Alaska Geobotany Center Library
Journal Articles - Reports - Posters - Powerpoint Presentations
Posters
2007 - 2006 - 2004 - 2002 - 2000
2008
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| Evaluating Arctic Tundra System Responses to Grazing Disturbances | |
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| Q. Yu, H. Epstein | |
| Introduction Arctic terrestrial ecosystems are assumed to be one of the most sensitive systems, enduring low temperatures, short growing seasons and freeze-thaw dynamics. The comparatively slow rates of productivity and decomposition may make it particularly difficult for these systems to recover from disturbances. One major disturbance in arctic terrestrial systems is grazing by caribou and reindeer, and different grazing intensities and climate regimes may result in different productivities and plant species compositions. European Geosciences Union General Assembly 2008, Vienna, Austria, 13 - 18 April 2008 | |
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| Spatial Patterns of Land Surface Temperature and NDVI on the Yamal Peninsula, Russia | |
| M.K. Raynolds, D.A. Walker, J.C. Comiso | |
| Introduction The Yamal Peninsula in Russia is used extensively by local reindeer herders and is undergoing rapid resource development. Like much of the Arctic it is also experiencing rapid changes in climate. A major question facing scientists and local managers is, "How will these changes affect the patterns of plant production in the region?" In most of the Arctic, plant production is strongly related to the amount of summer warmth available for plant growth. We investigate two quest here: 1. How strongly are the patterns of plant production on the Yamal related to summer land surface temperatures? 2. How strongly is plant production on the Yamal related to other mapped variables? 2008 NASA Carbon Cycle and Ecosystems Joint Science Workshop | |
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| Ecosystem Properties Along a Latitudinal Gradient of the Yamal Peninsula, Russia | |
| H.E. Epstein, D.A. Walker, P. Kuss, E. Kaarlejavi, G. Matyshek | |
| Introduction An understanding of land-atmosphere and biogeochemical cycling in any system is predicated by knowledge of the spatial distribution of vegetation and soil properties, and the capacity for elements to move among the various system components, including plants, soils, and atmosphere. In many regions of the Siberian arctic tundra, this baseline information on vegetation and soils in a spatial context does not exist in any systematic fshion. As part of a U.S. NASA/NEESPI Land Cover Land Use change project, we analyzed in detail the vegetation and soil properties of three tundra locations along a latitudinal gradient in forest-tundra and arctic tundra in the Yamal Region of Siberia east of the Ural Mountains. European Geosciences Union General Assembly 2008, Vienna, Austria, 13 - 18 April 2008 | |
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| Application of Space-based Technologies and Models to Address Land-cover/Land-use Change Problems on the Yamal Peninsula, Russia | |
| U. Bhatt, D.A. Walker, M.K. Raynolds, J. Comiso | |
| GOAL: Understand tundra-climate relationships 80(60)% of the Arctic tundra (3.2 million km2) is within 100(50) km of ocean Positive trend in NDVI identified over Alaska, N. America & the Arctic, suggests enhanced photosynthesis. Are these Arctic tundra vegetation changes associated with (forced by) changes in sea-ice? How? HYPOTHESIS: Earlier ice melt leads to increased summer warmth and higher NDVI and enhanced greenness (plant biomass & change in vegetation). DATA: Use 25 km resolution SSMI passive microwave Bootstrap Sea Ice Concentration (SIC), AVHRR Surface Temperature (Ts), and GIMMS NDVI. TIME: January 1982 to December 2007 (25 years, monthly & weekly) with NDVI to 2006. AREA AVERAGING: Construct indices of SIC & Ts for total & 50 km buffer areas in Bioclimate Subzones and Treshnikov divisions. ANALYSIS: Examine the variability and trends regionally and on pan-arctic scales. Correlate detrended time series. European Geosciences Union General Assembly 2008, Vienna, Austria, 13 - 18 April 2008 | |
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| Application of Space-based Technologies and Models to Address Land-cover/Land-use Change Problems on the Yamal Peninsula, Russia | |
| D. A. (Skip) Walker, H.E. Epstein, E. Kaarlejärvi, J.P. Kuss, M.O. Leibman, G.V. Matyshak, N.G. Moskalenko, V.E. Romanovsky | |
