Afghanistan the Islamic Republic of Afghanistan, is a landlocked country located in South-Central Asia. Afghanistan is bordered by Pakistan in the south and east, its territory covers 652,000 square kilometers and much of it is covered by the Hindu Kush mountain range, which experiences cold winters. The north consists of fertile plains, while the south-west consists of deserts where temperatures can get hot in summers. Kabul serves as its largest city. Human habitation in Afghanistan dates back to the Middle Paleolithic Era, the country's strategic location along the Silk Road connected it to the cultures of the Middle East and other parts of Asia; the land has been home to various peoples and has witnessed numerous military campaigns, including those by Alexander the Great, Muslim Arabs, British and since 2001 by the United States with NATO-allied countries. It has been called "unconquerable" and nicknamed the "graveyard of empires"; the land served as the source from which the Kushans, Samanids, Ghaznavids, Khaljis, Hotaks and others have risen to form major empires.
The political history of the modern state of Afghanistan began with the Hotak and Durrani dynasties in the 18th century. In the late 19th century, Afghanistan became a buffer state in the "Great Game" between British India and the Russian Empire, its border with British India, the Durand Line, was formed in 1893 but it is not recognized by the Afghan government and it has led to strained relations with Pakistan since the latter's independence in 1947. Following the Third Anglo-Afghan War in 1919 the country was free of foreign influence becoming a monarchy under King Amanullah, until 50 years when Zahir Shah was overthrown and a republic was established. In 1978, after a second coup Afghanistan first became a socialist state and a Soviet Union protectorate; this evoked the Soviet–Afghan War in the 1980s against mujahideen rebels. By 1996 most of Afghanistan was captured by the Islamic fundamentalist group the Taliban, who ruled most of the country as a totalitarian regime for over five years.
The Taliban were forcibly removed by the NATO-led coalition, a new democratically-elected government political structure was formed, but they still control a significant portion of the country. Afghanistan is a unitary presidential Islamic republic with a population of 31 million composed of ethnic Pashtuns, Tajiks and Uzbeks, it is a member of the United Nations, the Organisation of Islamic Cooperation, the Group of 77, the Economic Cooperation Organization, the Non-Aligned Movement. Afghanistan's economy is the world's 108th largest, with a GDP of $64.08 billion. The name Afghānistān is believed to be as old as the ethnonym Afghan, documented in the 10th-century geography book Hudud ul-'alam; the root name "Afghan" was used in reference to a member of the ethnic Pashtuns, the suffix "-stan" means "place of" in Persian. Therefore, Afghanistan translates to land of the Afghans or, more in a historical sense, to land of the Pashtuns. However, the modern Constitution of Afghanistan states that "he word Afghan shall apply to every citizen of Afghanistan."
Excavations of prehistoric sites by Louis Dupree and others suggest that humans were living in what is now Afghanistan at least 50,000 years ago, that farming communities in the area were among the earliest in the world. An important site of early historical activities, many believe that Afghanistan compares to Egypt in terms of the historical value of its archaeological sites; the country sits at a unique nexus point where numerous civilizations have interacted and fought. It has been home to various peoples through the ages, among them the ancient Iranian peoples who established the dominant role of Indo-Iranian languages in the region. At multiple points, the land has been incorporated within large regional empires, among them the Achaemenid Empire, the Macedonian Empire, the Indian Maurya Empire, the Islamic Empire. Many empires and kingdoms have risen to power in Afghanistan, such as the Greco-Bactrians, Hephthalites, Kabul Shahis, Samanids, Ghurids, Kartids, Timurids and the Hotak and Durrani dynasties that marked the political origins of the modern state.
