The tropics are the region of the Earth surrounding the Equator. They are delimited in latitude by The Tropic of Cancer in the Northern Hemisphere at 23°26′12.4″ N and the Tropic of Capricorn in the Southern Hemisphere at 23°26′12.4″ S. The tropics are referred to as the tropical zone and the torrid zone; the tropics include all the areas on the Earth where the Sun contacts a point directly overhead at least once during the solar year - thus the latitude of the tropics is equal to the angle of the Earth's axial tilt. The tropics are distinguished from the other climatic and biomatic regions of Earth, which are the middle latitudes and the polar regions on either side of the equatorial zone; the tropics contain 36 % of the Earth's landmass. As of 2014, the region is home to 40% of the world population, this figure is projected to reach 50% by the late 2030s. "Tropical" is sometimes used in a general sense for a tropical climate to mean warm to hot and moist year-round with the sense of lush vegetation.
Many tropical areas have a wet season. The wet season, rainy season or green season is the time of year, ranging from one or more months, when most of the average annual rainfall in a region falls. Areas with wet seasons are disseminated across portions of the subtropics. Under the Köppen climate classification, for tropical climates, a wet-season month is defined as a month where average precipitation is 60 millimetres or more. Tropical rainforests technically do not have dry or wet seasons, since their rainfall is distributed through the year; some areas with pronounced rainy seasons see a break in rainfall during mid-season when the intertropical convergence zone or monsoon trough moves poleward of their location during the middle of the warm season. When the wet season occurs during the warm season, or summer, precipitation falls during the late afternoon and early evening hours; the wet season is a time when air quality improves, freshwater quality improves and vegetation grows leading to crop yields late in the season.
Floods cause rivers to overflow their banks, some animals to retreat to higher ground. Soil nutrients erosion increases; the incidence of malaria increases in areas. Animals have survival strategies for the wetter regime; the previous dry season leads to food shortages into the wet season, as the crops have yet to mature. However, regions within the tropics may well not have a tropical climate. Under the Köppen climate classification, much of the area within the geographical tropics is classed not as "tropical" but as "dry", including the Sahara Desert, the Atacama Desert and Australian Outback. There are alpine tundra and snow-capped peaks, including Mauna Kea, Mount Kilimanjaro, the Andes as far south as the northernmost parts of Chile and Argentina. Tropical plants and animals are those species native to the tropics. Tropical ecosystems may consist of tropical rainforests, seasonal tropical forests, dry forests, spiny forests and other habitat types. There are significant areas of biodiversity, species endemism present in rainforests and seasonal forests.
Some examples of important biodiversity and high endemism ecosystems are El Yunque National Forest in Puerto Rico, Costa Rican and Nicaraguan rainforests, Amazon Rainforest territories of several South American countries, Madagascar dry deciduous forests, the Waterberg Biosphere of South Africa, eastern Madagascar rainforests. The soils of tropical forests are low in nutrient content, making them quite vulnerable to slash-and-burn deforestation techniques, which are sometimes an element of shifting cultivation agricultural systems. In biogeography, the tropics are divided into Neotropics. Together, they are sometimes referred to as the Pantropic; the Neotropical region should not be confused with the ecozone of the same name. "Tropicality" refers to the geographic imagery that many people outside the tropics have of that region. The idea of tropicality gained renewed interest in modern geographical discourse when French geographer Pierre Gourou published Les Pays Tropicaux, in the late 1940s.
