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Northern Forests and Tundra
L. Kullman. Ambio (2001) 30(2):72-80. After a slight retardation during some cooler decades after 1940, a new active phase of tree-limit advance has occurred with a series of exceptionally mild winters and some warm summers during the 1990s.
A comparison of multi-spectral, multi-angular, and multi-temporal remote sensing datasets for fractional shrub canopy mapping in Arctic Alaska
D.J. Selkowitz. Remote Sensing of Environment (2010) 114(7):1338-1352. Shrub cover appears to be increasing across many areas of the Arctic tundra biome, and increasing shrub cover in the Arctic has the potential to significantly impact global carbon budgets and the global climate system.
A.H. Lloyd et al. Global Change Biology (2011) 17(5):1935-1945. The authors' findings suggest that increased productivity with warming is likely only in the northern reaches of the Siberian taiga. An increased prevalence of evergreen conifers in areas currently dominated by deciduous Larix species also seems likely.
A richer, greener and smaller alpine world: Review and projection of warming-induced plant cover change in the Swedish Scandes
L. Kullman. Ambio (2010) 39(2):159-169. Upper range margin rise of trees and low-altitude (boreal) plant species, expansion of alpine grasslands and dwarf-shrub heaths are the modal biotic adjustments during the past few decades, after a century of substantial climate warming in the Swedish Scandes.
Above ground biomass changes in the mountain birch forests and mountain heaths of Finnmarksvidda, northern Norway, in the period 1957-2006
H. TÃ¸mmervik et al. Forest Ecology and Management (2009) 257(1):244-257. Using vegetation maps based on aerial photographs and satellite images from 7 years in combination with statistical data and ground estimation data of biomass in the period 1957-2006, the authors were able to assess the transitions among mountain heaths and different types of forest, the displacement of the altitudinal forest line, and hence the change in biomass.
The Alaska Geobotany Center (AGC) is dedicated to understanding northern ecosystems through ecological studies of landscape patterns and changes.
E. Weise. USA Today (updated 5/31/06). Alaska is important in measuring the effect of global warming on the USA because what happens here soon will be felt in the Lower 48 states.
S.D. Wilson, C. Nilsson. Global Change Biology (2009) 15:1676-1684. Recent arctic warming experiments have recorded significant vegetation responses, typically an increase in shrub cover and a loss of species richness. The authors report similar changes in vegetation along an arctic mountainside in northern Sweden over 20 years.
J.O. Kaplan, M. New. Climatic Change (2006) 79:213-241. A number of nations, organizations, and scientists have suggested that global mean temperature should not rise over 2°C above preindustrial levels. However, even a relatively moderate target of 2°C has serious implications for the Arctic, where temperatures are predicted to increase at least 1.5 to 2 times as fast as global temperatures. High-latitude vegetation plays a significant role in the lives of humans and animals, and in the global energy balance and carbon budget. These ecosystems are expected to be among the most strongly impacted by climate change over the next century.
J. Qiu, Nature News, September 2, 2009. Just as climate change may fuel fires, fires may accelerate climate change. Vast areas of tundra store about 14% of the world's soil carbon at the surface alone. Fires could release a large amount of that, either directly through combustion or indirectly by modifying the tundra ecosystem.
NPR's "All Things Considered," August 30, 2000. Science correspondent Richard Harris reports that scientists have been surprised by a rapid change in the Arctic tundra. When the Arctic air warmed up in the 1980s, this delicate ecosystem started venting large quantities of carbon dioxide gas into the atmosphere, potentially adding to global climate change. But a study in the journal Nature finds that Arctic plant life has adapted to the changing climate and is helping soak up some carbon dioxide.
E. Chung, CBC News, August 15, 2011. The Arctic will switch from being a carbon sink to a carbon source by the end of this century as the permafrost thaws and emits greenhouse gases, a new study suggests.
P. Ball, Nature News, August 31, 2000. Walter Oechel of San Diego State University, California, has spent many years studying the interactions between climate and the processes of growth and decay in ecosystems of the Arctic regions. He and his colleagues have now found that, in just a few decades, these important natural systems can partly absorb and offset the effect of the changes in global climate.
A. Hartmann. Earth (2008). According to a new study, past estimates of organic carbon concentrations in Arctic soils are too low, which has some scientists worried about vast amounts of carbon being released as temperatures warm.
A. Witze, Nature News, December 15, 2009. Researchers have identified a climate feedback effect suggesting that, as vegetation creeps northward, it will accelerate warming trends already in place.
Chapter 7 (pages 243-352) of ACIA Scientific Report, Cambridge University Press, 2005. Forest is very likely to replace a significant proportion of the tundra, and this will have a great effect on the composition of species. Displacement of tundra by forest will lead to a decrease in albedo, which will increase the positive feedback to the climate system. (PDF, 3.61 MB)
B. Sherwonit. Yale Environment 360 (2010). The treeless ecosystem of mosses, lichens, and berry plants is giving way to shrub land and boreal forest. As scientists study the transformation, they are discovering that major warming-related events, including fires and the collapse of slopes due to melting permafrost, are leading to the loss of tundra in the Arctic.
ScienceDaily, November 18, 2010. In September 2007, the Anaktuvuk River Fire burned more than 1,000 square kilometers of tundra on Alaska's North Slope, doubling the area burned in that region since record keeping began in 1950. Models built on 60 years of climate and fire data found that even moderate increases in warm-season temperatures in the region dramatically increase the likelihood of such fires.
