2003 — 2006 |
Mann, Daniel |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Collaborative Research: the Role of Loess Weathering in Global Geochemical Cycles @ University of Alaska Fairbanks Campus
ABSTRACT Anderson OPP-0240676 Mann OPP-0240919
This is a collaborative proposal by Principal Investigators at the Universities of California-Santa Cruz and Alaska -Fairbanks. This award will be jointly supported by the Arctic Natural Sciences Program and Geology and Paleontology Program in the Division of Earth Sciences. Glaciers produce large amounts of fine-grained sediment, exposing vast amounts of mineral surface area to chemical weathering processes. Despite the tremendous potential for glaciers to influence global weathering rates and hence atmospheric carbon dioxide (CO2) levels, this effect has not yet been demonstrated. Silicate weathering rates underneath glaciers are subdued, and rates in recently deglaciated terrain are below average. The hypothesis is that loess weathering provides the key link between the physical erosion done by glaciers and global geochemical cycles. This project is to study silicate weathering fluxes from glacial loess, and assess their global significance. Loess is a silt-clay sized sediment, transported by wind off unvegetated braid plains of glacier-fed rivers, and deposited over broad vegetated areas. Both the fine grain size and vegetation should render loess deposits highly susceptible to silicate weathering. These deposits effectively extend the impact of glaciation to a much broader area than the extent of glacier ice. Weathering of loess has never been examined from the perspective of contribution to global geochemical cycles. The project is designed to answer two questions: 1) does loess deposition increase the silicate weathering flux from a soil profile, and 2) does the weathering of loess occur at rates that can affect global weathering rates, and hence, global CO2 levels? Laboratory experiments, field measurements, and modeling will be used to address these questions. The field site is the Delta River valley in central Alaska, a glacial outwash system with on-going loess deposition at variable rates. Results from lab and fieldwork will be synthesized in a one-dimensional model of soil weathering fluxes as a function of loess deposition rate, precipitation rate, organic matter content, and grain size distributions. The model will be extended to the landscape scale to assess the global significance of loess deposition on CO2 consumption. Weathering of loess may be a significant, but it is still an unrecognized, component of carbon cycling. If this proves to be the case, then loess formation and weathering over timescales much longer than the duration of glaciation must be considered in models of atmospheric CO2 variation.
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0.943 |
2003 — 2005 |
Mann, Daniel Stone, John |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Deglaciation of the Marble Hills, Southern Ellsworth Mountains @ University of Washington
This award supports a project to date a series of samples that were collected during some reconnaissance fieldwork in the Marble Hills, at the southern end of the Ellsworth Mountains, where the WAIS flows into the head of the Ronne- Filchner Ice Shelf. These glacial erratic samples cover a range of altitudes up to 500 m above the present ice surface and are mostly faceted till stones that were stranded as overriding, glacial-maximum ice retreated from the highest point in the Marble Hills to its present level. The samples will be dated with cosmogenic 10 Be, allowing us to obtain a preliminary thinning history for this largely unconstrained sector of the ice sheet. The results will provide the first numerical dating control on the history of the WAIS in the Weddell Sea region since the last glacial maximum. This new data will constrain ice sheet reconstructions, which up to now have been based heavily on geomorphological observations lacking age control, in the Ellsworth Mountains. The results will complement marine geophysical constraints on the expansion of grounded ice into the Weddell Sea during the glacial maximum, and mapping and dating of ice limits along the northern coasts of the Weddell Sea. The exposure ages from the Marble Hills will provide an interesting comparison with reconstructions of the time-course of Holocene deglaciation in the Ross Sea and in Marie Byrd Land. Because of differences in climate, bathymetry, and bed characteristics between these regions, comparison of their deglaciation histories will provide insight into the dynamics of the ice sheet, and perhaps help to explain the prolonged WAIS retreat in and around the Ross Sea. The Weddell Sea is also an important site of Antarctic Bottom Water (AABW) formation, and it may act as an important link between the WAIS and the global climate system. Because an expanded ice sheet in the Weddell Sea would have altered the distribution of AABW production, knowing the timing of deglaciation is important for understanding the establishment of present-day patterns of ocean circulation.
