Chernozem is a black-colored soil containing a high percentage of humus and high percentages of phosphoric acids and ammonia. Chernozem is fertile and can produce high agricultural yields with its high moisture storage capacity. Chernozems are a Reference Soil Group of the World Reference Base for Soil Resources; the name comes from the Russian terms for soil, earth or land. The soil, rich in organic matter presenting a black color, was first identified by Russian geologist Vasily Dokuchaev in 1883 in the tallgrass steppe or prairie of European Russia. Chernozems cover about 230 million hectares of land. There are two "chernozem belts" in the world. One is the Eurasian steppe which extends from eastern Croatia, along the Danube to northeast Ukraine across the Central Black Earth Region of Central Russia, southern Russia into Siberia; the other stretches from the Canadian Prairies in Manitoba through the Great Plains of the US as far south as Kansas. Similar soil types occur in Hungary. Chernozem layer thickness may vary from several centimetres up to 1.5 metres in Ukraine, as well as the Red River Valley region in the Northern US and Canada.
The terrain can be found in small quantities elsewhere. It exists in Northeast China, near Harbin; the only true Chernozem in Australia is located around Nimmitabel, with some of the richest soils in the nation. There is a large black market for the soil in Ukraine; the sale of agricultural land has been illegal in Ukraine since 1992, but the soil, transported by truck, has US$900 million annually in black market sales. Chernozemic soils are a soil type in the Canadian system of soil classification and the World Reference Base for Soil Resources. Theories of Chernozem origin: 1761 — Johan Gottschalk Wallerius 1763 — Mikhail Lomonosov 1799 — Peter Simon Pallas 1835 — Charles Lyell 1840 — Sir Roderick Murchison 1850 — Karl Eichwald 1851 — А. Petzgold 1852 — Nikifor Borisyak 1853 — Vangengeim von Qualen 1862 — Rudolf Ludwig 1866 — Franz Josef Ruprecht 1879 — First chernozem papers translated from Russian 1883 — Vasily Dokuchaev published his book Russian Chernozem with a complete study of this soil in European Russia.
1929 — Otto Schlüter 1999 — Michael W. I Schmidt Dark earth Terra preta profile photos WRB homepage profile photos IUSS World of Soils IUSS Working Group WRB: World Reference Base for Soil Resources 2014, Update 2015. World Soil Resources Reports 106, FAO, Rome 2015. ISBN 978-92-5-108369-7; the dictionary definition of chernozem at Wiktionary
Physical geography is one of the two major sub-fields of geography. Physical geography is the branch of natural science which deals with the study of processes and patterns in the natural environment like the atmosphere, hydrosphere and geosphere, as opposed to the cultural or built environment, the domain of human geography. Physical Geography can be divided into several sub-fields, as follows: Geomorphology is the field concerned with understanding the surface of the Earth and the processes by which it is shaped, both at the present as well as in the past. Geomorphology as a field has several sub-fields that deal with the specific landforms of various environments e.g. desert geomorphology and fluvial geomorphology. Geomorphology seeks to understand landform history and dynamics, predict future changes through a combination of field observation, physical experiment, numerical modeling. Early studies in geomorphology are the foundation for pedology, one of two main branches of soil science Hydrology is predominantly concerned with the amounts and quality of water moving and accumulating on the land surface and in the soils and rocks near the surface and is typified by the hydrological cycle.
Thus the field encompasses water in rivers, aquifers and to an extent glaciers, in which the field examines the process and dynamics involved in these bodies of water. Hydrology has had an important connection with engineering and has thus developed a quantitative method in its research. Similar to most fields of physical geography it has sub-fields that examine the specific bodies of water or their interaction with other spheres e.g. limnology and ecohydrology. Glaciology is the study of glaciers and ice sheets, or more the cryosphere or ice and phenomena that involve ice. Glaciology groups the latter as continental glaciers and the former as alpine glaciers. Although research in the areas are similar with research undertaken into both the dynamics of ice sheets and glaciers, the former tends to be concerned with the interaction of ice sheets with the present climate and the latter with the impact of glaciers on the landscape. Glaciology has a vast array of sub-fields examining the factors and processes involved in ice sheets and glaciers e.g. snow hydrology and glacial geology.