| Abstract The Yamal Peninsula in northern Russia has undergone extensive changes during the past 20 years due to gas and oil development, grazing and trampling by reindeer herds, and changes in climate. We are using a combination of ground-based studies, remote-sensing studies, and studies of land-use activities to help develop vegetation-change models. In 2007-2008 we are establishing a latitudinal transect of six locations in the Yamal Peninsula region. Here we present a summary of ground-based measurements of vegetation, soil, permafrost, active-layer, and spectral reflectance at three sites visited in Aug 2007: Nadym (northern boreal forest), Laborovaya (southern tundra), and Vaskiny Dachi (typical tundra). Biomass varies from about 1800-2300 g m-2 for tundra and forest understory at Nadym to about 1000-1300 g m-2 at Vaskiny Dachi). Areas with sandy soils have 250-350 g m-2 less biomass than comparable clayey sites, with less mosses and graminoids, and much more lichen biomass than nearby areas with more clayey soils. Lichen biomass was especially large in the ungrazed areas near Nadym – over 1000 g m-2 in two areas studied at Nadym compared to less than 250 g m-2 in areas where reindeer grazing has occurred annually. Ground-based measurements of NDVI and optically-measured LAI showed little correspondence to the biomass data, demonstrating the difficulty of linking ground-based measurements of NDVI and LAI to biomass data at the plot level. However, space-based measurements of NDVI along the climate gradient in both North America and Eurasia show clear latitudinal trends that correspond to the biomass data. The baseline of information established along the Yamal transect could be extremely useful for monitoring long-term changes in plant biomass, permafrost temperatures, and active layer depths as temperatures warm in the region. European Geosciences Union General Assembly 2008, Vienna, Austria, 13 - 18 April 2008 - Abstract |
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| North American Arctic Transect | |
| D.A. Walker | |
| Introduction The broad vision for the network of terrestrial observatories includes both the established flagship observatories and a more widely dispersed network of sites that are currently not represented. It is also important to consider how the terrestrial network is coordinated with the ocean and sea-ice observing networks. The North American Arctic Transect was established as part of a Biocomplexity of the Patterned Ground project (http://naat.geobotany.org/index.html). Of particular importance are the locations of Mould Bay and Isachsen in the coldest part of the Canadian Archipelago. These sites are cold because they are in the region of perennial sea ice where summer air temperatures are held close to 0°C all summer. These areas are likely to undergo major changes in climate if the perennial sea ice vanishes. 2008 Annual Meeting and Arctic Forum - Abstract | |
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| Cumulative impacts analysis on the Yamal Peninsula, Russia: A blueprint for a comparative study in Northern Alaska? | |
| Donald (Skip) A. Walker, Bruce C. Forbes, Florian Stammler, Timo Kumpula, Anatoli Gubarkov, Elina Karlejäarvi, Uma Bhatt, Martha Raynolds, Vladimir Romanovsky, Patrick Kuss, Marina Leibman, Natalia Moskalenko, Artem Khomutov, Howie Epstein, Qin Yu, Jiong Jia, Joey Comiso, Jed Kaplan | |
| Abstract Oil and gas activities over the past 30+ years have had profound effects on the social-ecological systems of the Yamal region of Russia and northern Alaska. Both regions are also undergoing rapid climate warming, with important ramifications for tundra vegetation and permafrost soils. Russian, and Finnish scientists are studying the terrain, permafrost, and socio-ecological impacts of development on the Yamal Peninsula, and are collaborating with US scientists, who are primarily examining the climate-related impacts to the vegetation and how these are related to the changing sea-ice concentrations and are employing state-of-the-art vegetation change models to predict the combined effects of land-cover changes due to altered climate and and industrial development. Here we summarize some of the recorded effects in the Yamal region of industrial development, the role of terrain sensitivity, reindeer herding, and climate change. Our aim is the co-production of knowledge relevant to assessing the overall cumulative effects – both positive and negative – from past resource exploration and from climate change. We point the way to a comparative study of cumulative effects in North America that would draw on the different lessons learned in both regions, with a goal of collaborating intensively with the local people to develop tools to better predict the cumulative effects of resource development and climate change in these and other regions of the Arctic. 2008 Annual Meeting and Arctic Forum - Abstract | |
