THE FORESTS OF THE world occur in several climatic¶zones, which range from the subpolar to tropical¶regions.
The taiga is the name given to the forests that¶border the tundra meadows and dwarf shrublands of¶polar latitudes where annual temperature regimes prohibit¶the growth of trees.
These forests are dominated¶by coniferous species.¶The name derives from the Russian word for "land¶of little sticks," which reflects the impact of climate on¶tree growth in continental interiors.
The greatest extent¶of taiga occurs in the Northern Hemisphere because of¶the greater expanse of land between northern latitudes¶50 degrees N and 70 degrees N as compared with the¶domination of ocean in equivalently located southern¶latitudes.
The taiga forms a forest belt across North¶America and Eurasia, with the tundra on its northern¶border and the temperate forests and grasslands to the¶south.¶This BIOME is often referred to as the boreal zone¶though in northern CANADA there are also large expanses¶of muskeg, a type of wetland/peatland, within¶the forest.
These northern forests occupy some 6.1 million¶square mi (15.8 million square km); a further .2¶million square mi (.5 million square km) of coniferous¶forest extends along the ocean coast from ALASKA to¶CALIFORNIA.¶Climatic conditions in these regions vary enormously,¶from harsh continental to more favorable¶northern maritime regimes.
Overall, cold, dry conditions¶prevail along with a big range of temperature; average¶temperatures of -22 degrees F (-30 degrees C)¶occur during the winter, while the average temperature¶in the summer months is 59 degrees F (15 degrees C).¶There is a growing season that varies from only 50¶days in continental interiors to 100 days in southerly¶and near coastal regions.
The risk of frost is high even¶during the summers which are characterized by a long¶day, and the change of seasons tends to be abrupt.¶Precipitation is on average 20 in (50 cm), but¶amounts also vary considerably; coastal areas of Scandinavia¶and the west coast of North America receive¶up to 80 in (200 cm).
Most precipitation falls as rain in¶the summer months with some precipitation falling as¶snow in the winter.
The harsh conditions affect soil¶type in the taiga, which was either directly glaciated or¶experienced polar desert conditions during the last ice¶age.
Glacial and periglacial deposits are the substrates¶on which young soils have developed.
These are often¶sandy and acidic with some organic material rich in¶lignin from accumulating coniferous needles.¶Permafrost also occurs but is discontinuous, and¶the operation of freeze-thaw cycles in soils causes soil¶movement and the formation of hummocks and hollows.¶The hollows are favored by trees, mosses, and¶shrubs, and the hummocks by lichens.
Naturally occurring¶fire plays a significant role in taiga dynamics.¶Many conifers require fire to release seeds from their¶cones, and fire promotes new growth.¶The dominant taiga tree type is the conifer with¶needlelike leaves.
Most species are evergreen, which¶means that they shed needles year-round, the main exception¶being the larches that dominate the vast expanses¶of SIBERIA.
These are deciduous, which means¶that they shed their leaves annually.
Worldwide, the¶taiga is a considerable store of carbon, both within the¶living trees and within the organic material of the soils¶that derives from the trees.
Although there are similarities¶in the structure or physiognomy of the plant communities¶in this biome, there is considerable variation¶in the species composition.¶In North America, white spruce, black spruce, and¶tamarack (a species of larch) are the most widespread,¶but many other species occur where climatic, topographic,¶or soil conditions are favorable.
Shrubs,¶grasses, sedges, herbs, lichens, and mosses are also¶common in taiga communities, while large herbivores,¶for example, caribou in North America and reindeer in¶Eurasia, are the most conspicuous animals.
A wide¶range of insects also characterizes the taiga, and sometimes¶population outbreaks can cause significant defoliation.¶Taiga communities can also be classified according¶to their relationships with adjacent communities.¶There are four zones, as follows:¶Forest-tundra (transitional zone between the two¶major biomes): Stunted trees in isolated stands, lichenand¶moss-dominated communities.¶Open taiga (boreal woodlands): Discontinuous¶stands of trees and shrubs with lichens and mosses.¶Closed taiga (boreal woodlands): Continuous¶stands of trees with a closed canopy, a shrub understory.¶Taiga-mixed forest or taiga-grassland (transitional¶zone with southern ecosystems of the temperate forest¶of grassland): Mixed forests of conifers and deciduous¶hardwoods or a mixture of conifers in grassland.¶Economically, the taiga forests are very important.¶They provide the raw materials for forestry industries¶in Canada, the UNITED STATES, Scandinavia, and RUSSIA¶and are the source of considerable wealth generation.¶The major products are roundwood, sawnwood and¶pulp for paper making.
Canada is the leading producer¶of wood products from its forests.¶However, much forest exploitation is unsustainable,¶especially where large tracts of land are left treeless¶by clear felling.
The situation is particularly serious¶in eastern Siberian forests, which are diminishing rapidly.¶The plight of the taiga rarely achieves the publicity¶attention or media interest garnered by tropical¶RAINFORESTS.
- American civil pilots are getting queasy
"During the week two men who were piloting a civil plane felt sickish.
The United Airlines flight routing from Huston to San Francisco with 187 people aboard, including the crew group suddenly the pilot became ill and incapacitated. Therefore, the pilot-captain had to make an emergency landing.
Before that there had been another accident. American Airlines plane from Boston to Phoenix had to make an emergency landing at the Syracuse Airport because one of the pilots died. The stewardess, who provided first hand medical attention failed to save him. There were 147 people onboard that day. "
- Another European railway strike
"The French railway strike is planned on October 8, and Belgium strike will be held the next day.
It is supposed that French train staff will stop working on the evening of October 7 and will resume it by the morning 9 October. The aim of the strike is to attract the attention of the authorities due to the worsened working conditions and also their payment dissatisfaction. To be more precise, the trade unions want to reassure the authorities not to reform the Labor Code and pension payroll system.
Their Belgium colleagues wish to come up with the same requirements. It was also reported that high-speed trains Eurostar will be routed between London and Lille without reaching Brussels due to the strike. Thalys trains connecting Belgium and French capital cities will be canceled. The tourists would better think of an alternative way or choose some other means of transport. "