A forest is an

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

characterized by a dense

community A community is a social unit (a group of people) with a shared socially-significant characteristic, such as place, set of norms, culture, religion, values, customs, or identity. Communities may share a sense of place situated in a given g ...

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...

s. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations'

Food and Agriculture Organization The Food and Agriculture Organization of the United Nations; . (FAO) is a specialized agency of the United Nations that leads international efforts to defeat hunger and improve nutrition and food security. Its Latin motto, , translates ...

(FAO) defines a forest as, "Land spanning more than 0.5 hectares with trees higher than 5 meters and a canopy cover of more than 10 percent, or trees able to reach these thresholds ''

in situ is a Latin phrase meaning 'in place' or 'on site', derived from ' ('in') and ' ( ablative of ''situs'', ). The term typically refers to the examination or occurrence of a process within its original context, without relocation. The term is use ...

''. It does not include land that is predominantly under agricultural or urban use." Using this definition, '' Global Forest Resources Assessment 2020'' found that forests covered , or approximately 31 percent of the world's land area in 2020. Forests are the largest terrestrial ecosystems of

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

by area, and are found around the globe. 45 percent of forest land is in the tropical latitudes. The next largest share of forests are found in

subarctic climate The subarctic climate (also called subpolar climate, or boreal climate) is a continental climate with long, cold (often very cold) winters, and short, warm to cool summers. It is found on large landmasses, often away from the moderating effects of ...

s, followed by

temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

, and subtropical zones. Forests account for 75% of the

gross primary production In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through ...

of the Earth's

biosphere The biosphere (), also called the ecosphere (), is the worldwide sum of all ecosystems. It can also be termed the zone of life on the Earth. The biosphere (which is technically a spherical shell) is virtually a closed system with regard to mat ...

, and contain 80% of the Earth's plant

biomass Biomass is a term used in several contexts: in the context of ecology it means living organisms, and in the context of bioenergy it means matter from recently living (but now dead) organisms. In the latter context, there are variations in how ...

. Net primary production is estimated at 21.9

gigatonne The tonne ( or ; symbol: t) is a unit of mass equal to 1,000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton in the United States to distinguish it from the non-metric units of the sh ...

s of biomass per year for

tropical forest Tropical forests are forested ecoregions with tropical climates – that is, land areas approximately bounded by the Tropic of Cancer, tropics of Cancer and Tropic of Capricorn, Capricorn, but possibly affected by other factors such as prevailing ...

s, 8.1 for

temperate forest A temperate forest is a forest found between the tropical and boreal regions, located in the temperate zone. It is the second largest terrestrial biome, covering 25% of the world's forest area, only behind the boreal forest, which covers about 3 ...

s, and 2.6 for

boreal forest Taiga or tayga ( ; , ), also known as boreal forest or snow forest, is a biome characterized by pinophyta, coniferous forests consisting mostly of pines, spruces, and larches. The taiga, or boreal forest, is the world's largest land biome. I ...

s. Forests form distinctly different

biome A biome () is a distinct geographical region with specific climate, vegetation, and animal life. It consists of a biological community that has formed in response to its physical environment and regional climate. In 1935, Tansley added the ...

s at different latitudes and elevations, and with different precipitation and

evapotranspiration Evapotranspiration (ET) refers to the combined processes which move water from the Earth's surface (open water and ice surfaces, bare soil and vegetation) into the Atmosphere of Earth, atmosphere. It covers both water evaporation (movement of w ...

rates. These biomes include boreal forests in subarctic climates, tropical moist forests and tropical dry forests around the

Equator The equator is the circle of latitude that divides Earth into the Northern Hemisphere, Northern and Southern Hemisphere, Southern Hemispheres of Earth, hemispheres. It is an imaginary line located at 0 degrees latitude, about in circumferen ...

, and

s at the

middle latitudes The middle latitudes, also called the mid-latitudes (sometimes spelled midlatitudes) or moderate latitudes, are spatial regions on either Hemispheres of Earth, hemisphere of Earth, located between the Tropic of Cancer (latitude ) and the Arctic ...

. Forests form in areas of the Earth with high rainfall, while drier conditions produce a transition to

savanna A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) biome and ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach th ...

. However, in areas with intermediate rainfall levels, forest transitions to savanna rapidly when the percentage of land that is covered by trees drops below 40 to 45 percent. Research conducted in the

Amazon rainforest The Amazon rainforest, also called the Amazon jungle or Amazonia, is a Tropical and subtropical moist broadleaf forests, moist broadleaf tropical rainforest in the Amazon biome that covers most of the Amazon basin of South America. This basin ...

shows that trees can alter rainfall rates across a region, releasing water from their leaves in anticipation of seasonal rains to trigger the wet season early. Because of this, seasonal rainfall in the Amazon begins two to three months earlier than the climate would otherwise allow.

Deforestation Deforestation or forest clearance is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. Ab ...

in the Amazon and anthropogenic

climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...

hold the potential to interfere with this process, causing the forest to pass a threshold where it transitions into savanna. Deforestation threatens many forest ecosystems. Deforestation occurs when humans remove trees from a forested area by cutting or burning, either to harvest

timber Lumber is wood that has been processed into uniform and useful sizes (dimensional lumber), including beams and planks or boards. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, window frames). ...

or to make way for farming. Most deforestation today occurs in tropical forests. The vast majority of this deforestation is because of the production of four commodities:

wood Wood is a structural tissue/material found as xylem in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulosic fibers that are strong in tension and embedded in a matrix of lignin t ...

beef Beef is the culinary name for meat from cattle (''Bos taurus''). Beef can be prepared in various ways; Cut of beef, cuts are often used for steak, which can be cooked to varying degrees of doneness, while trimmings are often Ground beef, grou ...

