A desert is a barren area of landscape where little precipitation occurs and living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to the processes of denudation. About one-third of the land surface of the world is semi-arid; this includes much of the polar regions where little precipitation occurs and which are sometimes called polar deserts or "cold deserts". Deserts can be classified by the amount of precipitation that falls, by the temperature that prevails, by the causes of desertification or by their geographical location. Deserts are formed by weathering processes as large variations in temperature between day and night put strains on the rocks which break in pieces. Although rain occurs in deserts, there are occasional downpours that can result in flash floods. Rain falling on hot rocks can cause them to shatter and the resulting fragments and rubble strewn over the desert floor are further eroded by the wind; this wafts them aloft in sand or dust storms.
Wind-blown sand grains striking any solid object in their path can abrade the surface. Rocks are smoothed down, the wind sorts sand into uniform deposits; the grains are piled high in billowing sand dunes. Other deserts are flat, stony plains where all the fine material has been blown away and the surface consists of a mosaic of smooth stones; these areas are known as desert pavements and little further erosion takes place. Other desert features include rock outcrops, exposed bedrock and clays once deposited by flowing water. Temporary lakes may form and salt pans may be left when waters evaporate. There may be underground sources of water in the form of seepages from aquifers. Where these are found, oases can occur. Plants and animals living in the desert need special adaptations to survive in the harsh environment. Plants tend to be tough and wiry with small or no leaves, water-resistant cuticles and spines to deter herbivory; some annual plants germinate and die in the course of a few weeks after rainfall while other long-lived plants survive for years and have deep root systems able to tap underground moisture.
Animals need to find enough food and water to survive. Many stay in the shade or underground during the heat of the day, they tend to be efficient at conserving water, extracting most of their needs from their food and concentrating their urine. Some animals remain in a state of dormancy for long periods, ready to become active again during the rare rainfall, they reproduce while conditions are favorable before returning to dormancy. People have struggled to live in the surrounding semi-arid lands for millennia. Nomads have moved their flocks and herds to wherever grazing is available and oases have provided opportunities for a more settled way of life; the cultivation of semi-arid regions encourages erosion of soil and is one of the causes of increased desertification. Desert farming is possible with the aid of irrigation, the Imperial Valley in California provides an example of how barren land can be made productive by the import of water from an outside source. Many trade routes have been forged across deserts across the Sahara Desert, traditionally were used by caravans of camels carrying salt, gold and other goods.
Large numbers of slaves were taken northwards across the Sahara. Some mineral extraction takes place in deserts, the uninterrupted sunlight gives potential for the capture of large quantities of solar energy. English desert and its Romance cognates all come from the ecclesiastical Latin dēsertum, a participle of dēserere, "to abandon"; the correlation between aridity and sparse population is complex and dynamic, varying by culture and technologies. In English before the 20th century, desert was used in the sense of "unpopulated area", without specific reference to aridity. Phrases such as "desert island" and "Great American Desert", or Shakespeare's "deserts of Bohemia" in previous centuries did not imply sand or aridity. A desert is a region of land, dry because it receives low amounts of precipitation has little coverage by plants, in which streams dry up unless they are supplied by water from outside the area. Deserts receive less than 250 mm of precipitation each year; the potential evapotranspiration may be large but the actual evapotranspiration may be close to zero.
