Sunday, January 2, 2011

About forestry jobs in pakistan, forests, etymology, distribution and classification of forests.

Forest ( forestry jobs in pakistan )

A forest ( forestry jobs in pakistan ) (also called a wood, woodland, wold, weald, holt, frith, or firth) is an area with a high density of trees ( forestry jobs in pakistan ). There are many definitions of a forest ( forestry jobs in pakistan ), based on the various criteria.These plant communities cover approximately 9.4% of the Earth's surface (or 30% of total land area), though they once covered much more (about 50% of total land area), in many different regions and function as habitats for organisms, hydrologic flow modulators, and soil conservers, constituting one of the most important aspects of the Earth's biosphere. Although a forest ( forestry jobs in pakistan ) is classified primarily by trees a forest ( forestry jobs in pakistan ) ecosystem is defined intrinsically with additional species such as fungi.

Etymology

The word "forest" ( forestry jobs in pakistan ) comes from Middle English forest ( forestry jobs in pakistan ), from Old French forest  ( forestry jobs in pakistan )(also forès) "forest ( forestry jobs in pakistan ), 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" ( forestry jobs in pakistan ). Foresta  ( forestry jobs in pakistan ) 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" ( forestry jobs in pakistan ) in the Romance languages evolved out of the Latin word silva "forest, wood" ( forestry jobs in pakistan ); cf. Italian, Spanish, Portuguese selva; Romanian silvă; Old French selve); and cognates in Romance languages, such as Italian foresta ( forestry jobs in pakistan ), Spanish and Portuguese floresta ( forestry jobs in pakistan ), etc. are all ultimately borrowings of the French word. The exact origin of Medieval Latin foresta ( forestry jobs in pakistan ) is obscure. Some authorities claim the word derives from the Late Latin phrase forestam silvam, ( forestry jobs in pakistan ) meaning "the outer wood"; others claim the term is a latinisation of the Frankish word *forhist "forest ( forestry jobs in pakistan ), wooded country", assimilated to forestam silvam (a common practise among Frankish scribes). Frankish *forhist is attested by Old High German forst "forest" ( forestry jobs in pakistan ), Middle Low German vorst "forest" ( forestry jobs in pakistan ), Old English fyrhþ "forest ( forestry jobs in pakistan ), 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 ( forestry jobs in pakistan )", from Proto-Indo-European *perkwu- "a coniferous or mountain forest, wooded height". Uses of the word "forest" ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan )). These hunting forests ( forestry jobs in pakistan ) were not necessarily wooded much, if at all. However, as hunting forests ( forestry jobs in pakistan ) did often include considerable areas of woodland, the word "forest" ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ), 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 ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ). As a general rule, forests dominated by angiosperms (broadleaf forests ( forestry jobs in pakistan )) are more species-rich than those dominated by gymnosperms (conifer, montane, or needleleaf forests ( forestry jobs in pakistan )), although exceptions exist.
Forests ( forestry jobs in pakistan ) sometimes contain many tree species only within a small area (as in tropical rain and temperate deciduous forests ( forestry jobs in pakistan )), or relatively few species over large areas (e.g., taiga and arid montane coniferous forests ( forestry jobs in pakistan )). Forests ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) contains lignin, which is relatively slow to decompose compared with other organic materials such as cellulose or carbohydrate.
Forests ( forestry jobs in pakistan ) are differentiated from woodlands by the extent of canopy coverage: in a forest ( forestry jobs in pakistan ), 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 ( forestry jobs in pakistan ). 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 ( forestry jobs in pakistan ) biomes are:

Classification

Forests ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) composed predominantly of broadleaf trees, coniferous (needle-leaved) trees ( forestry jobs in pakistan ), or mixed.
A number of global forest ( forestry jobs in pakistan ) classification systems have been proposed, but none has gained universal acceptance.UNEP-WCMC's forest ( forestry jobs in pakistan ) category classification system is a simplification of other more complex systems (e.g. UNESCO's forest ( forestry jobs in pakistan ) and woodland 'subformations'). This system divides the world's forests ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ), members of the Araucariaceae and Podocarpaceae, occur in mixtures with broadleaf species that are classed as broadleaf and mixed forests ( forestry jobs in pakistan ).