S. Sitch et al. Ecological Applications (2007) 17(1):213-234. This paper reviews the current status of using remote sensing and process-based modeling approaches to assess the contemporary and future circumpolar carbon balance of Arctic tundra, including the exchange of both carbon dioxide and methane with the atmosphere.
D. Biello. Scientific American online edition, June 14, 2007. Arctic plants have retreated and advanced in their colonization of fertile regions with great speed and over vast distances as the climate changes.
J. Olofsson et al. Nature Climate Change (2011) 1:220-223. The authors show that, although plant growth was favored by the insulating effects of increased snow cover in experimental plots in Sweden, plant biomass decreased over a seven-year study. The decline in biomass was caused by an outbreak of a host-specific parasitic fungus, Arwidssonia empetri, which killed the majority of the shoots of the dominant plant species, Empetrum hermaphroditum, after six years of increased snow cover.
M.C. Mack et al. Nature (2011) 475:489-492. Arctic tundra soils store large amounts of carbon in organic soil layers hundreds to thousands of years old that insulate, and in some cases maintain, permafrost soils. Fire has been largely absent from most of this biome since the early Holocene epoch, but its frequency and extent are increasing, probably in response to climate warming. Here, the authors studied the effects of the Anaktuvuk River fire of 2007. Listen to clips of interviews with two of the authors that aired on APRN's "Alaska News Nightly" August 2, 2011. (MP3) [2:39 min] Read more about the study on NPR's news blog from July 28, 2011. Finally, read a related article by BBC environmental correspondent Richard Black. This interviews requires the use of the QuickTime, which can be downloaded from QuickTime's Web site at no charge.
A.L. Swann et al. Proceedings of the National Academy of Sciences (2010) 107(4):1295-1300. Land surface albedo change is considered to be the dominant mechanism by which trees directly modify climate at high latitudes, but the authors suggest an additional mechanism through transpiration of water vapor and feedbacks from the ocean and sea ice.
P.S.A. Beck et al. Ecology Letters (2011) 14(4):373-379. The authors evaluated changes in forest productivity since 1982 across boreal Alaska by linking satellite estimates of primary productivity and a large tree-ring data set. Trends in both records show consistent growth increases at the boreal-tundra ecotones that contrast with drought-induced productivity declines throughout interior Alaska.
R.A. Klady et al. Global Change Biology (2011) 17(4):1611-1624. The authors provide new information on changes in tundra plant sexual reproduction in response to long-term (12 years) experimental warming in the High Arctic.
Science Daily, May 23, 2011. The predictability and scale of seasonal changes in a habitat help determine the distance migratory species move and whether the animals always travel together to the same place or independently to different locations.
Changes in vegetation in northern Alaska under scenarios of climate change, 2003-2100: Implications for climate feedbacks
E.S. Euskirchen et al. Ecological Applications (2009) 19(4):1022-1043. This study examines potential changes in the dominant plant functional types (PFTs) of the sedge tendra, shrub tundra, and boreal forest ecosystems in ecotonal northern Alaska for the years 2003-2010.
U.S. Bhatt et al. Earth Interactions (2010) 14(8):1-20. The authors use a newly available Arctic Normalized Difference Vegetation Index (NDVI) dataset (a measure of vegetation photosynthetic capacity) to document coherent temporal relationships between near-coastal sea ice, summer tundra land surface temperatures, and vegetation productivity.
E.A. Lenart et al. Canadian Journal of Zoology (2002) 80(4):664-678. Climate variation and subsequent effects on forage plants have the potential to influence the population dynamics of caribou through effects on their food supply. (PDF, 604.2 KB)
G.M. MacDonald et al. Philosophical Transactions of the Royal Society B (2008) 363(1501):2283-2299. The Russian treeline is a dynamic ecotone typified by steep gradients in summer temperature and regionally variable gradients in albedo and heat flux. The location of the treeline is largely controlled by summer temperatures and growing season length. Temperatures have responded strongly to twentieth-century global warming and will display a magnified response to future warming. (PDF, 795.5 KB)
Science Daily, July 7, 2011. A University of Alberta study shows that climate change over the past 70 years has pushed some of the province's native wildflowers and trees into earlier blooming times, making them more vulnerable to damaging frosts and, ultimately, threatening reproduction.
ScienceDaily, June 30, 2011. Ground-level ozone is an air pollutant that harms humans and plants. Both climate and weather play a major role in ozone damage to plants. Researchers at the University of Gothenburg, Sweden, have now shown that climate change has the potential to significantly increase the risk of ozone damage to plants in northern and central Europe by the end of this century.
Climate change tipping points for populations, not just species: Survival, reproduction of thousands of Arctic and alpine plants measured
ScienceDaily, October 21, 2010. As Earth's climate warms, species are expected to shift their geographical ranges away from the equator or to higher elevations.
C.J. Lemieux, D.J. Scott. Canadian Geographer (2005) 49(4):384-397. Vegetation-modeling results project that 37-48 percent of Canada's protected areas could experience a change in terrestrial biome type under doubled atmospheric carbon-dioxide conditions.
J. Moen. Ambio (2008) 37(4):304-311. This paper examines potential effects of predicted climate changes on the forage conditions during both summer and winter for semidomesticated reindeer in Sweden. Positive effects in summer ranges include higher plant productivity and a longer growing season, while negative effects include increased insect harassment.
M. Sturm et al. Nature (2002) 411:546-547. The authors present evidence for a widespread increase in shrub abundance over more than 320 square kilometers of Arctic landscape during the past 50 years, based on a comparison of historic and modern aerial photographs.
