Ecology/Taiga

Taiga is one of the biomes discussed in the Ecology event.

Overview
The taiga is the largest land biome and the largest forest in the world covering 50 million acres or about 17% of the Earth's land and accounts for 27% of the world's forests. It covers most of northern Canada and Russia, and is characterized by many coniferous trees and  often very cold weather in the winter. The word Taiga comes from the Russian word for forest swamp.

Boreal Forest
The name boreal forest is often used as a synonym for taiga, however, strictly speaking, the boreal forest only represents the southern part of the taiga; the part where conditions are suitable for trees to grow. In the northern taiga conditions are so cold and dry that trees can not sustain life.

General Information

 * The angle of incidence for incoming solar radiation is low and twilight lasts many hours


 * Seasons are divided into short, moist and moderately warm summers and long, cold, dry winters.


 * Temperature – vary greatly from summer to winter (-65 to +70 degrees Fahrenheit)


 * Variable precipitation: 6-40 in (15-100 cm).
 * Fire a major factor in maintaining the biome

Soils
The soil is very thin because it was scraped by glaciers during the last ice age and in some places, there is a good deal of permafrost which prevents plants from establishing deep root systems. Permafrost does not absorb water so much of the taiga's soil is very soggy. Sometimes bogs form.

The soil is not very dynamic because the dominant trees are conifers. These trees lay down waxy needles that take a long time to decompose into soil. The cold temperatures further slow the process of decomposition. When the needles do decompose, they decompose to form highly acidic soil with a pH around 5. This soil is rather infertile and limits the species of plants that can grow in that soil. The absence of earth-churning invertebrates such as earthworms makes the soil hard and compact.

Muskeg
Muskeg is a soil type characteristic of the taiga. It is synonymous with bog land. It forms when a stagnant pool of water begins to fill with plant litter. As the plant litter falls in the water, it does not decompose very quickly because the water is very low in oxygen and the cold temperatures slow decomposition. Rather than forming soil, peat is formed. The peat is highly acidic and fairly low in nutrients, however some plants and trees can grow in it. The peat is not very firm and walking around in muskeg can actually make surrounding trees sway. This inspired one particular forest in Manitoba, Canada to be named the Drunken Forest.

Flora
The dominant flora of the taiga is the White Spruce Tree. Plant life is mostly limited by precipitation and temperature.

Deciduous trees found in taiga: birch, alder, aspen, larch


 * White Spruce(Picea glauca): 75 ft & 2 ft in diameter, Needles concentrated on upper side of branches, needles 1 inch in length, needles diamond-shaped in cross-section, like Black Spruce, but cones are bigger (2 in) & cone scales are flexible not brittle at maturity, lives 600 yrs


 * Balsam Fir (Abies balsamea): medium sized 40-60 ft, 1 to 1.5 ft in diameter, typical broad base with narrow top, shallow root system only 35 in deep, branches are at right angles, lower branches usually dead & droop to ground, leaves are dark green above & white below, 1 & 1/2 in long, flat with distinct curve & rounded tip, bark is resinous, smooth, gray, cones are purple & 2-4 in, Balsam is major food for deer, low swampy ground, moose, squirrels, & others during winter, resin is used for mounting biological specimens on microscope slides. It is a climax species that is not fire resistant and usually appears around 30-50 years after a disturbance occurs.


 * Black Spruce (Picea mariana): usually 20-40 ft (rarely more than 100), diameter  usually less than 1 foot, but for big specimens 3 feet, grows in poor soil with cold climate, common is wet soils & bogs, shorter branches than most conifers, sharp needles 1/2 in long with 4 sides, bark is rough, thick, gray-brown in color, cones are .5 to 1 in long, cone scales are brittle at maturity, pinecones are major food for birds in Taiga


 * Jack Pine (Pinus banksiana): 70ft tall, young jacks have reddish bark, older jacks have gray bark, branches are long, slender, & bear needle leaves, this allows Jacks to adapt in snowfall & cold weather, found in semi-cold regions of taiga, needles & pinecones are food sources for rodents & others, needles in bundles of 2 from 1-1.5 in, need fire to release seeds, prefer drier, warmer sites at high altitudes


 * Tamarack (Larix): clumps of needles, mature are usually 50-75 ft tall, diameter 1-1.75 ft, cones are .5-.8 in length, needles flattened & triangular in cross-section; color: blue-green. 8-1.3 in length, bark is gray to red-brown thin, scaly, wide range, damp boggy habitat, loamy soils sometimes


 * Red Spruce: like Black Spruce, but cones are slightly bigger, tree occurs in drier & better drained soil


 * Larch Forests (Larix larichina): live in thin, waterlogged substrate in level areas with permafrost. Under stories of shrubs, mosses, & lichens.


 * Douglas Fir (Pseutotsuga menziesii): 330 ft high, trunk is 16 ft wide, forms forests in the Rocky Mountains, common in mixed conifer and broad-leaf forests of North America's Pacific Coast


 * Scotch Pine (Pinus sylvestris): most widespread light conifer in Europe


 * Clematis: the only climbing plants that live in the Taiga


 * Alder: symbiote with fungi, fungi live in Alders' roots and fix nitrogen from the air. The fungus gets a place to live.


 * Shrubs of the Taiga: Alders, wild roses, junipers, raspberries, and honeysuckle, shrubs typically are below 13 ft


 * Herbaceous plants: Twinflowers, Starflowers, May lilies, and common wood sorrel. Below 2 ft in height.

Conservation
The largest threats to taiga conservation are human activity, particularly logging. In Canada, less than eight percent of the boreal forest is protected from development and more than 50% has been allocated to logging companies for cutting. 80% of the boreal forest products from Canada are exported to the USA.

Spruce Bark Beetles
Due to global warming, bark beetles have been able to survive farther north than ever before and are decimating Spruce populations in the taiga. The beetles burrow into Spruce trees which can result in a drastically reduced growth rate in the trees or death. Many species depend on mature Spruce trees and are placed under greater competition pressures due to decreased resources. However, there are benefits from these beetles. They aid in secondary succession by removing mature Spruce trees which allows other trees to grow in their wake.

Treatment
A variety of methods are used to control the beetle population. Some methods include:
 * Removing infested trees: This prevents larva in the tree from infesting other trees
 * Trap trees: A trap tree is a tree that has already been felled (usually from a different location where it is unwanted) and is placed in a forest. These trees are debarked which makes the tree more appealing to the beetles because they must normally bore through bark. Because these trees are more appealing, they can soak up large amounts of the bark beetle population, at which time they are removed from the forest.
 * Solar Heat: Beetle mortality increases when exposed to direct sunlight. Removal of the brush and surrounding trees around an infected tree will control beetle population.
 * Pheromones: Pheromones from the beetles can be placed in traps. These pheromones only attract the bark beetle species, which lowers the rate in which non-target insects are killed.
 * Insecticides: Insecticides disrupt the nervous system of the beetle which quickly leads to death.

Importance

 * Taiga filters millions of liters of water


 * It stores large amounts of carbon


 * Produces oxygen


 * It rebuilds soils and restores nutrients


 * Bogs and marshes provides habitats for large numbers of species from fish to birds