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0.955 |
2009 — 2013 |
Mann, Daniel Rupp, T. Scott Duffy, Paul |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Collaborative: How the Timing of Summer Precipitation Affects the Responses of Boreal Forest to Climate Change @ University of Alaska Fairbanks Campus
This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
Abstract
There is increasing evidence that ecological processes at high latitude are just as sensitive to the timing of events as to their magnitudes. In the boreal forest, moisture availability in summer affects both tree growth and the fire regime. Summers are brief and seasonal transitions rapid, so even slight shifts in the timing of precipitation patterns can have large impacts. One of the most striking, seasonal phenomena in the Alaskan boreal forest is the onset of frequent frontal storms in late summer. This event usually comes in mid-July but is delayed into August or even September in some years. Summers when the rains are delayed have a greater chance of being mega-fires seasons when >1.6 million ha burn. This project will test the hypothesis that shifts in the seasonality of warm-season precipitation could be a key driver of the boreal forest?s responses to future climate changes. The effect of late-summer precipitation on tree growth and fire in Alaska will be quantified in two ways: First, by analyzing interactions between climate, fire, and tree growth (specifically ring-width, ring density, and wood-isotope composition); second, by analyzing fire-climate relationships using a new statistical approach. Together, these results will improve parameterization of the forest model ALFRESCO, which will then be used to test additional hypotheses about the interconnections among future climates, tree growth, fire, and their collective feedbacks to the global climate system.
The shifting seasonality of water availability during the warm season may be of key importance in determining how the global boreal forest responds to future climate changes. The multidisciplinary research proposed here represents a new approach to answering a novel question. No one has examined the impacts of seasonal shifts in the timing and magnitude of warm-season precipitation on vegetation distribution, tree growth, and fire regime in the boreal forest before. This will be the first time that tree rings from deciduous species in the boreal forest are used to describe past variations in summer rainfall through measurements of ring-width, late-wood density, and wood isotopes. The generalized boosting technique we propose using has not been previously applied to climate-fire records. The results of these tree-ring and statistical analyses will improve parameterization of the ALFRESCO forest model and allow us to explore the interactions among components of this part of the Arctic system with greater realism.
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0.943 |
2012 — 2016 |
Mann, Daniel |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Collaborative Research: Glacial Retreat and the Cultural Landscape of Ice Floe Sealing At Yakutat Bay, Alaska @ University of Alaska Fairbanks Campus
This multidisciplinary study of the ancient, historical, and contemporary harvest of harbor seals at icefloe pupping grounds near Hubbard Glacier in Yakutat Bay, Alaska models the reshaping of both an environment and a human hunting system in response to Late Holocene climate change. The project joins indigenous knowledge, language, and oral heritage with the material and chronometric evidence of archaeology, geology, and paleoenvironmental studies to document the cultural history and landscape of Yakutat Bay, where dramatic glacial recession after C. E. 1100 attracted major concentrations of harbor seals and opened the fiord for Sugpiaq, Eyak, Ahtna, and Tlingit settlement. The research team proposes that a clan-based system of local and external access rights developed around Yakutat sealing because of its economic centrality for peoples of the eastern Gulf of Alaska; that sealing camps shifted from the outer to the inner bay over time to follow the receding glacial front; and that the locations, artifact assemblages, faunal remains, and spatial layouts of camps express the cultural and social organization of hunting in different eras. They hypothesize that situated knowledge of Yakutat Bay's human and environmental history is encoded in living oral traditions and multilingual toponyms that richly delineate this nine-century cultural landscape, and that oral heritage can be chronologically correlated with archaeological and geological data. The study leads from the past to the present day, when the continuity of sealing and of the community's cultural and linguistic heritage are matters of urgent local concern. The methodologies and results of this study are highly relevant to questions of human adaptation and resiliency in the changing North and to the challenge of building coherence between indigenous and scientific knowledge systems.