Tropicality encompasses at least two contradictory imageries. One is that the tropics represent a Garden of a heaven on Earth; the latter view was discussed in Western literature—more so than the first. Evidence suggests that over time the more primitive view of the tropics in popular literature has been supplanted by more nuanced interpretations that reflect historical changes in values associated with tropical culture and ecology, although some primitive associations are persistent. Western scholars theorized about the reasons that tropical areas were deemed "inferior" to regions in the Northern Hemisphere. A popular explanation focused on the differences in climate—tropical regions have much warmer weather than northern regions; this theme led some scholars, including Gourou, to argue that warmer climates correlate to primitive indigenous populations lacking control over nature, compared to northern popul
Africa is the world's second largest and second most-populous continent, being behind Asia in both categories. At about 30.3 million km2 including adjacent islands, it covers 6% of Earth's total surface area and 20% of its land area. With 1.2 billion people as of 2016, it accounts for about 16% of the world's human population. The continent is surrounded by the Mediterranean Sea to the north, the Isthmus of Suez and the Red Sea to the northeast, the Indian Ocean to the southeast and the Atlantic Ocean to the west; the continent includes various archipelagos. It contains 54 recognised sovereign states, nine territories and two de facto independent states with limited or no recognition; the majority of the continent and its countries are in the Northern Hemisphere, with a substantial portion and number of countries in the Southern Hemisphere. Africa's average population is the youngest amongst all the continents. Algeria is Africa's largest country by area, Nigeria is its largest by population. Africa central Eastern Africa, is accepted as the place of origin of humans and the Hominidae clade, as evidenced by the discovery of the earliest hominids and their ancestors as well as ones that have been dated to around 7 million years ago, including Sahelanthropus tchadensis, Australopithecus africanus, A. afarensis, Homo erectus, H. habilis and H. ergaster—the earliest Homo sapiens, found in Ethiopia, date to circa 200,000 years ago.
Africa encompasses numerous climate areas. Africa hosts a large diversity of ethnicities and languages. In the late 19th century, European countries colonised all of Africa. African nations cooperate through the establishment of the African Union, headquartered in Addis Ababa. Afri was a Latin name used to refer to the inhabitants of then-known northern Africa to the west of the Nile river, in its widest sense referred to all lands south of the Mediterranean; this name seems to have referred to a native Libyan tribe, an ancestor of modern Berbers. The name had been connected with the Phoenician word ʿafar meaning "dust", but a 1981 hypothesis has asserted that it stems from the Berber word ifri meaning "cave", in reference to cave dwellers; the same word may be found in the name of the Banu Ifran from Algeria and Tripolitania, a Berber tribe from Yafran in northwestern Libya. Under Roman rule, Carthage became the capital of the province it named Africa Proconsularis, following its defeat of the Carthaginians in the Third Punic War in 146 BC, which included the coastal part of modern Libya.
The Latin suffix -ica can sometimes be used to denote a land. The Muslim region of Ifriqiya, following its conquest of the Byzantine Empire's Exarchatus Africae preserved a form of the name. According to the Romans, Africa lay to the west of Egypt, while "Asia" was used to refer to Anatolia and lands to the east. A definite line was drawn between the two continents by the geographer Ptolemy, indicating Alexandria along the Prime Meridian and making the isthmus of Suez and the Red Sea the boundary between Asia and Africa; as Europeans came to understand the real extent of the continent, the idea of "Africa" expanded with their knowledge. Other etymological hypotheses have been postulated for the ancient name "Africa": The 1st-century Jewish historian Flavius Josephus asserted that it was named for Epher, grandson of Abraham according to Gen. 25:4, whose descendants, he claimed, had invaded Libya. Isidore of Seville in his 7th-century Etymologiae XIV.5.2. Suggests "Africa comes from the Latin aprica, meaning "sunny".
Massey, in 1881, stated that Africa is derived from the Egyptian af-rui-ka, meaning "to turn toward the opening of the Ka." The Ka is the energetic double of every person and the "opening of the Ka" refers to a womb or birthplace. Africa would be, for the Egyptians, "the birthplace." Michèle Fruyt in 1976 proposed linking the Latin word with africus "south wind", which would be of Umbrian origin and mean "rainy wind". Robert R. Stieglitz of Rutgers University in 1984 proposed: "The name Africa, derived from the Latin *Aphir-ic-a, is cognate to Hebrew Ophir." Ibn Khallikan and some other historians claim that the name of Africa came from a Himyarite king called Afrikin ibn Kais ibn Saifi called "Afrikus son of Abrahah" who subdued Ifriqiya. Africa is considered by most paleoanthropologists to be the oldest inhabited territory on Earth, with the human species originating from the continent. During the mid-20th century, anthropologists discovered many fossils and evidence of human occupation as early as 7 million years ago.
