To The Graduate School: The members of the Committee approve the thesis of Forrest G. McCarthy presented on March 7, 2008.

Dr. John Logan Allen, Chairperson, Faculty Emeritus, Department of Geography

Dr. Jacqueline J. Shinker, Co-Chair, Assistant Professor, Department of Geography

Dr. Daniel B. Tinker, Graduate Faculty Representative, Department of Botany

Dr. Gary P. Kofinas, Associate Professor, Institute of Arctic Biology University of Alaska Fairbanks

APPROVED:

Dr. Gerald R. Webster, Department Chair, Department of Geography

Don Roth, Dean, The Graduate School

McCarthy, Forrest G., Landcover Change in Arctic Alaska: Observations Through Repeat Photography, M.A., Department of Geography, May 2008.

Abstract: During June and July of 2006 thirty-two landscape photographs from three early explorations of Arctic Alaska were reproduced. The pairs of historic and contemporary photos provided the opportunity to observe arctic landcover change over fifty and one hundred year time periods. Qualitative photo-pair comparisons revealed: glacier and aufeis cover has decreased; lake and pond cover has both increased and decreased; observations of decreased river channel cover was more common than increased; and observations of increased tundra, shrub, and tree cover was common than decreased. The character of these observations suggests a landscape wide response to observed changes in the arctic climate.

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LANDCOVER CHANGE IN ARCTIC ALASKA: OBSERVATIONS THROUGH REPEAT PHOTOGRAPHY

by Forrest G. McCarthy

A thesis submitted to the Department of Geography and the Graduate School of The University of Wyoming in partial fulfillment of the requirements for the degree of

MASTER OF ARTS In GEOGRAPHY

Laramie, Wyoming May, 2008

ACKNOWLEDGMENTS This thesis is dedicated to Dr. Olaus Murie who committed his life to the conservation of Arctic Alaska, its wildlife, and its wild landscapes. Without his vision and commitment, the untrammeled arctic landscape would be very different today and this research would not have been feasible. And in his footsteps, Dr. George Schaller, who extended this commitment to the preservation of wildlife and wild places throughout the world, while never forgetting the importance of the Arctic National Wildlife Refuge, I owe much gratitude. Spending six weeks with Dr. Schaller in the Arctic was truly a gift. I gratefully acknowledge my committee members Dr. John Logan Allen, Dr. Jacqueline J. Shinker, Dr. Daniel B. Tinker, and Dr. Gary P. Kofinas, whose patience and guidance helped mold this thesis into a cohesive scientific paper. The inspiration for my research in this remote wilderness is largely attributed to the members of the 1956 Sheenjek expedition, including: Mardy Murie, Dr. Olaus Murie, Dr. George Schaller, Dr. Robert Krear, and Dr. Brina Kessel. Following in their footsteps a half-century later, I was joined on the 2006 Arctic Traverse by Jonathan Waterman, Dr. George Schaller, Martin Robards, and Betsy Young, and to each of them I am extremely grateful to have shared that unique journey. I would like to thank Linda Franklin formally of the Murie Center, who helped locate and digitize the 1956 Murie Expedition photographs, as well as the helpful staff at the USGS Denver Library Photo Archives. Additionally, I would like to personally acknowledge the assistance and insight provided by Janet Jorgenson, Dr. Roman Dial, and Thomas Turiano.

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Spending the summer in Arctic Alaska would not have been possible without the supporters of the 2006 Arctic Traverse: The National Geographic Society, The Murie Center, Patagonia, and Alpacka Raft. Above all, I would like to thank my wife, Amy McCarthy, for her support, patience, and compassion. I hit the jackpot when she agreed to marry me.

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TABLE OF CONTENTS Page 1. INTRODUCTION ……………………………………………..…….….. .....................1 1.1. Overview of the Arctic Environment …………...….……………….... .................1 1.2. Research Objectives ……………………….……….……………...…....................3 1.3. Limitations ………….………………………….…………………….....................3 1.4. Study Area ……….……………………………….……………………………….4 2. ARCTIC LANDCOVER CHANGE ……………………………….……………….….6 2.1. Glaciers …………………………………………..………………...… ...................7 2.2. Aufeis ……………………………………………………………….......................9 2.3. Lakes, Ponds, and Permafrost ………………..………………………..................11 2.4. River Channels …………………………………..……………..……...................13 2.5. Tundra …………………………………………..……………..……....................15 2.6. Shrubs ……………………………………………..………………………..……17 2.7. Trees …….…………………………………………………………… .................18 3. METHODS .…..………….…………………………………………………..... ..........21 3.1. Repeat Photography …………..…………………………………….....................21 3.2. Historic Photographs …………..……...………………...…………,… ................21 3.3. Contemporary Photographs .………..………………………...………. ................23 3.4. Photo-pair Analysis ………………………………………………….. .................23 4. RESULTS ..……………………………….………………………………….... ..........27 4.1. Glaciers ..……………...…………………………………………..….. .................27 iv

4.2. Aufeis ..…………………………………………………………..…….................28 4.3. Lakes and Ponds …..…………....…………………………..………… ................28 4.4. River Channels ......……………………………...………………..…....................29 4.5. Tundra ..………………………………………………………….….....................29 4.6. Shrubs ......…………………………………………………………..... .................30 4.7. Trees ..……………………………………………………………….. .................31 5. DISCUSSION .…………………………………………………………..……...........32 5.1. Glaciers ..……………...…………………………………………..…. ..................33 5.2. Aufeis ..…………………………………………………………..….....................34 5.3. Lakes, Ponds, and Permafrost .……………………………..……….....................35 5.4. River Channels ......……………………………...………………..…....................36 5.5. Tundra ..………………………………………………………………..................37 5.6. Shrubs ......……………………………………………………………... ...............38 5.7. Trees ..……………………………………………………………… ...................39 6. CONCLUSIONS .………………………………………………………… ................40 7. REFERENCES ..........................................................................................……. ..........42 8. PHOTO PAIRS .……………………………………………….………………...........49 9. MAPS ...…………………………………………………………………........ ...........81 10. APPENDICES ……………..……………..……………………………......... ...........84 10.1. List of Figures ……………………………………………………......................84 10.2. List of Tables ……………………………………………………...... ................86 10.3. Visible Landcover Change ……...……………………………...……. ...............86 10.4. Photograph Information ……………………………………………...................88 v

1. INTRODUCTION 1.1. Overview of the Arctic Environment In 2005 an international effort of eight nations produced a comprehensive and authoritative scientific synthesis of available information about observed and projected changes in arctic climate and environment. The synthesis report, the Arctic Climate Impact Assessment (ACIA), found climate change is amplified in the Arctic, resulting in average arctic temperature rise of 2-30 Celsius in the last fifty years. Additionally, the 2005 ACIA reports rapid warming is significantly altering the arctic landscape including; melting glaciers, declining snow cover, diminishing lake and river ice, thawing permafrost, and shifts in vegetation. The Arctic is unique in its biota and landscapes. The effects of extreme annual variations in insolation and temperature have driven the development of unique species, ecosystems (Stonehouse, 1989), landscapes, and hydrologic processes (Smith et al., 1989). The thermal regime controlling the abrupt threshold and phase change from ice to water at 00 Celsius limits a variety of biological and physical processes. Rapid changes in the arctic thermal regime will have considerable effects on the landscape (Hinzman et al., 2005). Due to ocean currents and atmospheric wind patterns both climate models and observations indicate global warming is amplified in the Arctic (Serrez and Barry, 2005). Climate observations during the last fifty years have documented an average trans-arctic temperature increase of 0.90 Celsius per decade. This is 50% greater than the 0.60 Celsius warming per decade for the planet. Over the last 100 years arctic precipitation has increased by about 8%, mostly in the form of rain (Serrez and Barry, 2005). 1

In the time since the Last Glacial Maximum (LGM), approximately 21,000 calendar years B.P., the general trend in the Arctic has been one of warming temperatures (Ellis et al., 1984). This overall warming trend is non-linear and includes periods of both warming and cooling (Simpson et al., 2002). Treeline advanced all the way to the Arctic Ocean in the last seven thousand years B.P., during the early Holocene (Bigelow et al., 2003; MacDonald et al., 1998). In more recent history (1400-1880 A.D.) the Arctic experienced a cooler climate. This period is referred to as the Little Ice Age (LIA) (Mann et al., 2002; Overpeck et al., 1997). The climate trends since the LIA have been an overall warming with a cooler period in the first half of the 20th century and rapid warming during the second half of the 20th century. The rate of arctic warming over the last thirty years has been rapid and without precedent (ACIA, 2005). As a result of the increasing release of greenhouse gasses in the atmosphere and positive feedback loops climate models forecast that arctic warming will continue to accelerate (Kattsov & Källén, 2004). Uncertainties in these models result primarily from two major variables. The first variable is anthropologic; it is unknown how much CO2 will continue to be emitted into the atmosphere (Houghton et al., 2001). The other area of uncertainty is associated with positive feedbacks that have the potential to accelerate arctic warming. These feedbacks include the release of additional CO2 and other greenhouse gasses like methane (CH4) from thawing permafrost, changes in albedo due to decreasing snowcover and sea ice, increasing plant mass, and changes in ocean currents as a result of an increasing fresh water supply into the Arctic Ocean (Callaghan et al., 2004; Serrez and Barry, 2005).

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The response of arctic landcover to observed and projected warming is likely to be significant. By comparing historic photos to contemporary photos of the exact geographic location the responses of arctic landcover can be assessed. Photo-pairs of historic and contemporary images are created and compared in an effort to detect visible changes in a diversity of arctic landcover types. Landcover types included: glaciers, aufeis or over-flow ice, river channels, ponds, lakes, tundra, shrubs, and trees.

1.2. Research Objectives This study incorporates the use of paired-photo analysis to asses the type and extent of landcover change in arctic Alaska. The objectives of this study are: ••

Compare historic and contemporary landscape photos to detect and document changes in arctic landscape.

••

Determine what types of landcover have changed, how they have changed, and when they have changed.

1.3. Limitations This study was geographically limited by the availability of historic photographs and the itinerary of the 2006 Arctic Traverse. There are numerous historic photographs of arctic Alaska. Contemporary photographs for this study were collected during the 2006 Arctic Traverse and matched with available historic photographs. The 2006 Arctic Traverse, sponsored by the National Geographic Society, celebrated the 50th anniversary of Olaus and Margaret Murie’’s historic 1956 expedition, by returning to northern Alaska. The 2006 Arctic Traverse had a pre-arranged itinerary and historic photographs were 3

selected from those locations that would be visited during the expedition. The coastal plain offers an additional geographic challenge. While historic photographs are available for this region, they lacked defining landmarks needed for their relocation. Additional variables such as weather affected photo opportunities. The assessment of landcover change in photo-pairs is by nature somewhat subjective. In an effort to confirm changes in landcover the author, when possible, visited the exact site where current landcover appeared different from what was displayed in historic photographs. However, the scale and remoteness of the study area made this more than challenging.

1.4. Study Area The region of this study, where the photo-pairs were generated, was within the eastern half of the Brooks Range in northern Alaska (Fig. 1). The majority of the photographs were located within The Arctic National Wildlife Refuge. The remaining photographs were located within Gates of the Arctic National Park. Almost all the land displayed in the photographs is part of the National Wilderness Preservation System and is managed to maintain its pristine character. Human activities are restricted to nonmotorized recreation, subsistence harvesting, scientific research, and other non-invasive activities. Logging, mining, roads, mechanized vehicles, and other forms of development are prohibited (Wilderness Act, 1964). With the exception of several photographs that display human disturbance from the Alaska Pipeline, and the accompanying Dalton Highway, the region is pristine and void of direct anthropologic change.

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The Brooks Range runs east to west across northern Alaska. The Continental Divide, between the Arctic and Pacific Oceans, roughly follows its crest. The south slope of the range is dominated by boreal forests of white and black spruce. On the north slope of the range, trees are absent, and the landscape is covered by tundra and shrubs. Landcover on the crest of the range is limited to alpine tundra, lichen, barren ground, seasonal snow fields, and in the highest locales, glaciers. The historic photos used in this study were made during three early arctic expeditions. In 1899, as part of a USGS survey, F.C. Schrader explored the Dietrich Fork River. The Schrader photos are the farthest west and south used in this study. In 1910, on another USGS survey, E.K. Leffingwell explored the Canning River Drainage. The Leffingwell photographs are the farthest north in this study. In 1956, The Murie Expedition, sponsored by the New York Zoological Society, spent two months camped in the Sheenjek River Valley, the farthest east location in this study.