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2007
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| Legacy IPY Hierarchic GIS Database for the Arctic Observatory at Toolik Lake | |
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| D.A. Walker, H.A. Maier, E.M. Barbour, A.W. Balser, J.P. Grimes, T.A. Heinrichs, M. Nolan, P. Prokein, C.L. Pylant, M.K. Raynolds, L.M. Rogan, V.L. Sharpton, D.L. Stahlke, and S.G. Vockeroth | |
| Abstract The Arctic Geobotanical Atlas (AGA) is a web-based multi-scale GIS database that focuses on the research sites at the Toolik Lake Field Station, and also covers the Kuparuk River Basin, northern Alaska, Arctic Alaska, and the Circumpolar Arctic – 7 scales in all. The map themes, legends, and colors are consistent across scales. The maps can be viewed by a variety of tools to enhance downloading, and use of the maps, including PDF versions, downloads of the GIS databases, and various viewing options including the GINA SwathViewer, GINA Map Server, and EarthSLOT software. The AGA is part of a regional GIS node at the University of Alaska Fairbanks (UAF) and a circum-Arctic GIS network. The site is in progress and currently includes maps covering the circumpolar Arctic, and arctic Alaska. This poster shows the latest addition to the hierarchy of maps – The vegetation of the Upper Kuparuk River Region and Toolik Lake Alaska. Inset maps contain the satellite image and maps of glacial geology, surficial geology, and NDVI/Biomass. It is anticipated that the hierarchy of maps for Toolik Lake will be completed in 2007. | |
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2006
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| Application of Space-based Technologies and Models to Address Land-cover/Land-use Change Problems on the Yamal Peninsula, Russia | |
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| D.A. Walker, U. Bhatt, J. Comiso, H.E. Epstein, B. Forbes, J. Jia, J. Kaplan, G. Kofinas, M. Leibman, H. Maier, N. Moskalenko, M.K. Raynolds, V. Romanovsky | |
| Abstract The Yamal Peninsula and the way of life of the native Nenets reindeer herders are undergoing rapid change caused by extensive gas development and changing land-cover due to climate warming. We are examining the environmental, social, and economic consequences of these changes. Key elements of the study include: (1) ground-based observations of vegetation and key terrain variables; (2) a spatial and temporal analysis of images from space-based sensors of greening trends on the Yamal and how these are linked to historical climate and land-use; (3) a study of the Nenets reindeer herding patterns in relationship to changes in the vegetation, and (4) modeling studies that will compare the Yamal to a similar but less impacted transect in North America. This research is in response to the NASA-USDA sponsored Northern Eurasia Earth Science Partnership Initiative (NEESPI). The project is also the intersection of three International Polar Year (IPY) initiatives: (1) “Greening of the Arctic” (GOA), (2) “Cold Land Processes in NEESPI” (CLPN) and (3) “CircumArctic Rangifer Monitoring and Assessment” (CARMA). | |
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| Arctic Geobotanical Atlas | |
| E.M. Barbour, H.A. Maier, D.A. Walker, A.W. Balzer, J.P. Grimes, T.A. Heinrichs, M. Nolan, P. Prokein, C.L. Pylant, M.K. Raynolds, L.M. Rogan, V.L. Sharpton, D.L. Stahlke, and S.G. Vockeroth | |
| Introduction The Circumpolar Geobotanical Atlas (AGA) is a web-based multi-scale (plant-to-planet) collection of geobotanical maps and supporting data. Vegetation is mapped at eight scales ranging from 1:1 scale (1-m plots) to 1:7,500,00 (entire Arctic). Visualization tools allow users to view thematic maps and raster data by several methods. The AGA currently focuses on the Circumpolar Arctic, Arctic Alaska, the upper Kuparuk River Region, Alaska, and the Arctic Long-Term Ecological Research site at Toolik Lake, Alaska. Diverse geobotanical themes include vegetation, geology, topography, landforms, surficial geomorphology and soil type. Vegetation data is linked to the primary literature, providing detailed community and species descriptions. The maps and website were developed at the Alaska Geobotany Center in collaboration with several other groups at the University of Alaska Fairbanks, including: Water and Environmental Research Center (WERC, http://www.uaf.edu/water/), Geographic Information Network of Alaska (GINA, http://www.gina.alaska.edu/), and Toolik Field Station (TFS, http://www.uaf.edu/toolik/). | |