, soy, and palm oil. Over the past 2,000 years, the area of land covered by forest in

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

has been reduced from 80% to 34%. Large areas of forest have also been cleared in

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

and in the eastern

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

, in which only 0.1% of land was left undisturbed. Almost half of Earth's forest area (49 percent) is relatively intact, while 9 percent is found in fragments with little or no connectivity. Tropical rainforests and boreal coniferous forests are the least fragmented, whereas subtropical dry forests and temperate oceanic forests are among the most fragmented. Roughly 80 percent of the world's forest area is found in patches larger than . The remaining 20 percent is located in more than 34 million patches around the world – the vast majority less than in size. Human society and forests can affect one another positively or negatively. Forests provide

ecosystem services Ecosystem services are the various benefits that humans derive from Ecosystem, ecosystems. The interconnected Biotic_material, living and Abiotic, non-living components of the natural environment offer benefits such as pollination of crops, clean ...

to humans and serve as tourist attractions. Forests can also affect people's health. Human activities, including unsustainable use of forest resources, can negatively affect forest ecosystems.

Definitions

Although the word ''forest'' is commonly used, there is no universally recognised precise definition, with more than 800 definitions of forest used around the world. Although a forest is usually defined by the presence of trees, under many definitions an area completely lacking trees may still be considered a forest if it grew trees in the past, will grow trees in the future, or was legally designated as a forest regardless of vegetation type. There are three broad categories of definitions of forest in use: administrative,

land use Land use is an umbrella term to describe what happens on a parcel of land. It concerns the benefits derived from using the land, and also the land management actions that humans carry out there. The following categories are used for land use: fo ...

, and land cover. Administrative definitions are legal designations, and may not reflect the type of vegetation that grows upon the land; an area can be legally designated "forest" even if no trees grow on it. Land-use definitions are based on the primary purpose the land is used for. Under a land-use definition, any area used primarily for harvesting timber, including areas that have been cleared by harvesting, disease, fire, or for the construction of roads and infrastructure, are still defined as forests, even if they contain no trees. Land-cover definitions define forests based upon the density of trees, area of

tree canopy In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only p ...

cover, or area of the land occupied by the cross-section of tree trunks (

basal area Basal area is the cross-sectional area of trees at breast height (1.3m or 4.5 ft above ground). It is a common way to describe stand density. In forest management, basal area usually refers to merchantable timber and is given on a per hectare ...

) meeting a particular threshold. This type of definition depends upon the presence of trees sufficient to meet the threshold, or at least of immature trees that are expected to meet the threshold once they mature. Under land-cover definitions, there is considerable variation on where the cutoff points are between a forest,

woodland A woodland () is, in the broad sense, land covered with woody plants (trees and shrubs), or in a narrow sense, synonymous with wood (or in the U.S., the '' plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunli ...

, and

. Under some definitions, to be considered a forest requires very high levels of tree canopy cover, from 60% to 100%, which excludes woodlands and savannas, which have a lower canopy cover. Other definitions consider savannas to be a type of forest, and include all areas with tree canopies over 10%. Some areas covered with trees are legally defined as agricultural areas, for example Norway spruce plantations, under Austrian forest law, when the trees are being grown as Christmas trees and are below a certain height.

Etymology

The word ''

forest A forest is an ecosystem characterized by a dense ecological community, community of trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, ...

'' derives from the

Old French Old French (, , ; ) was the language spoken in most of the northern half of France approximately between the late 8th Frankish or Old High German">Old Frankish">Frankish or Old High German, of the Medieval Latin">Old_High_German.html" ;"title="Old Frankish">Frankish or Old High German">Old Frankish">Frankish or Old High German, of the Medieval Latin , denoting "open wood", Carolingian scribes first used ''foresta'' in the Carolingian Empire#Capitularies, capitularies of Charlemagne, specifically to denote the royal hunting grounds of the king. The word was not endemic to the

Romance languages The Romance languages, also known as the Latin or Neo-Latin languages, are the languages that are Language family, directly descended from Vulgar Latin. They are the only extant subgroup of the Italic languages, Italic branch of the Indo-E ...

, e.g., native words for ''forest'' in the Romance languages derived from the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

''silva'', which denoted "forest" and " wood(land)" (

cf. The abbreviation cf. (short for either Latin or , both meaning 'compare') is generally used in writing to refer the reader to other material to make a comparison with the topic being discussed. However some sources offer differing or even contr ...

the English ''sylva'' and ''sylvan''; the Italian, Spanish, and Portuguese ''selva''; the Romanian ''silvă''; the Old French ''selve''). Cognates of forest in Romance languages—e.g., the Italian ''foresta'', Spanish and Portuguese ''floresta'', etc.—are all ultimately derivations of the French word. The precise origin of Medieval Latin is obscure. Some authorities claim the word derives from the

Late Latin Late Latin is the scholarly name for the form of Literary Latin of late antiquity.Roberts (1996), p. 537. English dictionary definitions of Late Latin date this period from the 3rd to 6th centuries CE, and continuing into the 7th century in ...

phrase ''forestam silvam'', denoting "the outer wood"; others claim the word is a Latinisation of the Frankish *''forhist'', denoting "forest, wooded country", and was assimilated to ''forestam silvam'', pursuant to the common practice of Frankish scribes. The Old High German ''forst'' denoting "forest"; Middle Low German ''vorst'' denoting "forest";

Old English Old English ( or , or ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the Early Middle Ages. It developed from the languages brought to Great Britain by Anglo-S ...

''fyrhþ'' denoting "forest, woodland, game preserve, hunting ground" (English '' frith''); and

Old Norse Old Norse, also referred to as Old Nordic or Old Scandinavian, was a stage of development of North Germanic languages, North Germanic dialects before their final divergence into separate Nordic languages. Old Norse was spoken by inhabitants ...