Biogeography is the science which deals with geographic patterns of species distribution and the processes that result in these patterns. Biogeography emerged as a field of study as a result of the work of Alfred Russel Wallace, although the field prior to the late twentieth century had been viewed as historic in its outlook and descriptive in its approach; the main stimulus for the field since its founding has been that of evolution, plate tectonics and the theory of island biogeography. The field can be divided into five sub-fields: island biogeography, paleobiogeography, phylogeography and phytogeography Climatology is the study of the climate, scientifically defined as weather conditions averaged over a long period of time. Climatology examines both the nature of micro and macro climates and the natural and anthropogenic influences on them; the field is sub-divided into the climates of various regions and the study of specific phenomena or time periods e.g. tropical cyclone rainfall climatology and paleoclimatology.
Meteorology is the interdisciplinary scientific study of the atmosphere that focuses on weather processes and short term forecasting. Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the eighteenth century. Meteorological phenomena are observable weather events which illuminate and are explained by the science of meteorology. Pedology is the study of soils in their natural environment, it is one of two main branches of the other being edaphology. Pedology deals with pedogenesis, soil morphology, soil classification. In physical geography pedology is studied due to the numerous interactions between climate, soil life, the mineral materials within soils and its position and effects on the landscape such as lateralization. Palaeogeography is a cross-disciplinary study that examines the preserved material in the stratigraphic record to determine the distribution of the continents through geologic time. All the evidence for the positions of the continents comes from geology in the form of fossils or paleomagnetism.
The use of this data has resulted in evidence for continental drift, plate tectonics, supercontinents. This, in turn, has supported palaeogeographic theories such as the Wilson cycle. Coastal geography is the study of the dynamic interface between the ocean and the land, incorporating both the physical geography and the human geography of the coast, it involves an understanding of coastal weathering processes wave action, sediment movement and weathering, the ways in which humans interact with the coast. Coastal geography, although predominantly geomorphological in its research, is not just concerned with coastal landforms, but the causes and influences of sea level change. Oceanography is the branch of physical geography that studies seas, it covers a wide range including marine organisms and ecosystem dynamics.
Russia the Russian Federation, is a transcontinental country in Eastern Europe and North Asia. At 17,125,200 square kilometres, Russia is by far or by a considerable margin the largest country in the world by area, covering more than one-eighth of the Earth's inhabited land area, the ninth most populous, with about 146.77 million people as of 2019, including Crimea. About 77 % of the population live in the European part of the country. Russia's capital, Moscow, is one of the largest cities in the world and the second largest city in Europe. Extending across the entirety of Northern Asia and much of Eastern Europe, Russia spans eleven time zones and incorporates a wide range of environments and landforms. From northwest to southeast, Russia shares land borders with Norway, Estonia, Latvia and Poland, Ukraine, Azerbaijan, China and North Korea, it shares maritime borders with Japan by the Sea of Okhotsk and the U. S. state of Alaska across the Bering Strait. However, Russia recognises two more countries that border it, Abkhazia and South Ossetia, both of which are internationally recognized as parts of Georgia.
The East Slavs emerged as a recognizable group in Europe between the 3rd and 8th centuries AD. Founded and ruled by a Varangian warrior elite and their descendants, the medieval state of Rus arose in the 9th century. In 988 it adopted Orthodox Christianity from the Byzantine Empire, beginning the synthesis of Byzantine and Slavic cultures that defined Russian culture for the next millennium. Rus' disintegrated into a number of smaller states; the Grand Duchy of Moscow reunified the surrounding Russian principalities and achieved independence from the Golden Horde. By the 18th century, the nation had expanded through conquest and exploration to become the Russian Empire, the third largest empire in history, stretching from Poland on the west to Alaska on the east. Following the Russian Revolution, the Russian Soviet Federative Socialist Republic became the largest and leading constituent of the Union of Soviet Socialist Republics, the world's first constitutionally socialist state; the Soviet Union played a decisive role in the Allied victory in World War II, emerged as a recognized superpower and rival to the United States during the Cold War.