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2004
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| Cassiope tetragona - Dryas integrifolia Non-acidic Snowbed Communities Along the Thompson River, Banks Island, Canada | |
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| P. Kuss | |
| Introduction This student's research is the result of the three weeks lasting Arctic Ecology Course 2003 that was taught along the Thomson River on Banks Island in the Canadian Arctic Archipelago (N 73° 13´ W 119° 32´ – N 73° 50´ W 119° 53´). The Thomson River lays within Bioclimatic subzone C with a mean July temperature of 5 – 7° C. Using the Braun-Blanquet approach of vegetation description it was attempted to gain an overview of Cassiope tetragona-dominated snowbed communities of different expositions on non-acidic substrates. 23 releves from five transects allowed him to classify the distinct vegetation units and to suggest a northern vicarant of the Tetragono-Dryadetum integrifoliae Barret 1972. |
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| The Driving Force of Frost Boils and Hummocks Formation | |
| Y. Shur, C.L. Ping | |
| Introduction Genesis of frost boils and hummocks have been widely attributed to cryoturbations – a complex of seasonally interchanging processes of frost heave and thaw settlement. Existing hypotheses do not consider changes in the upper permafrost as factors of frost boil and hummock formation. They cannot explain the bowl shape of the boils, the formation of an organice layer at the periphery of the frost boils, the elevated center of the boils. | |
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2002
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| Vegetation and Cryoturbation Interactions in Alaskan Arctic Tundra | |
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| A. Kade, D.A. Walker | |
| Introduction The vegetation pattern in arctic tundra is strongly influenced by the distribution of frost boils, small landforms typical of many permafrost regions. Frost heave, caused by ice-lens formation, controls self-organization processes and results in frost boils, which are patterned, circular ground features. Once frost boils have formed, they are self-perpetuating in nature. They display tight linkages among vegetation, soil and cryoturbation. In theory, ice-lens formation and the degee of frost heave determine the type of vegetation and quantity of plant biomass that a frost boil can support. Fewer frost heave disturbances should favor a thicker vegetation mat. In turn the vegetation mat covering the frost boil should insulate and shade the soil, decreasing heat flux between the soil surface and air, thus decreasing the amount of frost heave. |
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 Side 1  Side 2 | |
| Draft of the Circumpolar Arctic Vegetation Map | |
| CAVM Mapping Team | |
| Introduction The Circumpolar Arctic Vegetation Map shows the types of vegetation that occur across the Arctic, between the ice-covered Arctic Ocean to the north and the treeline to the south (the northern limit of forests). Environmental and climatic conditions are extreme, with a short growing season and low summer temperatures. The region supports plants, such as dwarf shrubs, herbs, lichen, and mosses, which have adapted to the extreme conditions by growing close to the ground. As one moves southward (outward from the map's center in all directions), the amount of warmth available for plant growth increases considerably. Warmer summer temperatures cause the size, abundance, and variety of plants to increase. Climate and other environmental controls, such as landscape, topography, soil chemistry, soil moisture, and the available plants that historically colonized an area (see Side 2, below), influence the distribution of plant communities. | |
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| Differences in Vegetation and Thaw Depths of Frost Boils and Inter-boils of Acidic and Non-acidic Tundra | |
| E.E. Cushing, D.A. Walker, A.N. Kade, A.M. Kelley | |