T.R. Christensen. Nature Geoscience (2009) 2(3):163-164. Tundra is a fascinating example of a dynamic and sensitive ecosystem that interacts with, and responds very sensitively to, changes in climate. This cold, treeless environment, where low temperatures limit the growth of most plants, is a highly significant component of the global climate system.
A. Thompson. Nature Geoscience (2007) doi:10.1038/ngeo.2007.45. Shrub encroachment into the Arctic tundra could cause early snowmelts and warmer springtime temperatures.
Comprehensive conservation planning to protect biodiversity and ecosystem services in Canadian boreal regions under a warming climate and increasing exploitation
D.W. Schindler, P.G. Lee. Biological Conservation (2010) 143(7):1571-1586. Boreal regions contain more than half of the carbon in forested regions of the world and over 60% of the world's surface freshwater. Carbon storage and the flood control and water filtration provided by freshwaters and wetlands have recently been identified as the most important ecosystem services provided by boreal regions. Climate warming, via its effect on permafrost melting, insect damage, and forest fire, threatens to trigger large positive carbon feedbacks that may enhance the concentrations of greenhouse gases in the atmosphere, further amplifying climate warming.
Connecting landscapes into the future: A regional strategic habitat conservation climate change project
Lecture #3 in U.S. Fish & Wildlife Service's Climate Change Lecture Series, presented April 22, 2009, by Karen Murphy, U.S. Fish & Wildlife Service (R7) Regional Fire Ecologist, Division of Refuges. (WMV) [47:37 min] This interview requires the use of the Windows Media Player, which can be downloaded from Windows Media Player's Web site at no charge.
Decrease of lichens in Arctic ecosystems: The role of wildfire, caribou, reindeer, competition and climate in north-western Alaska
K. Joly et al. Polar Research (2009) 28(3):433-442. Lichens constitute the primary winter forage for large, migratory caribou and reindeer herds, which in turn are a critical subsistence resource for rural residents in Alaska.
S. Löfgrena, T. Zetterberg. Science of the Total Environment (2011) 409(10):1916-1926. During the last two decades, there is a common trend of increasing concentrations of dissolved organic carbon (DOC) in streams and lakes in Europe, Canada, and the US. However, long-term soil water data from Sweden and Norway indicate that there are either decreasing or indifferent DOC concentrations. In this study, the authors test the acidification recovery hypothesis on long-term soil water data (25 and 50 cm soil depth) from 68 forest covered sites in southern Sweden, showing clear signs of recovery from acidification.
K.M. Buckeridge, P. Grogan. Applied Soil Ecology (2008) 39(2):210-222. Microbial activity in the long Arctic cold season is low but cumulatively important. In particular, the size of the microbial biomass and soil solution nutrient pool at the end of winter may control the quantity of nutrients available to plants in the following spring. Increasingly severe soluble carbon (C) shortages may be exacerbated by the warmer temperatures and increased winter precipitation that are consistently predicted for a large part of the low Arctic.
Detecting changes in Arctic tundra plant communities in response to warming over decadal time scales
H.E. Epstein et al. Global Change Biology (2004) 10:1325-1334. Field data coupled with ArcVeg simulations of climate change scenarios indicate that some changes in plant community composition may be detectable within two decades following the onset of warming, and shrubs and mosses might be the key indicators of community change.
Z. Chen et al. Arctic (2010) 63(3):315-326. Long-term satellite remote sensing data, when properly calibrated and validated against ground monitoring, could provide valuable data sets for assessing climate change impacts on ecosystems, wildlife, and other important aspects of life in the Arctic. In this paper, the authors report an adapted method for quantifying percent plant cover based on plot digital photograph classification (PDPC). (PDF, 1.57 MB)
M. Turunen et al. Polar Biology (2009) 32(6)813-832. The northward and upward movement of the tree line and gradual replacement of lichens with vascular plants associated with increasing temperatures and nutrient availability may change the reindeer pastures in Northern Fennoscandia. The productivity of reindeer forage will most probably increase, but their protein (nitrogen) concentrations may decrease because of higher temperatures and CO2 concentration.
A. Witze, Nature News, August 4, 2009. If the tundra becomes increasingly warm and wet, which is anticipated as global temperatures rise, it might emit more carbon than expected.
N. Zhang et al. Environmental Research Letters (2011) 6(2):024003. Larch taiga, also known as Siberian boreal forest, plays an important role in global and regional water-energy-carbon (WEC) cycles and in the climate system. This study suggests that future global warming could drastically alter the larch-dominated taiga-permafrost coupled system in Siberia, with associated changes of WEC processes and feedback to climate.
E. Post et al. Science (2009) 325(5946):1355-1358. Arctic ecosystems and the trophic relationships that structure them have been severely perturbed. These rapid changes may be a bellwether of changes to come at lower latitudes and have the potential to affect ecosystem services related to natural resources, food production, climate regulation, and cultural integrity.
National Academy of Sciences, 2009. This booklet is based on the report Ecological Impacts of Climate Change (2008), by the Committee on Ecological Impacts of Climate Change. (PDF, 8.14 MB)
M.C. Mack et al. Nature (2004) 431:440-443. One-third of the global soil carbon pool is stored in northern latitudes, so there is considerable interest in understanding how the carbon balance of northern ecosystems will respond to climate warming. This study suggests that projected release of soil nutrients associated with high-latitude warming may further amplify carbon release from soils, causing a net loss of ecosystem carbon and a positive feedback to climate warming.