Temperate broadleaf and mixed

Temperate broadleaf and mixed forests ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) types as the mixed deciduous forests ( forestry jobs in pakistan ) of the USA and their counterparts in China and Japan, the broadleaf evergreen rain forests ( forestry jobs in pakistan ) of Japan, Chile and Tasmania, the sclerophyllous forests ( forestry jobs in pakistan ) of Australia, Central Chile, the Mediterranean and California, and the southern beech Nothofagus forests ( forestry jobs in pakistan ) of Chile and New Zealand.

Tropical moist

Tropical moist forests ( forestry jobs in pakistan ) include many different forest ( forestry jobs in pakistan ) types. The best known and most extensive are the lowland evergreen broadleaf rainforests include, for example: the seasonally inundated várzea and igapó forests ( forestry jobs in pakistan ) and the terra firma forests ( forestry jobs in pakistan ) of the Amazon Basin; the peat swamp forests ( forestry jobs in pakistan ) and moist dipterocarp forests ( forestry jobs in pakistan ) of Southeast Asia; and the high forests ( forestry jobs in pakistan ) of the Congo Basin. The forests ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) include cloud forest ( forestry jobs in pakistan ), those forests ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) also fall within this broad category, as do most of the tropical coniferous forests ( forestry jobs in pakistan ) of Central America.

Tropical dry

Tropical dry forests ( forestry jobs in pakistan ) are characteristic of areas in the tropics affected by seasonal drought. The seasonality of rainfall is usually reflected in the deciduousness of the forest ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) are characterised as "sclerophyllous". Thorn forest ( forestry jobs in pakistan ), 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 ( forestry jobs in pakistan ) with open canopies of 10-30% crown cover. They occur principally in areas of transition from forested ( forestry jobs in pakistan ) to non-forested ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) or taiga, growing conditions are not adequate to maintain a continuous closed forest ( forestry jobs in pakistan ) cover, so tree cover is both sparse and discontinuous. This vegetation is variously called open taiga, open lichen woodland, and forest ( forestry jobs in pakistan ) tundra. It is species-poor, has high bryophyte cover, and is frequently affected by fire.

Forest ( forestry jobs in pakistan ) plantations

Forest ( forestry jobs in pakistan ) plantations, generally intended for the production of timber and pulpwood increase the total area of forest ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) for timber and fuelwood production.

Forest ( forestry jobs in pakistan ) categories

28 forest ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) types

  1. Evergreen needleleaf forest ( forestry jobs in pakistan ) - Natural forest ( forestry jobs in pakistan ) with > 30% canopy cover, in which the canopy is predominantly (> 75%) needleleaf and evergreen.
  2. Deciduous needleleaf forests ( forestry jobs in pakistan ) - Natural forests with > 30% canopy cover, in which the canopy is predominantly (> 75%) needleleaf and deciduous.
  3. Mixed broadleaf/needleleaf forest ( forestry jobs in pakistan ) - Natural forest ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) - Natural forests ( forestry jobs in pakistan ) with > 30% canopy cover, the canopy being > 75% evergreen and broadleaf.
  5. Deciduous broadleaf forest ( forestry jobs in pakistan ) - Natural forests ( forestry jobs in pakistan ) with > 30% canopy cover, in which > 75% of the canopy is deciduous and broadleaves predominate (> 75% of canopy cover).
  6. Freshwater swamp forest ( forestry jobs in pakistan ) - Natural forests ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) - Natural forest ( forestry jobs in pakistan ) with > 30% canopy cover, in which the canopy is mainly composed of sclerophyllous broadleaves and is > 75% evergreen.
  8. Disturbed natural forest ( forestry jobs in pakistan ) - Any forest ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) with > 30% canopy cover, which have been planted by people with species that occur naturally in that country.
  12. *Unspecified forest ( forestry jobs in pakistan ) plantation - Forest ( forestry jobs in pakistan ) plantations showing extent only with no further information about their type, This data currently only refers to the Ukraine.
  13. *Unclassified forest ( forestry jobs in pakistan ) data - Forest ( forestry jobs in pakistan ) data showing forest ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) type, hence 26 categories are quoted, not 28 shown here.