''fýri'', denoting " coniferous forest"; all of which derive from the

Proto-Germanic Proto-Germanic (abbreviated PGmc; also called Common Germanic) is the linguistic reconstruction, reconstructed proto-language of the Germanic languages, Germanic branch of the Indo-European languages. Proto-Germanic eventually developed from ...

*''furhísa-'', *''furhíþija-'', denoting "a fir-wood, ''coniferous'' forest", from the

Proto-Indo-European Proto-Indo-European (PIE) is the reconstructed common ancestor of the Indo-European language family. No direct record of Proto-Indo-European exists; its proposed features have been derived by linguistic reconstruction from documented Indo-Euro ...

*''perk^wu-'', denoting "a ''coniferous'' or mountain forest, wooded height" all attest to the Frankish *''forhist''. Uses of ''forest'' in English to denote any uninhabited and unenclosed area are presently considered archaic. The Norman rulers of England introduced the word as a legal term, as seen in Latin texts such as

Magna Carta (Medieval Latin for "Great Charter"), sometimes spelled Magna Charta, is a royal charter of rights agreed to by King John of England at Runnymede, near Windsor, on 15 June 1215. First drafted by the Archbishop of Canterbury, Cardin ...

, to denote uncultivated land that was legally designated for hunting by feudal

nobility Nobility is a social class found in many societies that have an aristocracy. It is normally appointed by and ranked immediately below royalty. Nobility has often been an estate of the realm with many exclusive functions and characteristics. T ...

(see royal forest). These hunting forests did not necessarily contain any trees. Because that often included significant areas of woodland, "forest" eventually came to connote woodland in general, regardless of tree density. By the beginning of the fourteenth century, English texts used the word in all three of its senses: common, legal, and archaic. Other English words used to denote "an area with a high density of trees" are ''firth'', ''frith'', ''holt'', ''weald'', ''wold'', ''wood'', and ''woodland''. Unlike ''forest'', these are all derived from Old English and were not borrowed from another language. Some present classifications reserve ''woodland'' for denoting a locale with more open space between trees, and distinguish kinds of woodlands as ''open forests'' and ''closed forests'', premised on their crown covers. Finally, ''sylva'' (plural ''sylvae'' or, less classically, ''sylvas'') is a peculiar English spelling of the Latin ''silva'', denoting a "woodland", and has precedent in English, including its plural forms. While its use as a

synonym A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

of ''forest'', and as a

ate word denoting a woodland, may be admitted; in a specific technical sense it is restricted to denoting the ''species'' of trees that comprise the woodlands of a region, as in its sense in the subject of

silviculture Silviculture is the practice of controlling the growth, composition/structure, as well as quality of forests to meet values and needs, specifically timber production. The name comes from the Latin ('forest') and ('growing'). The study of forests ...

. The resorting to ''sylva'' in English indicates more precisely the denotation that the use of ''forest'' intends.

Evolutionary history

The first known forests on Earth arose in the

Middle Devonian In the geological timescale, the Middle Devonian epoch (from 393.3 ± 1.2 million years ago to 382.7 ± 1.6 million years ago) occurred during the Devonian period, after the end of the Emsian age. The Middle Devonian epoch is subdivided into two ...

(approximately 390

million years ago Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to (i.e. years), or approximately 31.6 teraseconds. Usage Myr is in common use in fields such as Earth science and cosmology. Myr is also used w ...

), with the evolution of cladoxylopsid plants like '' Calamophyton''. Appeared in the

Late Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era during the Phanerozoic eon, spanning 60.3 million years from the end of the preceding Silurian period at million years ago ( Ma), to the beginning of the succeeding ...

, '' Archaeopteris'' was both tree-like and

fern The ferns (Polypodiopsida or Polypodiophyta) are a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. They differ from mosses by being vascular, i.e., having specialized tissue ...

-like plant, growing to in height or more. It quickly spread throughout the world, from the equator to subpolar latitudes. It is the first species known to cast shade due to its fronds and forming soil from its roots. ''Archaeopteris'' was

deciduous In the fields of horticulture and botany, the term deciduous () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed Leaf, leaves, usually in the autumn; to the shedding of petals, aft ...

, dropping its fronds onto the forest floor, the shade, soil, and forest duff from the dropped fronds creating the early forest. The shed organic matter altered the freshwater environment, slowing its flow and providing food. This promoted freshwater fish.

Ecology

Forests account for 75% of the gross primary productivity of the Earth's

, and contain 80% of the Earth's plant biomass.

Biomass Biomass is a term used in several contexts: in the context of ecology it means living organisms, and in the context of bioenergy it means matter from recently living (but now dead) organisms. In the latter context, there are variations in how ...

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 In biology, detritus ( or ) is organic matter made up of the decomposition, decomposing remains of organisms and plants, and also of feces. Detritus usually hosts communities of microorganisms that colonize and decomposition, decompose (Reminera ...

. The woody component of a forest contains

lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidit ...

, which is relatively slow to decompose compared with other organic materials such as

cellulose Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important s ...

or carbohydrate. The world's forests contain about 606 gigatonnes of living biomass (above- and below-ground) and 59 gigatonnes of dead wood. The total biomass has decreased slightly since 1990, but biomass per unit area has increased. Forest ecosystems broadly differ based on

climate Climate is the long-term weather pattern in a region, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteoro ...

; latitudes 10° north and south of the

equator The equator is the circle of latitude that divides Earth into the Northern Hemisphere, Northern and Southern Hemisphere, Southern Hemispheres of Earth, hemispheres. It is an imaginary line located at 0 degrees latitude, about in circumferen ...

are mostly covered in

tropical rainforest Tropical rainforests are dense and warm rainforests with high rainfall typically found between 10° north and south of the Equator. They are a subset of the tropical forest biome that occurs roughly within the 28° latitudes (in the torrid zo ...