Ecosystem feedbacks and cascade processes: Understanding their role in the responses of Arctic and alpine ecosystems to environmental change
P.A. Wookey et al. Global Change Biology (2009) 15:1153-1172. Global environmental change, related to climate change and the deposition of airborne N-containing contaminants, has already resulted in shifts in plant community composition among plant functional types in Arctic and temperate alpine regions.
Ecosystems and global climate change: A review of potential impacts on U.S. terrestrial ecosystems and biodiversity
Report prepared for the Pew Center on Global Climate Change, December 2000. This is the fifth in a series of Pew Center reports examining the potential impacts of climate change on the U.S. environment. It details the very real possibility that warming over this century will jeopardize the integrity of many of the terrestrial ecosystems on which we depend. (PDF, 728 KB)
A.O. Stuanes et al. Ambio (2008) 37(1):2-8. Projected climate change might increase the deposition of nitrogen by about 10% to seminatural ecosystems in southern Norway.
Effect of warming on the temperature dependence of soil respiration rate in Arctic, temperate and tropical soils
Y.S. Bekku et al. Applied Soil Ecology (2003) 22(3):205-210. The authors examined the response of the temperature coefficient for soil respiration rate to changes in environmental temperature through a laboratory incubation experiment. Soil samples were collected from three climatic areas: Arctic (Svalbard, Norway), temperate (Tsukuba, Japan), and tropical (Pasoh, Malaysia). Results suggest that the response of microbial respiration to climatic warming may differ between soils from different latitudes.
Effects of hard frost and freeze-thaw cycles on decomposer communities and N mineralisation in boreal forest soil
P. Sulkava, V. Huhta. Applied Soil Ecology (2003) 2(3):225-239. Decomposition and mineralization rates generally increase with increasing moisture and temperature. The expected global climate change may enhance precipitation and raise the temperatures at boreal latitudes, but absence of snow together with occasional low temperatures may cause disturbances in soil processes and faunal communities.
G. Gutman, A. Reissel (eds.) Springer, 2011, 306 pages. This volume is a compilation of studies on interactions of land-cover/land-use change with climate in a region where the climate warming is most pronounced compared to other areas of the globe.
NPR's "Morning Edition," July 29, 2011. One big blaze released more carbon into the atmosphere than the entire tundra absorbs every year. [3:40 min]
Chapter 14 (pages 781-862) of ACIA Scientific Report, Cambridge University Press, 2005. While the most restrictive definitions limit the Arctic to treeless tundra, snow, and ice in the high latitudes, most definitions of the Arctic encompass some elements of the boreal forest. This chapter focuses on the northernmost portion of the boreal forest region. (PDF, 3.38 MB)
I.D. Hodkinson, P.A. Wookey. Applied Soil Ecology (1999) 11(2-3):111-126. The resilience and response of tundra communities to change are discussed, and the possible alteration in community structure and function that may result from shifting climate patterns are reviewed.
S.M. Natali, M.C. Mack. Nature Climate Change (2011) 1:192-193. Climate change is known to affect the carbon balance of Arctic tundra ecosystems by influencing plant growth and decomposition. Less predictable climate-driven biotic events, such as disease outbreaks, are now shown to potentially shift these ecosystems from net carbon sinks to sources.
A. Wolf et al. Climatic Change (2008) 87(1-2):51-73. Surprisingly, shrublands will decrease in extent as they are replaced by forest at their southern margins and restricted to areas high up in the mountains and to areas in northern Russia. Open ground vegetation will largely disappear in the Scandinavian mountains. Also counter-intuitively, tundra will increase in abundance due to the occupation of previously unvegetated areas in the northern part of the Barents Region.
L.S. Vors, M.S. Boyce. Global Change Biology (2009) 15:2626-2633. Caribou and reindeer herds are declining across their circumpolar range, coincident with increasing arctic temperatures and precipitation, and anthropogenic landscape change.
The Greening of the Arctic (GoA) IPY initiative is comprised of four projects, each contributing to documenting, mapping, and understanding the rapid and dramatic changes to terrestrial vegetation expected across the circumpolar Arctic as a result of a changing climate.
C-L Ping et al. Nature Geoscience (2008) 1(9):615-619. The authors estimate that the total organic carbon pool in North American Arctic soils, together with the average amount of carbon per unit area, is considerably higher than previously thought. Their estimates will form an important basis for studies examining the impact of climate warming on CO2 release in the region.
How landscape dynamics link individual- to population-level movement patterns: A multispecies comparison of ungulate relocation data
T. Mueller et al. Global Ecology and Biogeography (2011) DOI: 10.1111/j.1466-8238.2010.00638.x. The aim of this study was to demonstrate how the interrelations of individual movements form large-scale population-level movement patterns and how these patterns are associated with the underlying landscape dynamics by comparing ungulate movements across species. Study locations were Arctic tundra in Alaska and Canada, temperate forests in Massachusetts, Patagonian Steppes in Argentina, and Eastern Steppes in Mongolia.
BBC News, August 14, 2005. Greenland's ice is melting rapidly. In some places, glacial levels have been falling by 10 meters a year and ultimately contributing to rising sea levels. Traveling to Greenland, BBC's Richard Hollingham sees the impact of climate change for himself.
Impacts of a recent storm surge on an Arctic delta ecosystem examined in the context of the last millennium
M.F.J. Pisaric et al. Proceedings of the National Academy of Sciences (2011) 108(22):8960-8965. One of the most ominous predictions related to recent climatic warming is that low-lying coastal environments will be inundated by higher sea levels. The threat is especially acute in polar regions because reductions in extent and duration of sea ice cover increase the risk of storm surge occurrence. The authors examined growth rings of alder shrubs and diatoms preserved in dated lake sediment cores to show that a recent marine storm surge in 1999 caused widespread ecological changes across a broad extent of the outer Mackenzie Delta.