Tropical forest ( forestry jobs in pakistan ) types

  1. Lowland evergreen broadleaf rain forest ( forestry jobs in pakistan ) - Natural forests ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) - Natural forests ( forestry jobs in pakistan ) with > 30% canopy cover, between 1200–1800 m altitude, with any seasonality regime and leaf type mixture.
  3. Upper montane forest ( forestry jobs in pakistan ) - Natural forests ( forestry jobs in pakistan ) with > 30% canopy cover, above 1,800 m (5,906 ft) altitude, with any seasonality regime and leaf type mixture.
  4. Freshwater swamp forest ( forestry jobs in pakistan ) - Natural forests ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) - Natural forests ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) - Natural forests ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) - Natural forest ( forestry jobs in pakistan ) with > 30% canopy cover, below 1,200 m (3,937 ft) altitude, in which the canopy is predominantly (> 75%) needleleaf.
  8. Mangroves - Natural forests ( forestry jobs in pakistan ) with > 30% canopy cover, composed of species of mangrove tree, generally along coasts in or near brackish or seawater.
  9. Disturbed natural forest ( forestry jobs in pakistan ) - Any forest ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) - Natural forests ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) - Natural forests ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) - Natural forests ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) with > 30% canopy cover, which have been planted by people with species that occur naturally in that country.

Forest ( forestry jobs in pakistan ) loss and management

The scientific study of forest ( forestry jobs in pakistan ) species and their interaction with the environment is referred to as forest ( forestry jobs in pakistan ) ecology, while the management of forests ( forestry jobs in pakistan ) is often referred to as forestry ( forestry jobs in pakistan ). Forest ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) management. Forest ( forestry jobs in pakistan ) ecologists concentrate on forest ( forestry jobs in pakistan ) patterns and processes, usually with the aim of elucidating cause and effect relationships. Foresters ( forestry jobs in pakistan ) who practice sustainable forest ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) include logging, urban sprawl, human-caused forest ( forestry jobs in pakistan ) fires, acid rain, invasive species, and the slash and burn practices of swidden agriculture or shifting cultivation. The loss and re-growth of forest ( forestry jobs in pakistan ) leads to a distinction between two broad types of forest ( forestry jobs in pakistan ), primary or old-growth forest ( forestry jobs in pakistan ) and secondary forest ( forestry jobs in pakistan ). There are also many natural factors that can cause changes in forests ( forestry jobs in pakistan ) over time including forest ( forestry jobs in pakistan ) fires, insects, diseases, weather, competition between species, etc. In 1997, the World Resources Institute recorded that only 20% of the world's original forests ( forestry jobs in pakistan ) remained in large intact tracts of undisturbed forest ( forestry jobs in pakistan ). More than 75% of these intact forests ( forestry jobs in pakistan ) lie in three countries - the Boreal forests ( forestry jobs in pakistan ) of Russia and Canada and the rainforest of Brazil. In 2006 this information on intact forests ( forestry jobs in pakistan ) was updated using latest available satellite imagery.
Canada has about 4,020,000 square kilometres (1,550,000 sq mi) of forest ( forestry jobs in pakistan ) land. More than 90% of forest ( forestry jobs in pakistan ) land is publicly owned and about 50% of the total forest ( forestry jobs in pakistan ) area is allocated for harvesting. These allocated areas are managed using the principles of sustainable forest ( forestry jobs in pakistan ) management, which includes extensive consultation with local stakeholders. About eight percent of Canada’s forest ( forestry jobs in pakistan ) is legally protected from resource development (Global Forest ( forestry jobs in pakistan ) Watch Canada)(Natural Resources Canada). Much more forest ( forestry jobs in pakistan ) land — about 40 percent of the total forest ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) (Natural Resources Canada)
By December 2006, over 1,237,000 square kilometers of forest ( forestry jobs in pakistan ) land in Canada (about half the global total) had been certified as being sustainably managed (Canadian Sustainable Forestry ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) have historically been affected by humans to some degree, though in recent years improved forestry ( forestry jobs in pakistan ) practices has helped regulate or moderate large scale or severe impacts. However, the United States Forest ( forestry jobs in pakistan ) Service estimates a net loss of about 2 million hectares (4,942,000 acres) between 1997 and 2020; this estimate includes conversion of forest ( forestry jobs in pakistan ) land to other uses, including urban and suburban development, as well as afforestation and natural reversion of abandoned crop and pasture land to forest ( forestry jobs in pakistan ). 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 ( forestry jobs in pakistan ), with loggers complaining that a lack of thinning and proper forest ( forestry jobs in pakistan ) management has resulted in large forest ( forestry jobs in pakistan ) fires.
Old-growth forest ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ) 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 ( forestry jobs in pakistan ), 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 ( forestry jobs in pakistan ) 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.
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