Taiga ( Jobs Forestry )

Taiga ( Jobs Forestry ) is the world's largest land biome ( Jobs Forestry ), and makes up 27% of the world's forest ( Jobs Forestry ) cover; the largest areas are located in Russia and Canada ( Jobs Forestry ). The taiga ( Jobs Forestry ) is the terrestrial biome ( Jobs Forestry ) with the lowest annual average temperatures after the tundra and permanent ice caps. However, extreme minimums in the taiga ( Jobs Forestry ) are typically lower than those of the tundra ( Jobs Forestry ). The lowest reliably recorded temperatures in the Northern Hemisphere were recorded in the taiga ( Jobs Forestry ) of northeastern Russia. The taiga ( Jobs Forestry ) or boreal forest ( Jobs Forestry ) has a subarctic climate with very large temperature range between seasons, but the long and cold winter is the dominant feature ( Jobs Forestry ). This climate is classified as Dfc, Dwc, Dsc, Dfd, Dwd and Dsd in the Köppen climate classification scheme, meaning that the short summer (24-hr average 10°C or more) lasts 1–3 months and always less than 4 months. There are also some much smaller areas grading towards the oceanic Cfc climate with milder winters. The mean annual temperature generally varies from -5°C to 5°C, but there are taiga areas in both eastern Siberia and interior Alaska-Yukon where the mean annual reaches down to -10°C. According to some sources, the boreal forest ( Jobs Forestry ) grades into a temperate mixed forest ( Jobs Forestry ) when mean annual temperature reaches about 3 °C. Permafrost is common in areas with mean annual temperature below 0 °C. The winters last 5 – 7 months, with average temperatures below freezing ( Jobs Forestry ). Temperatures vary from −54 °C to 30 °C (-65 °F to 86 °F) throughout the whole year.
The summers, while short, are generally warm and humid. In much of the taiga ( Jobs Forestry ), -20 °C would be a typical winter day temperature and 18 °C an average summer day.
The growing season, when the vegetation in the taiga ( Jobs Forestry ) comes alive, is usually slightly longer than the climatic definition of summer as the plants of the boreal biome ( Jobs Forestry ) have a lower threshold to trigger growth. In Canada, Scandinavia and Finland, the growing season is often estimated by using the period of the year when the 24-hr average temperature is 5 °C or more. For the Taiga Plains in Canada, growing season varies from 80 to 150 days, and in the Taiga ( Jobs Forestry ) Shield from 100 to 140 days. Some sources claim 130 days growing season as typical for the taiga ( Jobs Forestry ). Other sources mention that 50 - 100 frost-free days are characteristic. Data for locations in southwest Yukon gives 80 - 120 frost-free days ( Jobs Forestry ). The closed canopy boreal forest ( Jobs Forestry ) in Kenozersky near Plesetsk, Arkhangelsk Province, Russia, on average has 108 frost-free days. The longest growing season is found in the smaller areas with oceanic influences; in coastal areas of Scandinavia and Finland, the growing season of the closed boreal forest ( Jobs Forestry ) can be 145 – 180 days. The shortest growing season is found at the northern taiga - tundra ecotone, where the northern taiga forest ( Jobs Forestry ) no longer can grow and the tundra dominates the landscape when the growing season is down to 50 – 70 days, and the 24-hr average of the warmest month of the year usually is 10°C or less. High latitudes mean that the sun does not rise far above the horizon, and less solar energy is received than further south. But the high latitude also ensures very long summer days, as the sun stays above the horizon nearly 20 hours each day, with only around 6 hours of daylight occurring in the dark winters, depending on latitude. The areas of the taiga ( Jobs Forestry ) inside the Arctic circle have midnight sun in mid-summer and polar night in mid-winter.
The taiga ( Jobs Forestry ) experiences relatively low precipitation throughout the year (generally 200–750 mm annually, 1,000 mm in some areas), primarily as rain during the summer months, but also as fog and snow ( Jobs Forestry ). As evaporation is also low for most of the year, precipitation exceeds evaporation, and is sufficient to sustain the dense vegetation growth. Snow may remain on the ground for as long as nine months in the northernmost extensions of the taiga ( Jobs Forestry ) ecozone.
In general, taiga ( Jobs Forestry ) grows to the south of the 10 °C July isotherm, but occasionally as far north as the 9 °C July isotherm. The southern limit is more variable, depending on rainfall; taiga ( Jobs Forestry ) may be replaced by forest ( Jobs Forestry ) steppe south of the 15 °C July isotherm where rainfall is very low, but more typically extends south to the 18 °C July isotherm, and locally where rainfall is higher (notably in eastern Siberia and adjacent northern Manchuria) south to the 20 °C July isotherm. In these warmer areas, the taiga ( Jobs Forestry ) has higher species diversity, with more warmth-loving species such as Korean Pine, Jezo Spruce and Manchurian Fir, and merges gradually into mixed temperate forest ( Jobs Forestry ), or more locally (on the Pacific Ocean coasts of North America and Asia) into coniferous temperate rainforests ( Jobs Forestry ).
Much of the area currently classified as taiga was recently glaciated. As the glaciers receded, they left depressions in the topography that have since filled with water, creating lakes and bogs (especially muskeg soil), found throughout the taiga.
Soils ( Jobs Forestry )Taiga soil tends to be young and nutrient-poor; it lacks the deep, organically-enriched profile present in temperate deciduous forests ( Jobs Forestry ). The thinness of the soil is due largely to the cold, which hinders the development of soil and the ease with which plants can use its nutrients. Fallen leaves and moss can remain on the forest floor for a long time in the cool, moist climate, which limits their organic contribution to the soil; acids from evergreen needles further leach the soil, creating spodosol. Since the soil is acidic due to the falling pine needles, the forest floor has only lichens and some mosses growing on it. ( Jobs Forestry )
Flora ( Jobs Forestry )Since North America and Asia used to be connected by the Bering land bridge, a number of animal and plant ( Jobs Forestry ) species (more animals than plants) were able to colonize both continents and are distributed throughout the taiga ( Jobs Forestry ) biome ( Jobs Forestry ) (see Circumboreal Region). Others differ regionally, typically with each genus having several distinct species, each occupying different regions of the taiga. Taigas ( Jobs Forestry ) also have some small-leaved deciduous trees ( Jobs Forestry ) like birch, alder, willow, and poplar; mostly in areas escaping the most extreme winter cold. However, the Dahurian Larch tolerates the coldest winters in the northern hemisphere in eastern Siberia ( Jobs Forestry ). The very southernmost parts of the taiga may have trees such as oak, maple, elm, and tilia scattered among the conifers, and there is usually a gradual transition into a temperate mixed forest ( Jobs Forestry ), such as the Eastern forest ( Jobs Forestry )-boreal  ( Jobs Forestry ) transition of eastern Canada. In the interior of the continents with the driest climate, the boreal forests ( Jobs Forestry ) might grade into temperate grassland.
There are two major types of taiga ( Jobs Forestry ). The southern part is the closed canopy forest ( Jobs Forestry ), consisting of many closely-spaced trees with mossy ground cover. In clearings in the forest ( Jobs Forestry ), shrubs and wildflowers are common, such as the fireweed. The other type is the lichen woodland or sparse taiga ( Jobs Forestry ), with trees that are farther-spaced and lichen ground cover; the latter is common in the northernmost taiga ( Jobs Forestry ). In the northernmost taiga ( Jobs Forestry ) the forest ( Jobs Forestry ) cover is not only more sparse, but often stunted in growth form; moreover, ice pruned asymmetric Black Spruce (in North America) are often seen, with diminished foliage on the windward side. In Canada, Scandinavia and Finland, the boreal forest ( Jobs Forestry ) is usually divided into three subzones: The high boreal (north boreal) or taiga zone; the middle boreal (closed forest ( Jobs Forestry )); and the southern boreal, a closed canopy boreal forest ( Jobs Forestry ) with some scattered temperate deciduous trees among the conifers, such as maple, elm and oak. This southern boreal forest ( Jobs Forestry ) has the longest and warmest growing season of the biome, and in some regions (including Scandinavia, Finland and western Russia) this subzone is commonly used for agricultural purposes. The boreal forest ( Jobs Forestry ) is home to many types of berries; some are confined to the southern and middle closed boreal forest ( Jobs Forestry ) (such as raspberry), others grow in most areas of the taiga ( Jobs Forestry ) (such as cranberry and cloudberry), and some can grow in both the taiga ( Jobs Forestry ) and the low arctic (southern part of) tundra (such as bilberry and lingonberry).
The forests ( Jobs Forestry ) of the taiga ( Jobs Forestry ) are largely coniferous, dominated by larch, spruce, fir, and pine. The woodland mix varies according to geography and climate so for example the Eastern Canadian forests ( Jobs Forestry ) ecoregion of the higher elevations of the Laurentian Mountains and the northern Appalachian Mountains in Canada is dominated by balsam fir Abies balsamea, while further north the Eastern Canadian Shield taiga ( Jobs Forestry ) of northern Quebec and Labrador is notably black spruce Picea mariana and tamarack larch Larix laricina.
Evergreen species in the taiga ( Jobs Forestry ) (spruce, fir, and pine) have a number of adaptations specifically for survival in harsh taiga ( Jobs Forestry ) winters, although larch, the most cold-tolerant of all trees ( Jobs Forestry ), citation needed] is deciduous. Taiga ( Jobs Forestry ) trees tend to have shallow roots to take advantage of the thin soils, while many of them seasonally alter their biochemistry to make them more resistant to freezing, called "hardening". The narrow conical shape of northern conifers, and their downward-drooping limbs, also help them shed snow. ( Jobs Forestry )