Archaeological exploration done in the 20th century suggests that the geographical area of Afghanistan has been connected by culture and trade with its neighbors to the east and north. Artifacts typical of the Paleolithic, Neolithic and Iron ages have been found in Afghanistan. Urban civilization is believed to have begun as early as 3000 BCE, the early city of Mundigak may have been a colony of the nearby Indus Valley Civilization. More recent findings established that the Indus Valley Civilisation stretched up towards modern-day Afghanistan, making the ancient civilisation today part of Pakistan and India. In more detail, it extended from what today is northwest Pakistan to northwest India and northeast Afghanistan. An Indus Valley site has been found on the Oxus River at Shortugai in northern Afghanistan. There are several smaller IVC colonies to be found in Afghanistan as well. After 2000 BCE, successive waves of semi-nomadic
In ecology, a habitat is the type of natural environment in which a particular species of organism lives. It is characterized by both biological features. A species' habitat is those places where it can find food, shelter and mates for reproduction; the physical factors are for example soil, range of temperature, light intensity as well as biotic factors such as the availability of food and the presence or absence of predators. Every organism has certain habitat needs for the conditions in which it will thrive, but some are tolerant of wide variations while others are specific in their requirements. A habitat is not a geographical area, it can be the interior of a stem, a rotten log, a rock or a clump of moss, for a parasitic organism it is the body of its host, part of the host's body such as the digestive tract, or a single cell within the host's body. Habitat types include polar, temperate and tropical; the terrestrial vegetation type may be forest, grassland, semi-arid or desert. Fresh water habitats include marshes, rivers and ponds, marine habitats include salt marshes, the coast, the intertidal zone, reefs, the open sea, the sea bed, deep water and submarine vents.
Habitats change over time. This may be due to a violent event such as the eruption of a volcano, an earthquake, a tsunami, a wildfire or a change in oceanic currents. Other changes come as a direct result of human activities; the introduction of alien species can have a devastating effect on native wildlife, through increased predation, through competition for resources or through the introduction of pests and diseases to which the native species have no immunity. The word "habitat" has been in use since about 1755 and derives from the Latin habitāre, to inhabit, from habēre, to have or to hold. Habitat can be defined as the natural environment of an organism, the type of place in which it is natural for it to live and grow, it is similar in meaning to a biotope. The chief environmental factors affecting the distribution of living organisms are temperature, climate, soil type and light intensity, the presence or absence of all the requirements that the organism needs to sustain it. Speaking, animal communities are reliant on specific types of plant communities.
Some plants and animals are generalists, their habitat requirements are met in a wide range of locations. The small white butterfly for example is found on all the continents of the world apart from Antarctica, its larvae feed on a wide range of Brassicas and various other plant species, it thrives in any open location with diverse plant associations. The large blue butterfly is much more specific in its requirements. Disturbance is important in the creation of biodiverse habitats. In the absence of disturbance, a climax vegetation cover develops that prevents the establishment of other species. Wildflower meadows are sometimes created by conservationists but most of the flowering plants used are either annuals or biennials and disappear after a few years in the absence of patches of bare ground on which their seedlings can grow. Lightning strikes and toppled trees in tropical forests allow species richness to be maintained as pioneering species move in to fill the gaps created. Coastal habitats can become dominated by kelp until the seabed is disturbed by a storm and the algae swept away, or shifting sediment exposes new areas for colonisation.
Another cause of disturbance is when an area may be overwhelmed by an invasive introduced species, not kept under control by natural enemies in its new habitat. Terrestrial habitat types include forests, grasslands and deserts. Within these broad biomes are more specific habitats with varying climate types, temperature regimes, soils and vegetation types. Many of these habitats grade into each other and each one has its own typical communities of plants and animals. A habitat may suit a particular species well, but its presence or absence at any particular location depends to some extent on chance, on its dispersal abilities and its efficiency as a coloniser. Freshwater habitats include rivers, lakes, ponds and bogs. Although some organisms are found across most of these habitats, the majority have more specific requirements; the water velocity, its temperature and oxygen saturation are important factors, but in river systems, there are fast and slow sections, pools and backwaters which provide a range of habitats.
Aquatic plants can be floating, semi-submerged, submerged or grow in permanently or temporarily saturated soils besides bodies of water. Marginal plants provide important habitat for both invertebrates and vertebrates, submerged plants provide oxygenation of the water, absorb nutrients and play a part in the reduction of pollution. Marine habitats include brackish water, bays, the open sea, the intertidal zone, the sea bed and deep / shallow water zones. Further variations include rock pools, sand banks, brackish lagoons and pebbly beaches, seagrass beds, all supporting their own flora and fauna; the benth
The United Kingdom the United Kingdom of Great Britain and Northern Ireland, sometimes referred to as Britain, is a sovereign country located off the north-western coast of the European mainland. The United Kingdom includes the island of Great Britain, the north-eastern part of the island of Ireland, many smaller islands. Northern Ireland is the only part of the United Kingdom that shares a land border with another sovereign state, the Republic of Ireland. Apart from this land border, the United Kingdom is surrounded by the Atlantic Ocean, with the North Sea to the east, the English Channel to the south and the Celtic Sea to the south-west, giving it the 12th-longest coastline in the world; the Irish Sea lies between Great Ireland. With an area of 242,500 square kilometres, the United Kingdom is the 78th-largest sovereign state in the world, it is the 22nd-most populous country, with an estimated 66.0 million inhabitants in 2017. The UK is constitutional monarchy; the current monarch is Queen Elizabeth II, who has reigned since 1952, making her the longest-serving current head of state.