Fossil remains of several species of early apelike humans thought to have evolved into modern man, such as Australopithecus afarensis (radiometrically dated to 3.9–3.0 million years BP, Paranthropus boisei and Homo ergaster have been discovered. After the evolution of Homo sapiens sapiens 150,000 to 100,000 years BP in Africa, the continent was populated by groups of hunter-gatherers; these first modern humans left Africa and populated the rest of the globe during the Out of Africa II migration dated to 50,000 years BP, exiting the continent eith
The flowering plants known as angiosperms, Angiospermae or Magnoliophyta, are the most diverse group of land plants, with 64 orders, 416 families 13,164 known genera and c. 369,000 known species. Like gymnosperms, angiosperms are seed-producing plants. However, they are distinguished from gymnosperms by characteristics including flowers, endosperm within the seeds, the production of fruits that contain the seeds. Etymologically, angiosperm means a plant; the term comes from the Greek words sperma. The ancestors of flowering plants diverged from gymnosperms in the Triassic Period, 245 to 202 million years ago, the first flowering plants are known from 160 mya, they diversified extensively during the Early Cretaceous, became widespread by 120 mya, replaced conifers as the dominant trees from 100 to 60 mya. Angiosperms differ from other seed plants in several ways, described in the table below; these distinguishing characteristics taken together have made the angiosperms the most diverse and numerous land plants and the most commercially important group to humans.
Angiosperm stems are made up of seven layers. The amount and complexity of tissue-formation in flowering plants exceeds that of gymnosperms; the vascular bundles of the stem are arranged such that the phloem form concentric rings. In the dicotyledons, the bundles in the young stem are arranged in an open ring, separating a central pith from an outer cortex. In each bundle, separating the xylem and phloem, is a layer of meristem or active formative tissue known as cambium. By the formation of a layer of cambium between the bundles, a complete ring is formed, a regular periodical increase in thickness results from the development of xylem on the inside and phloem on the outside; the soft phloem becomes crushed, but the hard wood persists and forms the bulk of the stem and branches of the woody perennial. Owing to differences in the character of the elements produced at the beginning and end of the season, the wood is marked out in transverse section into concentric rings, one for each season of growth, called annual rings.
Among the monocotyledons, the bundles are more numerous in the young stem and are scattered through the ground tissue. They once formed the stem increases in diameter only in exceptional cases; the characteristic feature of angiosperms is the flower. Flowers show remarkable variation in form and elaboration, provide the most trustworthy external characteristics for establishing relationships among angiosperm species; the function of the flower is to ensure fertilization of the ovule and development of fruit containing seeds. The floral apparatus may arise terminally from the axil of a leaf; as in violets, a flower arises singly in the axil of an ordinary foliage-leaf. More the flower-bearing portion of the plant is distinguished from the foliage-bearing or vegetative portion, forms a more or less elaborate branch-system called an inflorescence. There are two kinds of reproductive cells produced by flowers. Microspores, which will divide to become pollen grains, are the "male" cells and are borne in the stamens.
The "female" cells called megaspores, which will divide to become the egg cell, are contained in the ovule and enclosed in the carpel. The flower may consist only of these parts, as in willow, where each flower comprises only a few stamens or two carpels. Other structures are present and serve to protect the sporophylls and to form an envelope attractive to pollinators; the individual members of these surrounding structures are known as petals. The outer series is green and leaf-like, functions to protect the rest of the flower the bud; the inner series is, in general, white or brightly colored, is more delicate in structure. It functions to attract bird pollinators. Attraction is effected by color and nectar, which may be secreted in some part of the flower; the characteristics that attract pollinators account for the popularity of flowers and flowering plants among humans. While the majority of flowers are perfect or hermaphrodite, flowering plants have developed numerous morphological and physiological mechanisms to reduce or prevent self-fertilization.