Because the sun is low in the horizon for most of the year, it is difficult for plants ( Jobs Forestry ) to generate energy from photosynthesis. Pine, spruce and fir do not lose their leaves seasonally and are able to photosynthesize with their older leaves in late winter and spring when light is good but temperatures are still too low for new growth to commence. The adaptation of evergreen needles limits the water lost due to transpiration and their dark green color increases their absorption of sunlight. Although precipitation is not a limiting factor, the ground freezes during the winter months and plant ( Jobs Forestry ) roots are unable to absorb water, so desiccation can be a severe problem in late winter for evergreens.
Although the taiga ( Jobs Forestry ) is dominated by coniferous forests ( Jobs Forestry ), some broadleaf trees also occur, notably birch, aspen, willow, and rowan. Many smaller herbaceous plants ( Jobs Forestry ) grow closer to the ground. Periodic stand-replacing wildfires (with return times of between 20–200 years) clear out the tree ( Jobs Forestry ) canopies, allowing sunlight to invigorate new growth on the forest ( Jobs Forestry ) floor. For some species, wildfires are a necessary part of the life cycle in the taiga ( Jobs Forestry ); some, e.g. Jack Pine have cones which only open to release their seed after a fire, dispersing their seeds onto the newly cleared ground. Grasses grow wherever they can find a patch of sun, and mosses and lichens thrive on the damp ground and on the sides of tree trunks. In comparison with other biomes ( Jobs Forestry ), however, the taiga ( Jobs Forestry ) has low biological diversity.
Coniferous trees ( Jobs Forestry ) are the dominant plants of the taiga ( Jobs Forestry ) biome ( Jobs Forestry ). A very few species in four main genera are found: the evergreen spruce, fir, and pine, and the deciduous larch. In North America, one or two species of fir and one or two species of spruce are dominant. Across Scandinavia and western Russia, the Scots pine is a common component of the taiga ( Jobs Forestry ), while taiga ( Jobs Forestry ) of the Russian Far East and Mongolia is dominated by larch.
Fauna ( Jobs Forestry )The boreal forest ( Jobs Forestry ), or taiga ( Jobs Forestry ), supports a large range of animals. Canada's boreal forest ( Jobs Forestry ) includes 85 species of mammals, 130 species of fish, and an estimated 32,000 species of insects. Insects play a critical role as pollinators, decomposers and as a part of the food chain; many nesting birds rely on them for food. The cold winters and short summers make the taiga a challenging biome for reptiles and amphibians, which depend on environmental conditions to regulate their body temperatures, and there are only a few species in the boreal forest ( Jobs Forestry ). Some hibernate underground in winter.
The taiga ( Jobs Forestry ) is home to a number of large herbivorous mammals, such as moose and reindeer/caribou. Some areas of the more southern closed boreal forest ( Jobs Forestry ) also have populations of other deer species such as the elk (wapiti) and roe deer. There is also a range of rodent species, including beaver, squirrel, mountain hare, snowshoe hare and vole ( Jobs Forestry ). These species have evolved to survive the harsh winters in their native ranges. Some larger mammals, such as bears, eat heartily during the summer in order to gain weight, and then go into hibernation during the winter. Other animals have adapted layers of fur or feathers to insulate them from the cold.
A number of wildlife species threatened or endangered with extinction can be found in the Canadian boreal forest ( Jobs Forestry ), including woodland caribou, American black bear, grizzly bear and wolverine. Habitat loss, mainly due to logging, is the primary cause of decline for these species.
Due to the climate, carnivorous diets are an inefficient means of obtaining energy; energy is limited, and most energy is lost between trophic levels. Predatory birds (owls and eagles) and other smaller carnivores, including foxes and weasels, feed on the rodents. Larger carnivores, such as lynx and wolves, prey on the larger animals. Omnivores, such as bears and raccoons are fairly common, sometimes picking through human garbage.
More than 300 species of birds have their nesting grounds in the taiga ( Jobs Forestry ). This includes Siberian Thrush, White-throated Sparrow and Black-throated Green Warbler, migrate to this habitat to take advantage of the long summer days and abundance of insects found around the numerous bogs and lakes. Of the 300 species of birds that summer in the taiga, only 30 stay for the winter. These are either carrion-feeding or large raptors that can take live mammal prey, including Golden Eagle, Rough-legged Buzzard, and Raven, or else seed-eating birds, including several species of grouse and crossbills.
Threats ( Jobs Forestry )Human activities ( Jobs Forestry )Large areas of Siberia’s taiga ( Jobs Forestry ) have been harvested for lumber since the collapse of the Soviet Union. In Canada, less than eight percent of the boreal forest ( Jobs Forestry ) is protected from development and more than 50% has been allocated to logging companies for cutting. The main form of forestry ( Jobs Forestry ) in the boreal forest ( Jobs Forestry ) of Canada is clearcutting, where most if not all trees are removed from an area of forest. Clearcuts upwards of 110 km² have been recorded in the Canadian boreal forest. Some of the products from logged boreal forests ( Jobs Forestry ) include toilet paper, copy paper, newsprint and lumber. More than 80% of boreal forest ( Jobs Forestry ) products from Canada are exported for consumption and processing in the United States. Some of the larger cities situated in this biome are Murmansk, Arkhangelsk, Yakutsk, Anchorage, Yellowknife, Tromsø, Luleå and Oulu ( Jobs Forestry ).
Most companies that harvest in Canadian forests ( Jobs Forestry ) are certified by an independent third party agency such as the Forest  ( Jobs Forestry ) Stewardship Council (FSC), Sustainable Forests ( Jobs Forestry ) Initiative (SFI), or the Canadian Standards Association (CSA). While the certification process differs between these various groups, all of them include forest ( Jobs Forestry ) stewardship, respect for aboriginal peoples, compliance with local, provincial and/or national environmental laws, forest ( Jobs Forestry ) worker safety, education and training, and other environmental, business and social requirements. The prompt renewal of all harvest sites by planting or natural renewal is also required.
Insects ( Jobs Forestry )Recent years have seen outbreaks of insect pests in forest-destroying plagues: the spruce-bark beetle (Dendroctonus rufipennis) in the Yukon Territory, Canada, and Alaska; the aspen-leaf miner; the larch sawfly; the spruce budworm (Choristoneura fumiferana); the spruce coneworm.
Protection ( Jobs Forestry )Many nations are taking direct steps to protect the ecology of the taiga by prohibiting logging, mining, oil and gas production, and other forms of development. In February 2010 the Canadian government established protection for 13,000 square kilometres of boreal forest by creating a new 10,700 square kilometre park reserve in the Mealy Mountains area of eastern Canada and a 3,000 square kilometre waterway provincial park that follows alongside the Eagle River from headwaters to sea. The taiga ( Jobs Forestry ) stores enormous quantities of carbon, possibly more than the temperate and tropical forests combined, much of it in peatland.
Natural disturbance ( Jobs Forestry )One of the biggest areas of research and a topic ( Jobs Forestry ) still full of unsolved questions is the recurring disturbance of fire and the role it plays in propagating the lichen woodland . The phenomenon of wildfire by lighting strike is the primary determinant of understory vegetation and because of this, it is considered to be predominate driving force behind community and ecosystem properties in the lichen woodland . The significance of fire is clearly evident when one considers that understory vegetation influences tree seedling germination in the short term and decomposition of biomass and nutrient availability in the long term . The recurrent cycle of large, damaging fire occurs approximately every 70 to 100 years . Understanding the dynamics of this ecosystem is entangled with discovering the successional paths that the vegetation exhibits after a fire. Trees ( Jobs Forestry ), shrubs ( Jobs Forestry ) and lichens ( Jobs Forestry ) all recover from fire induced damage through vegetative reproduction as well as invasion by propagules . Seeds that have fallen and become buried provide little help in re-establishment of a species ( Jobs Forestry ). The reappearance of lichens is reasoned to occur because of varying conditions and light/nutrient availability in each different microstate . Several different studies have been done that have led to the formation of the theory that post-fire development can be propagated by any of four pathways: self replacement, species-dominance relay, species replacement, or gap-phase self replacement . Self replacement is simply the re-establishment of the pre-fire ( Jobs Forestry ) dominant species. Species-dominance relay is a sequential attempt of tree ( Jobs Forestry ) species to establish dominance in the canopy. Species replacement is when fires occur in sufficient frequency to interrupt species dominance relay. Gap-Phase Self-Replacement is the least common and so far has only been documented in Western Canada. It is a self replacement of the surviving species into the canopy gaps after a fire kills another species. The particular pathway taken after a fire disturbance depends on how the landscape is able to support trees as well as fire frequency . Fire frequency has a large role in shaping the original inception of the lower forest ( Jobs Forestry ) line of the lichen woodland taiga ( Jobs Forestry ).
Centuries ago, the southern limits of lichen woodland taiga ( Jobs Forestry ) were only being formed . It has been hypothesized and subsequently proved by Serge Payette that the Spruce-Moss forest ( Jobs Forestry ) ecosystem was changed into the lichen woodland biome due to the initiation of two compounded strong disturbances . The two disturbances were large fire and the appearance and attack of the spruce budworm. The spruce budworm is a deadly insect to the spruce populations in the southern regions of the taiga ( Jobs Forestry ). J.P. Jasinski confirmed this theory five years later stating “Their [lichen woodlands] persistence , along with their previous moss forest histories and current occurrence adjacent to closed moss forests ( Jobs Forestry ), indicate that they are an alternative stable state to the spruce–moss forests ( Jobs Forestry )” .
Climate and geography ( Jobs Forestry )

