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studies investigating changes in the forest structure (i.e., density, height, and extension) over northwestern Canada. Payette and Filion (1985) found that white spruce tree lines in northern Quebec have not substantially changes over the past centuries, whereas Suarez et al. (1999) found that the tundra–taiga tree line in Alaska advanced northward between 80 and 100 m north over the last 200 years. Gamache and Payette (2004) studied black spruce height near the Arctic tree line in eastern
studies investigating changes in the forest structure (i.e., density, height, and extension) over northwestern Canada. Payette and Filion (1985) found that white spruce tree lines in northern Quebec have not substantially changes over the past centuries, whereas Suarez et al. (1999) found that the tundra–taiga tree line in Alaska advanced northward between 80 and 100 m north over the last 200 years. Gamache and Payette (2004) studied black spruce height near the Arctic tree line in eastern
1. Introduction In northern regions, the snow cover insulates the ground from the winter cold air and therefore plays a key role in the permafrost thermal regime ( Zhang 2005 ). With global warming, shrubs are expanding on Arctic tundra ( Ju and Masek 2016 ; Tremblay et al. 2012 ) and this has been observed to lead to increases in snow height in some cases ( Busseau et al. 2017 ; Sturm et al. 2001 ). Here, we use the term “snow height” rather than the more common “snow depth” because we
1. Introduction In northern regions, the snow cover insulates the ground from the winter cold air and therefore plays a key role in the permafrost thermal regime ( Zhang 2005 ). With global warming, shrubs are expanding on Arctic tundra ( Ju and Masek 2016 ; Tremblay et al. 2012 ) and this has been observed to lead to increases in snow height in some cases ( Busseau et al. 2017 ; Sturm et al. 2001 ). Here, we use the term “snow height” rather than the more common “snow depth” because we
of snow water resources and hazards, but snow depth and mass distributions also have important influences on climate and ecology. Snow redistributed to shrubs in the low Arctic contains high chemical loads of essential plant nutrients such as inorganic nitrogen, and shrubs have deeper snow than adjacent sparsely vegetated tundra ( Pomeroy et al. 1995 ). Snow cover provides a direct physical protection to plant stems from abrasion by blowing-snow grains, and deeper snowpacks reduce overwinter soil
of snow water resources and hazards, but snow depth and mass distributions also have important influences on climate and ecology. Snow redistributed to shrubs in the low Arctic contains high chemical loads of essential plant nutrients such as inorganic nitrogen, and shrubs have deeper snow than adjacent sparsely vegetated tundra ( Pomeroy et al. 1995 ). Snow cover provides a direct physical protection to plant stems from abrasion by blowing-snow grains, and deeper snowpacks reduce overwinter soil
1. Introduction The increase in global air temperature, which is twice as pronounced in polar regions than in all other parts of the world ( Chylek et al. 2009 ), is changing the distribution of vegetation zones ( Myers-Smith and Hik 2018 ). This change is particularly notable in the forest–tundra ecotone ( Payette et al. 2001 ) at the interface between the boreal forest and the Arctic shrub tundra. This region is characterized by a mosaic of forest patches, usually restricted to humid, wind
1. Introduction The increase in global air temperature, which is twice as pronounced in polar regions than in all other parts of the world ( Chylek et al. 2009 ), is changing the distribution of vegetation zones ( Myers-Smith and Hik 2018 ). This change is particularly notable in the forest–tundra ecotone ( Payette et al. 2001 ) at the interface between the boreal forest and the Arctic shrub tundra. This region is characterized by a mosaic of forest patches, usually restricted to humid, wind
and simulations in the Arctic tundra region have been carried out in various areas. Pomeroy et al. (1997) and Essery et al. (1999) simulated a snow distribution and verified their results with a snow survey in Trail Valley Creek (68°43′N, 130°40′W). According to Pomeroy et al. (1997) and Essery et al. (1999) , vegetation has a strong control on snow accumulation, and taller vegetation such as shrub of sparse forest traps more wind-blown snow. Averaged snow mass in shrub tundra and sparse