Heteromorphic flowers have short carpels and long stamens, or vice versa, so animal pollinators cannot transfer pollen to the pistil. Homomorphic flowers may employ a biochemical mechanism called self-incompatibility to discriminate between self and non-self pollen grains. In other species, the male and female parts are morphologically separated, developing on different flowers; the botanical term "Angiosperm", from the Ancient Greek αγγείον, angeíon and σπέρμα, was coined in the form Angiospermae by Paul Hermann in 1690, as the name of one of his primary divisions of the plant kingdom. This included flowering plants possessing seeds enclosed in capsules, distinguished from his Gymnospermae, or flowering plants with achenial or schizo-carpic fruits, the whole fruit or each of its pieces being here regarded as a seed and naked; the term and its antonym were maintained by Carl Linnaeus with the same sense, but with restricted application, in the names of the orders of his class Didynamia. Its use with any
Seychelles the Republic of Seychelles, is an archipelago country in the Indian Ocean. The capital of the 115-island country, lies 1,500 kilometres east of mainland East Africa. Other nearby island countries and territories include Comoros, Madagascar, Réunion and Mauritius to the south. With a population of 94,228, it has the smallest population of any sovereign African country. Seychelles is a member of the African Union, the Southern African Development Community, the Commonwealth of Nations, the United Nations. After proclamation of independence from the United Kingdom in 1976, Seychelles has developed from a agricultural society to a market-based diversified economy, with agriculture being supplanted by rising service and public sectors as well as tourism. From 1976 until 2015, nominal GDP output has increased nearly sevenfold and the purchasing power parity nearly sixteenfold. In late 2010s, the President Danny Faure and the National Assembly presented plans to encourage foreign investment in order to further upgrade these sectors.
Today, Seychelles boasts the highest nominal excluding the French regions. It is one of only a handful of countries in Africa with a high Human Development Index. Despite the country's newfound economic prosperity, poverty remains widespread due to a high level of economic inequality, one of the highest in the world, unequal wealth distribution among the populace which vastly favors the upper and ruling class; the Seychelles were uninhabited throughout most of recorded history. Some scholars assume that Austronesian seafarers and Maldivian and Arab traders were the first to visit the uninhabited Seychelles; this assumption is based on the discovery of tombs, visible until 1910. The earliest recorded sighting by Europeans took place on 15 March 1503, recorded by Thomé Lopes aboard "Rui Mendes de Brito" part of the fleet of the Portuguese Admiral Vasco da Gama. Da Gama's ships passed close to an elevated island Silhouette Island and the following day Desroches Island; the earliest recorded landing was in January 1609, by the crew of the "Ascension" under Captain Alexander Sharpeigh during the fourth voyage of the British East India Company.
A transit point for trade between Africa and Asia, the islands were said to be used by pirates until the French began to take control starting in 1756 when a Stone of Possession was laid on Mahé by Captain Nicholas Morphey. The islands were named after Louis XV's Minister of Finance; the British frigate "Orpheus" commanded by Captain Henry Newcome arrived at Mahé on 16 May 1794. Terms of capitulation were drawn up and the next day Seychelles was surrendered to Britain. Jean Baptiste Quéau de Quincy, the French administrator of Seychelles during the years of war with the United Kingdom, declined to resist when armed enemy warships arrived. Instead, he negotiated the status of capitulation to Britain which gave the settlers a privileged position of neutrality. Britain assumed full control upon the surrender of Mauritius in 1810, formalised in 1814 at the Treaty of Paris. Seychelles became a crown colony separate from Mauritius in 1903. Elections were held in 1966 and 1970. Independence was granted in 1976 as a republic within the Commonwealth.
In the 1970s Seychelles was "the place to be seen, a playground for film stars and the international jet set". In 1977, a coup d'état by France Albert René ousted the first president of the republic, James Mancham. René discouraged over-dependence on tourism and declared that he wanted "to keep the Seychelles for the Seychellois"; the 1979 constitution declared a socialist one-party state, which lasted until 1991. In the 1980s there were a series of coup attempts against President René, some of which were supported by South Africa. In 1981, Mike Hoare led a team of 43 South African mercenaries masquerading as holidaying rugby players in the 1981 Seychelles coup d'état attempt. There was a gun battle at the airport, most of the mercenaries escaped in a hijacked Air India plane; the leader of this hijacking was German mercenary D. Clodo, a former member of the Rhodesian SAS. Clodo stood trial in South Africa as well as in his home country Germany for air-piracy. In 1986, an attempted coup led by the Seychelles Minister of Defence, Ogilvy Berlouis, caused President René to request assistance from India.
In Operation Flowers are Blooming, the Indian naval vessel INS Vindhyagiri arrived in Port Victoria to help avert the coup. The first draft of a new constitution failed to receive the requisite 60% of voters in 1992, but an amended version was approved in 1993. In January 2013, Seychelles declared a state of emergency; the Seychelles president, head of state and head of government, is elected by popular vote for a five-year term of office. The cabinet is presided over and appointed by the president, subject to the approval of a majority of the legislature; the unicameral Seychellois parliament, the National Assembly or Assemblée Nationale, consists of 34 members, 25 of whom are elected directly by popular vote, while the remaining nine seats are appointed proportionally according to the percentage of votes received by each party. All members serve five-year terms; the Supreme Court of Seychelles, created in 1903, is the highest trial court in Seychelles and the first court of appeal from all the lower courts and tribunals.