, and the latitudes between 53°N and 67°N have

. As a general rule, forests dominated by angiosperms (''broadleaf forests'') are more species-rich than those dominated by

gymnosperms The gymnosperms ( ; ) are a group of woody, perennial Seed plant, seed-producing plants, typically lacking the protective outer covering which surrounds the seeds in flowering plants, that include Pinophyta, conifers, cycads, Ginkgo, and gnetoph ...

(''conifer'', ''montane'', or ''needleleaf forests''), although exceptions exist. The trees that form the principal structural and defining component of a forest may be of a great variety of species (as in

s and temperate deciduous forests), or relatively few species over large areas (e.g.,

taiga Taiga or tayga ( ; , ), also known as boreal forest or snow forest, is a biome characterized by coniferous forests consisting mostly of pines, spruces, and larches. The taiga, or boreal forest, is the world's largest land biome. In North A ...

and arid montane coniferous forests). The biodiversity of forests also encompasses

shrubs A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...

, herbaceous plants,

moss Mosses are small, non-vascular plant, non-vascular flowerless plants in the taxonomic phylum, division Bryophyta (, ) ''sensu stricto''. Bryophyta (''sensu lato'', Wilhelm Philippe Schimper, Schimp. 1879) may also refer to the parent group bryo ...

es,

lichen A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

, and a variety of

animal Animals are multicellular, eukaryotic organisms in the Biology, biological Kingdom (biology), kingdom Animalia (). With few exceptions, animals heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, ...

s. Trees rising up to in height add a vertical dimension to the area of land that can support plant and animal species, opening up numerous

ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of Resource (biology), resources an ...

s for

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The hab ...

animal species,

epiphyte An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphyt ...

s, and various species that thrive under the regulated microclimate created under the canopy. Forests have intricate three-dimensional structures that increase in complexity with lower levels of disturbance and greater variety of tree species. The biodiversity of forests varies considerably according to factors such as forest type, geography, climate, and soils – in addition to human use. Most forest habitats in temperate regions support relatively few animal and plant species, and species that tend to have large geographical distributions, while the montane forests of Africa, South America, Southeast Asia, and lowland forests of Australia, coastal Brazil, the Caribbean islands, Central America, and insular Southeast Asia have many species with small geographical distributions. Areas with dense human populations and intense agricultural land use, such as Europe, parts of Bangladesh, China, India, and North America, are less intact in terms of their biodiversity. Northern Africa, southern Australia, coastal Brazil, Madagascar, and South Africa are also identified as areas with striking losses in biodiversity intactness.

Components

A forest consists of many components that can be broadly divided into two categories: biotic (living) and abiotic (non-living). The living parts include

shrub A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...

vine A vine is any plant with a growth habit of trailing or scandent (that is, climbing) stems, lianas, or runners. The word ''vine'' can also refer to such stems or runners themselves, for instance, when used in wicker work.Jackson; Benjamin; Da ...

grass Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family (biology), family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and spe ...

es and other herbaceous (non-woody) plants,

es,

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

reptile Reptiles, as commonly defined, are a group of tetrapods with an ectothermic metabolism and Amniotic egg, amniotic development. Living traditional reptiles comprise four Order (biology), orders: Testudines, Crocodilia, Squamata, and Rhynchocepha ...

amphibian Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...

s, and microorganisms living on the plants and animals and in the soil, connected by mycorrhizal networks.

Layers

The main layers of all forest types are the forest floor, the understory, and the canopy. The emergent layer, above the canopy, exists in tropical rainforests. Each layer has a different set of plants and animals, depending upon the availability of sunlight, moisture, and food. * The Forest floor is covered in dead plant material such as fallen leaves and decomposing logs, which detritivores break down into new soil. The layer of decaying leaves that covers the soil is necessary for many insects to overwinter and for amphibians, birds, and other animals to shelter and forage for food.

Leaf litter Plant litter (also leaf litter, tree litter, soil litter, litterfall, or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that has fallen to the ground. This detritus or dead organic material and its constituen ...

also keeps the soil moist, stops erosion, and protects roots against extreme heat and cold. The

fungal A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as one of the tradit ...

mycelium Mycelium (: mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Its normal form is that of branched, slender, entangled, anastomosing, hyaline threads. Fungal colonies composed of mycelium are fo ...

that helps form the mycorrhizal network transmits nutrients from decaying material to trees and other plants. The forest floor supports a variety of plants, ferns, grasses, and tree seedlings, as well as animals such as

ants Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of ...

spider Spiders (order (biology), order Araneae) are air-breathing arthropods that have eight limbs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude spider silk, silk. They are the largest order of arachnids and ran ...

s, and

millipede Millipedes (originating from the Latin , "thousand", and , "foot") are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name derive ...

s. * Understory is made up of bushes, shrubs, and young trees that are adapted to living in the shade of the canopy. * Canopy is formed by the mass of intertwined branches, twigs, and leaves of mature trees. The crowns of the dominant trees receive most of the sunlight. This is the most productive part of the trees, where maximum food is produced. The canopy forms a shady, protective "umbrella" over the rest of the forest. * Emergent layer exists in a tropical rain forest and is composed of a few scattered trees that tower over the canopy. In botany and countries like Germany and Poland, a different classification of forest vegetation is often used: tree, shrub, herb, and moss layers (see stratification (vegetation)).

Types

La foresta sopra la vista del lago di Ridracoli

Forests are classified differently and to different degrees of specificity. One such classification is in terms of the

s in which they exist, combined with leaf longevity of the dominant species (whether they are

evergreen In botany, an evergreen is a plant which has Leaf, foliage that remains green and functional throughout the year. This contrasts with deciduous plants, which lose their foliage completely during the winter or dry season. Consisting of many diffe ...

