Alaska Geobotany Center Library
Posters
2008 - 2007 - 2006 - 2004 - 2002 - 2000
2009
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Toolik Grid Plots: Baseline canopy height and species composition in 1990
Walker DA
Explanation: Permanent 1 x 1-m plots were sampled in 1990 to establish a baseline for monitoring changes to the vegetation at 85 grid points of the 1.2 x 1.1-km Toolik Lake Grid (see location map, D.A. Walker and Maier 2008). The grid points are spaced 100 meters apart. Each 1-m2 plot was located in a random direction from the grid stake within 2 m of the grid point stake and in the same vegetation type as at the stake. An aluminum point-quadrat frame was used for the sampling (Figure 1). A methodology developed for the International Tundra Experiment (ITEX) permits near-exact repositioning of the frame for long-term monitoring (M.D.Walker 1996). The plots are being monitored every 6 years using the same methods.
Mapping and Monitoring of Nordic Vegetation and Landscapes, Hveragerdi, Iceland, 16-18 September 2009
Citation: Walker, D. A., M. D. Walker, N. A. Auerbach, H. A. Maier, and G. P. Neufeld. 2009. Toolik Lake Grid Plots: Baseline canopy heights and species composition in 1990. Poster presented at the Mapping and Monitoring of Nordic Vegetation and Landscapes, 16-18 September 2009, Hveragerdi, Iceland.
Simulating soil organic nitrogen and grazing effects on arctic tundra vegetation dynamics on the Yamal Peninsula, Russia
Yu Q, Epstein HE, Walker DA
Land Cover, Land Use Change Spring Science Team M, Bethesda, MD, 31 March - 2 April 2009Decadal changes of phenological patterns over Arctic tundra biome
Jia GJ, Epstein HE, Walker DA, Hu Y, Wang H
Land Cover, Land Use Change Spring Science Team M, Bethesda, MD, 31 March - 2 April 2009
Spatiotemporal trends in tree and tall shrub cover in the circumpolar Arctic: evidence from repeat ground photographs and 1960s satellite imagery
Frost GV, Epstein HE, Jorgenson MT
Land Cover, Land Use Change Spring Science Team M, Bethesda, MD, 31 March - 2 April 2009Biomass-NDVI-LAI patterns and relationships on the Yamal Peninsula, Russia
Epstein, HE, Walker DA, Kaarlejärvi E, Kuss P, Moskalenko NG, Orekhov PT, Gubarkov AA, Khomutov AV, Leibman MO, Matyshak GV
Land Cover, Land Use Change Spring Science Team Meeting, Bethesda, MD, 31 March - 2 April 2009Greening of Arctic tundra is linked to warming summer land temperatures and sea-ice declines
Bhatt US, Walker DA, Raynolds MK, Comiso JC, Epstein HE, Jia GJ, Gens R
Land Cover, Land Use Change Spring Science Team M, Bethesda, MD, 31 March - 2 April 2009Vegetation greenness on the Yamal Peninsula, Russia: Disturbance-climate-change interactions
Walker DA, Leibman MO, Epstein HE, Forbes BC, Bhatt US, Raynolds MK, Comiso JC, Gubarkov AA, Khomutov AV, Jia GJ, Kaarlejarvi E, Kaplan JO, Kumpula T, Kuss P, Matyshak G, Orekhov P, Moskalenko NG, Romanovsky V, Ukralentseva NK, Yu Q
Land Cover, Land Use Change Spring Science Team Meeting, Bethesda, MD, 31 March - 2 April 2009Modelling the distribution of circumpolar arctic vegetation
Raynolds MK, Walker DA, Verbyla D, Huettman F
Land Cover, Land Use Change Spring Science Team Meeting, Bethesda, MD, 31 March - 2 April 2009
Evaluating Environmental Controls on Arctic Tundra Vegetation Dynamics on Yamal Peninsula, Russia
Yu Q, Epstein HE, Walker DA
EnviroDay, University of Virginia, VA, January 12th, 2009
2008
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Decadal changes of phenological patterns over Arctic tundra biome
Jia GJ, Epstein HE, Walker DA, and Wang H
AGU Fall Meeting, San Francisco, CA, Dec. 15-19, 2008
Abstract C21C-0559
Citation: (3) Jia, G.J., H. E. Espstein, D. A. Walker, and H. Wang. 2008. Decadal changes of phenological patterns over arctic tundra biome. Eos Trans. AGU, 89(53), Fall Meet. Suppl., Abstract C21C-0559.