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Fig. 1. Study Area. This study examined landcover change in the arctic region of northeast Alaska within the Brooks Range of Northeast Alaska. The location of the three photo sets from previous expeditions are shown As follows A) 1899 F.C. Schrader; B) 1919 Earnest Leffingwell; and C) 1956 Murie and Schaller. 2. ARCTIC LANDCOVER CHANGE The combined observations of diverse and substantial research on arctic climate warming, and its associated effects on the cryosphere and biosphere, provide convincing evidence for a changing arctic landscape (ACIA 2005). The observed warming 2-30 Celsius in the last fifty years in northern Alaska has been reported and predicted to alter the arctic landscape (Serrez and Barry, 2005). Landscape responses to the known warming include receding glaciers, reduced aufeis, narrower river changes, increased tundra cover, increased shrub cover, increases and decreases in tree cover, and thawing

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permafrost, which contributes to both increased and decreased lake and pond cover (Hinzman, et. al., 2005). The overwhelming evidence is for a complex shift in landcover consistent with rapid and recent warming.

2.1. Glaciers Unlike permanent snowfields, glaciers are moving bodies of ice, a mass of snow and ice that flows mostly down-gradient due to gravity (Pielou, 1994). Glaciers contain two important zones, separated by the firn line, that differ quantitatively in the fate of their ““permanent”” ice and annual snow deposition. The accumulation zone is where more snow accumulates than is lost through melting and ablation; it is the source region for most of the glacier’’s mass balance. The ablation zone, generally below the accumulation zone, is where more ice is lost through melting and evaporation (Oerlemans, 2001); it is the zone of most ice loss. The most important measures for understanding a glacier’’s dynamics are mass balance and the elevation of the firn line (Dyurgerov, 2000). Mass balance reflects the accumulation, transport, and ablation of glacier snow and ice. Changes in mass balance indicate a glacier’’s response to climatic variation (Mayo 1984, and Oerlemans, et. al., 2000). If the mass balance is hovering near zero, then a glacier is in equilibrium with its climatic environment, the elevation of the firn line is static, and its land cover remains constant. If the mass balance is positive, the firn line descends, the glacier advances and its landcover increases. If the mass balance is negative, then a glacier is receding, the firn line is ascending, and its landcover decreases (Oerlemans, 2001).

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Across the Circumpolar North glaciologists have documented a glacial recession (retreat from the terminus) and/or mass wastage (thinning) of arctic glaciers and ice caps (Arendt et al., 2002; Braun et al., 2004; Brown et al., 2001; Dowesdell et al., 1997; Dyurgerov et al., 2000; Jania et al., 1996; Mayo, 1984; Nolan et al., 2005; Rabus et al., 1998). Although it is generally accepted that there has been an overall decrease in glacier mass since the last glacial maximum or LGM (21,000 years before present), and more recently the Little Ice Age or LIA, recent mass balance measurements indicate the wastage of arctic glaciers is rapidly accelerating (Brown et al., 2001). More importantly, the variation among rates of mass across various regions appears to be consistent with similar variation among rates of observed warming (Hinzman, et. al., 2005). The Romanzof and Franklin Mountains of the Northeast Brooks Range (Fig.1) support the highest concentration of alpine glaciers in the Brooks Range. The McCall Glacier near Mt. Isto has been intermittently surveyed since 1956 (Rabus et al., 1998). Nolan et al.,(2004 and 2005) utilized repeat photography (Fig. 2) to document the mass wastage of the McCall Glacier, where comparison of 1958 to 2003 photos show a dramatic glacial recession and thinning.

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Fig. 2. McCall Glacier. This photo-pair of the McCall Glacier documents a negative mass balance and the resulting recession during a 45 year time lapse. Changes in climate and the associated negative mass have led to dramatic wastage of the McCall and other glaciers in Arctic Alaska. Photos: (left) Austin Post (1958) and (right) Mathew Nolan (2003). 2.2. Aufeis Aufeis (Fig. 3), frequently called ““overflow ice”” or even ““glacier ice”” by local Alaskans, is ice that accumulates during winter along stream and river valleys by the upwelling of river water through cracked river ice, blockage behind ice dams, and by ground-water discharge through unconstrained fluvial sediments. During winter, successive freezing of the overlapping ice layers can lead to aufeis accumulations several meters thick (Wanty, 2002). Aufeis in Alaska’’s more southerly ranges melts every summer; however, in the more northerly Brooks Range, with a colder climate, lower annual insolation, and continued permafrost, aufeis may not entirely melt in some places. Indeed, there is evidence that the more massive fields of aufeis in the Brooks Range can be perennial. Harden et al., (1977) reported that remnants of the largest fields of aufeis in the Brooks Range, such as those along the Kongakut, Sagavanirktok, and Canning Rivers, existed into September 1973, and it is probable that large fields of aufeis 9

persist for more than one season. In the vicinity of Last Lake in the Sheenjek Valley, members of the 1956 Murie Expedition reported that large aufeis fields persisted throughout the summer (Krear, 1990). Several Gwich’’in elders in Arctic Village reported that aufeis fields that once persisted year-round along the Chandalar River, are now smaller or completely gone (Gilbert, 2006). Recent analysis of aufeis on the Kuparuk River utilizing SAR imagery from 1996 to 2006 indicated that 3––18% of the maximum aufeis accumulation remained at the end of the summer (Yoshikawa et al., 2007). In the Eastern Brooks Range, Yoshikawa et al.,(2007) examined the recent (100 years) historical volume of the aufeis formations through the use of narratives, photographs, satellite imagery, and isotope analyses. While Yoshikawa (et al., 2007) states the size of the aufeis formations may be different today than in the past because the cumulative volume of discharge and climatic conditions have changed, they found no evidence of an overall decrease in aufeis. Analysis of repeat aerial photography collected over the past fifty years for the Hulahula, Sadlerochit, and Kongakut Rivers indicate that the aufeis fields have not dramatically changed in either volume or extent (Fig 3). Yoshikawa (et al., 2007) concludes the formation and melting of aufeis is less sensitive to climatic change, but very sensitive to the source spring water properties such as the temperature and the volume of discharge. To further understand the history of aufeis deposits in the Brooks Range Yoshikawa (et al., 2007) collected and dated soil samples from Sadlerochit and Hulahula aufeis areas. These efforts found the extent of aufeis cover, on the North Slope of the Brooks Range, has been consistent since the LGM (Last Glacier Maxium) (Yoshikawa et al., 2007). 10

Fig. 3. Aufeis on the Hulahula River. Aerial photographs (1950 and 1979) and Landsat TM (2001) image demonstrate the historical distribution of aufeis (Yoshikawa et al., 2007). 2.3. Lakes, Ponds, and Permafrost Permafrost is soil or rock that remains below 0°C throughout the year, and forms when the ground cools sufficiently in winter to produce a frozen layer that persists throughout the following summer (Pielou, 1994). The presence of permafrost depends on both the amount of heat lost in winter due to cold winter temperatures and the amount of heat gained in summer due to high summer temperatures. Permafrost can be as thick as 500 meters (Smith, et. al., 1989). Continuous permafrost refers to areas where the permafrost is uninterrupted; discontinuous permafrost refers to areas where the permafrost is more extensive than unfrozen ground; and patchy permafrost occurs where there is some frozen ground, but mostly unfrozen (Smith, et. al., 1989). Climate is the main factor determining the existence of permafrost (Heginbottom, 2000). In the continuous permafrost on the north slope of Alaska’’s Brooks Range permafrost temperatures in boreholes have displayed a 2––40 Celsius increase over the last 50––100 years (Lachenbruch, et. al., 1986). In a similar study on the north slope of the Brooks Range, Clow et. al., (2002) found permafrost warmed 30 Celsius since the late 11

1980s. Discontinuous permafrost is also warming and thawing and extensive areas of thermokarst terrain (marked subsidence of the surface resulting from thawing of ice-rich permafrost) are now developing as a result of climatic change, particularly in boreal regions (Osterkamp et. al., 1999; Osterkamp, et. al., 2000). The thawing of permafrost is known to visibly influence arctic landscape through the formation of ice wedges and the resulting drainage or expansion of tundra ponds and lakes (Hinzman et al., 1991; McNamara et al., 1998; Kane et al., 1991; Kane et al., 2000; Jorgenson et al., 2001). An ice wedge is a narrow mass of ice that can be 3 or 4 meters wide at ground surface and extend up to 10 meters downwards. Ice wedges begin during winter when the water in the ground freezes and expands, forming cracks. In the spring when the snow melts the melt-water flows into these cracks, re-freezing almost immediately, exerting pressure on the cracks, and forcing them to widen. The following year the ground cracks again along the same weak points and again in spring the water flows in and refreezes, expanding the wedges even further (Pielou 1994). The formation of ice wedges in previously stable permafrost has been quantified through repeat photography by Jorgenson (et. al., 2006). Jorgenson et. al., (2006) used extensive aerial photographs to determine the percentage of landmass affected by ice wedges. In sites underlain by ice-rich permafrost, trees die when their roots are regularly flooded, causing wet sedge meadows, bogs and thermokarst ponds and lakes to replace forests (Jorgenson et. al., 2006). Thawing permafrost in areas with lower water tables and thinner permafrost can result in the drainage of tundra ponds (Yoshikawa and Hinzman, 2003). Yoshikawa and Hinzman (2003) documented this phenomenon using repeat aerial 12

photography near Council, Alaska (Fig. 4). Moving through three time-slices from 1950, 1981, and 2000 Yoshikawa and Hinzman (2003) show a decrease in tundra pond extent. Riorden (et. al., 2006) believes that increased evapotranspiration due to warmer and longer growing seasons is another factor associated with decreased pond and lake cover.

Fig. 4. Tundra Ponds. Numerous tundra ponds near Council, Alaska, have decreased in surface area over the last 50 years. A probable mechanism for these shrinking ponds is internal drainage through the degradation of shallow permafrost (Yoshikawa and Hinzman, 2003). 2.4. River Channels Due to the lack of stream gauges with long-term records, evidence of changes in watershed runoff in Alaska is limited. Analyses of U.S. Geological Survey data from nine stream monitoring stations in central to northern Alaska with long-term records (those with about 50 years of data) do reveal interesting, statistically significant, trends (Hinzman, et. al., 2005). Basins with a substantial glacial component consistently display increasing trends in runoff, presumably due to increases in glacier melt. River basins

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lacking large glaciers tend to show decreasing runoff, probably because evapotranspiration rates have increased faster than increasing precipitation (Hinzman, et. al., 2005). In the past thirty years degrading permafrost has driven increased winter river flows and decreased summer peak flows (Bolton et al., 2000). Repeat photography (Fig. 5) has been used to show how increasing shrub cover may be affecting river channels causing them to become narrower, shrubbier, and more constrained (Sturm et al., 2005; Tape et al., 2006). Changes in river flows and shrubbery are the likely causes for the decreased surface area of river channels visible in photo-pairs.

Fig. 5. Decreased River Channels. Active stream channels and gravel bars in 1950 are colonized by shrubs in 2000. These images were taken near the Nimiuktuk River in northwestern Alaska (Sturm et. al., 2006). Photos: U.S. Navy (1950) and Ken Tape (2000). 14

2.5. Tundra The word tundra is derived from the Finnish word for barren or treeless land. Comprised of lichens, mosses, sedges, perennial forbs, and dwarf shrubs, tundra dominates the high artic (Stonehouse, 1989). Tundra warming experiments at the Long Term Ecological Research (LTER) site at Toolik Lake, Alaska, have shown immediate physiological and morphological responses resulting in a general increase in the stature and cover of shrubs and graminoids (Fig. 6) (Hollister et al., 2005). The experiments at Tooloik Lake manipulated temperature, nutrient availability, and light attenuation. In an effort to simulate predicted arctic warming, greenhouses were used to increase temperatures by 30 Celsius. Fertilizer was added to simulate predicted increase in nutrient availability from micro-biological activity in tundra soil. To understand the role of possible changes in cloud cover and light attenuation shade was added. The treatments revealed deciduous dwarf shrubs responded quickly to increases in temperature with the availability of nutrients a limiting factor (Chapin et. al., 1995; Hollister et. al., 2005). The experiments at Toolik Lake are a part of the larger International Tundra Experiment (ITEX). ITEX is a collaborative, multi-site experiment using a common temperature manipulation to examine variability in species response across climatic and geographic gradients of tundra ecosystems (Arft, et. al., 1999). The additional ITEX sites confirm the Toolik Lake results, shrubs were the tundra plants most responsive to environmental change (Bret-Harte, et. al., 2002). ITEX and Toolik Lake experiments both found increased temperatures drove a decline in overall biodiversity of tundra

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communities as deciduous shrubs flourished (Bret-Harte, et. al., 2002; Hollister et. al., 2005; Wahren, et. al., 2005). Changes in the composition, biomass, and diversity of tundra composed of dwarf shrubs, sedges, grasses, mosses, and lichens would be difficult to accurately assess at the landscape scale. Tape et al.,(2006) documented the transformations of tundra communities from dwarf shrub (<40 cm) to low shrub (40-200 cm) with photo-pair analyses. Photo-pair analysis has not previously been employed to document the expansion of tundra into areas of barren ground.

Fig. 6. Toolik Lake LTER Tundra Study Plot. Warming experiments have shown immediate physiological and morphological responses resulting in a general increase in vegetation stature and the cover of shrubs and graminoids (Hollister et al., 2005). Photo by Jonathan Waterman, June 2006.