The Soviet era saw some of the most significant technological achievements of the 20th century, including the world's first human-made satellite and the launching of the first humans in space. By the end of 1990, the Soviet Union had the world's second largest economy, largest standing military in the world and the largest stockpile of weapons of mass destruction. Following the dissolution of the Soviet Union in 1991, twelve independent republics emerged from the USSR: Russia, Belarus, Uzbekistan, Azerbaijan, Kyrgyzstan, Tajikistan and the Baltic states regained independence: Estonia, Lithuania, it is governed as a federal semi-presidential republic. Russia's economy ranks as the twelfth largest by nominal GDP and sixth largest by purchasing power parity in 2018. Russia's extensive mineral and energy resources are the largest such reserves in the world, making it one of the leading producers of oil and natural gas globally; the country is one of the five recognized nuclear weapons states and possesses the largest stockpile of weapons of mass destruction.
Russia is a great power as well as a regional power and has been characterised as a potential superpower. It is a permanent member of the United Nations Security Council and an active global partner of ASEAN, as well as a member of the Shanghai Cooperation Organisation, the G20, the Council of Europe, the Asia-Pacific Economic Cooperation, the Organization for Security and Co-operation in Europe, the World Trade Organization, as well as being the leading member of the Commonwealth of Independent States, the Collective Security Treaty Organization and one of the five members of the Eurasian Economic Union, along with Armenia, Belarus and Kyrgyzstan; the name Russia is derived from Rus', a medieval state populated by the East Slavs. However, this proper name became more prominent in the history, the country was called by its inhabitants "Русская Земля", which can be translated as "Russian Land" or "Land of Rus'". In order to distinguish this state from other states derived from it, it is denoted as Kievan Rus' by modern historiography.
The name Rus itself comes from the early medieval Rus' people, Swedish merchants and warriors who relocated from across the Baltic Sea and founded a state centered on Novgorod that became Kievan Rus. An old Latin version of the name Rus' was Ruthenia applied to the western and southern regions of Rus' that were adjacent to Catholic Europe; the current name of the country, Россия, comes from the Byzantine Greek designation of the Rus', Ρωσσία Rossía—spelled Ρωσία in Modern Greek. The standard way to refer to citizens of Russia is rossiyane in Russian. There are two Russian words which are commonly
In botany, a tree is a perennial plant with an elongated stem, or trunk, supporting branches and leaves in most species. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are usable as lumber or plants above a specified height. Trees are not a taxonomic group but include a variety of plant species that have independently evolved a woody trunk and branches as a way to tower above other plants to compete for sunlight. Trees tend to be long-lived, some reaching several thousand years old. In wider definitions, the taller palms, tree ferns and bamboos are trees. Trees have been in existence for 370 million years, it is estimated. A tree has many secondary branches supported clear of the ground by the trunk; this trunk contains woody tissue for strength, vascular tissue to carry materials from one part of the tree to another. For most trees it is surrounded by a layer of bark. Below the ground, the roots spread out widely. Above ground, the branches divide into smaller shoots.
The shoots bear leaves, which capture light energy and convert it into sugars by photosynthesis, providing the food for the tree's growth and development. Trees reproduce using seeds. Flowers and fruit may be present, but some trees, such as conifers, instead have pollen cones and seed cones. Palms and bamboos produce seeds, but tree ferns produce spores instead. Trees play a significant role in moderating the climate, they remove carbon dioxide from the atmosphere and store large quantities of carbon in their tissues. Trees and forests provide a habitat for many species of plants. Tropical rainforests are among the most biodiverse habitats in the world. Trees provide shade and shelter, timber for construction, fuel for cooking and heating, fruit for food as well as having many other uses. In parts of the world, forests are shrinking as trees are cleared to increase the amount of land available for agriculture; because of their longevity and usefulness, trees have always been revered, with sacred groves in various cultures, they play a role in many of the world's mythologies.