Semideserts are regions which receive between 250 and 500 mm and when clad in grass, these are known as steppes. Deserts have been defined and classified in a number of ways combining total precipitation, number of days on which this falls and humidity, sometimes additional factors. For example, Arizona, receives less than 250 mm of precipitation per year, is recognized as being located in a desert because of its aridity-adapted plants; the North Slope of Alaska's Brooks Range receives less than 250 mm of precipitation per year and is classified as a cold desert. Other regions of the world have cold deserts, including areas of the Himalayas and other high-altitude areas in other parts of the world. Polar deserts cover much of the ice-free
Konza Prairie Biological Station
The Konza Prairie Biological Station is a 3,487-hectare preserve of native tallgrass prairie in the Flint Hills of northeastern Kansas. It is located south of Manhattan and its southern boundary parallels Interstate 70. A scenic overlook exists on the preserve's eastern boundary along K-177. "Konza" is an alternative name for the Kansa or Kaw Indians who inhabited this area until the mid-19th century. The Konza Prairie is owned by The Nature Conservancy and Kansas State University, is operated as a field research station by the university's Division of Biology, it is one of 26 sites within the Long Term Ecological Research Network. It has a continental climate characterized by dry, cold winters. Average annual precipitation is sufficient to support savanna vegetation; the site is topographically complex with an elevation range from 1050 to 1457 ft. In addition to the dominant tallgrass prairie, Konza contains forest, claypan and riparian communities. Limestone outcrops are found throughout the landscape.
Konza Prairie is located within the largest remaining area of unplowed tallgrass prairie in North America, the Flint Hills. Konza supports a diverse mix of species including 576 vascular plants, 31 mammals, 208 bird species, 34 types of reptiles and amphibians, 20 kinds of fish, over 700 types of invertebrates. A herd of 300 bison is maintained on the Konza, native white-tailed deer and wild turkey are present in large numbers. Members of the public are allowed onto portions of the Konza Prairie through three loop hiking trails. Big Basin Prairie Preserve Tallgrass Prairie National Preserve Cimarron National Grassland Konza Prairie Partnership Long Term Ecological Research Program Konza Environmental Education Program Konza Prairie photos on Flickr UNESCO Biosphere Reserve Information
Pasture is land used for grazing. Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, sheep, or swine; the vegetation of tended pasture, consists of grasses, with an interspersion of legumes and other forbs. Pasture is grazed throughout the summer, in contrast to meadow, ungrazed or used for grazing only after being mown to make hay for animal fodder. Pasture in a wider sense additionally includes rangelands, other unenclosed pastoral systems, land types used by wild animals for grazing or browsing. Pasture lands in the narrow sense are distinguished from rangelands by being managed through more intensive agricultural practices of seeding and the use of fertilizers, while rangelands grow native vegetation, managed with extensive practices like controlled burning and regulated intensity of grazing. Soil type, minimum annual temperature, rainfall are important factors in pasture management. Sheepwalk is an area of grassland; the productivity of sheepwalk is measured by the number of sheep per area.
This is dependent, among other things, on the underlying rock. Sheepwalk is the name of townlands in County Roscommon and County Fermanagh, Northern Ireland. Unless factory farming, which entails in its most intensive form trough-feeding, managed or unmanaged pasture is the main food source for ruminants. Pasture feeding dominates livestock farming where the land makes crop sowing and/or harvesting difficult, such as in arid or mountainous regions, where types of camel, antelope and other ruminants live which are well suited to the more hostile terrain and rarely factory farmed. In more humid regions, pasture grazing is managed across a large global area for free range and organic farming. Certain types of pasture suit the diet and metabolism of particular animals, their fertilising and tending of the land may over generations result in the pasture combined with the ruminants in question being integral to a particular ecosystem. Grassland Heathland Machair Maquis Moorland Potrero Prairie Rangeland Rough pasture Savanna Steppe Wood pasture Veld Transhumance
A meadow is a open habitat, or field, vegetated by grass and other non-woody plants. They attract a multitude of wildlife and support flora and fauna that could not thrive in other conditions, they provide areas for courtship displays, food gathering, pollinating insects, sometimes sheltering, if the vegetation is high enough, making them ecologically important. There are multiple types of meadows, such as agricultural and perpetual, each important to the ecosystem. Meadows may be occurring or artificially created from cleared shrub or woodland. In agriculture, a meadow is grassland, not grazed by domestic livestock, but rather allowed to grow unchecked in order to produce hay. In the United Kingdom and Ireland, the term meadow is used in its original sense to mean a hay meadow, signifying grassland mown annually in the summer for making hay. Agricultural meadows are lowland or upland fields upon which hay or pasture grasses grow from self-sown or hand-sown seed. Traditional hay meadows are now in decline.