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2.6. Shrubs The three principle deciduous shrubs (taller then .5 meters), when considering landcover change in Arctic Alaska, are dwarf birch (Betula nana), willow (Salix alaxsensis) and green alder (Alnus crispa). Sturm (et al., 2000) hypothesized a positive feedback loop in which the warming Arctic and higher atmospheric CO2 concentrations are driving increases in the size and abundance of dwarf birch, willow, and green alder. Increasing shrub coverage then traps more winter snow insulating the ground surface and increasing the availability of nitrogen and the depth of the permafrost active layer, in turn driving shrub growth. An increase in shrub biomass further alters both the albedo and hydrologic cycles of the tundra landscape (Sturm et al., 2000). Tape et al.,(2006) replicated 50-year-old aerial photographs of Alaska’’s Brooks Range to test the hypothesis that a warming Arctic and higher atmospheric CO2 concentrations are driving increases in the size and abundance of shrubs. Evidence through repeat photography (Fig. 7) shows growth increases in the size of individual deciduous shrubs, the expansion of shrub patch boundaries, and the filling in of shrub patches vary in magnitude in relation to species, topography, and proximity to river channels (Tape et al., 2006). Additional studies utilizing remote sensing report increasing shrub coverage as well (Stow et al., 2004; Silapaswan et al., 2001).

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Fig. 7. Increasing abundance of shrubs in arctic Alaska. The photographs were taken in 1948 and 2002 at identical locations on the Colville River. Dark objects are individual shrubs 1 to 2 meters high and several meters in diameter. Similar changes have been detected at more than 200 other locations across arctic Alaska, where comparative photographs are available (Sturm, et. al., 2005). Photographs: U.S. Navy (1948) and Ken Tape (2002). 2.7. Trees The most important trees to consider in sub-arctic Alaska are black spruce (Picea mariana) and white spruce (Picea glauca). These two conifers dominate the northernmost forests at the tundra-forest ecotone or taiga. Both species are well adapted to the extreme conditions of sub-arctic Alaska. Black spruce possess a shallow root system that can grow on permafrost with an active layer only 25 cm thick. Black spruce thrive in heavy clay soils and wet peat bogs. White spruce require better-drained soils (Pielou, 1994). Temperature is the primary factor which limits tree growth at higher latitudes (Jacoby and D'Arrigo, 1989). The boundary between tundra and boreal forest ecosystems 18

is non-linear and may be highly sensitive to changes in climate because of the prominent role that temperature plays in determining the location of the forest-tundra ecotone (Holtmeier & Broll, 2005). Recent (e.g., 20th century) warming in Alaska has been accompanied by a widespread advance of trees into tundra ecosystems (Hinzman et. al., 2005). The increase in density of white spruce has been documented at arctic treeline in northwest Alaska (Suarez et al., 1999). The expansion of spruce forest has been observed on the Seward Peninsula (Lloyd et. al., 2002), in the Brooks Range (Sturm, et. al., 2001; Cooper, 1986), the White Mountains and the Alaska Range (Lloyd, et. al., 2003). The significant increase in tree density over time at all these sites is an important finding directly resulting from the warmer conditions allowing more trees to become established (Hinzman et. al., 2005). When the age of forests along transects that cross treeline is compared, it is apparent that forest age becomes progressively younger as one crosses from forest into tundra, in essence, direct evidence for treeline advance (Hinzman et. al., 2005). A treering study on the Seward Peninsula of western Alaska found spruce have advanced an average 10 km north since 1880 (Lloyd, et. al., 2003). Sturm (et. al., 2001) replicated 50year old aerial photographs (Fig. 8) to document the in-filling of spruce stands near treeline in Alaska’’s Brooks Range. Although the distributional change in spruce is an indicator that recent warming has affected the forest-tundra ecotone, the time scale on which ecosystem conversion occurs at this ecotone involves many decades to centuries (Hinzman et. al., 2005). A warmer environment may not always correspond with increased tree growth. Lloyd et., al., (2002) found that after 1950 warmer temperatures were associated with 19

decreased tree growth in all but the wettest regions. Although tree growth increased from 1900––1950 at almost all sites studied in Alaska, significant declines in tree growth were common after 1950. Lloyd et., al., (2002) also found substantial variability in response to climate variation according to distance to treeline. Inverse growth responses to temperature were more common at sites below the forest margin than at sites at the forest margin. Even in such close proximity to treeline, warm temperatures after 1950 have been associated with reduced tree growth. Growth declines were most common in the warmer and drier sites, and thus support the hypothesis that drought-stress may accompany increased warming in the boreal forest (Lloyd et., al., 2002). Despite the variation, the widespread nature of treeline advance in Alaska strongly suggests that this represents a directional response to regional climate (Hinzman et. al., 2005).

Fig. 8. The Kugururok River. The photo-pair documents the in-filling of spruce stands (A) and increased abundance of shrubs in the middle ground (B); A and B denote the same locations in the old and new photographs (Sturm, et. al., 2001).

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3. METHODS 3.1. Repeat Photography Repeat photography is a simple and valid method for documenting environmental change (Rogers, 1984). The methodology involves acquiring historic photographs, locating the site of a historical photograph, reoccupying the original camera position, and making a new photograph of the same scene (Rogers, 1984). This allows direct (versus inferred) comparison of changes on the landscape that may have occurred through time. The process of creating photo pairs for the scientific documentation of landscape change has been applied to a wide range of research (Rogers, 1984). Photo pairs have effectively documented glacier recession in Glacier National Park (Key, et al., 1998), the Sierra Nevada (Basagic et al., 2004), and throughout Alaska (Nolan et al., 2004; Jorgenson, 2005). Pairs of aerial photographs have been used to assess the degradation of permafrost (Jorgenson, et. al., 2006; Yoshikawa, et. al., 2003). Repeat photography has established changes in the treeline of Colorado (Elliott, 2004; Zier, 2005), Sweden (Rapp, 1996), and southwest Alaska (Jorgenson, 2005). In the Western United States repeat photography has been used to document shrub and forest encroachment (Allen, et al., 1995; Zier, 2005) along with changes in river channel morphology (Rogers, 1982). In Alaska photo-pairs have been utilized to assess the expansion of alders and other shrubs (Jorgenson, 2005; Sturm et al., 2005; Tape 2006, et. al).

3.2. Historic Photographs In an effort to assess changes in landcover in arctic Alaska, sixty-one historic photographs were obtained from governmental archives and private collections. Twenty21

three of the photographs where taken in 1899 by USGS surveyor F.C. Schrader (Figure 1 A) while exploring the headwaters of the Chandalar and Koyukuk Rivers (Schrader, 1900). Seventeen photos where taken in 1910 by Earnest Leffingwell (Figure 1 B) during a USGS survey of the Canning River Valley (Leffingwell, 1919). Digitized copies of the original prints taken during these surveys where obtained at the USGS Denver Library Photo Archives. During the 1956 Murie Expedition (Figure 1 C) to the Sheenjek Valley, many photographs where taken by several of the expedition members including Bob Krear, George Schaller, Brina Kessel, and Olaus Murie (Krear, 1990; Schaller, 1957; Murie, 1956). Nineteen photos where obtained from original slides at The Murie Center Archives in Moose, Wyoming. Dr. George Schaller (Figure 1 C) provided two additional photographs of glaciers at the head of the Sheenjek River. Through these four sources, sixty-one photographs where chosen for their quality and ability to relocate. The resolution and overexposure of many historic photographs was inadequate for potential photo-pair comparison. Other historic photographs lacked information on their location and/or recognizable landforms that would allow relocation. The lack of recognizable landforms eliminated many Leffingwell photographs of the featureless coastal plain located between the Brooks Range and the Arctic Ocean. Official reports along with original field notes provided varying levels of information on the location of the original photograph. Often photographs were labeled with place names not used on current maps. For many of the photographs general geographic references such as ““Forks of the Canning River”” (Leffingwell, 1919) were all that was provided. A proximal location of the photograph was made by matching photographed landforms to features on current 1:63,000 USGS maps. Once in the area, the specific location of the 22

original photographer was found by matching the scene to the historic photograph. In the case of several of Leffingwell photos, the photographer’’s original locations were marked with a cairn. During June and July of 2006, thirty-two out of the sixty-one historic photos were successfully duplicated. These photographs included four of F.C. Schrader’’s 1899 photos of the Dietrichs Fork, nine of Earnest Leffingwell’’s 1910 photos of the Canning River, and nineteen photos from the 1956 Murie Sheenjek Expedition. Limitations including time, weather, and difficulties relocating the original site, prevented the replication of the remaining photographs.

3.3. Contemporary Photographs Thirty-two contemporary photos were generated using a Canon 8.2 mega-pixel Digital Rebel XT with a 28-135 wide angle zoom lens. To guarantee the authenticity and maximize resolution photographs were recorded in RAW format. A Garmin E-Trax GPS was used to record the exact location in Decimal Minutes WGS 1984. Camera direction was recorded in true North. The time and date along with a general description of the current condition of landcover including vegetation and hydrologic features were noted (Table 3).

3.4. Photo-Pair Analysis In an effort to assess landcover change each of the 32 photo-pairs were segregated into several topographic scenes resulting in a total of 65 scenes or pairs. The photopairing and processing was performed in Adobe Photoshop CS version 8.0. Each pair of 23

scenes was then qualitatively evaluated for changes in the amount of shrub, tree, tundra, aufeis, river channel, pond, and glacier coverage. When possible each photo-pair was segregated into three scenes (Fig. 9) representing different landform types: mountain, valley, and hillside (Figures 10, 11, and 12, respectively). Some photo-pairs did not provide representation or adequate resolution of all three landform types (Fig. 10). In these cases only the representative landforms or scenes with adequate resolution were used.

Murie 1956

McCarthy 2006

Fig. 9. Murie 1. The Sheenjek Valley, complete with all three scenes; Mountain, Valley, and Hillside. 24

1956

2006 Fig. 10. Murie 1, Mountain Scene Cropped. The resolution is inadequate to assess most landcover changes.

1956

2006 Fig. 11. Murie 1, Valley Scene Cropped. Valley scene cropped. Decreased aufeis is clearly visible in lower left corner. The resolution is inadequate to assess changes in tundra and shrub cover.

25

1956

2006

Fig. 12. Murie 1, Hillside Scene Cropped. Increased tree density and height is detectible in center. On the right side the filling in of shrub patches is visible. Tundra cover is recorded as decreased due to its replacement by shrub and tree cover. Each scene was then evaluated for changes in landcover. Tundra, shrub, tree, river channel, ponds, aufeis, and glacier cover were then recorded as increased, stable, decreased, or not applicable. The following generalized classification of landcover types is used. Tundra includes both alpine and arctic tundra, consisting primarily of grasses, mosses and lichens and may contain dwarf shrubs. Shrubs refer to deciduous shrubs greater then .5 meters including birch (Betula nana and B. glandulosa), willow (Salix alaxsensis, S. pulchra, S. glauca) and alder (Alnus crispa). Trees include black spruce (Picea mariana) and white spruce (Picea glauca). Ponds include both tundra ponds and 26

thermokarst lakes. River channel cover included first, second and third order streams and their associated gravel bars. Aufeis refers to ““overflow ice”” that accumulates during winter along stream and river valleys by the upwelling of river water behind ice dams, or by groundwater discharge. Glaciers refer to alpine glaciers. Increase was recorded for a landcover type clearly occupying more area than the original photograph. Decrease was recorded when a particular landcover type clearly occupied less area. Stable was recorded when little or no change was visible. Not applicable (NA) was recorded when either the scene did not provide representation of a particular landcover or photo resolution was inadequate to determine change (Table 1). Tundra Shrubs Trees River Channels Ponds Aufeis Glaciers

Hillside decrease increase increase NA NA NA NA

Valley NA NA stable stable stable decrease NA

Mountain stable increase increase NA NA NA NA

Table 1. Murie 1, Landcover Change. This table is a sample of the different scenes and the assessment of changes in landcover. 4. RESULTS 4.1. Glaciers Two historic photographs, both taken by Dr. George Schaller during the 1956 Murie Expedition, contained glaciers. Only one was successfully replicated. The photopair represents a 50-year time lapse (Figure 49) with an extensive decrease in glacier cover clearly visible. The original camera location of the second photograph was not located and the historic photograph was not duplicated. 27

4.2. Aufeis Two scenes, with a 50-year time lapse, and three scenes, with a 100-year time lapse, display aufeis. In all five scenes extensive decreases in aufeis cover is clearly visible (Figures 22, 24, 30, 31, & 40). 4.3. Lakes and Ponds Ten scenes, with a 50-year time lapse, and three scenes, with a 100-year time lapse display pond and lake cover. In scenes with a 50-year time lapse lake and pond cover appear: stable in three scenes (30%), visibly increased in six scenes (60%), and visibly decreased in two scenes (10%). In scenes with a 100-year time lapse lake and pond cover appear: stable in one scene (33.3%) and visibly decreased in two scenes (66.6%). Lake and Pond Cover 100 90 80 66.6

70

% of scenes

60 60 50 40

33.3

30 30 20 10 10

0 0

stable

increase decrease 50 years

stable

increase decrease 100 years

Fig. 13. Pond and Lake Cover. In photo-pairs with a 50-year time lapse increased pond and lake cover is most common. In photo-pairs with a 100-year time lapse decreased lake and pond cover is most common. 28

4.4. River Channels Nine scenes, with a 50-year time lapse, and 16 scenes, with a 100-year time lapse display river channel cover. In scenes with a 50-year time lapse river channel cover appears: stable in five scenes (55.6%), visibly increased in one scene (11.1%), and visibly decreased in two scenes (33.3%). In scenes with a 100-year time lapse river channel cover appears: stable in seven scenes (43.8%), visibly increased in three scenes (18.8%) and visibly decreased in six scenes (37.5%). River Channel Cover 100 90 80

% of scenes

70 60

55.6

50

43.8 37.5

40

33.3

30 18.8

20 11.1 10 0

stable

increase decrease 50 years

stable

increase decrease 100 years

Fig. 14. River Channel Cover. In photo-pairs with a both 50-year and 100 time lapses decreased cover more common than increased cover. 4.5. Tundra Forty scenes, with a 50-year time lapse, and twenty-four scenes, with a 100-year time lapse display tundra cover. In scenes with a 50-year time lapse tundra cover appears: stable in twenty-four scenes (60%), visibly increased in ten scenes (25%), and visibly 29

decreased in six scenes (15%). In scenes with a 100-year time lapse tundra cover appears: stable in thirteen scenes (54.2%), visibly increased in ten scenes (41.7%), and visibly decreased in one scene (4.2%).

