educational opportunities. To achieve this goal, we convened a multi-disciplinary group of over 40 analytical experts, stable isotope researchers, database managers, and web developers to collaboratively design the database. This paper outlines the main features of IsoBank and provides a focused description of the core metadata structure. We present plans for future database and tool development and engagement across the scientific community. These efforts will help facilitate interdisciplinary collaboration among the many users of stable isotopic data while also offering useful data resources and standardization of metadata reporting across eco-geoinformatics landscapes.

Abstract Holocene sediments at Emerald Lake in central Utah (3090 m asl) document the paleohydroclimatic history of the western Upper Colorado River headwater region. Multi-proxy analyses of sediment composition, mineralogy, and stable isotopes of carbonate (δ18O and δ13C) show changes in effective moisture for the past ca. 10,000 years at millennial to decadal timescales. Emerald Lake originated as a shallow, closed-basin cirque pond during the Early Holocene. By ca. 7000 cal yr BP, higher lake levels and carbonate δ18O values indicate rising effective moisture and higher proportions of summer precipitation continued at least until ca. 5500 cal yr BP when a landslide entered the lake margin. Between ca. 4500 and 2400 cal yr BP dry conditions at Emerald Lake envelop the timing of the ‘Late Holocene Dry Period’ identified at lower elevations. For the past ca. 2500 years, Emerald Lake δ18O values were relatively low, indicating wetter conditions and higher snow input (compared to rain), except for dry periods at ca. 2000 cal yr BP and during the Medieval Climate Anomaly at ca. 1000 and ca. 500 cal yr BP. Results provide a long-term perspective on precipitation extremes that influence regional water supplies from a snow-dominated catchment typical of the predominant source region for the Upper Colorado River.

Reviewed by: The Storied Landscape of Iroquoia: History, Conquest, and Memory in the Native Northeast by Chad L. Anderson David L. Preston The Storied Landscape of Iroquoia: History, Conquest, and Memory in the Native Northeast. By Chad L. Anderson. Borderlands and Transcultural Studies. Lincoln: University of Nebraska Press, 2020. 288 pages. Cloth, ebook, pdf. John Mitchell's 1755 Map of the British and French Dominions in North America was so comprehensive and expansive that it remained influential in imperial boundary making for decades to come.1 As a summary view of the British imperial imagination, it drew upon previous cartographic work and expressed Britain's territorial claims to North America from the Mississippi to Newfoundland. Along the crest of the Appalachian Mountains, Mitchell engraved the word Iroquois in letters that stretched from Virginia's frontier northeast toward Montreal and the Saint Lawrence Valley. The Haudenosaunee, as the Six Nations or Iroquois are more accurately known, figured prominently in British imperial ambitions in North America, as they maintained a powerful and independent Indigenous confederation in the eighteenth-century Northeast. Mitchell's rendering captured the eighteenth-century British fiction that their Six Nations allies controlled those designated lands, based upon an equally fictional Haudenosaunee claim of having won them by right of conquest. As Chad L. Anderson makes clear, Iroquoia was a "storied landscape" that remained central in British and American imaginations, even after triumphant revolutionaries had expanded into that region and destroyed much of the Indigenous landscape in the years following the American Revolution. Anderson's The Storied Landscape of Iroquoia traces how early Americans both erased and appropriated the Native past as they imagined the new republic. Ignoring clear evidence of Haudenosaunee towns and agriculture, Americans increasingly portrayed Natives as forest fixtures rather than as skilled and settled farmers. They justified Native dispossession by arguing that American improvements and "progress" would lead to the "inevitable" decline of Native peoples. Echoing familiar themes of classic works by Anthony F. C. Wallace, Laurence M. Hauptman, and Alan Taylor, [End Page 389] the book's greatest value is in how well it captures contested European and American perceptions of the Haudenosaunee past and their meanings for the early republic.2 But in contrast to those authors, who deeply explored Haudenosaunee experiences and perspectives, Anderson focuses almost exclusively on European or American views of the Iroquoian landscape and past.3 Making a compelling case that a close examination of colonizers' ideologies is warranted, Anderson's central contribution is to trace the evolution of Americans' attitudes about the Haudenosaunee lands and landscape, past and present, as they "struggled over the meaning of conquest" (15). Unfolding like a series of focused journal essays, the book first explores the Haudenosaunee world and landscape in the mid-eighteenth century and argues that the "American Revolution marked the turning point in their ability to define the nature of settlement" (11). Anderson underscores that the Haudenosaunee were settlers with ineffable connections to their homelands. Haudenosaunee territories framed by the Saint Lawrence, Champlain, Mohawk, Susquehanna, and Ohio Valleys constituted a built and natural landscape brimming with historical, mythic, and spiritual meanings for the Haudenosaunee. On the eve of the American Revolution, the Haudenosaunee population of around nine thousand prospered in distinct towns and settlements with abundant agriculture. Anderson describes Haudenosaunee lands prior to the revolution as "relatively unknown to outsiders" (8), but his use of "relatively" misses a long and complicated interaction between Haudenosaunee and Euro-American settlers who had competed for land and resources since the early years of the eighteenth century. He claims, for example, that "Europeans did not permanently settle in the lands of the Haudenosaunee prior to the American Revolution" (19) but does not take into account scholarly literature examining how Palatine, Scottish, Dutch, and other European families had been permanently settled—in many cases cheek by jowl—alongside Oneida and Mohawk communities beginning in the 1720s.4 [End Page 390] Indeed, in the early years of the Mohawk Valley's settlement, Europeans initially requested permission of the Haudenosaunee owners to establish their farms. Similarly, French Canadian habitants lived intermixed with Haudenosaunee communities in the Saint Lawrence Valley (an area of Iroquoia that the book...