A Web-based Arctic Geobotanical Atlas and a New Hierarchy of Maps of the Toolik Lake Region, Alaska
Walker DA, Barbour EM, Maier HA
Accurate maps of arctic terrain at multiple scales are needed for spatial analyses, modeling and monitoring of permafrost responses to a changing climate. The Arctic Geobotanical Atlas (AGA) is a web-based multi-scale (plant-to-planet) collection of geobotanical maps and supporting data. A new set of geobotanical maps focuses on the area around the University of Alaska’s Toolik Field Station in the vicinity of Toolik Lake, Alaska, and includes the Upper Kuparuk River region (published at 1:63,360 scale), the Toolik Lake area (published at 1:20,000 scale), and a map of a 1.2-km2 intensive research grid on the south side of Toolik Lake (published at 1:5,000 scale). Here we present an overview of the AGA and the new maps.
Ninth International Conference on Permafrost, University of Alaska Fairbanks, Fairbanks, AK, June 29 - July 3, 20, 2008Landscape Change in the Russian Arctic: Ecological Implications of the Petroleum Industry for Nenets Reindeer Herding on the Yamal Peninsula
Kumpula T, Forbes BC, & Stammler F
2008 Annual Meeting and Arctic Forum, Washington, D.C., 13–15 May 2008
Cumulative impacts analysis on the Yamal Peninsula, Russia: A blueprint for a comparative study in Northern Alaska?
Walker DA, Forbes BC, Stammler F, Kumpula T, Gubarkov A, Karlejäarvi E, Bhatt U, Raynolds M, Romanovsky V, Kuss P, Leibman M, Moskalenko N, Khomutov A, Epstein H, Yu Q, Jia J, Comiso J, Kaplan J
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, Washington, D.C., 13-15 May 2008
Abstract
North American Arctic Transect
Walker DA
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, Washington, D.C., 13-15 May 2008
Abstract
Application of Space-based Technologies and Models to Address Land-cover/Land-use Change Problems on the Yamal Peninsula, Russia: Circumpolar and regional analysis of the relationship between sea-ice variability, summer land-surface temperatures, Arctic tundra greenness and large-scale climate drivers
Bhatt U, Walker DA, Raynolds MK, Comiso J
Recent dramatic reductions in summer sea ice may also impact the ecosystem at high latitudes. It is hypothesized that an earlier ice melt can force atmospheric and land-surface temperatures changes, leading to increased summer warmth and enhanced greenness of vegetation. Our study examines the time-series relationships between sea-ice concentrations, summer land-surface temperatures, vegetation greenness, and large-scale climate drivers within a 50-km buffer of the Arctic coastline for the total Arctic domain and regionally using the Arctic Ocean divisions of the Russian Arctic Atlas. The analysis employs 25-km resolution SSMI passive microwave 18 Jun-22 Jul sea ice concentration and AVHRR Surface Temperature data from 1982 to 2007. The 1982-2006 NASA GIMMS data at a 25-km resolution are used to represent summer NDVI.
NASA Carbon Cycle and Ecosystems Joint Science Workshop, Adelphi, MD, April 28 – May 2, 2008
European Geosciences Union General Assembly 2008, Vienna, Austria, 13 - 18 April 2008
Ecosystem Properties Along a Latitudinal Gradient of the Yamal Peninsula, Russia
Epstein HE, Walker DA, Kuss P, Kaarlejavi E, Matyshek G
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.
NASA Carbon Cycle and Ecosystems Joint Science Workshop, Adelphi, MD, April 28 – May 2, 2008
European Geosciences Union General Assembly 2009, Vienna, Austria, 14 - 18 April 2008
Application of Space-based Technologies and Models to Address Land-cover/Land-use Change Problems on the Yamal Peninsula, Russia: 2007 field studies along the bioclimate gradient
Walker DA, Epstein HE, Kaarlejärvi E, Kuss JP, Leibman MO, Matyshak GV, Moskalenko NG, Romanovsky VE
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.
NASA Carbon Cycle and Ecosystems Joint Science Workshop, Adelphi, MD, April 28 – May 2, 2008
European Geosciences Union General Assembly 2008, Vienna, Austria, 13 - 18 April 2008
Evaluating Arctic Tundra System Responses to Grazing Disturbances
Yu Q, Epstein HE
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.
NASA Carbon Cycle and Ecosystems Joint Science Workshop, Adelphi, MD, April 28 – May 2, 20
European Geosciences Union General Assembly 2008, Vienna, Austria, 14 - 18 April 2008
Spatial Patterns of Land Surface Temperature and NDVI on the Yamal Peninsula, Russia
Raynolds MK, Walker DA, Comiso JC
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 questions 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?