Although "tree" is a term of common parlance, there is no universally recognised precise definition of what a tree is, either botanically or in common language. In its broadest sense, a tree is any plant with the general form of an elongated stem, or trunk, which supports the photosynthetic leaves or branches at some distance above the ground. Trees are typically defined by height, with smaller plants from 0.5 to 10 m being called shrubs, so the minimum height of a tree is only loosely defined. Large herbaceous plants such as papaya and bananas are trees in this broad sense. A applied narrower definition is that a tree has a woody trunk formed by secondary growth, meaning that the trunk thickens each year by growing outwards, in addition to the primary upwards growth from the growing tip. Under such a definition, herbaceous plants such as palms and papayas are not considered trees regardless of their height, growth form or stem girth. Certain monocots may be considered trees under a looser definition.
Aside from structural definitions, trees are defined by use. The tree growth habit is an evolutionary adaptation found in different groups of plants: by growing taller, trees are able to compete better for sunlight. Trees tend some reaching several thousand years old. Several trees are among the oldest organisms now living. Trees have modified structures such as thicker stems composed of specialised cells that add structural strength and durability, allowing them to grow taller than many other plants and to spread out their foliage, they differ from shrubs, which have a similar growth form, by growing larger and having a single main stem. The tree form has evolved separately in unrelated classes of plants in response to similar environmental challenges, making it a classic example of parallel evolution. With an estimated 60,000-100,000 species, the number of trees worldwide might total twenty-five per cent of all living plant species; the greatest number of these grow in tropical regions and many of these areas have not yet been surveyed by botanists, making tree diversity and ranges poorly known.
The majority of tree species are angiosperms. There are about 1000 species of gymnosperm trees, including conifers, cycads and gnetales. Most angiosperm trees are eudicots, the "true dicotyledons", so named because the seeds contain two cotyledons or seed leaves. There are some trees among the old lineages of flowering plants called basal angiosperms or paleodicots. Wood gives structural strength to the trunk of most types of tree; the vascular system of trees allows water and other chemicals to be di
Archaic Greece was the period in Greek history lasting from the eighth century BC to the second Persian invasion of Greece in 480 BC, following the Greek Dark Ages and succeeded by the Classical period. The period began with a massive increase in the Greek population and a series of significant changes which rendered the Greek world at the end of the eighth century unrecognisable compared to its beginning. According to Anthony Snodgrass, the Archaic period in ancient Greece was bounded by two revolutions in the Greek world, it began with a "structural revolution" which "drew the political map of the Greek world" and established the poleis, the distinctively Greek city-states, ended with the intellectual revolution of the Classical period. The Archaic period saw developments in Greek politics, international relations and culture, it laid the groundwork for the Classical period, both politically and culturally. It was in the Archaic period that the Greek alphabet developed, that the earliest surviving Greek literature was composed, that monumental sculpture and red-figure pottery began in Greece, that the hoplite became the core of Greek armies.
In Athens, the earliest institutions of the democracy were implemented under Solon, the reforms of Cleisthenes at the end of the Archaic period brought in Athenian democracy as it was during the Classical period. In Sparta, many of the institutions credited to the reforms of Lycurgus were introduced during the period, the region of Messenia was brought under Spartan control, helotage was introduced, the Peloponnesian League was founded, making Sparta a dominant power in Greece; the word "archaic" derives from the Greek word archaios, which means "old". It refers to the period in ancient Greek history before the Classical; the period is considered to have lasted from the beginning of the eighth century BC until the beginning of the fifth century BC, with the foundation of the Olympic Games in 776 BC and the Second Persian invasion of Greece in 480 BC forming notional start and end dates. The Archaic period was long considered to have been less important and interesting than the Classical period, was studied as a precursor to it.