The United Kingdom's capital and largest city is London, a global city and financial centre with an urban area population of 10.3 million. Other major urban areas in the UK include Greater Manchester, the West Midlands and West Yorkshire conurbations, Greater Glasgow and the Liverpool Built-up Area; the United Kingdom consists of four constituent countries: England, Scotland and Northern Ireland. Their capitals are London, Edinburgh and Belfast, respectively. Apart from England, the countries have their own devolved governments, each with varying powers, but such power is delegated by the Parliament of the United Kingdom, which may enact laws unilaterally altering or abolishing devolution; the nearby Isle of Man, Bailiwick of Guernsey and Bailiwick of Jersey are not part of the UK, being Crown dependencies with the British Government responsible for defence and international representation. The medieval conquest and subsequent annexation of Wales by the Kingdom of England, followed by the union between England and Scotland in 1707 to form the Kingdom of Great Britain, the union in 1801 of Great Britain with the Kingdom of Ireland created the United Kingdom of Great Britain and Ireland.
Five-sixths of Ireland seceded from the UK in 1922, leaving the present formulation of the United Kingdom of Great Britain and Northern Ireland. There are fourteen British Overseas Territories, the remnants of the British Empire which, at its height in the 1920s, encompassed a quarter of the world's land mass and was the largest empire in history. British influence can be observed in the language and political systems of many of its former colonies; the United Kingdom is a developed country and has the world's fifth-largest economy by nominal GDP and ninth-largest economy by purchasing power parity. It has a high-income economy and has a high Human Development Index rating, ranking 14th in the world, it was the world's first industrialised country and the world's foremost power during the 19th and early 20th centuries. The UK remains a great power, with considerable economic, military and political influence internationally, it is sixth in military expenditure in the world. It has been a permanent member of the United Nations Security Council since its first session in 1946.
It has been a leading member state of the European Union and its predecessor, the European Economic Community, since 1973. The United Kingdom is a member of the Commonwealth of Nations, the Council of Europe, the G7, the G20, NATO, the Organisation for Economic Co-operation and Development and the World Trade Organization; the 1707 Acts of Union declared that the kingdoms of England and Scotland were "United into One Kingdom by the Name of Great Britain". The term "United Kingdom" has been used as a description for the former kingdom of Great Britain, although its official name from 1707 to 1800 was "Great Britain"; the Acts of Union 1800 united the kingdom of Great Britain and the kingdom of Ireland in 1801, forming the United Kingdom of Great Britain and Ireland. Following the partition of Ireland and the independence of the Irish Free State in 1922, which left Northern Ireland as the only part of the island of Ireland within the United Kingdom, the name was changed to the "United Kingdom of Great Britain and Northern Ireland".
Although the United Kingdom is a sovereign country, Scotland and Northern Ireland are widely referred to as countries. The UK Prime Minister's website has used the phrase "countries within a country" to describe the United Kingdom; some statistical summaries, such as those for the twelve NUTS 1 regions of the United Kingdom refer to Scotland and Northern Ireland as "regions". Northern Ireland is referred to as a "province". With regard to Northern Ireland, the descriptive name used "can be controversial, with the choice revealing one's political preferences"; the term "Great Britain" conventionally refers to the island of Great Britain, or politically to England and Wales in combination. However, it is sometimes used as a loose synonym for the United Kingdom as a whole; the term "Britain" is used both as a synonym for Great Britain, as a synonym for the United Kingdom. Usage is mixed, with the BBC preferring to use Britain as shorthand only for Great Britain and the UK Government, while accepting that both terms refer to the United K
Wastewater treatment is a process used to remove contaminants from wastewater or sewage and convert it into an effluent that can be returned to the water cycle with minimum impact on the environment, or directly reused. The latter is called water reclamation because treated wastewater can be used for other purposes; the treatment process takes place in a wastewater treatment plant referred to as a Water Resource Recovery Facility or a sewage treatment plant. Pollutants in municipal wastewater are broken down; the treatment of wastewater is part of the overarching field of sanitation. Sanitation includes the management of human waste and solid waste as well as stormwater management. By-products from wastewater treatment plants, such as screenings and sewage sludge may be treated in a wastewater treatment plant. Although disposal or reuse occurs after treatment, it must be considered first. Since disposal or reuse are the objectives of wastewater treatment, disposal or reuse options are the basis for treatment decisions.