). Another distinction is whether the forests are composed predominantly of broadleaf trees,

conifer Conifers () are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a sin ...

ous (needle-leaved) trees, or mixed. *

Boreal forest Taiga or tayga ( ; , ), also known as boreal forest or snow forest, is a biome characterized by pinophyta, coniferous forests consisting mostly of pines, spruces, and larches. The taiga, or boreal forest, is the world's largest land biome. I ...

s occupy the

subarctic The subarctic zone is a region in the Northern Hemisphere immediately south of the true Arctic, north of hemiboreal regions and covering much of Alaska, Canada, Iceland, the north of Fennoscandia, Northwestern Russia, Siberia, and the Cair ...

zone and are generally evergreen and coniferous. *

Temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

zones support both broadleaf deciduous forests (e.g., temperate deciduous forest) and evergreen coniferous forests (e.g.,

temperate coniferous forests Temperate coniferous forest is a terrestrial ecoregion, terrestrial biome defined by the World Wide Fund for Nature. Temperate coniferous forests are found predominantly in areas with warm summers and cool winters, and vary in their kinds of plant ...

and

temperate rainforest Temperate rainforests are rainforests with coniferous or Broad-leaved tree, broadleaf forests that occur in the temperate zone and receive heavy rain. Temperate rainforests occur in oceanic moist regions around the world: the Pacific temperate ...

s). Warm temperate zones support broadleaf evergreen forests, including laurel forests. * Tropical and

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones immediately to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Ge ...

forests include tropical and subtropical moist forests, tropical and subtropical dry forests, and

tropical and subtropical coniferous forests Tropical and subtropical coniferous forests are a tropical forest habitat (ecology), habitat type defined by the World Wide Fund for Nature. These forests are found predominantly in North America, North and Central America and experience low level ...

. * Forests are classified according to physiognomy based on their overall physical structure or developmental stage (e.g. old growth vs. second growth). * Forests can also be classified more specifically based on the climate and the dominant tree species present, resulting in numerous different forest types (e.g., Ponderosa pine/ Douglas fir forest). The number of trees in the world, according to a 2015 estimate, is 3 trillion, of which 1.4 trillion are in the tropics or sub-tropics, 0.6 trillion in the temperate zones, and 0.7 trillion in the coniferous boreal forests. The 2015 estimate is about eight times higher than previous estimates, and is based on tree densities measured on over 400,000 plots. It remains subject to a wide margin of error, not least because the samples are mainly from Europe and North America. Forests can also be classified according to the amount of human alteration.

Old-growth forest An old-growth forest or primary forest is a forest that has developed over a long period of time without disturbance. Due to this, old-growth forests exhibit unique ecological features. The Food and Agriculture Organization of the United Natio ...

contains mainly natural patterns of biodiversity in established seral patterns, and they contain mainly species native to the region and habitat. In contrast, secondary forest is forest regrowing following timber harvest and may contain species originally from other regions or habitats. Different global forest classification systems have been proposed, but none has gained universal acceptance.

UNEP The United Nations Environment Programme (UNEP) is responsible for coordinating responses to environmental issues within the United Nations system. It was established by Maurice Strong, its first director, after the Declaration of the United Nati ...

- WCMC's forest category classification system is a simplification of other, more complex systems (e.g.

UNESCO The United Nations Educational, Scientific and Cultural Organization (UNESCO ) is a List of specialized agencies of the United Nations, specialized agency of the United Nations (UN) with the aim of promoting world peace and International secur ...

's forest and woodland 'subformations'). This system divides the world's forests 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 in a separate section below.

Temperate needleleaf

Temperate needleleaf forests mostly occupy the higher latitudes of the

Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...

, as well as some warm temperate areas, especially on nutrient-poor or otherwise unfavourable soils. These forests are composed entirely, or nearly so, of coniferous species ( Coniferophyta). In the Northern Hemisphere,

pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. ''World Flora Online'' accepts 134 species-rank taxa (119 species and 15 nothospecies) of pines as cu ...

s ''Pinus'',

spruce A spruce is a tree of the genus ''Picea'' ( ), a genus of about 40 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal ecosystem, boreal (taiga) regions of the Northern hemisphere. ''Picea'' ...

s ''Picea'', larches ''Larix'',

fir Firs are evergreen coniferous trees belonging to the genus ''Abies'' () in the family Pinaceae. There are approximately 48–65 extant species, found on mountains throughout much of North and Central America, Eurasia, and North Africa. The genu ...

s ''Abies'', Douglas firs '' Pseudotsuga'', and hemlocks '' Tsuga'' make up the canopy; but other taxa are also important. In the Southern Hemisphere, most coniferous trees (members of

Araucariaceae Araucariaceae is a Family (biology), family of conifers with three living Genus, genera, ''Araucaria'', ''Agathis'', and ''Wollemia''. While the family's native distribution is now largely confined to the Southern Hemisphere, except for a few spe ...

and Podocarpaceae) occur mixed with broadleaf species, and are classed as broadleaf-and-mixed forests.

Temperate broadleaf and mixed

Temperate broadleaf and mixed forest Temperate broadleaf and mixed forest is a temperate climate terrestrial habitat type defined by the World Wide Fund for Nature, with broadleaf tree ecoregions, and with conifer and broadleaf tree mixed coniferous forest ecoregions. Thes ...

s include a substantial component of trees of the Anthophyta group. They are generally characteristic of the warmer temperate latitudes, but extend to cool temperate ones, particularly in the southern hemisphere. They include such forest types as the mixed deciduous forests of the United States and their counterparts in China and Japan; the broadleaf evergreen

rainforest Rainforests are forests characterized by a closed and continuous tree Canopy (biology), canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforests can be generally classified as tropi ...

s of Japan,

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

, and

Tasmania Tasmania (; palawa kani: ''Lutruwita'') is an island States and territories of Australia, state of Australia. It is located to the south of the Mainland Australia, Australian mainland, and is separated from it by the Bass Strait. The sta ...

; the sclerophyllous forests of Australia, central Chile, the

Mediterranean The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern ...

