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.
- The speeding train links Genoa and Rome
"The Italian Railway Company has shared plans about running a train between Genoa and Rome. It is expected that the Eternal City and the Liguria capital will be linked in a few months.
It is outlined that running high-speed trains following this route is defined by the low-cost airlines refusal. Low-costers considered the route Rome-Genoa to be unprofitable. The Spanish Vueling became the last discounter that announced the flight termination.
The route from Genoa to Rome will take about three hours by train. "
- The smog has affected tourists’ plans in Thailand
"Several flights were canceled due to the smoke.
The wildfires are storming around in Indonesia, the smoke of which extends 100 km away. Due to the wind direction smog has covered Phuket and Samui, the Thai’s islands. It is said that the smoke is neither life nor health threatening for tourists. There is no burning smell as well. Nevertheless, the tourists are not recommended to go in for sports outdoors. One of the country’s media centre states that the Phuket Island community has sent an open letter to the authorities of Thailand asking about taking steps on the smog elimination. According to what they say, the south part of the country is covered by the poisonous smoke that can cause development of various diseases among the local population. Also the islanders say that smog crashes the tourists’ plans that they cannot fly out because of the flight cancellation. For instance, only five airplanes that took off from Bangkok flying to Phuket and Samui were asked to make a reverse just in the air because of the low visibility conditions. "