The highest court of law
Malaysia is a country in Southeast Asia. The federal constitutional monarchy consists of 13 states and three federal territories, separated by the South China Sea into two sized regions, Peninsular Malaysia and East Malaysia. Peninsular Malaysia shares a land and maritime border with Thailand and maritime borders with Singapore and Indonesia. East Malaysia shares land and maritime borders with Brunei and Indonesia and a maritime border with the Philippines and Vietnam. Kuala Lumpur is the national capital and largest city while Putrajaya is the seat of federal government. With a population of over 30 million, Malaysia is the world's 44th most populous country; the southernmost point of continental Eurasia, Tanjung Piai, is in Malaysia. In the tropics, Malaysia is one of 17 megadiverse countries, with large numbers of endemic species. Malaysia has its origins in the Malay kingdoms which, from the 18th century, became subject to the British Empire, along with the British Straits Settlements protectorate.
Peninsular Malaysia was unified as the Malayan Union in 1946. Malaya was restructured as the Federation of Malaya in 1948, achieved independence on 31 August 1957. Malaya united with North Borneo and Singapore on 16 September 1963 to become Malaysia. In 1965, Singapore was expelled from the federation; the country is multi-cultural, which plays a large role in its politics. About half the population is ethnically Malay, with large minorities of Malaysian Chinese, Malaysian Indians, indigenous peoples. While recognising Islam as the country's established religion, the constitution grants freedom of religion to non-Muslims; the government system is modelled on the Westminster parliamentary system and the legal system is based on common law. The head of state is the king, known as the Yang di-Pertuan Agong, he is an elected monarch chosen from the hereditary rulers of the nine Malay states every five years. The head of government is the Prime Minister; the country's official language is a standard form of the Malay language.
English remains an active second language. Since independence, Malaysian GDP has grown at an average of 6.5% per annum for 50 years. The economy has traditionally been fuelled by its natural resources, but is expanding in the sectors of science, tourism and medical tourism. Today, Malaysia has a newly industrialised market economy, ranked fourth largest in Southeast Asia and 38th largest in the world, it is a founding member of the Association of Southeast Asian Nations, the East Asia Summit and the Organisation of Islamic Cooperation, a member of Asia-Pacific Economic Cooperation, the Commonwealth of Nations, the Non-Aligned Movement. The name "Malaysia" is a combination of the word "Malay" and the Latin-Greek suffix "-sia"/-σία; the word "melayu" in Malay may derive from the Tamil words "malai" and "ur" meaning "mountain" and "city, land", respectively. "Malayadvipa" was the word used by ancient Indian traders. Whether or not it originated from these roots, the word "melayu" or "mlayu" may have been used in early Malay/Javanese to mean to accelerate or run.
This term was applied to describe the strong current of the river Melayu in Sumatra. The name was adopted by the Melayu Kingdom that existed in the seventh century on Sumatra. Before the onset of European colonisation, the Malay Peninsula was known natively as "Tanah Melayu". Under a racial classification created by a German scholar Johann Friedrich Blumenbach, the natives of maritime Southeast Asia were grouped into a single category, the Malay race. Following the expedition of French navigator Jules Dumont d'Urville to Oceania in 1826, he proposed the terms of "Malaysia", "Micronesia" and "Melanesia" to the Société de Géographie in 1831, distinguishing these Pacific cultures and island groups from the existing term "Polynesia". Dumont d'Urville described Malaysia as "an area known as the East Indies". In 1850, the English ethnologist George Samuel Windsor Earl, writing in the Journal of the Indian Archipelago and Eastern Asia, proposed naming the islands of Southeast Asia as "Melayunesia" or "Indunesia", favouring the former.