More however, Archaic Greece has come to be studied for its own achievements. With this reassessment of the significance of the Archaic period, some scholars have objected to the term "archaic", due to its connotations in English of being primitive and outdated. No term, suggested to replace it has gained widespread currency and the term is still in use. Much of our evidence about the Classical period of ancient Greece comes from written histories, such as Thucydides' History of the Peloponnesian War. By contrast, we have no such evidence from the Archaic period. We have written accounts of life in the period in the form of poetry, epigraphical evidence, including parts of law codes, inscriptions on votive offerings, epigrams inscribed on tombs. However, none of this evidence is in the quantity. What is lacking in written evidence, however, is made up for in the rich archaeological evidence from the Archaic Greek world. Indeed, where much of our knowledge of Classical Greek art comes from Roman copies, all of the surviving Archaic Greek art is original.
Other sources for the period are the traditions recorded by Greek writers such as Herodotus. However, these traditions are not part of any form of history. Indeed, Herodotus does not record any dates before 480 BC. Politically, the Archaic period saw the development of the polis as the predominant unit of political organisation. Many cities throughout Greece came under the rule of autocratic leaders, called "tyrants"; the period saw the development of law and systems of communal decision-making, with the earliest evidence for law codes and constitutional structures dating to the period. By the end of the Archaic period, both the Athenian and Spartan constitutions seem to have developed into their classical forms; the Archaic period saw significant urbanisation, the development of the concept of the polis as it was used in Classical Greece. By Solon's time, if not before, the word "polis" had acquired its classical meaning, though the emergence of the polis as a political community was still in progress at this point, the polis as an urban centre was a product of the eighth century.
However, the polis did not become the dominant form of socio-political organisation throughout Greece in the Archaic period, in the north and west of the country it did not become dominant until some way into the Classical period. The urbanisation process in Archaic Greece known as "synoecism" – the amalgamation of several small settlements into a single urban centre – took place in much of Greece in the eighth century BC. Both Athens and Argos, for instance, began to coalesce into single settlements around the end of that century. In some settlements, this physical unification was marked by the construction of defensive city walls, as was the case in Smyrna by the middle of the eighth century BC, Corinth by the middle of the seventh century BC, it seems that the evolution of the polis as a socio-political structure, rather than a geographical one, can be attributed to this urbanisation, as well as a significant population increase in the eighth century. These two factors created a need for a new form of political organisation, as the political systems in place at the beginning of the Archaic period became unworkable.
Though in the early part of the Classical period the city of Athens was both culturally and politically dominant, i
A shrub or bush is a small- to medium-sized woody plant. Unlike herbaceous plants, shrubs have persistent woody, they are distinguished from trees by their multiple stems and shorter height, are under 6 m tall. Plants of many species may grow either depending on their growing conditions. Small, low shrubs less than 2 m tall, such as lavender and most small garden varieties of rose, are termed "subshrubs". An area of cultivated shrubs in a park or a garden is known as a shrubbery; when clipped as topiary, suitable species or varieties of shrubs develop dense foliage and many small leafy branches growing close together. Many shrubs respond well to renewal pruning, in which hard cutting back to a "stool" results in long new stems known as "canes". Other shrubs respond better to selective pruning to reveal their character. Shrubs in common garden practice are considered broad-leaved plants, though some smaller conifers such as mountain pine and common juniper are shrubby in structure. Species that grow into a shrubby habit may be either evergreen.
In botany and ecology, a shrub is more used to describe the particular physical structural or plant life-form of woody plants which are less than 8 metres high and have many stems arising at or near the base. For example, a descriptive system adopted in Australia is based on structural characteristics based on life-form, plus the height and amount of foliage cover of the tallest layer or dominant species. For shrubs 2–8 metres high the following structural forms are categorized: dense foliage cover — closed-shrub mid-dense foliage cover — open-shrub sparse foliage cover — tall shrubland sparse foliage cover — tall open shrublandFor shrubs less than 2 metres high the following structural forms are categorized: dense foliage cover — closed-heath or closed low shrubland— mid-dense foliage cover — open-heath or mid-dense low shrubland— sparse foliage cover — low shrubland sparse foliage cover — low open shrubland Those marked with * can develop into tree form
A Mediterranean climate or dry summer climate is characterized by rainy winters and dry summers, with less than 40 mm of precipitation for at least three summer months. While the climate receives its name from the Mediterranean Basin, these are located on the western coasts of continents, between 30 and 45 degrees north and south of the equator between oceanic climates towards the poles, semi-arid and arid climates towards the equator. In essence, due to the seasonal shift of the subtropical high-pressure belts with the apparent movement of the Sun, a Mediterranean climate is an intermediate type between these other climates, with winters warmer and drier than oceanic climates and summers imitating sunny weather in semi-arid and arid climates; the resulting vegetation of Mediterranean climates are the garrigue or maquis in the Mediterranean Basin, the chaparral in California, the fynbos in South Africa, the mallee in Australia, the matorral in Chile. Areas with this climate are where the so-called "Mediterranean trinity" of agricultural products have traditionally developed: wheat and olive.