Acceptable impurity concentrations may vary with the type of location of disposal. Transportation costs make acceptable impurity concentrations dependent upon location of disposal, but expensive treatment requirements may encourage selection of a disposal location on the basis of impurity concentrations. Ocean disposal is subject to international treaty requirements. International treaties may regulate disposal into rivers crossing international borders. Water bodies within the jurisdiction of a single nation may be subject to regulations of multiple local governments. Acceptable impurity concentrations may vary among different jurisdictions for disposal of wastewater to evaporation ponds, infiltration basins, or injection wells. Biological processes can be employed in the treatment of wastewater and these processes may include, for example, aerated lagoons, activated sludge or slow sand filters. To be effective, sewage must be conveyed to a treatment plant by appropriate pipes and infrastructure and the process itself must be subject to regulation and controls.
Some wastewaters require different and sometimes specialized treatment methods. At the simplest level, treatment of sewage and most wastewaters is carried out through separation of solids from liquids by sedimentation. By progressively converting dissolved material into solids a biological floc, settled out, an effluent stream of increasing purity is produced. Phase separation transfers impurities into a non-aqueous phase. Phase separation may occur at intermediate points in a treatment sequence to remove solids generated during oxidation or polishing. Grease and oil may be recovered for saponification. Solids require dewatering of sludge in a wastewater treatment plant. Disposal options for dried solids vary with the type and concentration of impurities removed from water. Production of waste brine, may discourage wastewater treatment removing dissolved inorganic solids from water by methods like ion exchange, reverse osmosis, distillation. Solids like stones, excretes etc. and non-polar Impurties liquid's may be removed from wastewater by gravity when density differences are sufficient to overcome dispersion by turbulence.
Gravity separation of solids is the primary treatment of sewage, where the unit process is called "primary settling tanks" or "primary sedimentation tanks". It is widely used for the treatment of other wastewaters. Solids that are heavier than water will accumulate at the bottom of quiescent settling basins. More complex clarifiers have skimmers to remove floating grease like soap scum and solids like feathers or wood chips. Containers like the API oil-water separator are designed to separate non-polar liquids. Suspended solids and colloidal suspensions of fine solids may following some form of coagulation, be removed by filtration through fine physical barriers distinguished from coarser screens or sieves by the ability to remove particles smaller than the openings through which the water passes. Other types of water filters remove impurities by chemical or biological processes described below. Oxidation reduces the biochemical oxygen demand of wastewater, may reduce the toxicity of some impurities.
Secondary treatment converts organic compounds into carbon dioxide and biosolids. Chemical oxidation is used for disinfection. Secondary treatment by biochemical oxidation of dissolved and colloidal organic compounds is used in sewage treatment and is applicable to some agricultural and industrial wastewaters. Biological oxidation will preferentially remove organic compounds useful as a food supply for the treatment ecosystem. Concentration of some less digestible compounds may be reduced by co-metabolism. Removal efficiency is limited by the minimum food concentration required to sustain the treatment ecosystem. Chemical oxidation is used to remove some persistent organic pollutants and concentrations remaining after biochemical oxidation. Disinfection by chemical oxidation kills bacteria and microbial pathogens by adding ozone, chlorine or hypochlorite to wastewater. Polishing refers to treatments made following the above methods; these treatments may be used independently for some industrial wastewater.