Ecologist Professor John Rodwell states that over the past century and Wales have lost about 97% of their hay meadows. Fewer than 15.000 hectares of lowland meadows remain in the UK and most sites are small and fragmented. 25% of the UK's meadows are found in Worcestershire, with Foster's Green Meadow managed by the Worcestershire Wildlife Trust being a major site. A similar concept to the hay meadow is the pasture, which differs from the meadow in that it is grazed through the summer, rather than being allowed to grow out and periodically be cut for hay. A pasture can refer to any land used for grazing, in this wider sense the term refers not only to grass pasture, but to non-grassland habitats such as heathland and wood pasture; the term, grassland, is used to describe both hay meadows and grass pastures. The specific agricultural practices in relation to the meadow can take on various expressions; as mentioned, this could be hay production or providing food for grazing cattle and livestock but to give room for orchards or honey production.
A transitional meadow occurs when a field, farmland, or other cleared land is no longer cut or grazed and starts to display luxuriant growth, extending to the flowering and self-seeding of its grass and wild flower species. The condition is however only temporary, because the grasses become shaded out when scrub and woody plants become well-established, being the forerunners of the return to a wooded state. A transitional state can be artificially-maintained through a double-field system, in which cultivated soil and meadows are alternated for a period of 10 to 12 years each. In North America prior to European colonization, Algonquians and other Native Americans peoples cleared areas of forest to create transitional meadows where deer and game could find food and be hunted. For example, some of today's meadows originated thousands of years ago, due to regular burnings by Native Americans. A perpetual meadow called a natural meadow, is one in which environmental factors, such as climatic and soil conditions, are favorable to perennial grasses and restrict the growth of woody plants indefinitely.
Types of perpetual meadows may include: Alpine meadows occur at high elevations above the tree line and maintained by harsh climatic conditions. Coastal meadows maintained by salt sprays. Desert meadows restricted by low lack of nutrients and humus. Prairies maintained by periods of severe subject to wildfires. Wet meadows saturated with water throughout much of the year. Artificially or culturally conceived meadows emerge from and continually require human intervention to persist and flourish. In many places, the natural, pristine populations of free roaming large grazers are either extinct or limited due to human activities; this reduces or removes their natural influence on the surrounding ecology and results in meadows only being created or maintained by human intervention. Existing meadows could and decline, if unmaintained by agricultural practices, but a reintroduction of large grazers could influence meadows to reappear as natural habitats in the landscape. Mankind has influenced the ecology and the landscape for millennia in many parts of the world, so it can sometimes be difficult to discern what is natural and what is cultural.
Meadows are one example. As extensive farming like grazing is diminishing in some parts of the world, the meadow is endangered as a habitat; some scientific projects are therefore experimenting with reintroduction of natural grazers. This includes deer, goat, wild horse, etc. depending on the location. A more exotic example with a wider scope, is the European Tauros Programme; some environmental organization recommend to convert Lawns to meadows by stopping or reducing mowing. They claim that meadows can better preserve biodiversity, reduce the use of fertilizers. For example, in 2018 environmental organizations with the support of the Department for Environment Food and Rural Affairs of England, concerned by the decline in the numbre of Bees worldwide, in the first day of Bees' Needs Week 2018 give some recommendation how preserve bees; the recommendations include 1) growing flowers and trees, 2) letting the garden grow wild, 3) cutting grass less 4) leaving insect nest and hibernation spots alone, 5) using careful consideration with pesticides.
Foundation for Restoring European Ecosystems UK Wild Meadows Website Irish Wild Meadows Website Meadow Planting A Year in a Meadow Grow a Back Yard Meadow Adrian Higgins, "Today, 32,000 Seedlings.