Tundra Cover 100 90 80 70

% of scenes

60 60

54.2

50 41.7 40 30

25

20

15

10

4.2

0

stable

increase decrease 50 years

stable

increase decrease 100 years

Fig. 15. Tundra Cover. In photo-pairs with both 50-year and 100-year time lapses, increased tundra cover is more common than decreased tundra cover. In photo-pairs with a 100-year time lapse, the ratio of increased tundra to decreased tundra cover is more significant. 4.6. Shrubs Thirty-eight scenes with a 50-year time lapse and twenty-five scenes with a 100year time lapse display shrub cover. In scenes with a 50-year time lapse shrub cover appears: stable in twenty-two scenes (57.9%), visibly increased in eleven scenes (28.9%), and visibly decreased in five scenes (13.2%). In scenes with a 100-year time lapse tundra cover appears: stable in fifteen scenes (60%), visibly increased in nine scenes (36%) and visibly decreased in one scene (4%). 30

Shrub Cover 100 90 80

% of scenes

70 60

60

57.9

50 36

40 28.9

30 20

13.2

10

4

0

stable

increase decrease 50 years

stable

increase decrease 100 years

Fig. 16. Shrub Cover. In photo-pairs, with 50-year and 100-year time lapses, increased shrub cover is more common than decreased shrub cover. In photo-pairs with a 100-year time lapse, the ratio of increased shrub cover to decreased shrub cover is more significant. 4.7. Trees Twenty-four scenes with a 50-year time lapse and four scenes with a 100-year time lapse displayed tree cover. In scenes with a 50-year time lapse tree cover appears: stable in ten scenes (41.7%), visibly increased in eleven scenes (45.8%), and visibly decreased in three scenes (12.5%). In scenes with a 100-year time lapse tree cover appears stable in all four scenes (100%).

31

Tree Cover 100 100 90 80

% of scenes

70 60 45.8

50 41.7 40 30 20

12.5

10 0

0

0

stable

increase decrease

stable

50 years

increase decrease 100 years

Fig. 17. Tree Cover. In photo-pairs with a 50-year time lapse increased tree cover slightly exceeds stable tree cover and is significantly more common than decreased tree cover. In photo-pairs with a 100-year time lapse no changes in tree cover are visible.

5. DISCUSION Photo-pair comparison of landcover with 50 and 100-year time lapses reveals visible changes in glaciers, aufeis, river channels, lakes and ponds, tundra, shrubs, and trees. A total of 94 observations of visible landcover change and 104 observations of no visible landcover change are recorded. In all five photo-pairs displaying glaciers or aufeis a significant decrease in cover is visible. In nine (68.3%) of the scenes displaying lake and pond cover change is visible. The majority (69.2%) of visible changes in river channel cover display decreased cover. While the majority (76.1%) of visible changes in tundra, shrub, and tree cover display an increase in cover.

32

While many of the observed changes can be associated with a warmer climate, succession, disturbance, and fluvial processes have likely also contributed to the visible changes. Succession is occurring at two time scales: local disturbance related to periglacial and fluvial processes on the order of decades and post-glacial recovery on the order of centuries. At a landscape scale and under the assumption of a stable climate, changes due to periglacial and fluvial disturbance and associated succession would approximately equal one another, leading to changes seen across the landscape over the time period of the historical photos, but with no net gain or loss in any landcover type. In regards to post-glacial recovery, the current rate of change is too fast to represent a linear post-glacial recovery of approximately 21,000 years since the Last Glacier Maximum (LGM). Consistent with other studies (Nolan et al.,2004 and 2005, Jorgenson et. al., 2006, Yoshikawa and Hinzman, 2003) observations of decreased glacier cover and changes in lake and pond cover provide direct physical evidence of rapid landscape response to recent climate warming. A visible increase in tundra, shrub, and tree cover corroborates other research (Tape et al., 2006, Lloyd et. al., 2002 and 2003, Sturm, et. al., 2001) on the biological response to the known recent and rapid warming. Decreased river channel cover represents both physical and biological response to known climate change.

5.1 Glaciers One photo-pair containing an alpine glacier at the head of the Sheenjek River displays obvious glacial recession within a 50-year time lapse. This observation of glacial recession is consistent with the findings of studies of glaciers in the Brooks Range 33

(Nolan et al., 2005), throughout Alaska (Arendt et al., 2002), and the circumpolar arctic (Jania et al., 1996). Although it is generally accepted that there has been a decrease in glacier mass since the Last Glacial Maximum (LGM), and more recently the Little Ice Age (LIA), recent mass balance measurements indicate recession of glaciers is rapidly accelerating (Brown et al., 2001). Variation among rates of observed warming is consistent with variation among rates of mass wastage and glacial recession across the various regions (Hinzman, et. al., 2005; Dyurgerov et al., 2000). Based on the findings of other research on the relationship of climate, mass balance and glacier recession, it can be presumed that the visible recession of the Sheenjek Glacier is driven by known changes in the arctic climate.

5.2 Aufeis In all five scenes that contain aufeis an extensive decrease in aufeis cover is clearly visible. Aufeis is ice that accumulates during winter along stream and river valleys by the upwelling of river water through cracked river ice, blockage behind ice dams, and by groundwater discharge through unconstrained fluvial sediments (Wanty, 2002). Aufeis in Alaska’’s more southerly ranges melts every summer; however, in the more northerly Brooks Range some aufeis does not entirely melt and may be perennial (Harden et al., 1977; Krear, 1990; Gilbert 2006; Yoshikawa, et al., 2007). Utilizing historical photographs and archives Yoshikawa (et al., 2007) found for at least the past 50 to 100 years, the aerial extent of aufeis has not significantly changed. While Yoshikawa (et al., 2007) found no evidence of an overall decrease in aufeis in the last 50 years he does not dismiss the possibility. The size of the aufeis formations 34

may be different today than in the past because the cumulative volumes of discharge and climatic conditions have changed (Yoshikawa, et al., 2007). Nolan (2007) believes the extent of this aufeis varies considerably with time and the changes attributed to climate. While some aufeis accumulations may be perennial, mass wastage occurs annually. To accurately assess long-term trends in aufeis cover replicated photos need to be taken on the exact anniversary of the historic photo. Neither Yoshikawa’’s photo-pairs nor the photo-pairs in this study are that temporally precise. The dramatic decreases in aufeis cover observed in this study may be the result of short-term weather patterns, intermittent changes in the water table, or differences in the date of replication.

5.3 Ponds, Lakes, and Permafrost Changes in lake and pond cover, including both increased and decreased cover, are visible in nine (69.2%) scenes. It is possible that thawing permafrost may be responsible for both the visible increases and decreases in lake and pond cover. Studies of permafrost temperatures in boreholes on the North Slope of the Brooks Range revealed a 2––40 C increase over the last 50––100 years (Lachenbruch, et. al., 1986) and a 30 C increase since the late 1980s (Clow et. al., 2002). While permafrost temperatures have not been measured on the south slope of the Brooks Range it is assumed comparable warming is occurring. Jorgenson (et. al., 2006) speculates that previously stable permafrost is susceptible to ice wedges, or cracks in the permafrost, when subjected to greater temperature fluctuations. The development of ice wedges allows the drainage or flooding of lakes and ponds in accordance with the local water table (Jorgenson et. al., 2006; 35

Yoshikawa and Hinzman, 2003). All the scenes recorded as increased lake cover were located in a poorly drained section of the Sheenjek Valley characterized by wet, deep permafrost. Jorgenson (et. al., 2006) believes areas with poor drainage, resulting in deep permafrost and a thick active layer, are susceptible to the impact of ice wedges. In sites underlain by ice-rich permafrost, trees die when their roots are regularly flooded, causing wet sedge meadows, bogs and thermokarst ponds and lakes to replace forests. Scenes that display decreased pond cover are located on better drained hillsides, which appear to have drier and thinner permafrost and may be more susceptible to drainage. Thawing permafrost in areas with lower water tables and thinner permafrost can result in the drainage of tundra ponds (Yoshikawa and Hinzman, 2003). If both increases and decreases in lake and pond cover are considered, in the context of their respective topography and permafrost, nine (69.2%) scenes display changes linked to thawing permafrost and a warmer climate.

5.4 River Channels Of the twenty-five scenes displaying river channels, twelve (48%) appear stable, four (16%) display increased cover, and nine (36%) display decreased cover. Two (50%) of the scenes displaying increased river channel cover are associated with decreased aufeis cover. The scenes displaying decreased river channel cover are most often accompanied by increased shrub and/or tundra cover. The observed changes in river channel and associated gravel bars are likely the result of shrub expansion, changes in precipitation, seasonal run-off, and/or fluvial disturbance and associated succession. Increases and decreases in river channel cover 36

driven by fluvial disturbance and associated succession, at the landscape scale, would be approximately equal, with no net gain or loss in cover. Shrub expansion (Sturm et al., 2000; Tape et al., 2006), changes in precipitation, and seasonal run-off (Hinzman, et. al., 2005), are associated with a warmer and dryer climate. The greater number of scenes displaying decreased river channel cover than increased river channel cover suggests a response to the rapid changes in the arctic climate.

5.5 Tundra Of the sixty-four scenes displaying tundra thirty-seven (57.8%) display no change in tundra cover, seven (10.9 %) display decreased tundra cover, and twenty (31.2%) display increased tundra cover. Tundra cover is susceptible to succession, fluvial processes, and disturbance such as landslides. It would be expected at the landscape scale, if natural succession and disturbance where the only drivers of changes in tundra cover that the number of observations of decreased versus increased tundra cover would be approximately equal. However, increased tundra cover accounts for 81.5% of observed changes in tundra cover. It has been hypothesized that climate warming will result in increased vegetation (including tundra) cover in the Arctic (Bret-Harte, et. al., 2002, Hollister et. al., 2005; Kaplan et. al., 2003). It is probable that climate is responsible for greater number of of scenes displaying increased tundra cover than decreased tundra cover. Increased tundra cover is more common (41.7%) in photo-pair scenes with a 100year to present time lapse and less common (25%) in photo-pair scenes with a 50-year to

37

present time lapse. This suggests that increases in tundra cover started before the rapid warming of the last thirty years.

5.6 Shrubs Of the sixty-three scenes displaying shrubs thirty-seven (58.7%) display no change in shrub cover, six (9.5 %) display decreased shrub cover, and twenty (31.7%) display increased tundra cover. Undoubtedly shrub cover is influenced by fluvial processes, succession and disturbance. It would be expected, at the landscape scale, if natural succession and disturbance where the only drivers of changes in shrub cover that the number of observations of decreased versus increased shrub cover would be approximately equal. However, increased shrub cover accounts for 76.2% of the visible changes in shrub cover. Sturm et al., (2000) hypothesized a positive feedback loop in which the warming Arctic and higher atmospheric CO2 concentrations are driving increases in the size and abundance of dwarf birch, willow, and green alder. Increasing shrub coverage then traps more winter snow insulating the ground surface and increasing the availability of nitrogen and the depth of the permafrost active layer, in turn driving shrub growth. An increase in shrub biomass further alters both the albedo and hydrologic cycles of the tundra landscape (Sturm et al., 2000). According to Tape et al., (2006) disturbance and plant succession operate on a much smaller scale than the observed pan-Arctic expansion leading them to conclude that increased shrub cover is a response to arctic warming. Increased shrub cover is more common in photo-pair scenes with a 100-year time lapse (36%) and less common (28.9%) in photo-pair scenes with a 50-year time lapse. 38

This observation supports Tape’’s et al., (2006) conclusion that the general expansion of shrubs in Alaska seems to predate the warming of the last 30 years.