Interior West Forests (jobs forestry) on Verge of Becoming Net Carbon Emitter

Forests (jobs forestry) in the Interior West could soon flip from carbon sink to carbon source, forest (jobs forestry) experts say.
The region's forests (jobs forestry) once absorbed and stored more carbon from the atmosphere than they released. But huge conflagrations -- like the 138,000-acre Hayman Fire in Colorado in 2002 and the Yellowstone fires of 1988, which scorched 1.2 million acres -- combined with a series of severe bark beetle infestations and disease outbreaks, have left large swaths of dead, decomposing trees in almost every major Western forest (jobs forestry).
Those dead trees are releasing massive amounts of carbon dioxide, turning the region into a net emitter of carbon rather than a CO2 sponge.
The reversal, which has already occurred in Colorado and is anticipated in several other states, is the result of misguided forest (jobs forestry) management practices and a changing climate, forest (jobs forestry) experts say.

Rising temperatures, resulting in shrinking snowpacks and drier conditions, have left the region's forests (jobs forestry) more susceptible to disturbances, such as wildfires, bark beetles and disease.
"In the Interior West, we've had a lot of these disturbances," said Dave Cleaves, the Forest (jobs forestry) Service's climate change adviser, who served as director of the agency's Rocky Mountain Research Station from 2005 to 2007.
But temperature alone is enough to cause mortality in some forests (jobs forestry), scientists have found. According to a study published last year in the journal Science, the death rate for Western old-growth forests (jobs forestry) -- which are generally more resilient and more stable than younger forests (jobs forestry) -- has doubled in the past few decades as temperatures have risen. More trees are dying, while regeneration rates remain unchanged, the study found (Land Letter, Jan. 29, 2009).
Forest (jobs forestry) management has also contributed to the increase in carbon releases.
For about a century, forest (jobs forestry) managers thought the best way to deal with forest (jobs forestry) fires was to suppress them. Eventually, forest (jobs forestry) ecologists learned that fire plays an important role in the ecosystem in many forest (jobs forestry) types, clearing brush and small trees. But the fuel accumulation from years of fire suppression, combined with severe droughts in the early part of this decade, created conditions that allowed large, hotter-than-usual fires to sweep through the Interior West's forests (jobs forestry).
"We've got several times more carbon per acre than those forests (jobs forestry) carried in the early days, when there was a natural fire disturbance interval there," Cleaves said. "And those systems are more susceptible to disturbances now. We've got a lot of acres in the Interior West that have reached that level."
Lost storage capacity
Fires themselves do not release that much carbon into the atmosphere, but the decomposition of the trees killed by fires does, said Michael Ryan, a research ecologist with the Forest (jobs forestry) Service's Rocky Mountain Research Station in Fort Collins, Colo.
As temperatures and mortality rates continue to climb, forests (jobs forestry) will have less carbon storage capacity, and their potential to offset carbon emissions from human sources, such as vehicles and power plants, is likely to decrease. Trees absorb carbon from the atmosphere during photosynthesis and store it in their trunks, branches and leaves.
But the shifting carbon dynamic in the West's forests (jobs forestry) is nothing new, Ryan said.