Contemporary art is the art of today, produced in the second half of the 20th century or in the 21st century. Contemporary artists work in a globally influenced, culturally diverse, technologically advancing world, their art is a dynamic combination of materials, methods and subjects that continue the challenging of boundaries, well underway in the 20th century. Diverse and eclectic, contemporary art as a whole is distinguished by the lack of a uniform, organising principle, ideology, or "-ism". Contemporary art is part of a cultural dialogue that concerns larger contextual frameworks such as personal and cultural identity, family and nationality. In vernacular English and contemporary are synonyms, resulting in some conflation of the terms modern art and contemporary art by non-specialists; some define contemporary art as art produced within "our lifetime," recognising that lifetimes and life spans vary. However, there is a recognition; the classification of "contemporary art" as a special type of art, rather than a general adjectival phrase, goes back to the beginnings of Modernism in the English-speaking world.
In London, the Contemporary Art Society was founded in 1910 by the critic Roger Fry and others, as a private society for buying works of art to place in public museums. A number of other institutions using the term were founded in the 1930s, such as in 1938 the Contemporary Art Society of Adelaide, an increasing number after 1945. Many, like the Institute of Contemporary Art, Boston changed their names from ones using "Modern art" in this period, as Modernism became defined as a historical art movement, much "modern" art ceased to be "contemporary"; the definition of what is contemporary is always on the move, anchored in the present with a start date that moves forward, the works the Contemporary Art Society bought in 1910 could no longer be described as contemporary. Particular points that have been seen as marking a change in art styles include the end of World War II and the 1960s. There has been a lack of natural break points since the 1960s, definitions of what constitutes "contemporary art" in the 2010s vary, are imprecise.
Art from the past 20 years is likely to be included, definitions include art going back to about 1970. And early 21st cent. Both an outgrowth and a rejection of modern art". Many use the formulation "Contemporary Art", which avoids this problem. Smaller commercial galleries and other sources may use stricter definitions restricting the "contemporary" to work from 2000 onwards. Artists who are still productive after a long career, ongoing art movements, may present a particular issue. Sociologist Nathalie Heinich draws a distinction between modern and contemporary art, describing them as two different paradigms which overlap historically, she found that while "modern art" challenges the conventions of representation, "contemporary art" challenges the notion of an artwork. She regards Duchamp's Fountain as the starting point of contemporary art, which gained momentum after World War II with Gutai's performances, Yves Klein's monochromes and Rauschenberg's Erased de Kooning Drawing. One of the difficulties many people have in approaching contemporary artwork is its diversity—diversity of material, subject matter, time periods.
It is "distinguished by the lack of a uniform organizing principle, ideology, or -ism" that we so see in other, oftentimes more familiar, art periods and movements. Broadly speaking, we see Modernism as looking at modernist principles—the focus of the work is self-referential, investigating its own materials. Impressionism looks at our perception of a moment through light and color as opposed to attempts at stark realism. Contemporary art, on the other hand, does not have single objective or point of view, its view instead is unclear reflective of the world today. It can be, contradictory and open-ended. There are, however, a number of common themes. While these are not exhaustive, notable themes include: identity politics, the body and migration, contemporary society and culture and memory, institutional and political critique. Post-modern, post-structuralist and Marxist theory have played important roles in the development of contemporary theories of art; the functioning of the art world is dependent on art institutions, ranging from major museums to private galleries, non-profit spaces, art schools and publishers, the practices of individual artists, writers and philanthropists.
A major division in the art world is between the for-profit and non-profit sectors, although in recent years the boundaries between for-profit private and non-profit public institutions have become blurred. Most well-known contemporary art is exhibited by professional artists at commercial contemporary art galleries, by private collectors, art auctions, corporation
An estuary is a enclosed coastal body of brackish water with one or more rivers or streams flowing into it, with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environments, they are subject both to marine influences—such as tides and the influx of saline water—and to riverine influences—such as flows of fresh water and sediment. The mixing of sea water and fresh water provide high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world. Most existing estuaries formed during the Holocene epoch with the flooding of river-eroded or glacially scoured valleys when the sea level began to rise about 10,000–12,000 years ago. Estuaries are classified according to their geomorphological features or to water-circulation patterns, they can have many different names, such as bays, lagoons, inlets, or sounds, although some of these water bodies do not meet the above definition of an estuary and may be saline.