5.7 Trees In the twenty-eight scenes displaying tree cover no changes in the location of treeline is visible. In eleven (39.3%) of the scenes increases in tree stand density is visible. In three (10.7%) scenes a decrease in tree cover, in the form of dead trees associated with lake expansion, is visible. In fourteen (50%) of the scenes, no changes in tree cover are visible. While tree cover is subject to fluvial processes, succession, and disturbance, it would be expected, at the landscape scale, the number of observations of decreased versus increased tree cover would be approximately equal. However, increased tree cover accounts for 78.6% of the visible changes in tree cover. It is not surprising that no changes in the location of treeline were visible. The majority of the photo-pair scenes displaying tree cover at the forest-tundra ecotone were of a 50-year time lapse. The time scale on which the forest-tundra ecotone (treeline) changes involves many decades to centuries (Hinzman et. al., 2005). Fifty years may be inadequate to observe visible changes in treeline or the location of treeline has not visibly responded to the rapid warming of the last thirty years. At high latitudes temperature is the limiting factor in tree growth and the location of treeline (Grace et. al., 2002; Jacoby and D'Arrigo, 1989; Holtmeier & Broll , 2005). Increased tree stand density is understood to be driven by a warmer climate (Hinzman et. al., 2005; Dial et. al., 2006). The average arctic temperature rise of 0.90 Celsius per

39

decade during the last fifty years (Serrez & Barry, 2005) is the suspected driver of the denser tree stands visible in eleven photo-pair scenes. All three scenes that display decreased tree cover were taken near Last Lake in the Sheenjek Valley. This region of the Sheenjek Valley is characterized by wet, deep permafrost and a thick active layer, therefore susceptible to the impact of ice wedges. In sites underlain by ice-rich permafrost, trees die when their roots are regularly flooded, causing wet sedge meadows, bogs and thermokarst ponds and lakes to replace forests (Jorgenson et. al., 2006). Last Lake has visibly expanded, and the expansion is likely the result of a warmer climate, thawing permafrost, and ice wedges. The expansion of Last Lake is the obvious driver of visible decreases in tree cover. Therefore the observations of decreased tree cover, adjacent to Last Lake, may also be a result of the warmer arctic climate.

6. CONCLUSION The results of photo-pair analyses indicate the arctic landscape is responding to the known recent and rapid warming trend. Visible landcover changes attributed to known arctic warming include a reduction in glacier and river channels; increased tundra and shrub cover; and both increases and decreases in tree, lake, and pond cover. While undoubtedly some of the visible landcover change is the result of succession, disturbance, fluvial processes, and post-glacial recovery, the character and speed of the change indicates a landscape-wide response consistent with observed changes in the arctic climate. These findings are consistent with the 2005 Arctic Climate Impact Assessment and other research (Hinzman et. al., 2005). 40

Understanding the extent and nature of landcover change is critical because, if widespread, the change has probably already begun to alter the heat and carbon budgets of the Arctic by amounts comparable with those associated with changes in sea ice (Tape et al., 2006). Changes in landcover influence the albedo of the arctic landscape. Decreased glacier, aufeis, and snow cover results in less shortwave radiation reflected from the surface and more energy absorbed leading to increased surface temperatures (Serrez and Barry, 2005). While increased tundra, shrub, and tree cover will absorb some atmospheric CO2, these reductions in greenhouse gasses, will be offset by increased absorption of shortwave radiation by the resulting change of the Arctic’’s terrestrial albedo (Tape et al., 2006). Additionally, thawing permafrost has the potential to release large amounts of both CO2 and methane into the atmosphere (Callaghan et al., 2004). Changes to the arctic landscape involve complex positive feedbacks with the potential to accelerate arctic and planetary climate and landcover change. Understanding arctic landcover response to climate warming is critical for better prediction and mediation of arctic and global climate change.

41

7. REFERENCES ACIA (2005) Arctic Impact Assessment: Scientific Report, Cambridge University Press. Allen, C. D., Betancourt, J.L., & Swetnam, T.W. (1995) LUHNA Pilot Project Southwestern United States, USGS. Arendt, A.A., Echelmeyer, K.A., Harrison, W.D., Lingle, C.S, & Valentine, V.B. (2002) Rapid Wastage of Alaska Glaciers and Their Contribution to Rising Sea Level, Science, Vol. 297, pp 382-386. Arft, A. M., Walker, M.D., Gurevitch, J., Alatalo, J.M., Bret-Harte, M.S., Dale, M., Diemer, M., Gugerli, F., Henry, G.H.R., Jones M.H., Hollister, R.D., Jonsdottir, I.S., Laine, K., Levesque, E., Marion, G.M., Molau, U., Molgaard, P., Nordenhall, V., Raszhivin, Robinson, C.H., Starr, G., Stenstrom, A., Stenstrom, M., Totland, O., Turner, P.L., Walker, L.J., Webber, P.J., Welker, J.M., & Wookey, P.A. (1999) Responses of Tundra Plants to Experimental Warming: Meta-Analysis of the International Tundra Experiment, Ecological Monographs, Vol. 69, No. 4 (Nov., 1999), pp 491-511. Basagic H., & Fountain, A. (2004) Documenting Twentieth Century Glacier Change with Repeat Photography in the Sierra Nevada, California, Poster. Bigelow, N.H., Brubaker, L.B., Edwards, M.E., Harrison, S.P., Prentice, I.C., Anderson, P.M., Andreev, A.A., Bartlein, P J., Christensen, T.R., Cramer, W., Kaplan, J.O., Lozhkin, A.V., Matveyeva, N.V., Murray, D.F., McGuire, A.D., Razzhivin, V.Y., Ritchie, J.C., Smith, B., Walker, D.A., Gajewski, K., Wolf, V., Holmqvist, B.H., Igarashi, Y., Kremenetskii, K., Paus, A., Pisaric, M.F.J., & Volkova, V.S. (2003) Climate change and Arctic Ecosystems: 1. Vegetation changes north of 55°N between the last glacial maximum, mid-Holocene, and present, Journal of Geophysical Research-Atmospheres, Vol. 108. Bolton, W.R., Hinzman, L.D., & Yoshikawa, K. (2000) Stream flow studies in a watershed underlain by discontinuous permafrost, American Water Resource Association Proceedings on Water Resources in Extreme Environments, Anchorage AK. Braun, Carsten, Hardy, D. R. & Bradley, R. S. (2004) Mass balance and area changes of four High Arctic plateau ice caps, 1959––2002, Geografiska Annaler, Vol. 86, pp 4352. Bret-Harte, S.M., Shaver, G.R., & Chapin, F.S. (2002) Primary and secondary stem growth in arctic shrubs: implications for community response to environmental change, Journal of Ecology, 90 (2), 251––267. 42

Brown, R D. & Alt, B.T., (2001) The state of the Arctic cryosphere during the extreme warm summer of 1998: documenting cryosphere variability in the Canadian Arctic, CCAF Summer 1998 Project Team, CCAF Final. Callaghan, Terry, V., Bjorn, L.O., Chernov, Y., Chapin, T., Christensen, T.R., Huntley, B., Ims, R.A., Johansson, M., Jolly, D., Jonasson,S., Matyeyeva, N., Panikov, N., Oechel, W., Shaver, G., Schaphoff, S., & Sitch, S. (2004) Effects of Changes in Climate on Landscape and Regional Processes, and Feedbacks to the Climate System, Ambio, Vol. 33, pp 459––468. Chapin, F.S., Shaver, G.R., Giblin, A.E., Nadelhoffer, K.J., & Laundre, J.E. (1995) Responses of Arctic Tundra to Experimental and Observed Changes in Climate, Ecology, Vol. 76, pp 694-711. Cooper, D. J. (1986) White spruce above and beyond treeline in the Arrigetch Peaks region, Brooks Range, Alaska. Arctic, Vol. 39, pp 247-252. Clow, G. D. & Urban, F. E. (2002) Large Permafrost Warming in Northern Alaska During the 1990’’s Determined from GTN-P Borehole Temperature Measurements, Fall Meeting, Eos Trans. American Geophysical Union, 83(47), Fall Meet. Suppl., Abstract B11E-04, December 6––10, 2002, San Francisco. Dial, R., Berg, E., Timm, K., McMahon, A., & Geck, J. (2008) Changes in the Alpine Forest-Tundra Ecotone Commensurate with Recent Warming in Southcentral Alaska: Evidence from Orthophotos and Field Plots. Biogeosciences, submitted for publication. Dowdeswell, J. A., Hagen, J.-O., Bj¨ornsson, H., Glazovsky, A. F., Harrison, W. D., Holmlund, P., Jania, J., Koerner, R. M., Lefauconnier, B., Ommanney, C. S. L., & Thomas, R. H. (1997) The mass balance of circum-arctic glaciers and recent climate change, Quarterly Research, Vol. 48, pp1––14. . Dyurgerov, M. B. & Meier, M. F. (2000) Twentieth century climate change: Evidence from small glaciers, Proceedings of the National Acadamy of Sciences, Vol. 97, pp 1406––1411. Elliott, Grant, & Baker, W.L. (2004) Quaking Aspen (Populus tremuloides) and Conifers at Treeline: A Century of Change in the San Juan Mountains, Colorado, U.S.A., Journal of Biogeography, Vol. 31, pp 733. Ellis, J.M., & Calkin, P.E. (1984) Chronology of Holocene glaciation, central Brooks Range, Alaska, Geological Society of America Bulletin, Vol. 95, pp 897-912. Harden, D., Barnes, P., and Reimnitz, E. (1977) Distribution and character of naleds in northeastern Alaska, Arctic, Vol. 30, no. 1, pp 28-40. 43

Gilbert, T. (2006) Personal interview at Arctic Village. Grace, J., Berniger, F., & Nagy, L. (2002) Impacts of Climate Change on the Tree Line, Annals of Botany, Vol. 90, pp 537-544. Heginbottom, J.A. (2000) Permafrost distribution and ground ice in surficial materials; in, The physical environment of the Mackenzie Valley, Northwest Territories: a base line for the assessment of environmental change; Dyke, L D; Brooks, G R. Geological Survey of Canada, Bulletin, Vol. 547, pp 31-39. Hinzman, L.D., Kane, D.L., Gieck, R.E., & Everett, K.R. (1991) Hydrologic and thermal properties of the active layer in the Alaskan arctic, Cold Regions Science and Technology, Vol. 19, pp 95-110. Hinzman, L.D., Bettez, N.D., Bolton, W.R., Chapin, F.S., Dyurgerov, M.B., Fastie, C.L., Griffith, B., Hollister, R.D., Hope, A., Huntington, H.P., Jensen, A.M., Gensuo, J.J., Jorgenson, T., Kane, D.L., Klein, D.R., Kofinas, G., Lynch, A.H., Lloyd, A.H., McGuire, A.D., Nelson, F.E., Oechel, W,C., Osterkamp, T.E., Racine, C.H., Romanovsky, V.E., Stone, R.S., Stow, D.A., Sturm, M., Tweedie, C.E., Vourlitis, G.S., Walker, M.D., Walker, D.A., Webber, P.J., Welker, J.M., Winker, K.S., & Yoshikawa, K. (2005) Evidence and Implications of Recent Climate Change in Northern Alaska and Other Arctic Regions, Climatic Change, Vol. 72, pp 251––298. Hollister, R.D., Webber, P.D., & Tweedie, C.E. (2005) The response of Alaskan arctic tundra to experimental warming: differences between short- and long-term responses, Global Change Biology, Vol. 11, pp 525. Holtmeier, F.K. & Broll G. (2005), Sensitivity and response of northern hemisphere altitudinal and polar treelines to environmental change at landscape and local scales. Global Ecology Biogeography, Vol. 14, pp 395-410. Houghton, J.T., Ding, Y., Griggs, D,J., Noguer, M., Linden, P.J. van der Dai, X., Maskell, K., & Johnson, C.A. (2001) Climate Change 2001: The Scientific Basis: Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change, University of Cambridge Press. Jania, J. & Hagen J.O. (1996) Mass Balance of Arctic Glaciers IASC Report No. 5, International Arctic Science Committee. Jacoby, G., & D'Arrigo, R. (1989) Reconstructed Northern Hemisphere annual temperature since 1671 based on high-latitude tree-ring data from North America. Climate Change., Vol. 14, Issue 1, pp 39-59.