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0.943 |
2015 — 2018 |
Mann, Daniel Groves, Pamela |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Collaborative Research: Land Bridges, Ice-Free Corridors, and Biome Shifts: Impacts On the Evolution and Extinction of Horses in Ice-Age Beringia @ University of Alaska Fairbanks Campus
Title: Land Bridges, Ice-Free Corridors, and Biome Shifts: Impacts on the Evolution and Extinction of Horses in Ice-Age Beringia
This study asks: How important was connectivity among populations of large arctic mammal species for maintaining genetic diversity, influencing evolutionary change, and mitigating extinction risk? What types of barriers affected this connectivity, and how permeable were these barriers to gene flow? The PIs will study how caballine horses, that inhabited ice-age Beringia (the biogeographic connector between Asia and North America), were affected by changes involving three different biogeographic barriers/corridors (1. the Bering Strait/Bering Land Bridge, which controlled dispersal and gene flow between Eurasia and Alaska; 2. the Ice-Free Corridor, which controlled gene flow between the Yukon and the Lower 48 States; and 3. biome shifts that periodically disrupted the spatial continuity of the Mammoth-Steppe, the unique ecosystem that stretched from France to the Yukon during the ice ages) during the last 30,000 years of the ice age. This study will evaluate the effects that each of these putative barriers to gene flow had on the abundance, distribution, and evolutionary trajectories of ice-age horses in the Arctic using new paleogenomic and paleoenvironmental data. The results will provide new insights into the roles played by environmental change and population fragmentation in determining extinction risk, and help predict how ongoing environmental changes will affect arctic ecosystems. This project will lead to advances in the rapidly developing field of paleogenetics and further the brand-new discipline of paleogenomic ecology. The Broader Impacts plan focuses on: a) research and professional development opportunities for graduate students, b) new training opportunities for undergraduate students who aspire to become STEM high school teachers, c) outreach to Native communities in rural Alaska, and d) outreach to K-12 students in Fairbanks, AK. At the end of each summer, the pre-service teachers, graduate students, and PIs will produce an inquiry activity module for grades 9-12 to be shared with local schools. Finally, the PIs will engage in both professional and public discourse, and use the results in media productions.
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0.943 |
2020 — 2023 |
Mann, Daniel Gaglioti, Benjamin |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Collaborative Research: P2c2: Extending Key Records of Holocene Climate Change and Glacier Fluctuations in the North Pacific Region Using Subfossil Wood From Southeastern Alaska @ University of Alaska Fairbanks Campus
This project aims to develop a multi-millennial, tree-ring chronology from subfossil trees exposed by retreating glaciers in Southeast Alaska to precisely calendar-date Holocene glacier fluctuations and compare them with a new record of climate seasonality. The multi-millennial tree-ring chronology will be used to extend reconstructions of spring and summer temperatures and build new records of winter storminess by analyzing traumatic resin ducts in annual tree rings. The winter storminess reconstruction is related to the strength of the Aleutian Low-pressure system (AL) and its analysis has the potential to transform the understanding of cold season ocean-atmospheric variability in the North Pacific. Specific goals of this project are to: 1) Generate 2,000-year-long records of wintertime AL along with summer temperature variability to determine how they responded to past climate forcing. 2) Use dendrochronology to precisely date when seven land-terminating and two tidewater glaciers advanced and retreated during the last 4000. 3) Test the hypothesis that the most extensive Holocene glacier advances in south coastal Alaska occurred when cooler summer air temperatures (reduced melt) coincided with a strengthened AL (increased snowfall).
The potential Broader Impacts include the collection of time-sensitive archives of buried wood that would be available to the scientific communities for multi-disciplinary investigations. The project will generate new reconstructions of spring-summer temperature, winter storminess and glacier advance/retreats to better understand the dynamics of climate-glacier mass balance and the North Pacific decadal variability at millennial time scales. This project will provide training for four undergraduate students as part of their undergraduate thesis including field work, data analysis and presentation of the results. The researchers will engage in public outreach by giving two talks at Glacier Bay National Park. In addition, a dendrochronology workshop in partnership with the Hoonah Indian Association and the Hoonah Native Forest Partnership will be organized in the Native Alaskan Village of Hoonah with the goal of engaging students in skill-based technique centered on the collection and analysis of tree-ring records.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
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0.943 |