The reason Western forests (jobs forestry) have been a carbon sink for most of the past century is the growth of new trees after extensive logging and land-clearing for agriculture during westward expansion. During the decades after European settlement of the West, large amounts of carbon were released into the atmosphere, and the region was most likely a source at that time, he said.
"Current forests (jobs forestry) are recovering from past land use as agriculture, pasture or [timber] harvest, and because this period of recovery will eventually end, the resulting forest carbon sink will not continue indefinitely," concluded a synthesis of the current science on forests and carbon that appeared in the Spring 2010 edition of Issues in Ecology, a publication of the Ecological Society of America.
Ryan, who was the lead author on that summary, said the best way to restore a disturbed forest's (jobs forestry) carbon-absorbing capacity is to boost regeneration, so that new growth can help offset the carbon lost by decomposition.
For example, regeneration of severely burned areas in Yellowstone, which has occurred more rapidly than scientists expected after the 1988 fires, has allowed the forest (jobs forestry) as a whole to achieve an almost carbon-neutral state.
"Our study shows it should be approaching this neutrality," Ryan said, referring to a separate study published in the January 2010 issue of Fire Science Briefs. "I think it can recover carbon pretty quickly, which is a surprise."
Cleaves said forest (jobs forestry) managers could improve the carbon-absorbing capacity of other Interior West forests (jobs forestry) by planting more seedlings to accelerate regeneration, especially in intensively burned areas where the forest (jobs forestry) is likely to be replaced by meadows or sparse stands.
"What you worry about is, when you have more fires that burn hotter, do you have some irreversible losses, and how quickly do you place a new system on there so that we're back into producing carbon and producing watershed services and wildlife habitat as quickly as possible after the disturbance?" he said.
Thinning and burning
But Cleaves and other forest (jobs forestry) experts emphasize that national forests (jobs forestry) have to be managed for multiple uses, not just carbon sequestration and storage (Land Letter, Nov. 4).
Thinning and prescribed burns, which help clear out overly dense forests (jobs forestry) and reduce the risk of large, unnaturally hot fires, could help preserve forest (jobs forestry) carbon over the long-term, they point out. But removing carbon at too large a scale could tip forests (jobs forestry) toward becoming a carbon source.
"Some studies show that if you do prescribed burning and thinning and there's a fire, you'll retain more carbon than if you haven't done thinning," Ryan said. "But thinning puts a lot of carbon in the atmosphere. So if there is a carbon benefit from that, it's going to be very small."
Cleaves said the Forest (jobs forestry) Service is taking a cautious approach in working carbon considerations into forest (jobs forestry) management.
"We're trying to manage the risk of carbon loss," Cleaves said. "Our objective is to have a long-term sequestration of carbon. We also want other ecosystem services, like water, habitat and other things you're providing on the same landscape."

The forest (jobs forestry) biome

About 420 million years ago, during the Silurian Period, ancient plants and arthropods began to occupy the land. Over the millions of years that followed, these land colonizers developed and adapted to their new habitat. The first forests (jobs forestry) were dominated by giant horsetails, club mosses, and ferns that stood up to 40 feet tall.
Life on Earth continued to evolve, and in the late Paleozoic, gymnosperms appeared. By the Triassic Period (245-208 mya), gymnosperms dominated the Earth's forests (jobs forestry). In the Cretaceous Period (144-65m mya), the first flowering plants (angiosperms) appeared. They evolved together with insects, birds, and mammals and radiated rapidly, dominating the landscape by the end of the Period. The landscape changed again during the Pleistocene Ice Ages — the surface of the planet that had been dominated by tropical forests for millions of years changed, and temperate forests (jobs forestry) spread in the Northern Hemisphere.
Today, forests (jobs forestry) occupy approximately one-third of Earth's land area, account for over two-thirds of the leaf area of land plants, and contain about 70% of carbon present in living things. They have been held in reverence in folklore and worshipped in ancient religions. However, forests (jobs forestry) are becoming major casualties of civilization as human populations have increased over the past several thousand years, bringing deforestation, pollution, and industrial usage problems to this important biome.
Present-day forest (jobs forestry) biomes, biological communities that are dominated by trees and other woody vegetation (Spurr and Barnes 1980), can be classified according to numerous characteristics, with seasonality being the most widely used. Distinct forest (jobs forestry) types also occur within each of these broad groups.
There are three major types of forests (jobs forestry), classed according to latitude:

• Tropical
• Temperate
• Boreal forests (jobs forestry) (taiga)

Tropical forest (jobs forestry)
Tropical forests (jobs forestry) are characterized by the greatest diversity of species. They occur near the equator, within the area bounded by latitudes 23.5 degrees N and 23.5 degrees S. One of the major characteristics of tropical forests (jobs forestry) is their distinct seasonality: winter is absent, and only two seasons are present (rainy and dry). The length of daylight is 12 hours and varies little.

• Temperature is on average 20-25° C and varies little throughout the year: the average temperatures of the three warmest and three coldest months do not differ by more than 5 degrees.
• Precipitation is evenly distributed throughout the year, with annual rainfall exceeding 2000 mm.
• Soil is nutrient-poor and acidic. Decomposition is rapid and soils are subject to heavy leaching.
• Canopy in tropical forests (jobs forestry) is multilayered and continuous, allowing little light penetration.
• Flora is highly diverse: one square kilometer may contain as many as 100 different tree species. Trees are 25-35 m tall, with buttressed trunks and shallow roots, mostly evergreen, with large dark green leaves. Plants such as orchids, bromeliads, vines (lianas), ferns, mosses, and palms are present in tropical forests (jobs forestry).
• Fauna include numerous birds, bats, small mammals, and insects.

Further subdivisions of this group are determined by seasonal distribution of rainfall:

• evergreen rainforest (jobs forestry): no dry season.
• seasonal rainforest (jobs forestry): short dry period in a very wet tropical region (the forest (jobs forestry) exhibits definite seasonal changes as trees undergo developmental changes simultaneously, but the general character of vegetation remains the same as in evergreen rainforests (jobs forestry)).
• semievergreen forest (jobs forestry): longer dry season (the upper tree story consists of deciduous trees, while the lower story is still evergreen).
• moist/dry deciduous forest (jobs forestry) (monsoon): the length of the dry season increases further as rainfall decreases (all trees are deciduous).

More than one half of tropical forests (jobs forestry) have already been destroyed.
Temperate forest (jobs forestry)
Temperate forests (jobs forestry) occur in eastern North America, northeastern Asia, and western and central Europe. Well-defined seasons with a distinct winter characterize this forest (jobs forestry) biome. Moderate climate and a growing season of 140-200 days during 4-6 frost-free months distinguish temperate forests (jobs forestry).

• Temperature varies from -30° C to 30° C.
• Precipitation (75-150 cm) is distributed evenly throughout the year.
• Soil is fertile, enriched with decaying litter.
• Canopy is moderately dense and allows light to penetrate, resulting in well-developed and richly diversified understory vegetation and stratification of animals.
• Flora is characterized by 3-4 tree species per square kilometer. Trees are distinguished by broad leaves that are lost annually and include such species as oak, hickory, beech, hemlock, maple, basswood, cottonwood, elm, willow, and spring-flowering herbs.
• Fauna is represented by squirrels, rabbits, skunks, birds, deer, mountain lion, bobcat, timber wolf, fox, and black bear.

Further subdivisions of this group are determined by seasonal distribution of rainfall:

• moist conifer and evergreen broad-leaved forests (jobs forestry): wet winters and dry summers (rainfall is concentrated in the winter months and winters are relatively mild).
• dry conifer forests (jobs forestry): dominate higher elevation zones; low precipitation.
• mediterranean forests (jobs forestry): precipitation is concentrated in winter, less than 1000 mm per year.
• temperate coniferous: mild winters, high annual precipitation (greater than 2000 mm).
• temperate broad-leaved rainforests (jobs forestry): mild, frost-free winters, high precipitation (more than 1500 mm) evenly distributed throughout the year.

Only scattered remnants of original temperate forests (jobs forestry) remain.
Boreal forest (jobs forestry) (taiga)
Boreal forests (jobs forestry), or taiga, represent the largest terrestial biome. Occuring between 50 and 60 degrees north latitudes, boreal forests (jobs forestry) can be found in the broad belt of Eurasia and North America: two-thirds in Siberia with the rest in Scandinavia, Alaska, and Canada. Seasons are divided into short, moist, and moderately warm summers and long, cold, and dry winters. The length of the growing season in boreal forests (jobs forestry) is 130 days.

• Temperatures are very low.
• Precipitation is primarily in the form of snow, 40-100 cm annually.
• Soil is thin, nutrient-poor, and acidic.
• Canopy permits low light penetration, and as a result, understory is limited.
• Flora consist mostly of cold-tolerant evergreen conifers with needle-like leaves, such as pine, fir, and spruce.
• Fauna include woodpeckers, hawks, moose, bear, weasel, lynx, fox, wolf, deer, hares, chipmunks, shrews, and bats.