S. Sharma et al. Global Change Biology (2009) 15(10):2549-2562. Arctic ecosystems are especially vulnerable to global climate change as temperature and precipitation regimes are altered. An ecologically and socially highly important northern terrestrial species that may be impacted by climate change is the caribou, Rangifer tarandus.
J. Haimi et al. Applied Soil Ecology (2005) 30(2):104-112. Responses of dominant soil decomposer animals in northern coniferous forests, enchytraeids and microarthropods, to elevated CO2 concentration and temperature were studied by sampling an experiment consisting of closed field chambers.
T.D. Prowse et al. Ambio (2009) 38(5):282-289. As the climate continues to change, there will be consequences for biodiversity shifts and for the ranges and distribution of many species with resulting effects on availability, accessibility, and quality of resources upon which human populations rely. This will have implications for the protection and management of wildlife, fish, and fisheries resources; protected areas; and forests.
Yale Environment 360, March 25, 2011. As Russia's enormous boreal forest undergoes rapid warming, a significant shift in tree species is occurring, with evergreen trees such as spruce and fir creeping poleward as the iconic tree of Russia's far north, the larch, is in decline, according to a new study.
A.C. Revkin, New York Times, November 11, 2011. Evergreen trees at the edge of Alaska's tundra are growing faster, suggesting that at least some forests may be adapting to a rapidly warming climate, says a new study.
Inclusion of local environmental conditions alters high-latitude vegetation change predictions based on bioclimatic models
H. Sormunen et al. Polar Biology (2011) 34(6):883-897. Current predictions of how species will respond to climate change are typically based on coarse-grained climate surfaces utilizing bioclimate envelope modelling. However, the suitability of environmental conditions for a given species might result from a variety of factors including some unrelated to climate. To address this issue, the authors investigated whether the inclusion of topographical and soil information in bioclimatic envelope models would significantly alter predictions of climate change.
J.M. Hudson, G.H. Henry. Ecology (2009) 90(10):2657-2663. This study provides plot-based evidence for the recent pan-Arctic increase in tundra productivity detected by satellite-based remote-sensing and repeat-photography studies. These types of ground-level observations are critical tools for detecting and projecting long-term community-level responses to warming.
D. Scherrer, C. Körner. Global Change Biology (2009). Rough mountain terrain offers climatic conditions (niches) to plants and animals poorly represented by conventional climate station data. However, the extent to which actual temperatures deviate from those of the freely circulating atmosphere had never been assessed at a landscape level.
Land use and land cover change in Arctic Russia: Ecological and social implications of industrial development
T. Kumpula et al. Global Environmental Change (2011) 21(2):550-562. Data are derived from field sampling, remote sensing, and intensive participant observation with indigenous Nenets reindeer herders and nonindigenous workers. Important trends include the rapid expansion of infrastructure, a large influx of workers who compete for freshwater fish, and extensive transformation from shrub- to grass- and sedge-dominated tundra.
J.M. Welker et al. Oikos (2005) 109(1):167-177. Accurate depiction and projections of how Arctic tundra plants and ecosystems will respond to global warming require measurements of leaf mineral nutrition under independent and combined climate change scenarios involving both winter and summer conditions.
D.R. Klein, M. Shulski. Ambio (2009) 38(1):11-16. A warmer, drier climate and decreased fog in recent decades contributed to deterioration of conditions favoring lichen growth on St. Matthew Island in the Bering Sea.
B. Kochtubajda et al. Arctic (2006) 59(2):211-221. The longer, warmer, and drier summer seasons projected to result from climate change are expected to increase the frequency and intensity of forest fires by the end of the 21st century. Their considerable consequences for forests and wildlife make these changes a concern for northern communities, forest managers, and wildlife biologists. (PDF, 3.1 MB)
Long-term ecosystem level experiments at Toolik Lake, Alaska, and at Abisko, Northern Sweden: Generalizations and differences in ecosystem and plant type responses to global change
M.T. Van Wijk et al. Global Change Biology (2003) 10(1):105-123. This paper presents the results of a meta-analysis performed on the results of long-term ecosystem-level experiments near Toolik Lake, Alaska, and Abisko, Sweden. (PDF, 518 KB)
O. W. Heal. Applied Soil Ecology (1999) 11(2-3):107-109. In Copenhagen in November 1996, about 50 soil biologists reviewed current research with emphasis on the impacts of climatic change on tundra soil processes and populations.
Managing climate change impacts to enhance the resilience and sustainability of Fennoscandian forests
F.S. Chapin III et al. Ambio (2007) 36(7):528-533. Projected warming in Sweden and other Fennoscandian countries will probably increase growth rates of forest trees near their northern limits, increase the probability of new pest outbreaks, and foster northerly migration of both native and exotic species.
R.F. Grant et al. Global Change Biology (2003) 9(1):16-36. Rising air temperatures are believed to be hastening heterotrophic respiration in arctic tundra ecosystems, which could lead to substantial losses of soil carbon.
Multi-decadal changes in tundra environments and ecosystems: The International Polar Year - Back to the Future Project (IPY-BTF)
T.V. Callaghan et al. Ambio (2011) 40(6):555-716. This entire issue of Ambio is dedicated to the findings of researchers who revisited IPY sites and data sets throughout the Arctic and some alpine regions. These efforts have amounted to a gamut of "BTF" studies that are collectively geographically expansive and disciplinary diverse. A selection of these studies are introduced and presented in the current issue together with a brief synthesis of their findings.