, and California; and the southern beech

Nothofagus ''Nothofagus'', also known as the southern beeches, is a genus of 43 species of trees and shrubs native to the Southern Hemisphere, found across southern South America (Chile, Argentina) and east and southeast Australia, New Zealand, New Guin ...

forests of Chile and New Zealand.

Tropical moist

There are many different types of tropical moist forests, with lowland evergreen broad-leaf

s: for example várzea and igapó forests and the terra firme forests of the

Amazon Basin The Amazon basin is the part of South America drained by the Amazon River and its tributary, tributaries. The Amazon drainage basin covers an area of about , or about 35.5 percent of the South American continent. It is located in the countries ...

; the peat swamp forests; dipterocarp forests of

Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...

; and the high forests of the Congo Basin.

Seasonal tropical forest Seasonal tropical forest, also known as moist deciduous, semi-evergreen seasonal, tropical mixed or monsoon forest, typically contains a range of tree species: only some of which drop some or all of their leaves during the dry season. This tropic ...

s, perhaps the best description for the colloquial term " jungle", typically range from the rainforest zone 10 degrees north or south of the

, to the

Tropic of Cancer The Tropic of Cancer, also known as the Northern Tropic, is the Earth's northernmost circle of latitude where the Sun can be seen directly overhead. This occurs on the June solstice, when the Northern Hemisphere is tilted toward the Sun ...

and Tropic of Capricorn. Forests located on mountains are also included in this category, divided largely into upper and lower montane formations, on the basis of the variation of physiognomy corresponding to changes in altitude.

Tropical dry

Tropical dry forests are characteristic of areas in the tropics affected by seasonal drought. The seasonality of rainfall is usually reflected in the deciduousness of the forest canopy, with most trees being leafless for several months of the year. Under some conditions, such as less fertile soils or less predictable drought regimes, the proportion of evergreen species increases and the forests are characterised as " sclerophyllous". Thorn forest, 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 or herbivory are recurrent phenomena,

s develop.

Sparse trees and savanna

Sparse trees and

are forests with sparse tree- canopy cover. They occur principally in areas of transition from forested to non-forested landscapes. The two major zones in which these

s occur are in the boreal region and in the seasonally dry tropics. At high latitudes, north of the main zone of boreal forestland, growing conditions are not adequate to maintain a continuously closed

forest cover Forest cover is the amount of trees that covers a particular area of land. It may be measured as relative (in percent) or absolute (in square kilometres/ square miles). Nearly a third of the world's land surface is covered with forest, with clos ...

, so tree cover is both sparse and discontinuous. This vegetation is variously called open

, open

woodland, and forest tundra. A savanna is a mixed

–

grassland A grassland is an area where the vegetation is dominance (ecology), dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes such as clover, and other Herbaceo ...

characterized by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken

herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition of ...

layer that consists primarily of grasses. Savannas maintain an open canopy despite a high tree density.

Plantations

Forest plantations are generally intended for the production of timber and pulpwood. Commonly mono-specific, planted with even spacing between the trees, and intensively managed, these forests are generally important as habitat for native

biodiversity Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distribut ...

. Some are managed in ways that enhance their biodiversity protection functions and can provide ecosystem services such as nutrient capital maintenance, watershed and soil structure protection and carbon storage.

Area

The annual net loss of forest area has decreased since 1990, but the world is not on track to meet the target of the United Nations Strategic Plan for Forests to increase forest area by 3 percent by 2030. While

deforestation Deforestation or forest clearance is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. Ab ...

is taking place in some areas, new forests are being established through natural expansion or deliberate efforts in other areas. As a result, the net loss of forest area is less than the rate of deforestation; and it, too, is decreasing: from per year in the 1990s to per year during 2010–2020. In absolute terms, the global forest area decreased by between 1990 and 2020, which is an area about the size of Libya.

Societal significance

Ecosystem services

Forests provide a diversity of

including: * Converting

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

into

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

and biomass. A full-grown tree produces about of net oxygen per year. * Acting as a

carbon sink A carbon sink is a natural or artificial carbon sequestration process that "removes a greenhouse gas, an aerosol or a precursor of a greenhouse gas from the atmosphere". These sinks form an important part of the natural carbon cycle. An overar ...

. Therefore, they are necessary to mitigate climate change. * Aiding in regulating

. For example, research from 2017 shows that forests induce rainfall. If the forest is cut, it can lead to

drought A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, ...

, and in the tropics to occupational heat stress of outdoor workers. * Purifying

water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...

. * Mitigating natural hazards such as

flood A flood is an overflow of water (list of non-water floods, or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant con ...

s. * Serving as a genetic reserve. * Serving as a source of

lumber Lumber is wood that has been processed into uniform and useful sizes (dimensional lumber), including beams and planks or boards. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, window frames). ...

and as

recreation Recreation is an activity of leisure, leisure being discretionary time. The "need to do something for recreation" is an essential element of human biology and psychology. Recreational activities are often done for happiness, enjoyment, amusement, ...

al areas. * Serving as a source of woodlands and trees for millions of people dependent almost entirely on forests for subsistence for their essential fuelwood, food, and fodder needs. The main ecosystem services can be summarized in the next table: Some researchers state that forests do not only provide benefits, but can in certain cases also incur costs to humans. Forests may impose an economic burden, diminish the enjoyment of natural areas, reduce the food-producing capacity of grazing land and cultivated land, reduce biodiversity, reduce available water for humans and wildlife, harbour dangerous or destructive wildlife, and act as reservoirs of human and livestock disease. An important consideration regarding carbon sequestration is that forests can turn from a carbon sink to a carbon source if plant diversity, density or forest area decreases, as has been observed in different tropical forests The typical tropical forest may become a carbon source by the 2060s. An assessment of European forests found early signs of carbon sink saturation, after decades of increasing strength. The Intergovernmental Panel on Climate Change (IPCC) concluded that a combination of measures aimed at increasing forest carbon stocks, andsustainable timber offtake will generate the largest carbon sequestration benefit.