In modern terminology, "Malay" remains the name of an ethnoreligious group of Austronesian people predominantly inhabiting the Malay Peninsula and portions of the adjacent islands of Southeast Asia, including the east coast of Sumatra, the coast of Borneo, smaller islands that lie between these areas. The state that gained independence from the United Kingdom in 1957 took the name the "Federation of Malaya", chosen in preference to other potential names such as "Langkasuka", after the historic kingdom located at the upper section of the Malay Peninsula in the first millennium CE; the name "Malaysia" was adopted in 1963 when the existing states of the Federation of Malaya, plus Singapore, North Borneo and Sarawak formed a new federation. One theory posits the name was chosen so that "si" represented the inclusion of Singapore, North Borneo, Sarawak to Malaya in 1963. Politicians in the Philippines contemplated renaming their state "Malaysia" before the modern country took the name. Evidence of modern human habitation in Malaysia dates back 40,000 years.
In the Malay Peninsula, the first inhabitants are thought to be Negritos. Traders and settlers from India and China arrived as early as the first century AD, establishing trading ports and coastal towns in the second and third centuries, their presence resulted in strong Indian and Chinese influences on the local cultures, the people of the Malay Peninsula adopted the religions of Hinduism and Buddhism. Sanskrit inscriptions appear as early as the fifth century; the Kingdom of
Rainforests are forests characterized by high rainfall, with annual rainfall in the case of tropical rainforests between 250 and 450 centimetres, definitions varying by region for temperate rainforests. The monsoon trough, alternatively known as the intertropical convergence zone, plays a significant role in creating the climatic conditions necessary for the Earth's tropical rainforests. Around 40% to 75% of all biotic species are indigenous to the rainforests. There may be many millions of species of plants and microorganisms still undiscovered in tropical rainforests. Tropical rainforests have been called the "jewels of the Earth" and the "world's largest pharmacy", because over one quarter of natural medicines have been discovered there. Rainforests are responsible for 28% of the world's oxygen turnover, sometimes misnamed oxygen production, processing it through photosynthesis from carbon dioxide and consuming it through respiration; the undergrowth in some areas of a rainforest can be restricted by poor penetration of sunlight to ground level.
If the leaf canopy is destroyed or thinned, the ground beneath is soon colonized by a dense, tangled growth of vines and small trees, called a jungle. The term jungle is sometimes applied to tropical rainforests generally. Rainforests as well as endemic rainforest species are disappearing due to deforestation, the resulting habitat loss and pollution of the atmosphere. Tropical rainforests are characterized by a warm and wet climate with no substantial dry season: found within 10 degrees north and south of the equator. Mean monthly temperatures exceed 18 °C during all months of the year. Average annual rainfall is no less than 168 cm and can exceed 1,000 cm although it lies between 175 cm and 200 cm. Many of the world's tropical forests are associated with the location of the monsoon trough known as the intertropical convergence zone; the broader category of tropical moist forests are located in the equatorial zone between the Tropic of Cancer and Tropic of Capricorn. Tropical rainforests exist in Southeast Asia to the Philippines, Indonesia, Papua New Guinea and Sri Lanka.
Tropical forests have been called the "Earth's lungs", although it is now known that rainforests contribute little net oxygen addition to the atmosphere through photosynthesis. Tropical forests cover a large part of the globe, but temperate rainforests only occur in few regions around the world. Temperate rainforests are rainforests in temperate regions, they occur in North America, in Europe, in East Asia, in South America and in Australia and New Zealand. A tropical rainforest has a number of layers, each with different plants and animals adapted for life in that particular area. Examples include the emergent, canopy and forest floor layers; the emergent layer contains a small number of large trees called emergents, which grow above the general canopy, reaching heights of 45–55 m, although on occasion a few species will grow to 70–80 m tall. They need to be able to withstand the hot temperatures and strong winds that occur above the canopy in some areas. Eagles, butterflies and certain monkeys inhabit this layer.
The canopy layer contains the majority of the largest trees 30 metres to 45 metres tall. The densest areas of biodiversity are found in the forest canopy, a more or less continuous cover of foliage formed by adjacent treetops; the canopy, by some estimates, is home to 50 percent of all plant species. Epiphytic plants attach to trunks and branches, obtain water and minerals from rain and debris that collects on the supporting plants; the fauna is similar to that found in the emergent layer, but more diverse. A quarter of all insect species are believed to exist in the rainforest canopy. Scientists have long suspected the richness of the canopy as a habitat, but have only developed practical methods of exploring it; as long ago as 1917, naturalist William Beebe declared that "another continent of life remains to be discovered, not upon the Earth, but one to two hundred feet above it, extending over thousands of square miles." True exploration of this habitat only began in the 1980s, when scientists developed methods to reach the canopy, such as firing ropes into the trees using crossbows.