Q. Zhuang et al. Ecological Applications (2007) 17(1):203-212. The authors used a biogeochemistry model, the Terrestrial Ecosystem Model (TEM), to study the net methane (CH4) fluxes between Alaskan ecosystems and the atmosphere.
C. Pala, The Daily Climate, July 19, 2010. An unprecedented effort to set aside huge swathes of Canada's boreal forest prompts all sides to rethink development goals, and for the first time some of the components have climate change mitigation as a key objective.
Yale Environment 360, July 1, 2011. A consortium of scientists has compiled a database that categorizes millions of traits for nearly a quarter of the world's plant species, a resource they say will help climate researchers more accurately model the effects of climate change in different environments.
PBS NewsHour, September 13, 2007. A vault in the Arctic archipelago of Svalbard, Norway, contains samples of the world's most important seeds, protecting the world's biodiversity in the event of a major disaster. Independent Television News reports on the project.
T.R. Christensen et al. Applied Soil Ecology (1999) 11(2-3):127-134. About 30% of the carbon in terrestrial ecosystems is stored in northern wetlands and boreal forest regions. Prevailing cold and wet soil conditions have largely been responsible for this carbon accumulation. It has been suggested that a warmer and drier climate in these regions might increase the decomposition rate and, hence, release more CO2 to the atmosphere than at present.
F. Girard et al. Global Ecology and Biogeography (2009) 18(3):291-303. Under global warming, warmer springs will lead to earlier low-intensity fires that do not remove as much organic matter, and hence prevent conditions suitable for black spruce regeneration. Also, spruce budworm reduces seed production for a certain time. The occurrence of fire during this period is critical for regeneration of black spruce.
R.D. Hollister et al. Ecology (2005) 86(6):1562-1570. This study examined natural temperature gradients, interannual climate variation, and experimental warming at sites near Barrow and Atqasuk in northern Alaska.
Plant species richness in continental southern Siberia: Effects of pH and climate in the context of the species pool hypothesis
Milan Chytrý et al. Global Ecology and Biogeography (2007) 16(5):668-678. Soil pH in continental southern Siberia is strongly negatively correlated with precipitation, and species richness is determined by the opposite effects of these two variables. Species richness increases with pH until the soil is very dry. In dry soils, pH is high but species richness decreases due to drought stress. Thus, the species richness-pH relationship is unimodal in treeless vegetation.
R.M.M. Crawford, Cambridge University Press, 2008. Part III of this 494-page book contains selected case studies, starting with Arctic treelines and the complex relationship with climatic continentality and paludification (chapter 5). Two other chapters chiefly focus on the Arctic tundra (chapters 6 and 9).
Potential alteration by climate change of the forest-fire regime in the boreal forest of central Yukon Territory
V.M. McCoy, C.R. Burn. Arctic (2005) 58(3):276-285. Statistical relations were obtained to describe the association between forest fires and climate for the Dawson and Mayo fire management districts, central Yukon Territory. Annual fire incidence, area burned, and seasonal fire severity rating were compared with summer observations of mean temperature, total precipitation, mean relative humidity, and mean wind speed. (PDF, 482.61 KB)
A.M. Fosaa et al. Global Ecology and Biogeography (2004) 13(5):427-437. Due to a possible weakening of the North Atlantic Current, it is difficult to predict whether the climate in the Faroe Islands will be warmer or colder as a result of global warming. Therefore, two scenarios are proposed. The first scenario assumes an increase in summer and winter temperature of 2°C, and the second a decrease in summer and winter temperature of 2°C.
Potential impact of climate change and reindeer density on tundra indicator species in the Barents Sea region
C. Zöckler et al. Climatic Change (2008) 87(1-2):119-130. Climate change is expected to alter the distribution of habitats and thus the distribution of species connected with these habitats in the terrestrial Barents Sea region. It is hypothesized that wild species connected with the tundra and open-land biome may be particularly at risk as forest area expands.
H. Roderfeld et al. Climatic Change (2008) 87(1-2):283-303. The EU project BALANCE (Global Change Vulnerabilities in the Barents region: Linking Arctic Natural Resources, Climate Change and Economies) aims to assess vulnerability to climate change in the Barents Sea Region.
Lecture #7 in U.S. Fish & Wildlife Service's Climate Change Lecture Series, presented November 17, 2009, by Elizabeth Bella PhD, Ecologist, Natural Resources Conservation Service, Homer. (WMV) [44:41 min] This interview requires the use of the Windows Media Player, which can be downloaded from Windows Media Player's Web site at no charge.
S. Rossi et al. Global Change Biology (2011) 17(1):614-625. In the next century, the boreal ecosystems are projected to experience greater rates of warming than most other regions of the world. As the boreal forest constitutes a reservoir of trees of huge ecological importance and only partially known economic potential, any possible climate-related change in plant growth and dynamics has to be promptly predicted and evaluated.