Forest-dependent people

The term forest-dependent people is used to describe any of a wide variety of livelihoods that are dependent on access to forests, products harvested from forests, or ecosystem services provided by forests, including those of Indigenous peoples dependent on forests. In

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

, approximately 22 percent of the population belongs to forest-dependent communities, which live in close proximity to forests and practice agroforestry as a principal part of their livelihood. People of

Ghana Ghana, officially the Republic of Ghana, is a country in West Africa. It is situated along the Gulf of Guinea and the Atlantic Ocean to the south, and shares borders with Côte d’Ivoire to the west, Burkina Faso to the north, and Togo to t ...

who rely on

and

bushmeat Bushmeat is meat from wildlife species that are Hunting, hunted for human consumption. Bushmeat represents a primary source of animal protein and a cash-earning commodity in poor and rural communities of humid tropical forest regions of the worl ...

harvested from forests and Indigenous peoples of the Amazon rainforest are also examples of forest-dependent people. Though forest-dependence by more common definitions is statistically associated with poverty and

rural In general, a rural area or a countryside is a geographic area that is located outside towns and cities. Typical rural areas have a low population density and small settlements. Agricultural areas and areas with forestry are typically desc ...

livelihoods, elements of forest-dependence exist in communities with a wide range of characteristics. Generally, richer households derive more cash value from forest resources, whereas among poorer households, forest resources are more important for home consumption and increase community resilience.

Indigenous peoples

Forests are fundamental to the culture and livelihood of indigenous people groups that live in and depend on forests, many of which have been removed from and denied access to the lands on which they lived as part of global

colonialism Colonialism is the control of another territory, natural resources and people by a foreign group. Colonizers control the political and tribal power of the colonised territory. While frequently an Imperialism, imperialist project, colonialism c ...

. Indigenous lands contain 36% or more of intact forest worldwide, host more biodiversity, and experience less deforestation. Indigenous activists have argued that degradation of forests and indigenous peoples' marginalization and land dispossession are interconnected. Other concerns among indigenous peoples include lack of Indigenous involvement in forest management and loss of knowledge related for the forest ecosystem. Since 2002, the amount of land that is legally owned by or designated for indigenous peoples has broadly increased, but land acquisition in lower-income countries by multinational corporations, often with little or no consultation of indigenous peoples, has also increased. Research in the Amazon rainforest suggests that indigenous methods of agroforestry form reservoirs of biodiversity. In the U.S. state of

Wisconsin Wisconsin ( ) is a U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest of the United States. It borders Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michig ...

, forests managed by indigenous people have more plant diversity, fewer invasive species, higher tree regeneration rates, and higher volume of trees.

Management

World Production Of Selected Forest Products

Forest management Forest management is a branch of forestry concerned with overall administrative, legal, economic, and social aspects, as well as scientific and technical aspects, such as silviculture, forest protection, and forest regulation. This includes man ...

has changed considerably over the last few centuries, with rapid changes from the 1980s onward, culminating in a practice now referred to as ''sustainable forest management''. Forest ecologists concentrate on forest patterns and processes, usually with the aim of elucidating cause-and-effect relationships. Foresters who practice sustainable forest management focus on the integration of ecological, social, and economic values, often in consultation with local communities and other stakeholders. Checkerboard forest in Idaho

Humans have generally decreased the amount of forest worldwide. Anthropogenic factors that can affect forests include logging,

urban sprawl Urban sprawl (also known as suburban sprawl or urban encroachment) is defined as "the spreading of urban developments (such as houses and shopping centers) on undeveloped land near a city". Urban sprawl has been described as the unrestricted ...

, human-caused

forest fire A wildfire, forest fire, or a bushfire is an unplanned and uncontrolled fire in an area of combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identified as a bushfire ( in Australia), dese ...

acid rain Acid rain is rain or any other form of Precipitation (meteorology), precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH). Most water, including drinking water, has a neutral pH that exists b ...

invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

, and the slash and burn practices of swidden agriculture or shifting cultivation. The loss and re-growth of forests lead to a distinction between two broad types of forest: primary or

old-growth forest An old-growth forest or primary forest is a forest that has developed over a long period of time without disturbance. Due to this, old-growth forests exhibit unique ecological features. The Food and Agriculture Organization of the United Natio ...

and secondary forest. There are also many natural factors that can cause changes in forests over time, including

forest fires A forest fire A wildfire, forest fire, or a bushfire is an unplanned and uncontrolled fire in an area of combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identified as a bushfire ( in Au ...

insects Insects (from Latin ') are hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed ...

diseases A disease is a particular abnormal condition that adversely affects the structure or function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical conditions that are asso ...

, weather, competition between species, etc. In 1997, the

World Resources Institute The World Resources Institute (WRI) is a global research non-profit organization established in 1982 with funding from the MacArthur Foundation under the leadership of James Gustave Speth. Subsequent presidents include Jonathan Lash (1993– ...

recorded that only 20% of the world's original forests remained in large intact tracts of undisturbed forest. More than 75% of these intact forests lie in three countries: the boreal forests of Russia and Canada, and the rainforest of Brazil. According to

's (FAO) ''Global Forest Resources Assessment 2020'', an estimated of forest have been lost worldwide through deforestation since 1990, but the rate of forest loss has declined substantially. In the most recent five-year period (2015–2020), the annual rate of deforestation was estimated at , down from annually in 2010–2015.