Current extensive logging in boreal forests (jobs forestry) may soon cause their disappearance.

Clout forests (jobs forestry), jobs forestry and Characteristics of forests.

A cloud forest (jobs forestry), also called a fog forest (jobs forestry), is a generally tropical or subtropical evergreen montane moist forest (jobs forestry) characterized by a persistent, frequent or seasonal low-level cloud cover, usually at the canopy level. Cloud forests (jobs forestry) often exhibit an abundance of mosses covering the ground and vegetation, in which case they are also referred to as mossy forests (jobs forestry). Mossy forests (jobs forestry) usually develop on the saddles of mountains, where moisture introduced by settling clouds is more effectively retained.

Distribution and climate  (jobs forestry)

Dependent on local climate, which is affected by the distance to the sea, the exposition and the latitude, the altitude varies from 500 m to 4000 m above sea level. Typically, there is a relatively small band of altitude in which the atmospheric environment is suitable for cloud forest (jobs forestry) development. This is characterized by persistent mist or clouds at the vegetation level, resulting in the reduction of direct sunlight and thus of evapotranspiration. Within cloud forests (jobs forestry), much of the precipitation is in the form of fog drip, where fog condenses on tree leaves and then drips onto the ground below.
Tropical cloud forests (jobs forestry) extend from 23°N to 25°S latitudes and occur in a relatively narrow altitudinal zone with a special atmospheric environment which is characterized by at the vegetation level. Annual rainfall can range from 500 to 10000 mm/year and mean temperature between 8 to 20°C.
While cloud forest (jobs forestry) today is the most widely used term, in some regions these ecosystems or special types of cloud forests (jobs forestry) are called mossy forest (jobs forestry), elfin forest (jobs forestry), montane thicket, dwarf cloud forest (jobs forestry), nuboselva, bosque montano nebuloso, selva de neblina, bosque nuboso, bosque de ceja, selva sublada, nebelwald, wolkenwald, forêt (jobs forestry) néphéliphile, forêt (jobs forestry) de nuage, unmu-rin, bosque anao, foresta (jobs forestry) nebular, mata nebular, matinha nebular, floresta (jobs forestry) fe neblina, floresta (jobs forestry) nuvigena, mata de neblina, matinha de altitude, floresta (jobs forestry) nublada, and floresta (jobs forestry) pluvial montana e/ou alto montana.
The definition of cloud forest (jobs forestry) can be ambiguous, with many countries not using the term (preferring such terms as Afromontane forest (jobs forestry) and upper montane rain forest (jobs forestry), or more localised terms such as the Bolivian yungas, and the laurisilva of the Atlantic Islands), and occasionally subtropical and even temperate forests (jobs forestry) in which similar meteorological conditions occur are considered to be cloud forests (jobs forestry).
Only 1% of the global woodland is covered by cloud forests (jobs forestry).
Important areas of cloud forest (jobs forestry) are in Central- and South America, East- and Central Africa, Indonesia, Malaysia, at the Philippines, Papua-New Guinea and in the Caribbean.

Temperate cloud forests (jobs forestry)

Although far from being universally accepted as true cloud forests (jobs forestry), several forests (jobs forestry) in temperate regions have strong similarities with tropical cloud forests (jobs forestry). The term is further confused by occasional reference to cloud forests (jobs forestry) in tropical countries as "temperate" due to the cooler climate associated with these misty forests (jobs forestry).

Characteristics of cloud forests  (jobs forestry)

In comparison with lower tropical moist forests (jobs forestry), cloud forests (jobs forestry) show a reduced tree stature combined with increased stem density and generally the lower diversity of woody plants. Trees in these regions are generally shorter and more heavily stemmed than in lower altitude forests (jobs forestry) in the same regions, often with gnarled trunks and branches, forming dense, compact crownes. Their leaves become smaller, thicker and harder with increasing altitude. The high moisture promotes the development of a high biomass and biodiversity of epiphyte, particularly bryophytes, lichens, ferns (including filmy ferns), bromeliads and orchids. The number of endemic plants can be very high.
An important feature of cloud forests (jobs forestry) is that the tree crowns can intercept the wind-driven cloud moisture, part of which drips to the ground. This water stripped from the clouds is termed horizontal or occult (because it is not recorded with normal rainfall measurement) precipitation, and can be an important contribution to the hydrologic cycle.
Due to the high water content of the soil, the reduced solar radiation and the low rates of decomposition and mineralization, the soil acidity is very high, with mor humus and peat often forming the upper soil layer.
Stadtmüller (1987) distinguishes two general types of tropical montane cloud forests (jobs forestry):

• Areas with a high annual precipitation due to a frequent cloud cover in combination with heavy and sometimes persistent orographic rainfall; such forests (jobs forestry) have a perceptible canopy strata, a high number of epiphytes and a thick peat layer which has a high storage capacity for water and control the runoff;
• In drier areas with mainly seasonal rainfall cloud stripping can amount to a large proportion of the annual precipitation.

Importance of cloud forests (jobs forestry)

Watershed function. Because of the cloud stripping strategy the effective rainfall can be doubled in dry seasons and increase the wet season rainfall by about 10 percent.Experiments of Costin and Wimbush (1961) showed that the tree canopies of non-cloud forests (jobs forestry) intercept and evaporate 20 percent more of the precipitation than cloud forests (jobs forestry), which means a loss to the land component of the hydrological cycle.

Vegetation. Tropical montane cloud forests (jobs forestry) are not as species-rich as tropical lowland forests (jobs forestry) but they provide the habitats for many species that are found nowhere else. For example, the Cerro de la Neblina, a cloud covered mountain in the south of Venezuela accommodates many shrubs, orchids and insectivorous plants which are restricted to this mountain only.

Fauna. The endemism in animals is also very high. In Peru, more than one third of the 270 endemic birds, mammals and frogs are found in cloud forests (jobs forestry). One of the best known cloud forest mammal is the Mountain Gorilla (Gorilla b. beringei). Many of those endemic animals have important functions such as seed dispersal and forest (jobs forestry) dynamics in this ecosystems.

Current situation

In 1970, the original extent of cloud forests (jobs forestry) was around 50 million hectares. Population growth, poverty and uncontrolled land use have contributed to the loss of cloud forests (jobs forestry). The 1990 Global Forest (jobs forestry) Survey found that 1.1% of tropical mountain and highland forests (jobs forestry) were lost each year, which was higher than in any other tropical forests (jobs forestry). In Colombia, one of the countries with the largest area of cloud forests (jobs forestry), only 10-20% of the initial cloud forest (jobs forestry) cover remains. Significant areas have been converted to plantations, or for use in agriculture and pasture. Important crops in montane forest (jobs forestry) zones are tea and coffee, but also logging special species such as Podocarpus causes changes to forest (jobs forestry) structure.
Currently, one third of all cloud forests (jobs forestry) are protected.

Impact of climate change on cloud forests (jobs forestry)

Because of their delicate dependency on local climate, cloud forests (jobs forestry) will be strongly affected by global climate change. A number of climate models suggest that the low-altitude cloudiness will be reduced, which means that the optimum climate for many cloud forest (jobs forestry) habitats will increase in altitude. Linked to the reduction of cloud moisture immersion and increasing temperature, the hydrological cycle will change with the consequence that the system will dry out. This can result in the wilting and the death of epiphytes, which rely on high humidity. Frogs and lizards are expected to suffer from increased drought. In addition, climate changes can result in a higher amount of hurricanes, which may increase damage to tropical montane cloud forests (jobs forestry). All in all the results of the climate change will be a loss in biodiversity, altitude shifts in species ranges and community reshuffling and, in some areas, complete loss of cloud forests (jobs forestry).