44

Jorgenson, M. T., Racine, C. H., Walters, J. C., & Osterkamp, T. E. (2001) Permafrost degradation and ecological changes associated with a warming climate in central Alaska, Climate Change, Vol. 48, pp 551––579. Jorgenson, M.T. (2005) Photographic Monitoring of Landscape Change, Southwest Alaska Network Science Symposium 2005, presentation. Jorgenson, M. T., Shur, Y.T., & Pullman, E.R. (2006) Abrupt increase in permafrost degradation in Arctic Alaska, Geophysical Research Letters, Vol. 33, Issue 2. Kane, D. L., Hinzman, L. D., and Zarling, J. P. (1991) Thermal response of the active layer to climatic warming in a permafrost environment, Cold Regions Science and Technology, Vol. 19, pp 111––122. Kane, D.L, Hinzman, L.D., McNamara, J.P., Zhang, Z., & Benson, C.S. (2000) An Overview of a Nested Watershed Study in Arctic Alaska, Nordic Hydrology, Vol. 31, pp 245-266. Kaplan, J.O., Bigelow, N.H., Prentice, I.C., Harrison, S.P., Bartlein, P.J., Christensen, T.R., Cramer, W., Mateveyeva, N.V., McGuire, A.D., Murray, D.F., Razzhivin, V.Y., Smith, B., Walker, D.A., Anderson, P.M., Brubaker, L.B., Edwards, M.E. & Lozhkin, A.V. (2003) Climate change and Arctic ecosystems: 2, Modeling, paleodata- model comparisons, and future projections, Journal of Geophysical Research, Vol. 108, No. D19, 8171. Kattsov, V. & Källén, E. (2004) ACIA Chapter 4: Future Changes of Climate: Modeling and Scenarios for the Arctic Region. Arctic Climate Impact Assessment. Key, C.H., Fagre D.B, & Menicke, R.K. (1998) Glacier retreat in Glacier National Park, Montana. eds. U.S. Geological Survey Professional Paper 13686-J. Krear, R. (1990) Chapter III The Olaus Murie Brooks Range Expedition, Future Publication, Cited with permission. Lachenbrunch, A.H. & Marshall, B.V. (1986) Changing Climate: geothermal evidence from permafrost in the Alaskan Arctic, Science, pp 689-696. Leffingwell, E. (1919) The Canning River Region Northern Alaska, Government Printing Office. Lloyd, A. & Fastie, C. (2002) Spatial and temporal variability in the growth and climate response of treeline trees in Alaska, Climate Change, Vol. 52, pp 481––509. Lloyd, A. & Fastie, C. (2003) Recent changes in treeline forest distribution and structure in interior Alaska, Ecoscience, Vol. 10, pp 176––185. 45

MacDonald, G.M., Szeicz, J.M., Claricoates, J., Claricoates, D., & Kursti, A. (1998) Response of the Central Canadian Treeline to Recent Climatic Changes, Annals of the Association of American Geographers, Vol. 88, pp 183-208. Mann, D. H., Peteet, D. M., Reanier, R. E., & Kunz, M. L. (2002) Responses of an arctic landscape to late glacial and early Holocene climatic changes: The importance of moisture, Quarterly Science Review, Vol. 21, pp 997––1021. Mayo, L.R., (1984) Glacier Mass Balance and Runoff Research in the U. S. A. Geografiska Annaler, Series A, Physical Geography, Vol. 66, pp 215-227. McNamara, J.P., Kane, D.L, & Hinzman, L.D. (1998) An analysis of streamflow hydrology in the Kuparuk River Basin, Arctic Alaska: a nested watershed approach, Journal of Hydrology, Vol. 206, pp 39-57. Murie, O.J. (1956) Sheenjek Field Notes, The Murie Center Archives, Moose, Wyoming. Nolan, M.D. & Takahashi, S. (2004) Uses of Several Photographic Methods to Detect Changes of Glaciers in Arctic Alaska, American Geophysical Union, Fall Meeting Abstracts. Nolan, M.D., Arendt, A., Rabus, B., & Hinzman, L. (2005) Volume change of McCall Glacier, Arctic Alaska, from 1956 to 2003, Annals of Glaciology, Vol. 42. Nolan, M. (2007) Personal correspondence. Oerlemans, J. & Reichert, B.K. (2000) Relating glacier mass balance to meteorological data by using a seasonal sensitivity characteristic, Journal of Glaciology, Vol. 46, pp 1-6. Oerlemans, J. (2001) Glaciers and climate change, A.A. Balkena Publishers, Rotterdam. Overpeck, J., Hughen, K., Hardy, D., Bradley, R., Case, R., Douglas, M., Finney, B., Gajewski, K., Jacoby, G., Jennings, A., Lamoureux, S., Lasca, A., MacDonald, G., Moore, J., Retelle, M., Smith, S., Wolfe, A., & Zielinski, G. (1997) Arctic Environmental Change of the Last Four Centuries, Science, Vol. 278, pp 12511256. Osterkamp, T.E., & Romanovsky, V.E. (1999) Changing climate: Geothermal evidence from permafrost in the Alaskan Arctic, Science, Vol. 234, pp 689-696. Osterkamp, T.E., Viereck, L., Shur, Y., Jorgenson, M. T., Racine, C. H., Doyle, A. P., & Boone, R.D. (2000) Observations of thermokarst in boreal forests in Alaska, Arctic, Antarctic, Alpine Research, 32(3), pp 303––315. 46

Pielou, I.E. (1994) A Naturalist’s Guide to the Arctic, The University of Chicago Press, Chicago. Rabus, B.T. & Echelmeyer, K.A. (1998) The mass balance of McCall Glacier, Brooks Range, Alaska, U.S.A.; its regional relevance and implications for climate change in the Arctic, Journal of Glaciology, Vol. 44, pp 333-351. Rapp, A. (1996) Photo documentation of landscape change in Northern Swedish mountains, Ecological Bulletin, Vol. 45, pp170––179. Riordan, R., Verbyla, D., & McGuire, A.D. (2006) Shrinking Ponds in subarctic Alaska based on 1950-2002 remotely sensed images, Journal of Geophysical Research, Vol 26, G04002, doi:10.1029/2005JG000150,2006. Rogers, G.F. (1982). Then and now: a photographic history of vegetation change in the central Great Basin Desert, University of Utah Press, Salt Lake City. Rogers, G.F. (1984) Bibliography of repeat photography for evaluating landscape change, University of Utah Press. Schaller, G.B. (1957) Arctic Valley: A Report on The 1956 Murie Brooks Range, Alaska Expedition, Unpublished. Schrader, F.C. (1900) Preliminary Report on a Reconnaissance along the Chandlar and Koyukuk Rivers, Alaska, in 1899, USGS 21st Annual Report, Part II, 1899-1900 Washington Government Printing Office. Serrez, M.C., & Barry, G. (2005) The Arctic Climate System, Cambridge University Press. Silapaswan, C.S., Verbyla, D.L., & McGuire, A.D. (2001) Land Cover Change on the Seward Peninsula: The Use of Remote Sensing to Evaluate the Potential Influences of Climate Warming on Historical Vegetation Dynamics, Canadian Journal of Remote Sensing, Vol. 27, pp 542-554. Simpson, J. J., Hufford, G. L., Fleming, M. D., Berg, J. S., and Ashton, J. B. (2002) Long-term climate patterns in Alaska surface temperature and precipitation and their biological consequences, IEEE Transactions On Geosciences and Remote Sensing, pp 1164––1184. Williams, P.J. & Smith, M.W. (1989) Frozen Earth: Fundamentals of Geocryology, Cambridge University Press, New York. Stonehouse, B. (1989) Polar Ecology, Blackie/Chapman and Hall.

47

Stow, D.A., Hope, A., McGuire, D., Verbyla, D., Gamon, J., Huemmrich, F., Houston, S., Racine, C., Sturm, M., & Tape, K. (2004) Remote sensing of vegetation and land-cover change in Arctic Tundra Ecosystems, Remote Sensing of Environment, Vol. 89, pp 281-308. Sturm, M., McFadden, J.P., Liston, F.S., Chapin F.S., Racine C.H., & Holmgrin, J. (2000) Snow-Shrub Interactions in Arctic Tundra: A Hypothesis with Climatic Implications, Journal of Climate, Vol. 14, pp 336-344. Sturm, M., Racine, C., & Tape, K. (2001) Climate change: Increasing shrub abundance in the Arctic, Nature, Volume 411, Issue 6837, pp 546-547. Sturm, M., Schimel, J., Michaelson, G., Welker, J.M., Oberbauer, S.F., Liston, G.E., Fahnestock, J., & Romanovsky, V.E. (2005) Winter Biological Processes Could Help Convert Arctic Tundra to Shrubland, BioScience, Vol. 55, pp 17––26. Sturm, M., & Racine, C. (2005) A Half-Century of change in arctic Alaskan shrubs: a photographic-based assessment, National Snow and Ice Data Center, DVD. Suarez, F., Binkley, D., Kaye, M.W., & Stottlemyer, R. (1999) Expansion of forest stands into tundra in the Noatak National Preserve, northwest Alaska, Ecoscience, Vol. 6, pp 465-470. Tape, K., Sturm, M., & Racine, C. (2006) The evidence for shrub expansion in Northern Alaska and the Pan-Arctic, Global Change Biology. Wahren, C. H. A., Walker, M. D. & Bret-Harte, M. S. (2005) Vegetation responses in Alaskan arctic tundra after 8 years of a summer warming and winter snow manipulation experiment, Global Change Biology, Vol. 11, pp 537-552. Wanty, R.B., Wang, B., Vohden, J., Day, W.C., & Gough, L.P. (2002) Aufeis Accumulations in Stream Bottoms in Arctic and Subarctic Environments as an Indicator of Geologic Structure, Paper Presentation, The Geological Society of America , 2002 Denver Annual Meeting Denver, CO. Wilderness Act (1964) Public Law 88-577, 88th Congress, S. 4, September 3, 1964. Yoshikawa, K. & Hinzman, L.D. (2003) Shrinking thermokarst ponds and groundwater dynamics in discontinuous permafrost near council, Alaska, Permafrost and Periglacial Processes, Vol. 14, pp 151-160. Yoshikawa K., L. D. Hinzman, & Kane, D.L. (2007), Spring and aufeis (icing) hydrology in Brooks Range, Alaska, Journal of Geophysical Research., Vol. 112, Zier, J.A. (2005) A Century of Vegetation Change in the San Juan Mountains, Colorado: An Analysis Using Repeat Photography, Department of Geography, University of Wyoming. 48

8. PHOTO PAIRS

B

B

A

A

Fig. 18. sfc00394. Mount Snowden with the Dietrich Fork River, The Alaska Pipeline, and The Dalton Highway in the foreground. Increased shrub cover and decreased river channel cover (A) are visible. Decreased vegetation cover (B) was a result of road construction and was not recorded. Top photo S.F. Schrader, 1899 and bottom photo F. McCarthy, 2006.

49

A

B B

C

A

B B

C

Fig.19. sfc00391. Table Mountain with the Dietrich Fork River, the Alaska Pipeline, and the Dalton Highway in the foreground. Tundra has expanded into barren ground (A). Increased shrubs and decreased river channels are visible (B). The decreased vegetation cover is the result of a barrow pit used during road construction and was not recorded in the data set (C). Top photo S.F. Schrader, 1899 and bottom photo F. McCarthy, 2006. 50

A

A

Fig. 20. sfc00388. Eakayruk Mountain. Tundra has filled former patches of barren ground (A). Top photo S.F. Schrader, 1899 and bottom photo F. McCarthy, 2006. 51

A

A

Fig. 21. sfc00386. Fault Mountain. Tundra has filled former patches of barren ground (A). Top photo S.F. Schrader, 1899 and bottom photo F. McCarthy, 2006. 52

A

A

Fig. 22. lek00057. Canning River. Increased tundra, shrubs, and river channels coincide with decreased aufeis (A). Top photo E.K. Leffingwell, 1910 and bottom photo F. McCarthy, 2006. 53

B A

A

B A

A

Fig. 23. lek00055. Canning River and Franklin Mountains. Decreased shrub and tundra cover coincides with increases in river channels (A). On the alluvial fan increased tundra and shrub cover coincides with decreased river channels (B). Top photo E.K. Leffingwell, 1910 and bottom photo F. McCarthy, 2006. 54

A

A

Fig. 24. lek00041. Forks of the Canning River. Increased tundra, shrubs, and river channels coincides with a massive decreases in aufeis (A). Top photo E.K. Leffingwell, 1910 and bottom photo F. McCarthy, 2006. 55

A

A

B

B

Fig. 25. lek00053. Franklin Mountains. Shrubs and tundra are now established on a previously barren river bank (A). A tundra pond is significantly smaller (B). Top photo E.K. Leffingwell, 1910 and bottom photo F. McCarthy, 2006. 56

A

A

Fig. 26. lek00050. Ikiakpuk and Ikiakpaurak Valleys. Increased tundra and shrub cover coincides with decreases in river channels along Eagle Creek (A). Top photo E.K. Leffingwell, 1910 and bottom photo F. McCarthy, 2006. 57

Fig. 27. lek00001. Franklin Mountains. No visible change in any landcover type. Top photo E.K. Leffingwell, 1910 and bottom photo F. McCarthy, 2006.