The forest transition

The transition of a region from forest loss to net gain in forested land is referred to as the forest transition. This change occurs through a few main pathways, including increase in commercial tree plantations, adoption of agroforestry techniques by small farmers, or spontaneous regeneration when former agricultural land is abandoned. It can be motivated by the economic benefits of forests, the ecosystem services forests provide, or cultural changes where people increasingly appreciate forests for their spiritual, aesthetic, or otherwise intrinsic value. According to the Special Report on Global Warming of 1.5 °C of the

Intergovernmental Panel on Climate Change The Intergovernmental Panel on Climate Change (IPCC) is an intergovernmental body of the United Nations. Its job is to "provide governments at all levels with scientific information that they can use to develop climate policies". The World Met ...

, to avoid temperature rise by more than 1.5 degrees above pre-industrial levels, there will need to be an increase in global forest cover equal to the land area of Canada () by 2050. China instituted a ban on logging, beginning in 1998, due to the erosion and flooding that it caused. In addition, ambitious tree-planting programmes in countries such as China, India, the United States, and Vietnam – combined with natural expansion of forests in some regions – have added more than of new forests annually. As a result, the net loss of forest area was reduced to per year between 2000 and 2010, down from annually in the 1990s. In 2015, a study for '' Nature Climate Change'' showed that the trend has recently been reversed, leading to an "overall gain" in global biomass and forests. This gain is due especially to reforestation in China and Russia. New forests are not equivalent to old growth forests in terms of species diversity, resilience, and carbon capture. On 7 September 2015, the FAO released a new study stating that over the last 25 years the global

rate has decreased by 50% due to improved management of forests and greater government protection. There is an estimated of forest in protected areas worldwide. Of the six major world regions, South America has the highest share of forests in protected areas, at 31 percent. The area of such areas globally has increased by since 1990, but the rate of annual increase slowed in 2010–2020. Smaller areas of

in cities may be managed as

urban forestry Urban forestry is the care and management of single trees and tree populations in Urban area, urban settings for the purpose of improving the urban environment. Urban forestry involves both planning and management, including the programming of ...

, 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 schools and

kindergartens Kindergarten is a preschool educational approach based on playing, singing, practical activities such as drawing, and social interaction as part of the transition from home to school. Such institutions were originally made in the late 18th cent ...

help young people to develop social as well as scientific skills in forests. These typically need to be close to where the children live.

Canada

Garibaldi National Park - Garibaldi Mountain

Canada has about of forest land. More than 90% of forest land is publicly owned and about 50% of the total forest area is allocated for harvesting. These allocated areas are managed using the principles of sustainable forest management, which include extensive consultation with local stakeholders. About eight percent of Canada's forest is legally protected from resource development. Much more forest land—about 40 percent of the total forest land base—is subject to varying degrees of protection through processes such as integrated

land use planning Land use planning or ''Land-use regulation'' is the process of regulating the Land use, use of land by a central authority. Usually, this is done to promote more desirable social and environmental outcomes as well as a more efficient resource u ...

or defined management areas, such as certified forests. By December 2006, over of forest land in Canada (about half the global total) had been certified as being sustainably managed.

Clearcutting Clearcutting, clearfelling or clearcut logging is a forestry/logging practice in which most or all trees in an area are uniformly cut down. Along with Shelterwood cutting, shelterwood and Seed tree, seed tree harvests, it is used by foresters t ...

, 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 new clear-cuts, although some older ones grew to over several years. The Canadian Forest Service is the government department which looks after Forests in Canada.

Latvia

Latvia has about of forest land, which equates to about 50.5% of Latvia's total area of of forest land (46% of total forest land) is publicly owned and of forest land (54% of the total) is in private hands. Latvia's forests have been steadily increasing over the years, which is in contrast to many other nations, mostly due to the forestation of land not used for agriculture. In 1935, there were only of forest; today this has increased by more than 150%. Birch is the most common tree at 28.2%, followed by pine (26.9%), spruce (18.3%), grey alder (9.7%), aspen (8.0%), black alder (5.7%), oak/ash (1.2%), with other hardwood trees making up the rest (2.0%).

United States

In the United States, most forests have historically been affected by humans to some degree, though in recent years improved

forestry Forestry is the science and craft of creating, managing, planting, using, conserving and repairing forests and woodlands for associated resources for human and Natural environment, environmental benefits. Forestry is practiced in plantations and ...

practices have helped regulate or moderate large-scale impacts. The

United States Forest Service The United States Forest Service (USFS) is an agency within the United States Department of Agriculture, U.S. Department of Agriculture. It administers the nation's 154 United States National Forest, national forests and 20 United States Natio ...

estimated a net loss of about between 1997 and 2020; this estimate includes conversion of forest land to other uses, including urban and suburban development, as well as afforestation and natural reversion of abandoned crop and

pasture Pasture (from the Latin ''pastus'', past participle of ''pascere'', "to feed") is land used for grazing. Types of pasture Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, c ...

land to forest. 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, with loggers complaining that a lack of thinning and proper forest management has resulted in large forest fires.

Sources

References

External links

Forests in danger

Intact Forests
with maps and reports (archived 8 September 2015)

by the

* (archived 24 January 2008)
Forest area is land under natural or planted stands of trees of at least 5 meters ''in situ'', whether productive or not, and excludes tree stands in agricultural production systems

Forest area (sq. km)
data from the

World Bank The World Bank is an international financial institution that provides loans and Grant (money), grants to the governments of Least developed countries, low- and Developing country, middle-income countries for the purposes of economic development ...

World Development Indicators World Development Indicators (WDI) is the World Bank’s premier compilation of international statistics on global development. Drawing from officially recognized sources and including national, regional, and global estimates, the WDI provides acce ...

, made available by Google * * * {{Authority control Habitats Trees Ecosystems

Definitions

Etymology

Evolutionary history

Ecology

Components

Layers

Types

Temperate needleleaf

Temperate broadleaf and mixed

Tropical moist

Tropical dry

Sparse trees and savanna

Plantations

Area

Societal significance

Ecosystem services

Forest-dependent people

Indigenous peoples

Management

The forest transition

Canada

Latvia

United States

See also

Sources

References

External links