and simulations in the Arctic tundra region have been carried out in various areas. Pomeroy et al. (1997) and Essery et al. (1999) simulated a snow distribution and verified their results with a snow survey in Trail Valley Creek (68°43′N, 130°40′W). According to Pomeroy et al. (1997) and Essery et al. (1999) , vegetation has a strong control on snow accumulation, and taller vegetation such as shrub of sparse forest traps more wind-blown snow. Averaged snow mass in shrub tundra and sparse
1. Introduction The transport of snow by wind is prevalent over tundra, high to midlatitude grasslands, high-altitude steppes, alpine zones, and ice sheets ( Berg 1986 ; Petropavlovskaya and Kalyuzhnyi 1986 ; Groisman et al. 1997 ; Mann et al. 2000 ). Observations of the frequency of occurrence of blowing-snow events range between 16 to 35 days a year in northern Kazahkhstan ( Petropavlovskaya and Kalyuzhnyi 1986 ) to over 90 days a year along the Russian Arctic coastal plain and in the
1. Introduction The transport of snow by wind is prevalent over tundra, high to midlatitude grasslands, high-altitude steppes, alpine zones, and ice sheets ( Berg 1986 ; Petropavlovskaya and Kalyuzhnyi 1986 ; Groisman et al. 1997 ; Mann et al. 2000 ). Observations of the frequency of occurrence of blowing-snow events range between 16 to 35 days a year in northern Kazahkhstan ( Petropavlovskaya and Kalyuzhnyi 1986 ) to over 90 days a year along the Russian Arctic coastal plain and in the
1. Introduction As Arctic land surface temperatures rise disproportionately in response to anthropogenic global warming, the area covered by high-latitude boreal forests is projected to increase ( Falloon et al. 2012 ; Jeong et al. 2011 ). Both observational ( Royer et al. 2005 ) and modeling ( Gallimore et al. 2005 ) studies of other warm periods in the paleoclimate record have noted similar northward expansions of the boreal forests. Plants themselves have a significant impact on their
1. Introduction As Arctic land surface temperatures rise disproportionately in response to anthropogenic global warming, the area covered by high-latitude boreal forests is projected to increase ( Falloon et al. 2012 ; Jeong et al. 2011 ). Both observational ( Royer et al. 2005 ) and modeling ( Gallimore et al. 2005 ) studies of other warm periods in the paleoclimate record have noted similar northward expansions of the boreal forests. Plants themselves have a significant impact on their
emissions dominate the Arctic tundra methane budget . Proc. Natl. Acad. Sci. USA , 113 , 40 – 45 , https://doi.org/10.1073/pnas.1516017113 .
emissions dominate the Arctic tundra methane budget . Proc. Natl. Acad. Sci. USA , 113 , 40 – 45 , https://doi.org/10.1073/pnas.1516017113 .
annually on the Arctic tundra ( Phillips 1990 ). Its scarce vegetation and long seasonal snow covers make the Arctic tundra especially susceptible to blowing snow and blizzard events ( Déry and Yau 1999b ). Apart from its hazardous aspects such as reduced optical visibilities, blowing snow associated with blizzards and other high-wind events is of much interest because of its twofold contribution to the surface water and energy budgets through mass divergence or convergence in addition to concurrent in
annually on the Arctic tundra ( Phillips 1990 ). Its scarce vegetation and long seasonal snow covers make the Arctic tundra especially susceptible to blowing snow and blizzard events ( Déry and Yau 1999b ). Apart from its hazardous aspects such as reduced optical visibilities, blowing snow associated with blizzards and other high-wind events is of much interest because of its twofold contribution to the surface water and energy budgets through mass divergence or convergence in addition to concurrent in
disappeared, has albedo values averaging 0.18 over tundra and 0.08 over lakes. The autumn transitional period, starting from early September to mid-October, is characterized by large surface albedo due to occasional snowfalls and alternating periods of freezing and thawing. Other studies at Barrow have suggested somewhat a basis for dividing the year into seasons or periods. An intensive field investigation of the microclimates of the arctic tundra at Barrow, Alaska, was carried out during 1971 and 1972
disappeared, has albedo values averaging 0.18 over tundra and 0.08 over lakes. The autumn transitional period, starting from early September to mid-October, is characterized by large surface albedo due to occasional snowfalls and alternating periods of freezing and thawing. Other studies at Barrow have suggested somewhat a basis for dividing the year into seasons or periods. An intensive field investigation of the microclimates of the arctic tundra at Barrow, Alaska, was carried out during 1971 and 1972