Chapter 10 (pages 539-596) of ACIA Scientific Report, Cambridge University Press, 2005. Climate change will result in changes in the productivity of ecosystems through photosynthesis and changes in the rates of decomposition. The balance between these two major processes will, to a large extent, determine the future nature of the arctic environment. (PDF, 1.94 MB)
Rapid northwards expansion of a forest insect pest attributed to spring phenology matching with sub-Arctic birch
J.U. Jepsen et al. Global Change Biology (2011) 17(6):2071-2083. Climate-induced range expansions have been shown for two irruptive forest defoliators, the geometrids Operophtera brumata and Epirrita autumnata, causing more extensive forest damage in sub-Arctic Fennoscandia. Here, the authors document a rapid northwards expansion of a novel irruptive geometrid, Agriopis aurantiaria, into the same region, with the aim of providing insights into mechanisms underlying the recent geometrid range expansions and subsequent forest damage.
M.R. Turetsky et al. Nature Geoscience (2011) 4(1):27-31. The authors examined the depth of ground-layer combustion in 178 sites dominated by black spruce in Alaska, using data collected from 31 fire events between 1983 and 2005.
S.J. Goetz et al. Chapter 2 of Eurasian Arctic land cover and land use in a changing climate, G. Gutman and A. Reissel (eds.), Springer, 2011. This chapter provides an overview of observed changes in vegetation productivity in Arctic tundra and boreal forest ecosystems over the past three decades based on satellite remote sensing and other observational records, and relates these to climate variables and sea ice conditions.(PDF, 1.28 MB)
Recent climate warming forces contrasting growth responses of white spruce at treeline in Alaska through temperature thresholds
M. Wilmking. Global Change Biology (2004) 10(10):1724-1736. Recent climate warming has intensified the negative growth response of a large proportion of trees at locally productive sites near treeline in Alaska. Trees on less favorable sites may be benefiting from earlier thaw and are now outperforming productive sites, reversing the historical growth relationship. (PDF, 524.32 KB)
G.B. Hill, G.H.R. Henry. Global Change Biology (2011) 17(1):276-287. Responses of tundra ecosystems to climate change have been examined primarily through short-term experimental manipulations, with few studies of long-term ambient change. This study investigates responses in above- and below-ground biomass of wet sedge tundra to the warming climate of the Canadian high Arctic over the past 25 years.
B.C. Forbes et al. Global Change Biology (2010) 16:1542-1554. Findings suggest a significant increase in shrub willow growth in the northwest Russian Arctic over the past six decades and are in line with field and remote sensing studies and qualitative observations by nomadic Nenets reindeer herders.
S.R. Karlsen et al. Global Ecology and Biogeography (2006) 15(4):416-430. The aim of this study was to test whether satellite-derived NDVI values obtained during the growing season as delimited by the onset of phenological phases can be used to map bioclimatically a large region such as Fennoscandia.
N.C. Larter, J.A. Nagy. Polar Research (2004) 23(2):131-140. Authors discuss herbivore diets in relation to foraging behavior and forage availability.
Sensitivity and response of northern hemisphere altitudinal and polar treelines to environmental change at landscape and local scales
F-K Holtmeier, G. Broll. Global Ecology and Biogeography (2005) 14(5):395-410. As treeline heterogeneity increases from global to regional and smaller scales, assessment of treeline sensitivity at the landscape and local scales requires a more complex approach than at the global scale. The sensitivity of treelines to changes in given factors (e.g., winter snow pack, soil moisture, temperature, evaporation, etc.) may vary among areas with differing climatic characteristics.
Sensitivity of high-resolution Arctic regional climate model projections to different implementations of land surface processes
H. Matthes et al. Climatic Change (2012) 111(2):197-214. This paper discusses the effects of vegetation cover and soil parameters on the climate change projections of a regional climate model over the Arctic domain.
J.K. Shuman et al. Global Change Biology (2011) 17(7):2370-2384. The Northern Hemisphere's boreal forests, particularly the Siberian boreal forest, may have a strong effect on Earth's climate through changes in dominant vegetation and associated regional surface albedo. The authors show that warmer climate will likely convert Siberia's deciduous larch (Larix spp.) to evergreen conifer forests, and thus decrease regional surface albedo.
Shifting climate, altered niche, and a dynamic conservation strategy for yellow cedar in the North Pacific coastal rainforest
Paul E. Hennon et al. BioScience (2012) 62(2):147-158. The authors document their approaches to resolving the causes of tree death, which they explain as a cascade of interacting topographic, forest-structure, and microclimate factors that act on a unique vulnerability of yellow cedar to fine-root freezing. Research on yellow-cedar decline is offered as a template for understanding and adapting to climate change for other climate-forest issues. (PDF, 1.05 MB)
Science Daily, March 3, 2011. Imagine the vast, empty tundra in Alaska and Canada giving way to trees, shrubs and plants typical of more southerly climates. Imagine similar changes in large parts of Eastern Europe, northern Asia and Scandinavia, as needle-leaf and broadleaf forests push northward into areas once unable to support them. Imagine part of Greenland's ice cover, once thought permanent, receding and leaving new tundra in its wake.
Shrub line advance in alpine tundra of the Kluane region: Mechanisms of expansion and ecosystem impacts
I. Myers-Smith. Arctic (2007) 60(4):447-451. With a warming climate, northern ecosystems will face significant ecological changes such as permafrost thaw, increased forest fire frequency, and shifting ecosystem boundaries, including the spread of tall shrubs into tundra. (PDF, 3.19 MB)
T.S. Rupp et al. Ecological Applications (2006) 16(5):1730-1743. Caribou commonly use older spruce woodlands with adequate terrestrial lichen, a preferred winter forage, in the understory. Changes in climate and fire regime pose a significant threat to the long-term sustainability of this important winter habitat.
EarthSky interview with Skip Walker, geobotanist at University of Alaska Fairbanks, March 5, 2009.
