Twentieth century erosion in Arctic Alaska foothills: The influence of shrubs, runoff, and permafrost

[1] Recent changes in the climate of Arctic Alaska, including warmer summers and a lengthened growing season, have increased vegetation productivity and permafrost temperatures. In this study, we use (1) time series imagery to examine the landscape pattern of tall shrub distribution and expansion in Arctic Alaska and (2) lake sediments from watersheds where shrub expansion is occurring to compare twentieth century temporal trends between shrub cover, erosion, and runoff. Landsat thematic mapper data from 1986 and 2009 were used to evaluate the expansion of tall shrubs across three regional subscenes in the Arctic foothills in northeast Alaska. We found that tall shrubs occupied floodplains and streams in 1986 and have been expanding their coverage along these corridors. The interaction between shrub expansion and erosion was examined by reconstructing the last 60–100 years of erosion from sediment cores in four lakes with shrub expansion in the surrounding watersheds. Three of the four lake cores show a steadily increasing or fluctuating erosion rate until 1980, after which these cores show a synchronous decline. We postulate that the increase in shrubs since 1980 in landscape positions prone to erosion has contributed to the decline in erosion. A decrease in the magnitude and frequency of runoff events has likely also contributed to the decline in erosion. Our results indicate a general decline in erosion since 1980 that is contemporaneous with shrub expansion and peak runoff decline, punctuated by episodic erosion events in one of four catchments.

[1]  A. P. Wolfe,et al.  Geochronology of high latitude lake sediments , 2004 .

[2]  R. Hooke.  Toward a uniform theory of clastic sediment yield in fluvial systems , 2000 .

[3]  Howard E. Epstein,et al.  Spatial heterogeneity of tundra vegetation response to recent temperature changes , 2006 .

[4]  M. Torre Jorgenson,et al.  Evolution of lakes and basins in northern Alaska and discussion of the thaw lake cycle , 2007 .

[5]  M. Sturm,et al.  Structure and wind transport of seasonal snow on the Arctic slope , 1993 .

[6]  F. S. Chapin,et al.  Permafrost carbon: Stock and decomposability of a globally significant carbon pool , 2006 .

[7]  F. Chapin,et al.  Calcium-rich tundra, wildlife, and the "Mammoth Steppe" , 2001 .

[8]  M. Jorgenson,et al.  Response of boreal ecosystems to varying modes of permafrost degradation , 2005 .

[9]  D. Kaufman,et al.  Pleistocene Maximum and Late Wisconsinan glacier extents across Alaska, U.S.A. , 2004 .

[10]  Donald A. Walker,et al.  Plant communities of a tussock tundra landscape in the Brooks Range Foothills, Alaska , 1994 .

[11]  M. Torre Jorgenson,et al.  Resilience and vulnerability of permafrost to climate change , 2010 .

[12]  W. Oechel,et al.  Energy and trace-gas fluxes across a soil pH boundary in the Arctic , 1998, Nature.

[13]  M. Torre Jorgenson,et al.  Abrupt increase in permafrost degradation in Arctic Alaska , 2006 .

[14]  John H. Bradford,et al.  Sediment and nutrient delivery from thermokarst features in the foothills of the North Slope, Alaska: Potential impacts on headwater stream ecosystems , 2008 .

[15]  L. Hinzman,et al.  Non-conductive heat transfer associated with frozen soils , 2001 .

[16]  Donald A. Walker,et al.  The Circumpolar Arctic Vegetation Map: AVHRR-derived base maps, environmental controls, and integrated mapping procedures , 2002 .

[17]  K. Joly,et al.  Changes in vegetative cover on Western Arctic Herd winter range from 1981 to 2005: potential effects of grazing and climate change , 2007 .

[18]  J. J. Ebersole.  Role of the seed bank in providing colonizers on a tundra disturbance in Alaska , 1989 .