NASA Carbon Cycle and Ecosystems Joint Science Workshop, Adelphi, MD, April 28 – May 2, 20
Cumulative Effects of Industrial Development, Reindeer Herding, and Climate Change on the Yamal Peninsula, Russia
Forbes B
European Geosciences Union General Assembly 2008, Vienna, Austria, 13 – 18 April 2008
2007
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Influence of Regional Sea Ice Variability on Arctic Tundra
Bhatt, US, Walker DA, Raynolds MK, Comiso JC
CMOS/CGU/AMS 2007 Congress Meeting, Canadian Meteorological and Oceanographic Society, Canadian Geophysical Union, American Meteorological Society, St John's, Newfoundland Canada, 31 May 2007 (poster date)
Legacy IPY Hierarchic GIS Database for the Arctic Observatory at Toolik Lake
Walker DA, Maier HA, Barbour EM, Balser AW, Grimes JP, Heinrichs TA, Nolan M, Prokein P, Pylant CL, Raynolds MK, Rogan LM, Sharpton VL, Stahlke DL, and Vockeroth SG
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.
41st Alaska Surveying and Mapping Conference, Westmark Hotel, Fairbanks, AK, 19-23 March 2007
Trends of Vegetation Greenness in the Arctic from 1982-2005
Jia GJ, Epstein HE, and Walker DA
AGU Fall Meeting, San Francisco, CA, December 10-14, 2007
The Relationship Between Permafrost Characteristics and the Distribution of Arctic Vegetation Types
Raynolds MK
AAAS Conference, Anchorage, AK, September 24-26, 2007
Project for interlinked Flora Arctica and Arctic Vegetation databases
Kuss P
Of all the global biomes, the Circumpolar Arctic Tundra Biome is the only one that has its entire known list of plants, including vascular plants, mosses and lichens, documented in up-to-date floras of the entire biome. These checklists are an essential first step in understanding the relationship of the flora and plant communities to climate and other geographical variables and how these might change under altered climate regimes. Our proposed project will use these pan-Arctic floras to make two databases that are needed for circumpolar studies of vegetation (1) The Flora Arctica database, (2) the Arctic Vegetation Database. We will furthermore analyze the databases to determine trends with respect to key physical and biotic variables and integrate the results as education tools in the Arctic Geobotanical Atlas (www.arcticatlas.org).
Fourth International CAFF Flora Group Workshop, Faroe Islands, Denmark, May 15-17, 2007
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
Walker DA, Bhatt U, Comiso J, Epstein HE, Forbes B, Jia J, Kaplan J, Kofinas G, Leibman M, Maier H, Moskalenko N, Raynolds MK, Romanovsky V
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).
Arctic Geobotanical Atlas
Maier HA, Walker DA, Barbour EM, Balzer AW, Grimes JP, Heinrichs TA, Nolan M, Prokein P, Pylant CL, Raynolds MK, Rogan LM, Sharpton VL, Stahlke DL, and Vockeroth SG
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/).
26th Annual ESRI International User Conference, San Diego, CA, August 7-12, 2006
Arctic Geobotanical Atlas
Barbour EM, Maier HA, Walker DA, Balzer AW, Grimes JP, Heinrichs TA, Nolan M, Prokein P, Pylant CL, Raynolds MK, Rogan LM, Sharpton VL, Stahlke DL, and Vockeroth SG
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/).
2006 Arctic Science Conference, Arctic AAAS Division Meeting, University of Alaska Fairbanks, Fairbanks, AK, October 2-4, 2006
2004
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The Driving Force of Frost Boils and Hummocks Formation
Shur Y, Ping CL
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.
Cassiope tetragona - Dryas integrifolia Non-acidic Snowbed Communities Along the Thompson River, Banks Island, Canada
Kuss P
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.
2002
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Vegetation and Cryoturbation Interactions in Alaskan Arctic Tundra
Kade A, Walker DA
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.
Draft of the Circumpolar Arctic Vegetation Map
CAVM Mapping Team
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, influence the distribution of plant communities.
Differences in Vegetation and Thaw Depths of Frost Boils and Inter-boils of Acidic and Non-acidic Tundra
Cushing EE, Walker DA, Kade AN, Kelley AM
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.
2000
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Biotic controls on spectral reflectance indices of tundra vegetation
Riedel SM, Epstein HE, Walker DA
AGU Fall Meeting, , 2000
AbstractCharacterization of Vegetation Biomass and Structure Along a Gradient from Tundra to Forest at Treeline in Council, Alaska
Copass CD, Beringer J, McGuire D, Chapin F, Walker DA
AGU Fall Meeting, , 2000
AbstractVegetation Characteristics Derived from an Integrated Vegetation Complex Map for the Canadian Arctic
Gould WA, Raynolds M, Walker DA
AGU Fall Meeting, , 2000
AbstractCharacteristics of Soils Associated With ATLAS Sites in Western Alaska
Ping C, Michaelson GJ, Dai X, Everett L, Kimble JM, Walker DA
AGU Fall Meeting, , 2000
Abstract