Forests management and jobs forestry

Forest (jobs forestry) management
is the branch of forestry (jobs forestry) concerned with the overall administrative, economic, legal, and social aspects and with the essentially scientific and technical aspects, especially silviculture, protection, and forest (jobs forestry) regulation. This includes management for aesthetics, fish, recreation, urban values, water, wilderness, wildlife, wood products, forest (jobs forestry) genetic resources and other forest (jobs forestry) resource values. Management can be based on conservation, economics, or a mixture of the two. Techniques include timber extraction, planting and replanting of various species, cutting roads and pathways through forests (jobs forestry), and preventing fire.

Public input and awareness (jobs forestry)

There has been an increased public awareness of natural resource policy, including forest (jobs forestry) management. Public concern regarding forest (jobs forestry) management may have shifted from the extraction of timber to the preservation of additional forest resources, including wildlife and old growth forest (jobs forestry), protecting biodiversity, watershed management, and recreation. Increased environmental awareness may contribute to an increased public mistrust of forest (jobs forestry) management professionals.
Many tools like GIS modelling have been developed to improve forest (jobs forestry) inventory and management planning

Wildlife considerations (jobs forestry)

The abundance and diversity of birds, mammals, amphibians and other wildlife are affected by strategies and types of forest (jobs forestry) management.

distribution and classification of forests.

Etymology

The word "forest" ( jobs forestry ) comes from Middle English forest ( jobs forestry ), from Old French forest  ( jobs forestry )(also forès) "forest ( jobs forestry ), vast expanse covered by trees", believed to be a borrowing (probably via Frankish or Old High German) of the Medieval Latin word foresta "open wood" ( jobs forestry ). Foresta  ( jobs forestry ) was first used by Carolingian scribes in the Capitularies of Charlemagne to refer specifically to the king's royal hunting grounds. The term was not endemic to Romance languages (e.g. native words for "forest" ( jobs forestry ) in the Romance languages evolved out of the Latin word silva "forest, wood" ( jobs forestry ); cf. Italian, Spanish, Portuguese selva; Romanian silvă; Old French selve); and cognates in Romance languages, such as Italian foresta ( jobs forestry ), Spanish and Portuguese floresta ( jobs forestry ), etc. are all ultimately borrowings of the French word. The exact origin of Medieval Latin foresta ( jobs forestry ) is obscure. Some authorities claim the word derives from the Late Latin phrase forestam silvam, ( jobs forestry ) meaning "the outer wood"; others claim the term is a latinisation of the Frankish word *forhist "forest ( jobs forestry ), wooded country", assimilated to forestam silvam (a common practise among Frankish scribes). Frankish *forhist is attested by Old High German forst "forest" ( jobs forestry ), Middle Low German vorst "forest" ( jobs forestry ), Old English fyrhþ "forest ( jobs forestry ), woodland, game preserve, hunting ground", and Old Norse fýri "coniferous forest", all of which derive from Proto-Germanic *furχísa-, *furχíþja- "a fir-wood, coniferous forest ( jobs forestry )", from Proto-Indo-European *perk^wu- "a coniferous or mountain forest, wooded height". Uses of the word "forest" ( jobs forestry ) in English to denote any uninhabited area of non-enclosure are now considered archaic. The word was introduced by the Norman rulers of England as a legal term (appearing in Latin texts like the Magna Carta) denoting an uncultivated area legally set aside for hunting by feudal nobility (see Royal Forest ( jobs forestry )). These hunting forests ( jobs forestry ) were not necessarily wooded much, if at all. However, as hunting forests ( jobs forestry ) did often include considerable areas of woodland, the word "forest" ( jobs forestry ) eventually came to mean wooded land more generally.By the start of the fourteenth century the word appeared in English texts, indicating all three senses: the most common one, the legal term and the archaic usage.
Other terms used to mean "an area with a high density of trees" are wood, woodland, wold, weald, holt, frith and firth. Unlike forest ( jobs forestry ), these are all derived from Old English and were not borrowed from another language. Some now reserve the term woodland for an area with more open space between trees.

Distribution

Forests ( jobs forestry ) can be found in all regions capable of sustaining tree growth, at altitudes up to the tree line, except where natural fire frequency or other disturbance is too high, or where the environment has been altered by human activity.
The latitudes 10° north and south of the Equator are mostly covered in tropical rainforest, and the latitudes between 53°N and 67°N have boreal forest ( jobs forestry ). As a general rule, forests dominated by angiosperms (broadleaf forests ( jobs forestry )) are more species-rich than those dominated by gymnosperms (conifer, montane, or needleleaf forests ( jobs forestry )), although exceptions exist.
Forests ( jobs forestry ) sometimes contain many tree species only within a small area (as in tropical rain and temperate deciduous forests ( jobs forestry )), or relatively few species over large areas (e.g., taiga and arid montane coniferous forests ( jobs forestry )). Forests ( jobs forestry ) are often home to many animal and plant species, and biomass per unit area is high compared to other vegetation communities. Much of this biomass occurs below ground in the root systems and as partially decomposed plant detritus. The woody component of a forest ( jobs forestry ) contains lignin, which is relatively slow to decompose compared with other organic materials such as cellulose or carbohydrate.
Forests ( jobs forestry ) are differentiated from woodlands by the extent of canopy coverage: in a forest ( jobs forestry ), the branches and the foliage of separate trees often meet or interlock, although there can be gaps of varying sizes within an area referred to as forest ( jobs forestry ). A woodland has a more continuously open canopy, with trees spaced further apart, which allows more sunlight to penetrate to the ground between them (also see: savanna).
Among the major forested ( jobs forestry ) biomes are:

• rain forest ( jobs forestry ) (tropical and temperate)
• taiga
• temperate hardwood forest ( jobs forestry )
• tropical dry forest ( jobs forestry )

Classification

Forests ( jobs forestry ) can be classified in different ways and to different degrees of specificity. One such way is in terms of the "biome" in which they exist, combined with leaf longevity of the dominant species (whether they are evergreen or deciduous). Another distinction is whether the forests ( jobs forestry ) composed predominantly of broadleaf trees, coniferous (needle-leaved) trees ( jobs forestry ), or mixed.

• Boreal forests ( jobs forestry ) occupy the subarctic zone and are generally evergreen and coniferous.
• Temperate zones support both broadleaf deciduous forests ( jobs forestry ) (e.g., temperate deciduous forest ( jobs forestry )) and evergreen coniferous forests ( jobs forestry ) (e.g., Temperate coniferous forests ( jobs forestry ) and Temperate rainforests ( jobs forestry )). Warm temperate zones support broadleaf evergreen forests ( jobs forestry ), including laurel forests ( jobs forestry ).
• Tropical and subtropical forests ( jobs forestry ) include tropical and subtropical moist forests ( jobs forestry ), tropical and subtropical dry forests ( jobs forestry ), and tropical and subtropical coniferous forests ( jobs forestry ).
• Physiognomy classifies forests ( jobs forestry ) based on their overall physical structure or developmental stage (e.g. old growth vs. second growth).
• Forests ( jobs forestry ) can also be classified more specifically based on the climate and the dominant tree species present, resulting in numerous different forest ( jobs forestry ) types (e.g., ponderosa pine/Douglas-fir forest ( jobs forestry )).

A number of global forest ( jobs forestry ) classification systems have been proposed, but none has gained universal acceptance.UNEP-WCMC's forest ( jobs forestry ) category classification system is a simplification of other more complex systems (e.g. UNESCO's forest ( jobs forestry ) and woodland 'subformations'). This system divides the world's forests ( jobs forestry ) into 26 major types, which reflect climatic zones as well as the principal types of trees. These 26 major types can be reclassified into 6 broader categories: temperate needleleaf; temperate broadleaf and mixed; tropical moist; tropical dry; sparse trees and parkland; and forest plantations. Each category is described as a separate section below.