[19]  S. Goetz,et al.  Satellite-observed photosynthetic trends across boreal North America associated with climate and fire disturbance. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[20]  J. Schimel,et al.  Increased snow depth affects microbial activity and nitrogen mineralization in two Arctic tundra communities , 2004 .

[21]  F. S. Chapin,et al.  Energy feedbacks of northern high‐latitude ecosystems to the climate system due to reduced snow cover during 20th century warming , 2007 .

[22]  F. Chapin,et al.  Role of Land-Surface Changes in Arctic Summer Warming , 2005, Science.

[23]  S. Goetz,et al.  Shrub Cover on the North Slope of Alaska: a circa 2000 Baseline Map , 2011 .

[24]  J. Canadell,et al.  Soil organic carbon pools in the northern circumpolar permafrost region , 2009 .

[25]  B. Markham,et al.  Summary of Current Radiometric Calibration Coefficients for Landsat MSS, TM, ETM+, and EO-1 ALI Sensors , 2009 .

[26]  J. Welker,et al.  Decomposition of old organic matter as a result of deeper active layers in a snow depth manipulation experiment , 2010, Oecologia.

[27]  Wayne H. Pollard,et al.  Fifty years of coastal erosion and retrogressive thaw slump activity on Herschel Island, southern Beaufort Sea, Yukon Territory, Canada , 2008 .

[28]  Trevor C. Lantz,et al.  Increasing rates of retrogressive thaw slump activity in the Mackenzie Delta region, N.W.T., Canada , 2008 .

[29]  F. Chapin,et al.  Ecosystem carbon storage in arctic tundra reduced by long-term nutrient fertilization , 2004, Nature.

[30]  G. Schaepman‐Strub,et al.  What are the main climate drivers for shrub growth in Northeastern Siberian tundra , 2011 .

[31]  John S. Kimball,et al.  Importance of recent shifts in soil thermal dynamics on growing season length, productivity, and carbon sequestration in terrestrial high‐latitude ecosystems , 2006 .

[32]  B. Forbes,et al.  Russian Arctic warming and ‘greening’ are closely tracked by tundra shrub willows , 2010 .

[33]  M. Sturm,et al.  The evidence for shrub expansion in Northern Alaska and the Pan‐Arctic , 2006 .

[34]  James P. McNamara,et al.  An analysis of streamflow hydrology in the Kuparuk river basin, Arctic Alaska : A nested watershed approach , 1998 .

[35]  Donald A. Walker,et al.  The Circumpolar Arctic vegetation map , 2005 .

[36]  Ted Lewis,et al.  Hydrological and sediment yield response to summer rainfall in a small high Arctic watershed , 2009 .

[37]  M. C. Brewer,et al.  Dissipation of the temperature effect of drilling a well in Arctic Alaska , 1958 .

[38]  A. Lewkowicz,et al.  Slope sediment yield in arid lowland continuous permafrost environments, Canadian Arctic Archipelago , 2002 .

[39]  G. Clow,et al.  Large Permafrost Warming in Northern Alaska During the 1990's Determined from GTN-P Borehole Temperature Measurements , 2002 .

[40]  F. Chapin,et al.  Competition causes regular spacing of alder in Alaskan shrub tundra , 1989, Oecologia.

[41]  C. Tucker,et al.  Circumpolar Arctic Tundra Vegetation Change Is Linked to Sea Ice Decline , 2010 .

[42]  J. Francis,et al.  The Arctic Amplification Debate , 2006 .

[43]  S. Schumm,et al.  Yield of sediment in relation to mean annual precipitation , 1958 .

[44]  C. Tucker,et al.  Increased plant growth in the northern high latitudes from 1981 to 1991 , 1997, Nature.

[45]  J. Welker,et al.  Winter Biological Processes Could Help Convert Arctic Tundra to Shrubland , 2005 .

[46]  T. E. Osterkamp,et al.  Characteristics of the recent warming of permafrost in Alaska , 2007 .

[47]  Sarah E. Gergel,et al.  Relative impacts of disturbance and temperature: persistent changes in microenvironment and vegetation in retrogressive thaw slumps , 2009 .