The banks of many estuaries are amongst the most populated areas of the world, with about 60% of the world's population living along estuaries and the coast. As a result, many estuaries suffer degradation from a variety of factors including: sedimentation from soil erosion from deforestation and other poor farming practices; the word "estuary" is derived from the Latin word aestuarium meaning tidal inlet of the sea, which in itself is derived from the term aestus, meaning tide. There have been many definitions proposed to describe an estuary; the most accepted definition is: "a semi-enclosed coastal body of water, which has a free connection with the open sea, within which sea water is measurably diluted with freshwater derived from land drainage". However, this definition excludes a number of coastal water bodies such as coastal lagoons and brackish seas. A more comprehensive definition of an estuary is "a semi-enclosed body of water connected to the sea as far as the tidal limit or the salt intrusion limit and receiving freshwater runoff.
This broad definition includes fjords, river mouths, tidal creeks. An estuary is a dynamic ecosystem having a connection to the open sea through which the sea water enters with the rhythm of the tides; the sea water entering the estuary streams. The pattern of dilution varies between different estuaries and depends on the volume of fresh water, the tidal range, the extent of evaporation of the water in the estuary. Drowned river valleys are known as coastal plain estuaries. In places where the sea level is rising relative to the land, sea water progressively penetrates into river valleys and the topography of the estuary remains similar to that of a river valley; this is the most common type of estuary in temperate climates. Well-studied estuaries include the Severn Estuary in the United Kingdom and the Ems Dollard along the Dutch-German border; the width-to-depth ratio of these estuaries is large, appearing wedge-shaped in the inner part and broadening and deepening seaward. Water depths exceed 30 m.
Examples of this type of estuary in the U. S. are the Hudson River, Chesapeake Bay, Delaware Bay along the Mid-Atlantic coast, Galveston Bay and Tampa Bay along the Gulf Coast. Bar-built estuaries are found in place where the deposition of sediment has kept pace with rising sea level so that the estuaries are shallow and separated from the sea by sand spits or barrier islands, they are common in tropical and subtropical locations. These estuaries are semi-isolated from ocean waters by barrier beaches. Formation of barrier beaches encloses the estuary, with only narrow inlets allowing contact with the ocean waters. Bar-built estuaries develop on sloping plains located along tectonically stable edges of continents and marginal sea coasts, they are extensive along the Atlantic and Gulf coasts of the U. S. in areas with active coastal deposition of sediments and where tidal ranges are less than 4 m. The barrier beaches that enclose bar-built estuaries have been developed in several ways: building up of offshore bars by wave action, in which sand from the sea floor is deposited in elongated bars parallel to the shoreline, reworking of sediment discharge from rivers by wave and wind action into beaches, overwash flats, dunes, engulfment of mainland beach ridges due to sea level rise and resulting in the breaching of the ridges and flooding of the coastal lowlands, forming shallow lagoons, elongation of barrier spits from the erosion of headlands due to the action of longshore currents, with the spits growing in the direction of the littoral drift.
Barrier beaches form in shallow water and are parallel to the shoreline, resulting in long, narrow estuaries. The average water depth is less than 5 m, exceeds 10 m. Examples of bar-built estuaries are Barnegat Bay, New Jersey. Fjords were formed where pleistocene glaciers deepened and widened existing river valleys so that they become U-shaped in cross s
Lepidoptera is an order of insects that includes butterflies and moths. About 180,000 species of the Lepidoptera are described, in 126 families and 46 superfamilies, 10 per cent of the total described species of living organisms, it is one of the most widespread and recognizable insect orders in the world. The Lepidoptera show many variations of the basic body structure that have evolved to gain advantages in lifestyle and distribution. Recent estimates suggest the order may have more species than earlier thought, is among the four most speciose orders, along with the Hymenoptera and Coleoptera. Lepidopteran species are characterized by more than three derived features; the most apparent is the presence of scales that cover the bodies, a proboscis. The scales are modified, flattened "hairs", give butterflies and moths their wide variety of colors and patterns. All species have some form of membranous wings, except for a few that have reduced wings or are wingless. Mating and the laying of eggs are carried out by adults near or on host plants for the larvae.