ABSTRACT A submillennial‐resolution record of lake water oxygen isotope composition (δ 18 O) from chironomid head capsules is presented from Burial Lake, northwest Alaska. The record spans the Last Glacial Maximum (LGM; ~20–16k cal a bp ) to the present and shows a series of large lake δ 18 O shifts (~5‰). Relatively low δ 18 O values occurred during a period covering the LGM, when the lake was a shallow, closed‐basin pond. Higher values characterize deglaciation (~16–11.5k cal a bp ) when the lake was still closed but lake levels were higher. A rapid decline between ~11 and 10.5k cal a bp indicates that lake levels rose to overflowing. Lake δ 18 O values are interpreted to reflect the combined effects of changes in lake hydrology, growing season temperature and meteoric source water as well as large‐scale environmental changes impacting this site, including opening of the Bering Strait and shifts in atmospheric circulation patterns related to ice‐sheet dynamics. The results indicate significant shifts in precipitation minus evaporation across the late Pleistocene to early Holocene transition, which are consistent with temporal patterns of vegetation change and paludification. This study provides new perspectives on the paleohydrology of eastern Beringia concomitant with human migration and major turnover in megafaunal assemblages.

First posted January 19, 2021 For additional information, contact: Alaska Regional Director4210 University DriveAnchorage, AK 99508907–786–7091 The U.S. Geological Survey (USGS), in collaboration with university, Federal, Tribal, and independent partners, conducts fundamental research on the distribution, vulnerability, and importance of permafrost in arctic and boreal ecosystems. Scientists, land managers, and policy makers use USGS data to help make decisions for development, wildlife habitat, and other needs. Native villages and cities can forecast landscape change and where soils are vulnerable to thaw with more certainty. The scientific community can use USGS data to develop scenarios of future permafrost change.

Abstract Sub‐centennial oxygen (δ18O) isotopes of ostracod and authigenic calcite from Squanga Lake provides evidence of hydroclimatic extremes and a series of post‐glacial climate system reorganizations for the interior region of northwest Canada. Authigenic calcite δ18O values range from −16‰ to −21‰ and are presently similar to modern lake water and annual precipitation values. Ostracod δ18O record near identical trends with calcite, offset by +1.7 ± 0.6‰. At 11 ka BP (kaBP = thousands of years before 1950), higher δ18O values reflect decreased precipitation−evaporation (P−E) balance from residual ice sheet influences on moisture availability. A trend to lower δ18O values until ∼8 ka BP reflects a shift to wetter conditions, and reorganization of atmospheric circulation. The last millennium and modern era are relatively dry, though not as dry as the early Holocene extreme. North Pacific climate dynamics remained an important driver of P−E balance in northwest Canada throughout the Holocene.