Chemical reduction or pH adjustment minimizes chemical reactivity of wastewater following chemical oxidation. Carbon filtering removes remaining contaminants and impurities by chemical absorption onto activated carbon. Filtration through sand or fabric filters is the most common method used in municipal wastewater treatment. Wastewater treatment plants may be distinguished by the t
The Czech Republic known by its short-form name, Czechia, is a landlocked country in Central Europe bordered by Germany to the west, Austria to the south, Slovakia to the east and Poland to the northeast. The Czech Republic covers an area of 78,866 square kilometres with a temperate continental climate and oceanic climate, it is a unitary parliamentary republic, with 10.6 million inhabitants. Other major cities are Brno, Ostrava and Pilsen; the Czech Republic is a member of the European Union, NATO, the OECD, the United Nations, the OSCE, the Council of Europe. It is a developed country with an advanced, high income export-oriented social market economy based in services and innovation; the UNDP ranks the country 14th in inequality-adjusted human development. The Czech Republic is a welfare state with a "continental" European social model, a universal health care system, tuition-free university education and is ranked 14th in the Human Capital Index, it ranks as the 6th safest or most peaceful country and is one of the most non-religious countries in the world, while achieving strong performance in democratic governance.
The Czech Republic includes the historical territories of Bohemia and Czech Silesia. The Czech state was formed in the late 9th century as the Duchy of Bohemia under the Great Moravian Empire. After the fall of the Empire in 907, the centre of power transferred from Moravia to Bohemia under the Přemyslid dynasty. In 1002, the duchy was formally recognized as an Imperial State of the Holy Roman Empire along with the Kingdom of Germany, the Kingdom of Burgundy, the Kingdom of Italy, numerous other territories, becoming the Kingdom of Bohemia in 1198 and reaching its greatest territorial extent in the 14th century. Beside Bohemia itself, the King of Bohemia ruled the lands of the Bohemian Crown, holding a vote in the election of the Holy Roman Emperor. In the Hussite Wars of the 15th century driven by the Protestant Bohemian Reformation, the kingdom faced economic embargoes and defeated five consecutive crusades proclaimed by the leaders of the Catholic Church. Following the Battle of Mohács in 1526, the whole Crown of Bohemia was integrated into the Habsburg Monarchy alongside the Archduchy of Austria and the Kingdom of Hungary.
The Protestant Bohemian Revolt against the Catholic Habsburgs led to the Thirty Years' War. After the Battle of the White Mountain, the Habsburgs consolidated their rule, eradicated Protestantism and reimposed Catholicism, adopted a policy of gradual Germanization; this contributed to the anti-Habsburg sentiment. A long history of resentment of the Catholic Church followed and still continues. With the dissolution of the Holy Roman Empire in 1806, the Bohemian Kingdom became part of the German Confederation 1815-1866 as part of Austrian Empire and the Czech language experienced a revival as a consequence of widespread romantic nationalism. In the 19th century, the Czech lands became the industrial powerhouse of the monarchy and were subsequently the core of the Republic of Czechoslovakia, formed in 1918 following the collapse of the Austro-Hungarian Empire after World War I. Czechoslovakia remained the only democracy in this part of Europe in the interwar period. However, the Czech part of Czechoslovakia was occupied by Germany in World War II, while the Slovak region became the Slovak Republic.
Most of the three millions of the German-speaking minority were expelled following the war. The Communist Party of Czechoslovakia won the 1946 elections and after the 1948 coup d'état, Czechoslovakia became a one-party communist state under Soviet influence. In 1968, increasing dissatisfaction with the regime culminated in a reform movement known as the Prague Spring, which ended in a Soviet-led invasion. Czechoslovakia remained occupied until the 1989 Velvet Revolution, when the communist regime collapsed and market economy was reintroduced. On 1 January 1993, Czechoslovakia peacefully dissolved, with its constituent states becoming the independent states of the Czech Republic and Slovakia; the Czech Republic joined NATO in 1999 and the EU in 2004. The traditional English name "Bohemia" derives from Latin "Boiohaemum", which means "home of the Boii"; the current English name comes from the Polish ethnonym associated with the area, which comes from the Czech word Čech. The name comes from the Slavic tribe and, according to legend, their leader Čech, who brought them to Bohemia, to settle on Říp Mountain.