Temperate needleleaf

Temperate needleleaf forests mostly occupy the higher latitude regions of the northern hemisphere, as well as high altitude zones and some warm temperate areas, especially on nutrient-poor or otherwise unfavourable soils. These forests ( jobs forestry ) are composed entirely, or nearly so, of coniferous species (Coniferophyta). In the Northern Hemisphere pines Pinus, spruces Picea, larches Larix, silver firs Abies, Douglas firs Pseudotsuga and hemlocks Tsuga, make up the canopy, but other taxa are also important. In the Southern Hemisphere most coniferous trees ( jobs forestry ), members of the Araucariaceae and Podocarpaceae, occur in mixtures with broadleaf species that are classed as broadleaf and mixed forests ( jobs forestry ).

Temperate broadleaf and mixed

Temperate broadleaf and mixed forests ( jobs forestry ) include a substantial component of trees in the Anthophyta. They are generally characteristic of the warmer temperate latitudes, but extend to cool temperate ones, particularly in the southern hemisphere. They include such forest ( jobs forestry ) types as the mixed deciduous forests ( jobs forestry ) of the USA and their counterparts in China and Japan, the broadleaf evergreen rain forests ( jobs forestry ) of Japan, Chile and Tasmania, the sclerophyllous forests ( jobs forestry ) of Australia, Central Chile, the Mediterranean and California, and the southern beech Nothofagus forests ( jobs forestry ) of Chile and New Zealand.

Tropical moist

Tropical moist forests ( jobs forestry ) include many different forest ( jobs forestry ) types. The best known and most extensive are the lowland evergreen broadleaf rainforests include, for example: the seasonally inundated várzea and igapó forests ( jobs forestry ) and the terra firma forests ( jobs forestry ) of the Amazon Basin; the peat swamp forests ( jobs forestry ) and moist dipterocarp forests ( jobs forestry ) of Southeast Asia; and the high forests ( jobs forestry ) of the Congo Basin. The forests ( jobs forestry ) of tropical mountains are also included in this broad category, generally divided into upper and lower montane formations on the basis of their physiognomy, which varies with altitude. The montane forests ( jobs forestry ) include cloud forest ( jobs forestry ), those forests ( jobs forestry ) at middle to high altitude, which derive a significant part of their water budget from cloud, and support a rich abundance of vascular and nonvascular epiphytes. Mangrove forests ( jobs forestry ) also fall within this broad category, as do most of the tropical coniferous forests ( jobs forestry ) of Central America.

Tropical dry

Tropical dry forests ( jobs forestry ) are characteristic of areas in the tropics affected by seasonal drought. The seasonality of rainfall is usually reflected in the deciduousness of the forest ( jobs forestry ) canopy, with most trees being leafless for several months of the year. However, under some conditions, e.g. less fertile soils or less predictable drought regimes, the proportion of evergreen species increases and the forests ( jobs forestry ) are characterised as "sclerophyllous". Thorn forest ( jobs forestry ), a dense forest of low stature with a high frequency of thorny or spiny species, is found where drought is prolonged, and especially where grazing animals are plentiful. On very poor soils, and especially where fire is a recurrent phenomenon, woody savannas develop (see 'sparse trees and parkland').

Sparse trees and parkland

Sparse trees and parkland are forests ( jobs forestry ) with open canopies of 10-30% crown cover. They occur principally in areas of transition from forested ( jobs forestry ) to non-forested ( jobs forestry ) landscapes. The two major zones in which these ecosystems occur are in the boreal region and in the seasonally dry tropics. At high latitudes, north of the main zone of boreal forest ( jobs forestry ) or taiga, growing conditions are not adequate to maintain a continuous closed forest ( jobs forestry ) cover, so tree cover is both sparse and discontinuous. This vegetation is variously called open taiga, open lichen woodland, and forest ( jobs forestry ) tundra. It is species-poor, has high bryophyte cover, and is frequently affected by fire.

Forest ( jobs forestry ) plantations

Forest ( jobs forestry ) plantations, generally intended for the production of timber and pulpwood increase the total area of forest ( jobs forestry ) worldwide. Commonly mono-specific and/or composed of introduced tree species, these ecosystems are not generally important as habitat for native biodiversity. However, they can be managed in ways that enhance their biodiversity protection functions and they are important providers of ecosystem services such as maintaining nutrient capital, protecting watersheds and soil structure as well as storing carbon. They may also play an important role in alleviating pressure on natural forests ( jobs forestry ) for timber and fuelwood production.

Forest ( jobs forestry ) categories

28 forest ( jobs forestry ) categories are used to enable the translation of forest types from national and regional classification systems to a harmonised global one:

Temperate and boreal forest ( jobs forestry ) types

1. Evergreen needleleaf forest ( jobs forestry ) - Natural forest ( jobs forestry ) with > 30% canopy cover, in which the canopy is predominantly (> 75%) needleleaf and evergreen.
2. Deciduous needleleaf forests ( jobs forestry ) - Natural forests with > 30% canopy cover, in which the canopy is predominantly (> 75%) needleleaf and deciduous.
3. Mixed broadleaf/needleleaf forest ( jobs forestry ) - Natural forest ( jobs forestry ) with > 30% canopy cover, in which the canopy is composed of a more or less even mixture of needleleaf and broadleaf crowns (between 50:50% and 25:75%).
4. Broadleaf evergreen forest ( jobs forestry ) - Natural forests ( jobs forestry ) with > 30% canopy cover, the canopy being > 75% evergreen and broadleaf.
5. Deciduous broadleaf forest ( jobs forestry ) - Natural forests ( jobs forestry ) with > 30% canopy cover, in which > 75% of the canopy is deciduous and broadleaves predominate (> 75% of canopy cover).
6. Freshwater swamp forest ( jobs forestry ) - Natural forests ( jobs forestry ) with > 30% canopy cover, composed of trees with any mixture of leaf type and seasonality, but in which the predominant environmental characteristic is a waterlogged soil.
7. Sclerophyllous dry forest ( jobs forestry ) - Natural forest ( jobs forestry ) with > 30% canopy cover, in which the canopy is mainly composed of sclerophyllous broadleaves and is > 75% evergreen.
8. Disturbed natural forest ( jobs forestry ) - Any forest ( jobs forestry ) type above that has in its interior significant areas of disturbance by people, including clearing, felling for wood extraction, anthropogenic fires, road construction, etc.
9. Sparse trees and parkland - Natural forests ( jobs forestry ) in which the tree canopy cover is between 10-30%, such as in the steppe regions of the world. Trees of any type (e.g., needleleaf, broadleaf, palms).
10. Exotic species plantation - Intensively managed forests ( jobs forestry ) with > 30% canopy cover, which have been planted by people with species not naturally occurring in that country.
11. Native species plantation - Intensively managed forests ( jobs forestry ) with > 30% canopy cover, which have been planted by people with species that occur naturally in that country.
12. *Unspecified forest ( jobs forestry ) plantation - Forest ( jobs forestry ) plantations showing extent only with no further information about their type, This data currently only refers to the Ukraine.
13. *Unclassified forest ( jobs forestry ) data - Forest ( jobs forestry ) data showing forest ( jobs forestry ) extent only with no further information about their type.

Those marked * have been created as a result of data holdings which do not specify the forest ( jobs forestry ) type, hence 26 categories are quoted, not 28 shown here.