58

Fig. 28. lek0001a. Franklin Mountains. No visible change in any landcover type. Top photo E.K. Leffingwell, 1910 and bottom photo F. McCarthy, 2006.

59

B A

A

B A A

Fig. 29. lek00052. Canning River. Increased tundra and shrub cover coincides with a decrease in river channels (A). A former pond is nearly gone (B). Top photo E.K. Leffingwell, 1910 and bottom photo F. McCarthy, 2006. 60

B

A

B

A

Fig. 30. lek00054. Confluence of Eagle Creek and Canning River. Increased tundra and shrub cover coincides with decreased river channels (A). Large decreases in aufeis fields are visible (B). Top photo E.K. Leffingwell, 1910 and bottom photo F. McCarthy, 2006. 61

C D

B

A

C D

B

A

Fig. 31. Murie01. Sheenjek Valley. Hillside shrubs have filled in (A) and hillside tree stand is denser (B). In the valley large decreases in aufeis coincides with the expansion of tundra and shrub cover (C). Valley tree cover has expanded (D). Top photo Murie Expedition, 1956 and bottom photo F. McCarthy, 2006. 62

B

A

B

A Fig. 32. Murie02. Camp Mountain. Shrubs stature has increased (A). Shrubs and tundra have decreased in cover (B). Top photo Murie Expedition, 1956 and bottom photo F. McCarthy, 2006. 63

A

A

A

A Fig. 33. Murie03. Last Lake. Increased lake cover coincides with decreased shrub and tundra cover (A). Top photo Murie Expedition 1956, and bottom photo F. McCarthy, 2006. 64

A B

A B

Fig. 34. Murie04. Bob Krear and Olaus Murie. In 2006 shrubs and tundra had expanded onto formally bare ground (A). Tree stand are denser (B). Top photo Murie Expedition, 1956 and bottom photo F. McCarthy, 2006. 65

A

A Fig. 35. Murie05. Olaus and Mardy Murie at Last Lake. Decreased tundra, shrub, and tree cover coincides with expansion of Last Lake (A). The exact location of the original photograph was impossible to reoccupy do to lake expansion. Top photo G. Schaller, 1956 and bottom photo F. McCarthy, 2006. 66

B A

B A

Fig. 36. Murie06. George Schaller and Bob Krear at Last Lake. Decreased tundra and shrub cover coincides with thermokarst and associated expansion of Last Lake (A). Tree stand are denser (B). Top photo B. Kessell, 1956 and bottom photo F. McCarthy, 2006. 67

A

B C

A

B

C

Fig. 37. Murie07. L.L. Bean Boots at Last Lake. Although tree stand appear denser (A), thermokarst lake expansion has resulted in overall decreased tree cover (B). Several of the taller trees are tilting, presumably due to thawing permafrost (A). Lake expansion coincides with decreased tundra and shrub cover (C). Top photo B. Krear, 1956 and bottom photo F. McCarthy, 2006. 68

A

A

Fig. 38. Murie08. Last Lake Camp. Trees stands are denser (A). Top photo B. Kessell, 1956 and bottom photo F. McCarthy, 2006. 69

C A B

C A

B Fig. 39. Murie 09. Last Lake. Trees stands (A) and shrubs (B) are denser and more common. Shore line has receded (C). Top photo Murie Expedition, 1956 and bottom photo F. McCarthy, 2006. 70

B

C

A

B

C A

Fig. 40. Murie10. Sheenjek Valley. Tundra expansion in the foreground (A) was not recorded due to uncertainty of the original photographer’’s exact position. Increased tundra and shrub cover coincides with decreased aufeis (B). Spruce trees are more numerous (C). Top photo Murie Expedition, 1956 and bottom photo F. McCarthy, 2006. 71

A

A

Fig. 41. Murie11. Murie Camp at Last Lake. Trees stands are denser (A). Top photo G. Schaller, 1956 and bottom photo F. McCarthy, 2006. 72

B

C

A A A

B

C

A A

A

Fig. 42. Murie12. Double Mountain. Tundra has advanced over a large region of bare ground (A). Increased tundra and shrub cover corresponds with a decrease in river channels (B).Tree stand are denser (C). Top photo Murie Expedition, 1956 and bottom photo F. McCarthy, 2006. 73

A

A

Fig. 43. Murie13. Camp Mountain. Tree stand are denser (A). Top photo Murie Expedition, 1956 and bottom photo F. McCarthy, 2006. 74

A B

B

A B

B

Fig. 44. Murie14. Alluvial fan in the Upper Sheenjek Valley. A decrease in tundra cover coincides with an increase in river channels (A). Shrub cover has increased along the river bank (B). Top photo Murie Expedition, 1956 and bottom photo F. McCarthy, 2006. 75

A

A

Fig. 45. Murie15. Upper Sheenjek. Increased tundra and shrub cover coincides with decreases in river channels and gravel bars (A). Top photo Murie Expedition, 1956 and bottom photo F. McCarthy, 2006. 76

A

A

Fig. 46. Murie 16. Alluvial fan in the Upper Sheenjek Valley. Increased tundra and shrub cover coincides with a decrease in river channels (A). Top photo Murie Expedition, 1956 and bottom photo F. McCarthy, 2006. 77

A A

A

A

Fig. 47. Murie17. Tundra Pond. A former pond has been replaced by tundra and shrubs (A). Top photo Murie Expedition, 1956 and bottom photo F. McCarthy, 2006. 78

Fig. 48. Murie18. Upper Sheenjek. No change in landcover is visible. Top photo Murie Expedition, 1956 and bottom photo F. McCarthy, 2006.

79

A B B

A B B Fig. 49. Murie19. The Sheenjek Glacier. The glacier has receded (A). Tundra has expanded into barren ground (B). Top photo G. Schaller, 1956 and bottom photo F. McCarthy, 2006. 80

9. MAPS

Fault Mountain

Figure 50. Schrader Photo Locations. All four F.C. Schrader 1899 photographs were taken from the summit of Fault Mountain near the Dietrich Fork River and the Dalton Highway. Ƈ Marks the photos location.

81

Figure 51. Leffingwell Photo Locations. All of Earnest Leffingwells 1910 photographs were taken in the Canning River Valley on the north slope of the Brooks Range. Ƈ Marks photo locations.

82

Figure 52. Murie Photo Locations. All nineteen of the photographs taken during the 1956 Murie expedition were taken in the Sheenjek River Valley on the south slope of the Brooks Range. Ƈ Marks photo locations.

83

10. APPENDICES 10.1. List of figures Figure 1. Study Area ………………………………………………………………………………………………………………………….………….

6

Figure 2. McCall Glacier …………………………………………………………………………………………………………………………...

9

Figure 3. Aufeis on the Hulahula River ………….………………………………………………………………..……..……..

11

Figure 4. Tundra Ponds ………………………………………………………………………………………………………………………………

13

Figure 5. Decreased River Channels ………………………………………………………………………………………………....

14

Figure 6. Toolik Lake LTER tundra study plot …………………………………………………………………………... 16 Figure 7. Increasing abundance of shrubs in arctic Alaska …………………………………………...……..

18

Figure 8. The Kugururok River …………………………………………………………………………………………...………………

20

Figure 9. Murie 1 Sheenjek Valley……………………………………………………………………………….………………....

24

Figure 10. Murie 1 Mountain scene cropped………………………………………………………………………………...

25

Figure 11. Murie 1 Valley scene cropped ………………………………………………………………………………..…….

25

Figure 12. Murie 1 Hillside scene cropped …………………………………………………………………………………….

26

Figure 13. Pond and Lake Cover ……………………………….……………………………………………………………………....

28

Figure 14. River Channel Cover …………..……………………………………………………………………………………...……

29

Figure 15. Tundra Cover ………………………………………………………………………………………………………………………….

30

Figure 16. Shrub Cover ……………………………………..…………………………………………………………………………………….

31

Figure 17. Tree Cover ..…………………………………………………………………………………………………………………………...

42

Figure 18. sfc00394 ……………………………………………………………………………………………………………………………….……

49

Figure 19. sfc000391 …………………………………………………………………………………………………………………………...……

50

Figure 20. sfc000388 …………………………………………………………………………………………………………………………..…….

51

Figure 21. sfc386 …………………………………………………………………………………………………………………………………….....

52 84

Figure 22. lek00057 …………………………………………………………………………………………………………………………………….

53

Figure 23. lek00055 ……………………………………………………………………………………………………………………………….....

54

Figure 24. lek00041 ……………………………………………………………………………………………………………………………….....

55

Figure 25. lek00053 …………………………………………………………………………………………………………………………………….

56

Figure 26. lek00050 ……………………………………………………………………...……………………………………………………..……

57

Figure 27. lek00001 ……………………………………………………………………………………………………………………………….……

58

Figure 28. lek00001a ……………………………………………………………………………………………………………………..………….

59

Figure 29. lek00052 …………………………………………………………………………………………………………………………...……..

60

Figure 30. lek00054 ……………………………………………………………………………………………………………………………….……

61

Figure 31. Murie01 ……………………………………………………………………………………………………………………………………..

62

Figure 32. Murie02 ………………………………………………………………………………………………………………………………..……

63

Figure 33. Murie03 ……………………………………………………………………………………………………………………………………..

64

Figure 34. Murie04 ……………………………………………………………………………………………………………………………….…….

65

Figure 35. Murie05 ………………………………………………………………………………………………………………………………..……

66

Figure 36. Murie06 ……………………………………………………………………………………………………………………………….…….

67

Figure 37. Murie07 ………………………………………………………………………………………………………………………………..……

68

Figure 38. Murie08 ………………………………………………………………………………………………………………………………..……

69

Figure 39. Murie09 ………………………………………………………………………………………………………………………………..……

70

Figure 40. Murie10 ……………………………………………………………………………………………………………………………………..

71

Figure 41. Murie11 ………………………………………………………………………………………………………………………………..……

72

Figure 42. Murie12 ……………………………………………………………………………………………………………………………………..

73

Figure 43. Murie13 ……………………………………………………………………………………………………………………………….…….

74

Figure 44. Murie14 ……………………………………………………………………………………………………………………………………..

75 85

Figure 45. Murie15 ……………………………………………………………………………………………………………………………………..

76

Figure 46. Murie16 ……………………………………………………………………………………………………………………………………..

77

Figure 47. Murie17 ……………………………………………………………………………………………………………………………………..

78

Figure 48. Murie18 ………………………………………………………………………………………………………………………………..……

79

Figure 49. Murie19 ………………………………………………………………………………………………………………………………..……

80

Figure 50. Schrader Photo Locations .…………………………………………………………………………...………………..

81

Figure 51. Leffingwell Photo Locations ………………………………………………………………………………………….

82

Figure 52. Murie Photo Locations ..……………………………………………………………………………………………………

83

10.2. List of Tables Table 1. Murie 1 landcover change …………………………………………………………………………………………………….

27

Table 2. Visible Landcover Change …………………………..………………………………………………...…………...…….

86

Table 3. Photo Information ………………………………..……………………………………..……………………………….………….