The etymology of the word Čech can be traced back to the Proto-Slavic root *čel-, meaning "member of the people. The country has been traditionally divided into three lands, namely Bohemia in the west, Moravia in the east, Czech Silesia in the northeast. Known as the lands of the Bohemian Crown since the 14th century, a number of other names for the country have been used, including Czech/Bohemian lands, Bohemian Crown and the lands of the Crown of Saint Wenceslas; when the country regained its independence after the dissolution of the Austro-Hungarian empire in 1918, the new name of Czechoslovakia was coined to reflect the union of the Czech and Slovak nations within the one country. After Czechoslovakia dissolved in 1992, the Czech part lac
Biodiversity refers to the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic and ecosystem level. Terrestrial biodiversity is greater near the equator, the result of the warm climate and high primary productivity. Biodiversity is not distributed evenly on Earth, is richest in the tropics; these tropical forest ecosystems cover less than 10 percent of earth's surface, contain about 90 percent of the world's species. Marine biodiversity is highest along coasts in the Western Pacific, where sea surface temperature is highest, in the mid-latitudinal band in all oceans. There are latitudinal gradients in species diversity. Biodiversity tends to cluster in hotspots, has been increasing through time, but will be to slow in the future. Rapid environmental changes cause mass extinctions. More than 99.9 percent of all species that lived on Earth, amounting to over five billion species, are estimated to be extinct. Estimates on the number of Earth's current species range from 10 million to 14 million, of which about 1.2 million have been documented and over 86 percent have not yet been described.
More in May 2016, scientists reported that 1 trillion species are estimated to be on Earth with only one-thousandth of one percent described. The total amount of related DNA base pairs on Earth is estimated at 5.0 x 1037 and weighs 50 billion tonnes. In comparison, the total mass of the biosphere has been estimated to be as much as 4 TtC. In July 2016, scientists reported identifying a set of 355 genes from the Last Universal Common Ancestor of all organisms living on Earth; the age of the Earth is about 4.54 billion years. The earliest undisputed evidence of life on Earth dates at least from 3.5 billion years ago, during the Eoarchean Era after a geological crust started to solidify following the earlier molten Hadean Eon. There are microbial mat fossils found in 3.48 billion-year-old sandstone discovered in Western Australia. Other early physical evidence of a biogenic substance is graphite in 3.7 billion-year-old meta-sedimentary rocks discovered in Western Greenland. More in 2015, "remains of biotic life" were found in 4.1 billion-year-old rocks in Western Australia.
According to one of the researchers, "If life arose quickly on Earth.. it could be common in the universe."Since life began on Earth, five major mass extinctions and several minor events have led to large and sudden drops in biodiversity. The Phanerozoic eon marked a rapid growth in biodiversity via the Cambrian explosion—a period during which the majority of multicellular phyla first appeared; the next 400 million years included repeated, massive biodiversity losses classified as mass extinction events. In the Carboniferous, rainforest collapse led to a great loss of animal life; the Permian–Triassic extinction event, 251 million years ago, was the worst. The most recent, the Cretaceous–Paleogene extinction event, occurred 65 million years ago and has attracted more attention than others because it resulted in the extinction of the dinosaurs; the period since the emergence of humans has displayed an ongoing biodiversity reduction and an accompanying loss of genetic diversity. Named the Holocene extinction, the reduction is caused by human impacts habitat destruction.
Conversely, biodiversity positively impacts human health in a number of ways, although a few negative effects are studied. The United Nations designated 2011–2020 as the United Nations Decade on Biodiversity. 1916 - The term biological diversity was used first by J. Arthur Harris in "The Variable Desert," Scientific American, JSTOR 6182: "The bare statement that the region contains a flora rich in genera and species and of diverse geographic origin or affinity is inadequate as a description of its real biological diversity." 1975 - The term natural diversity was introduced 1980 - Thomas Lovejoy introduced the term biological diversity to the scientific community in a book.. It became used. 1985 -The contracted form biodiversity was coined by W. G. Rosen 1985 - The term "biodiversity" appears in the article, "A New Plan to Conserve the Earth's Biota" by Laura Tangley. 1988 - The term biodiversity first appeared in a publication. The present - the term has achieved widespread use. "Biodiversity" is most used to replace the more defined and long established terms, species diversity and species richness.
Biologists most define biodiversity as the "totality of genes and ecosystems of a region". An advantage of this definition is that it seems to describe most circumstances and presents a unified view of the traditional types of biological variety identified: taxonomic diversity ecological diversity morphological diversity functional diversity This multilevel construct is consistent with Datman and Lovejoy. An explicit definition consistent with this interpretation was first given in a paper by Bruce A. Wilcox commissioned by the International Union for the Conservation of Nature and Natural Resources for the 1982 World National Parks Conference. Wilcox's definition was "Biological diversity is the variety of life forms...at all levels of biologi