Tropical forest ( jobs forestry ) types

1. Lowland evergreen broadleaf rain forest ( jobs forestry ) - Natural forests ( jobs forestry ) with > 30% canopy cover, below 1,200 m (3,937 ft) altitude that display little or no seasonality, the canopy being >75% evergreen broadleaf.
2. Lower montane forest ( jobs forestry ) - Natural forests ( jobs forestry ) with > 30% canopy cover, between 1200–1800 m altitude, with any seasonality regime and leaf type mixture.
3. Upper montane forest ( jobs forestry ) - Natural forests ( jobs forestry ) with > 30% canopy cover, above 1,800 m (5,906 ft) altitude, with any seasonality regime and leaf type mixture.
4. Freshwater swamp forest ( jobs forestry ) - Natural forests ( jobs forestry ) with > 30% canopy cover, below 1,200 m (3,937 ft) altitude, composed of trees with any mixture of leaf type and seasonality, but in which the predominant environmental characteristic is a waterlogged soil.
5. Semi-evergreen moist broadleaf forest ( jobs forestry ) - Natural forests ( jobs forestry ) with > 30% canopy cover, below 1,200 m (3,937 ft) altitude in which between 50-75% of the canopy is evergreen, > 75% are broadleaves, and the trees display seasonality of flowering and fruiting.
6. Mixed broadleaf/needleleaf forest ( jobs forestry ) - Natural forests ( jobs forestry ) with > 30% canopy cover, below 1,200 m (3,937 ft) altitude, in which the canopy is composed of a more or less even mixture of needleleaf and broadleaf crowns (between 50:50% and 25:75%).
7. Needleleaf forest ( jobs forestry ) - Natural forest ( jobs forestry ) with > 30% canopy cover, below 1,200 m (3,937 ft) altitude, in which the canopy is predominantly (> 75%) needleleaf.
8. Mangroves - Natural forests ( jobs forestry ) with > 30% canopy cover, composed of species of mangrove tree, generally along coasts in or near brackish or seawater.
9. Disturbed natural forest ( jobs forestry ) - Any forest ( jobs forestry ) type above that has in its interior significant areas of disturbance by people, including clearing, felling for wood extraction, anthropogenic fires, road construction, etc.
10. Deciduous/semi-deciduous broadleaf forest ( jobs forestry ) - Natural forests ( jobs forestry ) with > 30% canopy cover, below 1,200 m (3,937 ft) altitude in which between 50-100% of the canopy is deciduous and broadleaves predominate (> 75% of canopy cover).
11. Sclerophyllous dry forest ( jobs forestry ) - Natural forests ( jobs forestry ) with > 30% canopy cover, below 1,200 m (3,937 ft) altitude, in which the canopy is mainly composed of sclerophyllous broadleaves and is > 75% evergreen.
12. Thorn forest ( jobs forestry ) - Natural forests ( jobs forestry ) with > 30% canopy cover, below 1,200 m (3,937 ft) altitude, in which the canopy is mainly composed of deciduous trees with thorns and succulent phanerophytes with thorns may be frequent.
13. Sparse trees and parkland - Natural forests ( jobs forestry ) in which the tree canopy cover is between 10-30%, such as in the savannah regions of the world. Trees of any type (e.g., needleleaf, broadleaf, palms).
14. Exotic species plantation - Intensively managed forests ( jobs forestry ) with > 30% canopy cover, which have been planted by people with species not naturally occurring in that country.
15. Native species plantation - Intensively managed forests ( jobs forestry ) with > 30% canopy cover, which have been planted by people with species that occur naturally in that country.

Forest ( jobs forestry ) loss and management

The scientific study of forest ( jobs forestry ) species and their interaction with the environment is referred to as forest ( jobs forestry ) ecology, while the management of forests ( jobs forestry ) is often referred to as forestry ( jobs forestry ). Forest ( jobs forestry ) management has changed considerably over the last few centuries, with rapid changes from the 1980s onwards culminating in a practice now referred to as sustainable forest ( jobs forestry ) management. Forest ( jobs forestry ) ecologists concentrate on forest ( jobs forestry ) patterns and processes, usually with the aim of elucidating cause and effect relationships. Foresters ( jobs forestry ) who practice sustainable forest ( jobs forestry ) management focus on the integration of ecological, social and economic values, often in consultation with local communities and other stakeholders.
Anthropogenic factors that can affect forests ( jobs forestry ) include logging, urban sprawl, human-caused forest ( jobs forestry ) fires, acid rain, invasive species, and the slash and burn practices of swidden agriculture or shifting cultivation. The loss and re-growth of forest ( jobs forestry ) leads to a distinction between two broad types of forest ( jobs forestry ), primary or old-growth forest ( jobs forestry ) and secondary forest ( jobs forestry ). There are also many natural factors that can cause changes in forests ( jobs forestry ) over time including forest ( jobs forestry ) fires, insects, diseases, weather, competition between species, etc. In 1997, the World Resources Institute recorded that only 20% of the world's original forests ( jobs forestry ) remained in large intact tracts of undisturbed forest ( jobs forestry ). More than 75% of these intact forests ( jobs forestry ) lie in three countries - the Boreal forests ( jobs forestry ) of Russia and Canada and the rainforest of Brazil. In 2006 this information on intact forests ( jobs forestry ) was updated using latest available satellite imagery.
Canada has about 4,020,000 square kilometres (1,550,000 sq mi) of forest ( jobs forestry ) land. More than 90% of forest ( jobs forestry ) land is publicly owned and about 50% of the total forest ( jobs forestry ) area is allocated for harvesting. These allocated areas are managed using the principles of sustainable forest ( jobs forestry ) management, which includes extensive consultation with local stakeholders. About eight percent of Canada’s forest ( jobs forestry ) is legally protected from resource development (Global Forest ( jobs forestry ) Watch Canada)(Natural Resources Canada). Much more forest ( jobs forestry ) land — about 40 percent of the total forest ( jobs forestry ) land base — is subject to varying degrees of protection through processes such as integrated land-use planning or defined management areas such as certified forests ( jobs forestry ) (Natural Resources Canada)
By December 2006, over 1,237,000 square kilometers of forest ( jobs forestry ) land in Canada (about half the global total) had been certified as being sustainably managed (Canadian Sustainable Forestry ( jobs forestry ) Certification Coalition). Clearcutting, first used in the latter half of the 20th century, is less expensive, but devastating to the environment and companies are required by law to ensure that harvested areas are adequately regenerated. Most Canadian provinces have regulations limiting the size of clearcuts, although some older clearcuts can range upwards of 110 square kilometres (27,000 acres) in size which were cut over several years. China instituted a ban on logging, beginning in 1998, due to the destruction caused by clearcutting. Selective cutting avoids the erosion, and flooding, that result from clearcutting.
In the United States, most forests ( jobs forestry ) have historically been affected by humans to some degree, though in recent years improved forestry ( jobs forestry ) practices has helped regulate or moderate large scale or severe impacts. However, the United States Forest ( jobs forestry ) Service estimates a net loss of about 2 million hectares (4,942,000 acres) between 1997 and 2020; this estimate includes conversion of forest ( jobs forestry ) land to other uses, including urban and suburban development, as well as afforestation and natural reversion of abandoned crop and pasture land to forest ( jobs forestry ). However, in many areas of the United States, the area of forest is stable or increasing, particularly in many northern states. The opposite problem from flooding has plagued national forests ( jobs forestry ), with loggers complaining that a lack of thinning and proper forest ( jobs forestry ) management has resulted in large forest ( jobs forestry ) fires.
Old-growth forest ( jobs forestry ) contains mainly natural patterns of biodiversity in established seral patterns, and they contain mainly species native to the region and habitat. The natural formations and processes have not been affected by humans with a frequency or intensity to change the natural structure and components of the habitat. Secondary forest ( jobs forestry ) contains significant elements of species which were originally from other regions or habitats.
Smaller areas of woodland in cities may be managed as Urban forestry ( jobs forestry ), sometimes within public parks. These are often created for human benefits; Attention Restoration Theory argues that spending time in nature reduces stress and improves health, while forest ( jobs forestry ) schools and kindergartens help young people to develop social as well as scientific skills in forests. These typically need to be close to where the children live, for practical logistics.