Exploration of the canopy is still in its infancy, but other methods include the use of balloons and airships to float above the highest branches and the building of cranes and walkways planted on the forest floor. The science of accessing tropical forest canopy using airships or similar aerial platforms is called dendronautics; the understory or understorey layer lies between the forest floor. It is home to a number of birds and lizards, as well as predators such as jaguars, boa constrictors and leopards; the leaves are much larger at this level and insect life is abundant. Many seedlings that will grow to the canopy level are present in the understory. Only about 5% of the sunlight s
A forest is a large area dominated by trees. Hundreds of more precise definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing and ecological function. According to the used Food and Agriculture Organization definition, forests covered 4 billion hectares or 30 percent of the world's land area in 2006. Forests are the dominant terrestrial ecosystem of Earth, are distributed around the globe. Forests account for 75% of the gross primary production of the Earth's biosphere, contain 80% of the Earth's plant biomass. Net primary production is estimated at 21.9 gigatonnes carbon per year for tropical forests, 8.1 for temperate forests, 2.6 for boreal forests. Forests at different latitudes and elevations form distinctly different ecozones: boreal forests near the poles, tropical forests near the equator and temperate forests at mid-latitudes. Higher elevation areas tend to support forests similar to those at higher latitudes, amount of precipitation affects forest composition.
Human society and forests influence each other in both negative ways. Forests serve as tourist attractions. Forests can affect people's health. Human activities, including harvesting forest resources, can negatively affect forest ecosystems. Although forest is a term of common parlance, there is no universally recognised precise definition, with more than 800 definitions of forest used around the world. Although a forest is defined by the presence of trees, under many definitions an area lacking trees may still be considered a forest if it grew trees in the past, will grow trees in the future, or was designated as a forest regardless of vegetation type. There are three broad categories of forest definitions in use: administrative, land use, land cover. Administrative definitions are based upon the legal designations of land, bear little relationship to the vegetation growing on the land: land, designated as a forest is defined as a forest if no trees are growing on it. Land use definitions are based upon the primary purpose.
For example, a forest may be defined as any land, used for production of timber. Under such a land use definition, cleared roads or infrastructure within an area used for forestry, or areas within the region that have been cleared by harvesting, disease or fire are still considered forests if they contain no trees. Land cover definitions define forests based upon the type and density of vegetation growing on the land; such definitions define a forest as an area growing trees above some threshold. These thresholds are the number of trees per area, the area of ground under the tree canopy or the section of land, occupied by the cross-section of tree trunks. Under such land cover definitions, an area of land can only be known as forest if it is growing trees. Areas that fail to meet the land cover definition may be still included under while immature trees are establishing if they are expected to meet the definition at maturity. Under land use definitions, there is considerable variation on where the cutoff points are between a forest and savanna.
Under some definitions, forests require high levels of tree canopy cover, from 60% to 100%, excluding savannas and woodlands in which trees have a lower canopy cover. Other definitions consider savannas to be a type of forest, include all areas with tree canopies over 10%; some areas covered in trees are defined as agricultural areas, e.g. Norway spruce plantations in Austrian forest law when the trees are being grown as Christmas trees and below a certain height; the word forest comes from Middle English, from Old French forest "forest, vast expanse covered by trees". A borrowing of the Medieval Latin word foresta "open wood", foresta was first used by Carolingian scribes in the Capitularies of Charlemagne to refer to the king's royal hunting grounds; the term was not endemic to Romance languages. The exact origin of Medieval Latin foresta is obscure; some authorities claim the word derives from the Late Latin phrase forestam silvam, meaning "the outer wood". Frankish *forhist is attested by Old High German forst "forest", Middle Low German vorst "forest", Old English fyrhþ "forest, game preserve, hunting ground", Old Norse fýri "coniferous forest", all of which derive from Proto-Germanic *furhísa-, *furhíþija- "a fir-wood, coniferous forest", from Proto-Indo-European *perkwu- "a coniferous or mountain forest, wooded height".
Uses of the word "forest" 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 denoting an uncultivated area set aside for hunting by feudal nobility; these hunting forests were not neces