A. Jones et al., eds. European Commission, Office for Official Publications of the European Communities, 2010. The northern circumpolar region contains around 60% of the global soil carbon pool, much of it locked up in permanently or seasonally frozen ground. Understanding the evolution of these soils and associated vegetation patterns in relation to climate change, and also their use by society, is fundamental if we wish to assess fully global change processes.
ScienceDaily, November 30, 2010. The rate of global warming could lead to a rapid release of carbon from peatlands that would further accelerate global warming.
I.P. Hartley et al. Ecology Letters (2008) 11(10):1092-1100. The authors conclude that over the time scale of a few weeks to months warming-induced changes in the microbial community in Arctic soils will amplify the instantaneous increase in the rates of CO2 production and thus enhance C losses, potentially accelerating the rate of 21st century climate change.
V.I. Kharuk et al. Global Ecology and Biogeography (2010) 19(6):822-830. The spatial pattern of upper mountain forests as well as the response of forests to warming strongly depends on topographic relief features (elevation, azimuth, and slope steepness). Warming promotes migration of trees to areas that are less protected from winter desiccation and snow abrasion. Climate-induced forest response has significantly modified the spatial patterns of high-elevation forests in southern Siberia during the last four decades, as well as tree morphology.
G.J. Jia et al. Global Change Biology (2006) 12(1):42-55. The spatial heterogeneity of recent decadal dynamics in vegetation greenness and biomass in response to changes in summer warmth index (SWI) was investigated along spatial gradients on the Arctic Slope of Alaska.
K.D. Tape. University of Alaska Press, 2010. Historic photographs are paired with modern photographs of the same location. Scientific data and personal accounts accompany the visuals to discuss the impact of climate change on Arctic landscapes.
B.J. Graae et al. Polar Biology (2009) 32(8):1117-1126. Climate change will cause large-scale plant migration. Seedling recruitment constitutes a bottleneck in the migration process but is itself climate-dependent. The authors tested the effect of warming on early establishment of three Arctic pioneer species.
The Circle (2009), Issue 2. The Circle is published quarterly by the WWF International Arctic Programme. This edition of The Circle focuses on arctic conservation in times of rapid climate change. (PDF 2.9 MB)
D. Verbyla. Global Ecology and Biogeography (2008) 17(4):547-555. The author examines the trends of 1982-2003 satellite-derived normalized difference vegetation index (NDVI) values at several spatial scales within tundra and boreal forest areas of Alaska.
The impact of climate change on ecosystem carbon dynamics at the Scandinavian mountain birch forest–tundra heath ecotone
S. Sjögersten and P.A. Wookey. Ambio (2009) 38(1):2-10. Changes in temperature and moisture resulting from climate change are likely to strongly modify the ecosystem carbon sequestration capacity in high-latitude areas, both through vegetation shifts and via direct warming effects on photosynthesis and decomposition.
The importance of winter in annual ecosystem respiration in the High Arctic: Effects of snow depth in two vegetation types
E. Morgner et al. Polar Research (2010) 29(1):58-74. Winter respiration in snow-covered ecosystems strongly influences annual carbon cycling, underlining the importance of processes related to the timing and quantity of snow.
J.A. Foley. Science (2005) 310(5748):627-628. Reductions in highly reflective snow cover and expanding shrub and tree cover, both caused by recent warming in the Arctic, are amplifying the temperature changes in the region.
C.D. Brown. Arctic (2010) 63(4):488-492. The northern regions of Yukon and Alaska have experienced a 2ºC increase in summer temperatures since the 1960s. In the boreal forest, fires are expected to occur more often as the climate warms. Because of the long period black spruce require to become reproductively mature, an increase in fire activity may interrupt the cycle of post-fire self-replacement for this dominant boreal conifer. This interruption could initiate a change in the structure and function of these northern ecosystems that will have important implications for the global carbon cycle because it alters patterns of carbon accumulation and storage. (PDF, 1.82 MB)
M.M. Loranty et al. Environmental Research Letters (2011) 6(2):024014. Recent field experiments in tundra ecosystems describe how increased shrub cover reduces winter albedo, and how subsequent changes in surface net radiation lead to altered rates of snowmelt. These findings imply that tundra vegetation change will alter regional energy budgets. Using satellite observations and a pan-Arctic vegetation map, the authors examined the effects of shrub vegetation on albedo across the terrestrial Arctic.
M. Lund et al. Global Change Biology (2010) 16(9):2436-2448. Many wetland ecosystems such as peatlands and wet tundra hold large amounts of organic carbon (C) in their soils and are thus important in the terrestrial C cycle. The authors have synthesized data on the carbon dioxide (CO2) exchange obtained from eddy covariance measurements from 12 wetland sites across Europe and North America, spanning temperate to arctic climate zones.
L. Andreu-Hayles et al. Environmental Research Letters (2011) 6:DOI:10.1088/1748-9326/6/4/045503. The response of boreal forests to anthropogenic climate change remains uncertain, with potentially significant impacts for the global carbon cycle, albedo, canopy evapotranspiration, and feedbacks into further climate change. This study focuses on tree-ring data from the Firth River site at treeline in northeastern Alaska, in a tundra-forest transition region where pronounced warming has already occurred. (PDF, 508 KB)
Winter climate change in alpine tundra: Plant responses to changes in snow depth and snowmelt timing
S. Wipf. Climatic Change (2009) 94(1-2):105-121. Changes in winter climate and snow cover characteristics should be taken into account when predicting climate change effects on alpine ecosystems. (PDF, 435 KB)