Introduction

Source: NRDC

The boreal forest, commonly known as taiga, is a biome characterized by evergreen coniferous trees such as pines, spruces and larches. It is also called “Spruce Moose” in Alaska. The boreal forest is the largest terrestrial biome in the world covering 11 percent of the Earth’s surface (16). It is a humid, terrestrial subarctic biome that is found in high latitudes and high altitudes in places including North America, Russia, and Scandinavia. Because they overlap with territories controlled by developed countries, vast and intact boreal forests continue to support a natural food web of large carnivores such as bears and wolves, and thousands of other mammals, birds, and insects.

Image: http://www.nrdc.org/land/forests/boreal/images/map.gif


日本語：
タイガとして知られている北方林は、トウヒやカラマツなどの常緑針葉樹が特徴してるバイオームです。アラスカでは、「スプルースムース」と呼ばれています。北方林は地球の表面（16）の11％で、世界最大の陸生生物群系であります。北米、ロシア、スカンジナビアなどの様々な場所で高緯度や高地で発見された湿度の高い所にある、地上波亜寒帯バイオームです。先進国で制御領土と重複するので、広大な無傷の北方林は、クマやオオカミ、および他の哺乳動物、鳥類、昆虫の数千の大きな肉食動物の自然な食物網をサポートし続けています。

Map

Images: http://www.lter.uaf.edu/about_us.cfm http://www.adfg.alaska.gov/index.cfm?adfg=boreal.main

Images

 

Images: http://www.adfg.alaska.gov/index.cfm?adfg=boreal.main

http://www.ducks.org/conservation/western-boreal-forest-alaska

The Historical State

Source: USGS 

Alaska’s Boreal Forest is a land of extremes: low temperatures and precipitation levels in the winter, low diversity of dominant plant species, extremely high temperatures and humidity in the summer, and generally sparse human population (4). This forest is found in Alaska’s interior, extending from the Kenai Peninsula to the Tanana Valley near Fairbanks, and as far north as the foothills of the Brooks Range (10). Boreal forests experience extreme climatic shifts, with temperatures varying up to 160°F from summer to winter (7). Plants and animals that live in Alaska’s Boreal Forest have uniquely adapted to thrive in the long, bitter winters, short summers, and frequent fires.

Source: Chapin, F. Stuart. Alaska's Changing Boreal Forest

Source: Chapin, F. Stuart. Alaska's Changing Boreal Forest

With high moisture levels and cool climate, white spruce and black spruce dominate the boreal forest, setting it apart from deciduous woodlands and shrublands. In Alaska, the predominant conifers are white and black spruce (Picea glauca and Piciea mariana). Important deciduous trees are the two poplars: aspen poplar (Populus tremuloides) and balsam poplar (Populus balsamifera). White spruce forests grow on active floodplains with well-drained, permafrost-free soils; black spruce forests grow on poorly drained, permafrost-dominated soils (4). The slender conical shapes of boreal forest treesare an adaptation that helps them shed snow. Most boreal forest trees have relatively shallow root systems, which capitalize on the nutrients found in the thin layer of unfrozen soil. Black spruce trees can grow in soil only 20 inches deep (7). Black spruce and white spruce have waxy, drought- and frost-resistant needles year-round, extending their growth season. Due to this adaptation, spruces can photosynthesize later in autumn and earlier in spring than deciduous species (1). Boreal forest plants have adaptations to help them directly withstand fire as well. Most survive fires through basal resproutings, geranium, or winged seeds (9). Some boreal forest plants benefit from fire. Black spruce has semi-serotinous cones that are sealed with pitch, which only opens under extreme heat (1).

Source: FAO Washington Blog

Animals have adapted to the boreal forest through migration, hibernation, insulation, and camouflage. Birds migrate to avoid the arctic winter temperatures. Brown bears, black bears, marmots, wood frogs and many insects hibernate to avoid the stresses of winter. Caribou, wolves and ptarmigan have thick fur or feathers that insulate keeping them warm in the winter and cool in summer. In winter, the boreal forest's colors shift from greens, browns, yellows, and reds to whites and greys. Some animals, such as ermine, snowshoe hare, and ptarmigan, change their colors and camouflage as they forage or hunt (1). Some animals have evolved to adapt to the boreal forest. Boreal forest animals like the lynx and ptarmigan have developed snowshoes to improve movement in the snow. Moose have very long legs and caribou have hooves to improve movement (4).

Source: USGS

The modern boreal forest developed expeditiously. The White Spruce (Picea glauca) was probably the first boreal conifer to spread from the east to west across central Alaska between 9,000 and 8,000 cal. BP followed by the Black Spruce (Picea mariana) (13). With the changes in temperature and precipitation, increases in frequency and intensity of fires, thawing permafrost, changes in snow conditions, and increases in microbial activity due to increased soil temperatures, there was an acceleration in shrub growth, and the tree line shifted northward differing the boreal forest from the arctic (4). The severe weather conditions, limited growing period, and overall harsh environment made the boreal forest one of the least populated places. However, Athabaskans prospered in the boreal forest through their knowledge of the plants, properties of snow, fur, and other natural materials to keep warm and safe, and they studied the habits and movement of game animals (1). Still, because of the relative absence absence of roads and people, most of the forest is left intact and undisturbed. Industry in the interior of Alaska has been limited to small mills and cottage industries (7). There is an increasing threat from development, particularly from logging, mining, oil and gas, and hydropower. However the biggest problem is fire. Fire suppression around human habitations decreases forest diversity and wildlife populations (1).

Images:

http://pubs.usgs.gov/fs/2013/3054/
http://faowashington.org/ontario-moves-to-conserve-caribou-habitat-forest-jobs.html
Chapin, F. Stuart. Alaska's Changing Boreal Forest. (Oxford: Oxford UP, 2006. EBL Reader. UC Merced Library), 3-122.

Current Human Impacts

The Alaskan Boreal Forest overlaps with a few United States national parks and preserves. The overlap helps to protect the Alaskan Boreal Forest from development. Although the national parks and preserves provide a natural barrier, the Alaskan Boreal Forest is experiencing a gradual change from human impacts. The change in the ecosystem is due to a rise in temperatures from climate change. Carbon dioxide and methane emissions from humans contribute largely to the temperature rise. Since 1970, the Alaskan Boreal Forest’s “mean annual temperature” has increased by 35°F or 2°C and “has nearly doubled the annual area burned in Western North America in the last 20 years” (5).  Although fires are part of the ecosystem, rising temperatures have increased the frequency and severity of the fires.

The native white and black spruce coniferous trees are flammable and with the increase in fires the number of the native trees is decreasing. For example, temperature rise has increased droughts, which directly affects the white spruce forests. As the climate continues to warm, the white spruce forests growth decreases and bark beetle outbreaks increase (5). Furthermore, the Alaskan Boreal Forest is home to many native species like caribou. The caribou live in the forest during the winter but with more fires destroying their winter home the caribou struggle to find food and shelter during the cold winter (1). The caribou is one of many native species that are being affected by the increased fire activity.: 

http://www.arcus.org/witness-the-arctic/2009/3/article/507

http://denali101.com/

http://www.adfg.alaska.gov/index.cfm?adfg=boreal.main