88

10.2 Visible Landcover Change Photo ID sfc00394 sfc00394 sfc00394 sfc00391 sfc00391 sfc00391 sfc00388 sfc00386 lek00057 lek00057 lek00057 lek00055 lek00055 lek00055 lek00054 lek00053 lek00053 lek00053 lek00052

scene Valley Hillside Mountain Hillside Mountain Valley Mountain Mountain Valley Hillside Mountain Valley Hillside Mountain Valley Valley Hillside Mountain Valley

tundra stable stable stable stable increase NA increase increase increase stable stable decrease increase stable increase increase stable stable increase

shrubs increase stable stable increase stable Stable stable stable increase stable stable decrease increase stable increase increase stable stable increase

trees stable stable NA stable NA stable NA NA NA NA NA NA NA NA NA NA NA NA NA

river channel decrease stable NA decrease NA stable NA stable increase stable NA increase decrease stable decrease NA NA NA decrease

ponds NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA decrease NA decrease

aufeis NA NA NA NA NA NA NA NA decrease NA NA NA NA NA decrease NA NA NA NA

glacier NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA

year 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

86

lek00050 lek00050 lek00041 lek00041 lek0001a lek00001 Murie01 Murie01 Murie02 Murie02 Murie03 Murie03 Murie04 Murie04 Murie05 Murie05 Murie06 Murie07 Murie08 Murie08 Murie09 Murie09 Murie09 Murie10 Murie10 Murie10 Murie11 Murie11 Murie12 Murie12 Murie12 Murie13 Murie13 Murie14 Murie14 Murie14 Murie15 Murie15 Murie15 Murie16 Murie16 Murie16 Murie17 Murie18 Murie19 Murie19

Valley Hillside Valley Hillside Mountain Mountain Hillside Valley Mountain Hillside Valley Mountain Mountain Hillside Valley Mountain Valley Valley Hillside Mountain Hillside Mountain Valley Valley Hillside Mountain Hillside Mountain Valley Hillside Mountain Hillside Mountain Valley Hillside Mountain Valley Hillside Mountain Hillside Mountain Valley Hillside Hillside Hillside Mountain

increase stable increase stable stable stable stable increase decrease stable decrease stable increase stable decrease stable decrease decrease stable stable stable stable stable increase stable stable stable stable increase increase stable stable stable stable decrease stable increase stable stable increase stable stable increase stable increase increase

increase stable increase stable stable stable increase increase decrease increase decrease stable increase stable decrease stable decrease decrease stable stable increase stable stable increase stable stable stable stable increase stable stable stable stable increase stable stable increase stable stable increase stable stable increase stable NA NA

Table 3. Visible Landcover Change

NA NA NA NA NA NA increase increase NA NA decrease NA stable increase decrease stable increase decrease increase stable increase stable increase stable increase stable increase stable stable increase stable increase stable NA NA NA NA NA NA NA NA NA NA NA NA NA

decrease NA increase NA stable stable NA stable NA NA NA NA NA NA NA NA NA NA NA NA NA NA stable stable NA NA NA NA decrease NA NA NA NA stable increase NA decrease NA NA decrease NA stable NA NA NA NA

NA NA stable NA NA NA NA stable NA NA increase NA NA NA increase NA increase increase NA NA NA NA increase increase NA NA stable NA stable NA NA NA NA NA NA NA NA NA NA NA NA NA decrease NA NA NA

NA NA decrease NA NA NA NA decrease NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA

NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA decrease

100 100 100 100 100 100 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50

87

10.2. Photograph Information Historic Photo I.D.#

sfc00394

Original Photographer

F.C. Schrader

Date

1899

sfc00391

F.C. Schrader

1899

sfc00388

F.C. Schrader

1899

sfc00386

F.C. Schrader

1899

lek00057

lek00055

E.K. Leffingwell

E.K. Leffingwell

1910

1910

Photo Caption

Endicott Mountains, in upper Dietrich River Valley. Wiseman district, Yukon region, Alaska. Mountains of limestone and mica schist, on east side of Dietrich River, from Station 19, on Fault Mountain, 5400 feet. Looking north 55 degrees east. Mica schist mountains from Station 19 on Fault Mountain, 5400 feet. West bank of Dietrich River. Looking north 25 degrees west. No caption provided Notch cut by lateral glacial drainage, Canning River, AngloAmerican Polar Expedition. Canning district, Northern Alaska region, Alaska. C. 1908. Even sky line in the Franklin Mountains along the Canning River. Glaciated slopes in the foreground. AngloAmerican Polar Expedition. Canning district, Northern Alaska region, Alaska. C. 1910.

Replication Date and Time

Photo ID

General Location

Longitude Decimal Degrees

Latitude Decimal Degrees

Camera Direction

Notes The Mountain in view is Mount Snowden. Human disturbance from the pipeline and Dalton Highway are visible. Highway construction caused disturbance above road. Human disturbance from the pipeline and Dalton Highway are visible. A large area now void of vegetation is a barrow bit used during road construction.

June 19, 2006, 20:30

0691

Dietrich Fork, Central Brooks Range, Alaska

149.88882

67.87862

1480 SE

June 19, 2006, 20:30

0723

Dietrich Fork, Central Brooks Range, Alaska

149.88882

67.87862

720 E

June 19, 2006, 20:30

0753

Dietrich Fork, Central Brooks Range, Alaska

149.88882

67.87862

3420 N

Alpine tundra and dwarf shrub expansion into barren ground.

June 19, 2006, 20:30

0786

Dietrich Fork, Central Brooks Range, Alaska

149.88882

67.87862

2980 NW

Filled in patches of alpine tundra and dwarf shrubs.

July 5, 2006, 13:50

1406 1422

Confluence with the Marsh Fork, Canning River, Brooks Range, Alaska

145.99384

69.27489

3460 N 3200 NW

Had to use two photos. Decreased aufeis.

1444

Confluence with the Marsh Fork, Canning River, Brooks Range, Alaska

1040 S

Increased river channels. Less tundra and shrub cover on river bottom. Alluvial fan is more filled in.

July 5, 2006, 13:50

145.99384

69.27489

88

lek00041

lek00053

lek00050

E.K. Leffingwell

E.K. Leffingwell

E.K. Leffingwell

lek00001

E.K. Leffingwell

lek0001a

E.K. Leffingwell

lek00052

E.K. Leffingwell

1910

Forks of Canning River. Aufeis is covering flood plain in July. AngloAmerican Polar Expedition. Canning district, Northern Alaska region, Alaska. C. 1910.

1910

Relation of the Anatuvuk Plateau to the Arctic Mountains (Franklin Mountains). AngloAmerican Polar Expedition. Canning district, Northern Alaska region, Alaska. C. 1910.

1910

1910

1910

1910

Ikiakpuk and Ikiakpaurak Valleys, Canning River. AngloAmerican Polar Expedition. Canning district, Northern Alaska region, Alaska. C. 1910. Double fold at northern front of Franklin Mountains, Canning River. Anglo-American Polar Expedition. Canning district, Northern Alaska region, Alaska. C. 1910. Double fold at the northern front of Franklin Mountains on the Canning River. Circa 1910. Looking across the Canning River from Franklin Mountains. Anglo-American Polar Expedition. Canning district, Northern Alaska region, Alaska. C. 1910.

July 5, 2006, 13:50

July 6, 2006, 13:30

July 6, 2006, 13:30

July 6, 2006, 16:00

July 6, 2006, 16:00

July 6, 2006, 16:00

1516

Confluence with the Marsh Fork, Canning River, Brooks Range, Alaska

145.99384

69.27489

0

104 SE

Massive decreases in aufeis. Tundra, shrubs, and river channels now cover ground previously covered by aufeis.

1543

Confluence of Eagle Creek and Canning River, Brooks Range, Alaska

146.00477

69.36513

2470 SW

A cairn was found at photo site. Increased tundra and shrubs along river bank. The historic photo show more snow and may indicate it was taken earlier in the growing season. A pond is a fraction of its former size. Decreases in aufeis.

1576

Confluence of Eagle Creek and Canning River, Brooks Range, Alaska

146.00477

69.36513

490 NE

Increased tundra and shrubs along Eagle Creek.

1630

Confluence of Eagle Creek and Canning River, Brooks Range, Alaska

145.95924

69.36632

1130 E

A cairn was found at the photo site. No change is visible.

1661

Confluence of Eagle Creek and Canning River, Brooks Range, Alaska

145.95924

69.36632

820 E

Tundra cover appears stable.

1693

Confluence of Eagle Creek and Canning River, Brooks Range, Alaska

3220 NW

A cairn was found at the original photo site. Tundra and shrubs have replaced river channels. A pond is a fraction of its former size.

145.95924

69.36632

89

1910

Northern front of Franklin Mountains, west of Canning River. Anglo-American Polar Expedition. Canning district, Northern Alaska region, Alaska. C. 1910.

July 6, 2006, 16:00

Shrubs and tundra have expanded into former river channels and gravel bars. The shrubs, mostly alder, in the former river channels were several meters high. Decreased aufeis. Shrubs have expanded on hillside. Trees are taller. Trees have expanded in the valley. Aufeis on river bottom is disappearing.

1753

Confluence of Eagle Creek and Canning River, Brooks Range, Alaska

145.95924

69.36632

2400 SW

July 12, 2006, 16:00

2084

Last Lake, Sheenjek River, Brooks Range, Alaska

143.72276

68.56882

331 NW

143.67121

68.57532

222 SW

Shrubs and tundra have expanded into former bare ground.

143.75320

68.59029

323 NW

Last Lake is larger, reducing tree, shrub, and tundra cover.

143.75050

68.59072

130 SE

143.74998

68.59132

313 NW

143.7494

68.59096

334 NW

Last Lake is Larger. Trees are taller.

143.75024

68.59116

335 NW

Last Lake is expanded. Trees on far shore are both taller.

143.75101

68.59049

156 SE

Trees are taller and more filled in.

lek00054

E.K. Leffingwell

Murie01

Murie Expedition

1956

South Last Lake Camp, Sheenjek Valley View.

Murie02

Murie Expedition

1956

Alpine view Northeast from Southeast side of Camp Mountain.

July 12, 2006, 17:00

2095

Murie03

Murie Expedition

1956

Sheenjek Murie, Last Lake Looking West

July 12, 2006, 23:00

2177

Murie04

Murie Expedition

1956

Olaus Murie, Last Lake Looking East

July 12, 2006, 23:30

2186

Murie05

George Schaller

1956

Muries hiking along Last Lake

July 12, 2006, 23:35

2200

Murie06

Brina Kessell

1956

George Schaller and Bob Krear hiking along Last Lake

July 13, 2006, 12:00

2204

Murie07

Bob Krear

1956

LL Bean Boots at Last Lake

July 13, 2006, 12:17

2218

Morie08

Brina Kessell

1956

Tent by Woodpile

July 13, 2006, 12:40

2244

Camp Mountain, Sheenjek River, Brooks Range, Alaska Last Lake, Sheenjek River, Brooks Range, Alaska Last Lake, Sheenjek River, Brooks Range, Alaska Last Lake, Sheenjek River, Brooks Range, Alaska Last Lake, Sheenjek River, Brooks Range, Alaska Last Lake, Sheenjek River, Brooks Range, Alaska Last Lake, Sheenjek River, Brooks Range, Alaska

Trees are taller and more filled in. Tundra and shrubs have expanded into barren ground. It was difficult, if not impossible to find the exact location of the original photograph due the expansion of Last Lake.

90

Murie09

Murie Expedition

Murie10

Murie Expedition

Murie11

George Schaller

1956

Last Lake Camp, Sheenjek Valley, View Northwest, 1956

July 13, 2006, 15:40

1956

Last Lake, Sheenjek Valley, view SW, 1956

July 13, 2006, 16:12

1956

Last Lake Camp to Southeast over Lake

July 13, 2006, 17:00

2246

Last Lake, Sheenjek River, Brooks Range, Alaska

143.74176

68.58852

317 NW

2285

Last Lake, Sheenjek River, Brooks Range, Alaska

143.71942

68.59169

253 SW

Last Lake, Sheenjek River, Brooks Range, Alaska

143.75056

68.59223

161 SE

Trees are taller and more filled in.

2298

Shrubs have grown and expanded. Trees are taller, more filled in, and expanded into new areas. Alpine tundra has expanded into former barren ground, shrub are larger and more common, trees are taller and more filled in, Last Lake is larger, and aufeis is much smaller.

143.71371

68.67177

326 NW

Alpine tundra has expanded into barren ground, trees are taller and more filled, shrubs have expanded into gully’s on Double Mountain.

143.71838

68.72806

193 SW

Trees are taller and more filled in.

143.53686

68.83653

123 SE

Upper Sheenjek River, Brooks Range Alaska

143.55185

68.85868

357 NW

2444

Upper Sheenjek River, Brooks Range Alaska

143.59961

68.88669

20 NE

2471

Upper Sheenjek River, Brooks Range Alaska

143.60754

68.88552

332 NW

Murie12

Murie Expedition

1956

1956 Murie, Near Double Mountain

July 15, 2006, 12:22

2349

Murie13

Murie Expedition

1956

1956 Murie Sheenjek, looking back south at Camp Mountain

July 15, 2006, 14:41

2377

Murie14

Murie Expedition

1956

Upper Sheenjek Alluvial Fan

July 15, 2006, 22:00

2416

Murie15

Murie Expedition

July 22, 1956

1956 Murie, July 22, Sheenjek

July 16, 2006, 08:40

2433

Murie16

Murie Expedition

1956

1956 Murie, Upper Sheenjek Alluvial Fan

July 16, 2006, 10:15

Murie17

Murie Expedition

July 22, 1956

1956 Murie, Near head of Sheenjek, July 22

July 16, 2006, 11:16

Double Mountain, Sheenjek River, Brooks Range Alaska Double Mountain, Sheenjek River, Brooks Range Alaska Upper Sheenjek River, Brooks Range Alaska

Shrubs have expanded along western river bank. River Channels and gravel bars have succeeded to tundra and shrubs. Shrubs and near river banks appeared stable. Water channels and barren graven on alluvial fan have succeeded to tundra and shrubs. Very difficult to locate due to topographic changes. The pond is now completely drained.

91

Murie18

Murie19

Murie Expedition George Schaller

1956

1956

1956 Murie Sheenjek

Sheenjek Glacier

July 16, 2006, 11:35 July 17, 2006, 12:00

2490

Upper Sheenjek River, Brooks Range Alaska

2521

The head of the Sheenjek River, Brooks Range, Alaska

143.59268

144.04582

68.88018

69.02312

318 NW

The alder has decayed.

208 NW

The Sheenjek Glacier has significantly receded. Alpine tundra has expanded into formerly barren ground.

Table 2. Photograph Information

92