Most large, historic cities of the Mediterranean basin lie within Mediterranean climatic zones, including Algiers, Beirut, İzmir, Marseille, Rome and Valencia. Examples of major cities with Mediterranean climates that lie outside of the historic Mediterranean basin include major examples as Adelaide, Cape Town, Dushanbe, Los Angeles, Perth, San Francisco and Victoria. Under the Köppen climate classification, "hot dry-summer" climates and "cool dry-summer" climates are referred to as "Mediterranean". Under the Köppen climate system, the first letter indicates the climate group. Temperate climates or "C" zones have an average temperature above 0 °C, but below 18 °C, in their coolest months; the second letter indicates the precipitation pattern. Köppen has defined a dry summer month as a month with less than 30 mm of precipitation and with less than one-third that of the wettest winter month. Some, use a 40 mm level; the third letter indicates the degree of summer heat: "a" represents an average temperature in the warmest month above 22 °C, while "b" indicates the average temperature in the warmest month below 22 °C.
Under the Köppen classification, dry-summer climates occur on the western sides of continents. Csb zones in the Köppen system include areas not associated with Mediterranean climates but with Oceanic climates, such as much of the Pacific Northwest, much of southern Chile, parts of west-central Argentina, parts of New Zealand. Additional highland areas in the subtropics meet Cs requirements, though they, are not associated with Mediterranean climates, as do a number of oceanic islands such as Madeira, the Juan Fernández Islands, the western part of the Canary Islands, the eastern part of the Azores. Under Trewartha's modified Köppen climate classification, the two major requirements for a Cs climate are revised. Under Trewartha's system, at least eight months must have average temperatures of 10 °C or higher, the average annual precipitation must not exceed 900 mm. Thus, under this system, many Csb zones in the Köppen system become Do, the rare Csc zones become Eo, with only the classic dry-summer to warm winter, low annual rainfall locations included in the Mediterranean type climate.
During summer, regions of Mediterranean climate are influenced by cold ocean currents which keep the weather in the region dry and pleasant. Similar to desert climates, in many Mediterranean climates there is a strong diurnal character to daily temperatures in the warm summer months due to strong heating during the day from sunlight and rapid cooling at night. In winter, Mediterranean climate zones are no longer influenced by the cold ocean currents and therefore warmer water settles near land and causes clouds to form and rainfall becomes much more likely; as a result, areas with this climate receive all of their precipitation during their winter and spring seasons, may go anywhere from 3 to 6 months during the summer without having any significant precipitation. In the lower latitudes, precipitation decreases in both the winter and summer because they are closer to the Horse latitudes, thus bringing smaller amounts of rain. Toward the polar latitudes, total moisture increases; the rainfall tends to be more evenly distributed throughout the year in Southern Europe, while in the Eastern Mediterranean and in Southern California the summer is nearly or dry.
In places where evapotranspiration is higher, steppe climates tend to prevail, but still follow the weather pattern of the Mediterranean climate. The majority of the regions with Mediterranean climates have mild winters and warm summers; however winter and summer temperatures can vary between different regions with a Mediterranean climate. For instance, in the case of winters and Los Angeles experience mild temperatures in the winter, with frost and snowfall unknown, whereas Tashkent has colder winters with annual frosts and snowfall. Or to consider summer, Athens experiences rather high temperatures in that season. In contrast, San Francisco has cool summers with daily highs around 21 °C due to