| Introduction Frost boils are small patterned ground formations created by the formation of ice lenses and frost heave. A contrast can be seen between frost boils and inter-boil areas. Disturbance created by cryoturbation results in less vegetation on frost boils as compared to inter-boils. Well developed frost boils are sparsely vegetated by mosses and lichens. Prostrate dwarf shrubs, sedges and an overall greater amount of biomass characterize inter-boils. Differences are also observed in boil and inter-boil areas on different parent material. The purpose of this project was to study the differences in vegetative characteristics (biomass, leaf area index and normalized difference vegetation index) and thaw depth between 1) Frost-boil and inter-boil areas and 2) moist acidic and moist non-acidic tundra. The insulative properties of a heavy biomass layer (especially from moss) can affect seasonal thawing. The central hypothesis of this project was that vegetative differences between boil and inter-boil areas and between acidic and non-acidic tundra are the primary controlling factors on active layer thickness (thaw depth). Secondly, we hypothesized that a smaller amount of biomass would result in greater summer thawing. | |
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2000
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| Biotic controls on spectral reflectance indices of tundra vegetation | |
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| S.M. Riedel, H.E. Epstein, D.A. Walker | |
| Abstract The use of remotely sensed reflectance data has become a desirable option for examining spatial and temporal dynamics of vegetation at various scales. A key step in using remotely sensed data is correlating biophysical properties of vegetation to values of spectral reflectance measures, in other words, understanding what these measurements mean in terms of what is on the ground. Seasonal field measurements of the normalized difference vegetation index (NDVI), using a field spectroradiometer, were compared with biomass data to investigate relationships between vegetation properties and spectral reflectance indices for four distinct tundra vegetation types at Ivotuk, Alaska. | |
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| Characterization of Vegetation Biomass and Structure Along a Gradient from Tundra to Forest at Treeline in Council, Alaska | |
| C.D. Copass, J. Beringer, D. McGuire, F. Chapin, D.A. Walker | |
| Abstract Climate change has the potential to influence vegetation dynamics in high latitude ecosystems, which may in turn feedback to the climate system through alterations in water, energy, and carbon dynamics. Our research focuses on improving our understanding of the role of species, or groupings of species (plant functional types) in the water, energy, and carbon exchange of ecosystems located near Council on the Seward Peninsula, Alaska. The Council sites represent a structural transition analogous to transitions of arctic ecosystems that might occur in response to climatic warming. | |
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| Vegetation Characteristics Derived from an Integrated Vegetation Complex Map for the Canadian Arctic | |
| W.A. Gould, M. Raynolds, D.A. Walker | |
| Abstract Vegetation patterns in the Arctic are primarily controlled by climate, geology, and topography. Summer temperatures exert the strongest control, affecting patterns of species composition, vegetation cover, biomass, and net primary productivity along a 12° mean July temperature gradient from treeline to the northernmost land areas. The Canadian Arctic represents nearly 50% of the ice-free land area found above the northern limit of trees and displays the greatest range of vegetation response to this climatic gradient. Increases in summer Arctic temperatures will have effects on vegetation patterns and associated ecological properties and processes both within the Arctic and at a global scale. Mapping current patterns of vegetation properties is important in predicting and monitoring responses to climatic change. |
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| Characteristics of Soils Associated With ATLAS Sites in Western Alaska | |
| C. Ping, G.J. Michaelson, X. Dai, L. Everett, J.M. Kimble, D.A. Walker | |
| Abstract Soil profiles were sampled and characterized at 11 NSF-ATLAS study sites, including 4 in Ivotuk, 2 in Oumalik and 5 in Council, in the summer of 1999. The soil morphological properties were studied in the field and recorded in pedon (soil profile) descriptions. All samples were characterized for physical, chemical and mineralogical properties at the USDA National Soil Survey Center. |
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