Like most other insects and moths are holometabolous, meaning they undergo complete metamorphosis. The larvae are called caterpillars, are different from their adult moth or butterfly forms, having a cylindrical body with a well-developed head, mandible mouth parts, three pairs of thoracic legs and from none up to five pairs of prolegs; as they grow, these larvae change in appearance, going through a series of stages called instars. Once matured, the larva develops into a pupa. A few butterflies and many moth species spin a silk case or cocoon prior to pupating, while others do not, instead going underground. A butterfly pupa, called a chrysalis, has a hard skin with no cocoon. Once the pupa has completed its metamorphosis, a sexually mature adult emerges; the Lepidoptera have, over millions of years, evolved a wide range of wing patterns and coloration ranging from drab moths akin to the related order Trichoptera, to the brightly colored and complex-patterned butterflies. Accordingly, this is the most recognized and popular of insect orders with many people involved in the observation, collection, rearing of, commerce in these insects.
A person who collects or studies this order is referred to as a lepidopterist. Butterflies and moths play an important role in the natural ecosystem as pollinators and as food in the food chain. In many species, the female may produce from 200 to 600 eggs, while in others, the number may approach 30,000 eggs in one day; the caterpillars hatching from these eggs can cause damage to large quantities of crops. Many moth and butterfly species are of economic interest by virtue of their role as pollinators, the silk they produce, or as pest species; the term was coined by Linnaeus in 1735 and is derived from Greek λεπίς, gen. λεπίδος and πτερόν. Sometimes, the term Rhopalocera is used for the clade of all butterfly species, derived from the Ancient Greek ῥόπαλον and κέρας meaning "club" and "horn" coming from the shape of the antennae of butterflies; the origins of the common names "butterfly" and "moth" are varied and obscure. The English word butterfly is with many variations in spelling. Other than that, the origin is unknown, although it could be derived from the pale yellow color of many species' wings suggesting the color of butter.
The species of Heterocera are called moths. The origins of the English word moth are more clear, deriving from the Old English moððe" from Common Germanic, its origins are related to Old English maða meaning "maggot" or from the root of "midge", which until the 16th century was used to indicate the larva in reference to devouring clothes. The etymological origins of the word "caterpillar", the larval form of butterflies and moths, are from the early 16th century, from Middle English catirpel, catirpeller an alteration of Old North French catepelose: cate, cat + pelose, hairy; the Lepidoptera are among the most successful groups of insects. They are found on all continents, except Antarctica, inhabit all terrestrial habitats ranging from desert to rainforest, from lowland grasslands to mountain plateaus, but always associated with higher plants angiosperms. Among the most northern dwelling species of butterflies and moths is the Arctic Apollo, found in the Arctic Circle in northeastern Yakutia, at an altitude of 1500 m above sea level.
In the Himalayas, various Apollo species such as Parnassius epaphus have been recorded to occur up to an altitude of 6,000 m above sea level. Some lepidopteran species exhibit symbiotic, phoretic, or parasitic lifestyles, inhabiting the bodies of organisms rather than the environment. Coprophagous pyralid moth species, called sloth moths, such as Bradipodicola hahneli and Cryptoses choloepi, are unusual in that they are found inhabiting the fur of sloths, mammals found in Central and South America. Two species of Tinea moths have been recorded as feeding on horny tissue and have been bred from the horns of cattle; the larva of Zenodochium coccivorella is an internal parasite of the coccid Kermes species. Many species have been recorded as breeding in natural materials or refuse such as owl pellets, bat caves, honeycombs or diseased fruit; as of 2007, there was 174,250 lepi