[48]  M. Sturm,et al.  Climate change: Increasing shrub abundance in the Arctic , 2001, Nature.

[49]  G. Bonan,et al.  Changes in Arctic vegetation amplify high-latitude warming through the greenhouse effect , 2009, Proceedings of the National Academy of Sciences.

[50]  D. Peteet,et al.  Responses of an arctic landscape to Lateglacial and early Holocene climatic changes: the importance of moisture , 2002 .

[51]  T. Osterkamp.  Causes of warming and thawing permafrost in Alaska , 2007 .

[52]  W. Oswald,et al.  Late Quaternary vegetational history of the Howard Pass Area, northwestern Alaska , 1999 .

[53]  F. Stuart Chapin,et al.  Responses of Arctic Tundra to Experimental and Observed Changes in Climate , 1995 .

[54]  L. Hinzman,et al.  Vegetation‐soil‐thaw‐depth relationships along a low‐arctic bioclimate gradient, Alaska: synthesis of information from the ATLAS studies , 2003 .

[55]  Mikhail Kanevskiy,et al.  (www.interscience.wiley.com) DOI: 10.1002/ppp.656 Physical and Ecological Changes Associated with Warming Permafrost and Thermokarst in Interior Alaska , 2022 .

[56]  G. Schaepman‐Strub,et al.  Shrub expansion may reduce summer permafrost thaw in Siberian tundra , 2010 .

[57]  M. Binford,et al.  Calculation and uncertainty analysis of 210Pb dates for PIRLA project lake sediment cores , 1990 .

[58]  S. Lamoureux,et al.  Fluvial Impact of Extensive Active Layer Detachments, Cape Bounty, Melville Island, Canada , 2009 .

[59]  D. Walker,et al.  Greening of arctic Alaska, 1981–2001 , 2003 .

[60]  D. Verbyla.  The greening and browning of Alaska based on 1982-2003 satellite data , 2008 .

[61]  Rasim Latifovic,et al.  Recent (1986 - 2006) Vegetation-Specific NDVI Trends in Northern Canada from Satellite Data , 2009 .

[62]  S. Lamoureux,et al.  Hydroclimate controls over seasonal sediment yield in two adjacent High Arctic watersheds , 2008 .

[63]  N. Matsuoka,et al.  Solifluction rates, processes and landforms: a global review , 2001 .

[64]  G. Goldsmith,et al.  Clonal Diversity in an Expanding Community of Arctic Salix spp. and a Model for Recruitment Modes of Arctic Plants , 2010 .

[65]  W. Gould,et al.  Phytomass, LAI, and NDVI in northern Alaska: Relationships to summer warmth, soil pH, plant functional types, and extrapolation to the circumpolar Arctic , 2003 .

[66]  Martin Hallinger,et al.  Establishing a missing link: warm summers and winter snow cover promote shrub expansion into alpine tundra in Scandinavia. , 2010, The New phytologist.

[67]  P. Groves,et al.  Floodplains, permafrost, cottonwood trees, and peat: What happened the last time climate warmed suddenly in arctic Alaska? , 2010 .

[68]  N. Schmidt,et al.  Reconstructing Century-long Snow Regimes Using Estimates of High Arctic Salix arctica Radial Growth , 2006 .

[69]  G. Liston,et al.  Changing snow and shrub conditions affect albedo with global implications , 2005 .

[70]  J. J. West,et al.  Time‐dependent morphology of thaw lakes and taliks in deep and shallow ground ice , 2008 .

[71]  Frank Oldfield,et al.  The calculation of lead-210 dates assuming a constant rate of supply of unsupported 210Pb to the sediment , 1978 .

[72]  Michael N. Gooseff,et al.  Effects of Hillslope Thermokarst in Northern Alaska , 2009 .

[73]  M. Mack,et al.  Plant Species Composition and Productivity following Permafrost Thaw and Thermokarst in Alaskan Tundra , 2007, Ecosystems.