Rhamnus is a genus of about 110 accepted species of shrubs or small trees known as buckthorns, in the family Rhamnaceae. Its species range from 1 to 10 meters tall and are native in east Asia and North America, but found throughout the temperate and subtropical Northern Hemisphere, more locally in the subtropical Southern Hemisphere in parts of Africa and South America. Both deciduous and evergreen species occur; the leaves are simple, 3 to 15 centimeters long, arranged alternately, in opposite pairs, or paired. One distinctive character of many buckthorns is the way the veination curves upward towards the tip of the leaf; the plant bears fruits which are red berry-like drupes. The name is due to the woody spine on the end of each twig in many species. In the United States, buckthorn is considered an invasive species by many local jurisdictions and state governments, including Minnesota and Wisconsin. Rhamnus species are shrubs or small to medium-sized trees, with deciduous or evergreen foliage.
Branches are end in a woody spine. The leaf blades are pinnately veined. Leaf margins are serrate or entire. Most species have yellowish green, bisexual or unisexual polygamous flowers. Calyx tube campanulate to cup-shaped, with 4 or 5 ovate-triangular sepals, which are adaxially ± distinctly keeled. Petals 4 or 5 but a few species may lack petals; the petals are shorter than the sepals. Flowers have 5 stamens which are surrounded by and equal in length the petals or are shorter; the anthers are dorsifixed. The superior ovary is free, with 2-4 chambers. Fruits are a 2-4 stoned, berrylike drupe, obovoid-globose or globose shaped. Seeds are obovoid or oblong-obovoid shaped, unfurrowed or abaxially or laterally margined with a long, furrow; the seeds have fleshy endosperm. Rhamnus has a nearly cosmopolitan distribution, with about 150 species which are native from temperate to tropical regions, the majority of species are from east Asia and North America, with a few species in Europe and Africa. North American species include alder-leaf buckthorn occurring across the continent, Carolina buckthorn in the east, cascara buckthorn in the west, the evergreen California buckthorn or coffeeberry and hollyleaf buckthorn in the west.
In South America, Rhamnus diffusus is a small shrub native to the Valdivian temperate rain forests of Chile. Buckthorns may be confused with dogwoods; the two plants are easy to distinguish by pulling a leaf apart. The genus has been divided into two subgenera, which are treated as separate genera: Subgenus Rhamnus: flowers with four petals, buds with bud scales, leaves opposite or alternate, branches with spines. Species include: Rhamnus alaternus – Italian buckthorn Rhamnus alnifolia – alderleaf buckthorn, alder-leaved buckthorn Rhamnus arguta – sharp-tooth buckthorn Rhamnus bourgaeana – endemic to Mallorca Rhamnus cathartica – common buckthorn, purging buckthorn Rhamnus crocea – redberry buckthorn, hollyleaf buckthorn Rhamnus davurica – Dahurian buckthorn Rhamnus diffusa Rhamnus globosa – Lokao buckthorn Rhamnus ilicifolia – hollyleaf redberry Rhamnus japonica – Japanese buckthorn Rhamnus lanceolata – lanceleaf buckthorn Rhamnus libanotica – Lebanese buckthorn Rhamnus ludovici-salvatoris – endemic to Mallorca Rhamnus lycioides Rhamnus palaestina – Rhamnus pallasii – Fisch.
& C. A. Meyer, Rhamnus persica – Persian Buckthorn, Boiss.& Hohen, Rhamnus petiolaris – Rhamnus pirifolia – island redberry buckthorn Rhamnus prinoides – shiny-leaf buckthorn Rhamnus pumila - dwarf buckthorn Rhamnus saxatilis – rock Buckthorn, Avignon buckthorn, Avignon berry Rhamnus serrata – sawleaf buckthorn Rhamnus smithii – Smith's buckthorn Rhamnus staddo – Staddo Rhamnus taquetii – Jejudo buckthorn Rhamnus utilis – Chinese buckthorn Subgenus Frangula: flowers with five petals, buds without bud scales, leaves always alternate, branches without spines. Species include: Rhamnus betulaefolia – birchleaf buckthorn Rhamnus californica – California buckthorn, coffeeberry Rhamnus caroliniana – Carolina buckthorn, Indian cherry Rhamnus frangula – alder buckthorn, glossy buckthorn, breaking buckthorn, black dogwood Rhamnus glandulosa – sanguino Rhamnus hintonii – M. C. Johnst. & L. A. Johnst. Rhamnus purshiana – cascara buckthorn Rhamnus rubra – red buckthorn Some species are invasive outside their natural ranges.
R. cathartica was introduced into the United States as a garden shrub and has become an invasive species in many areas there. It is a primary host of the soybean aphid, a pest for soybean farmers across the US; the aphids use the buckthorn as a host for the winter and spread to nearby soybean fields in the spring. Italian buckthorn, an evergreen species from the Mediterranean region, has become a serious weed in some parts of New Zealand on Hauraki Gulf islands. Buckthorns are used as food plants by the larvae of many Lepidoptera sp
The tree line is the edge of the habitat at which trees are capable of growing. It is found at high latitudes. Beyond the tree line, trees cannot tolerate the environmental conditions; the tree line is sometimes distinguished from a lower timberline or forest line, the line below which trees form a forest with a closed canopy. At the tree line, tree growth is sparse and deformed by wind and cold; this is sometimes known as krummholz. The tree line appears well-defined, but it can be a more gradual transition. Trees grow shorter and at lower densities as they approach the tree line, above which they cease to exist. Several types of tree lines are defined in ecology and geography: An alpine tree line is the highest elevation that sustains trees; the climate above the tree line of mountains is called an alpine climate, the terrain can be described as alpine tundra. Treelines on north-facing slopes in the northern hemisphere are lower than on south-facing slopes, because the increased shade on north-facing slopes means the snowpack takes longer to melt.
This shortens the growing season for trees. In the southern hemisphere, the south-facing slopes have the shorter growing season; the alpine tree line boundary is abrupt: it forms a transition zone between closed forest below and treeless alpine tundra above. This zone of transition occurs "near the top of the tallest peaks in the northeastern United States, high up on the giant volcanoes in central Mexico, on mountains in each of the 11 western states and throughout much of Canada and Alaska". Environmentally dwarfed shrubs form the upper limit; the decrease in air temperature due to increasing elevation causes the alpine climate. The rate of decrease can vary in different mountain chains, from 3.5 °F per 1,000 feet of elevation gain in the dry mountains of the western United States, to 1.4 °F per 1,000 feet in the moister mountains of the eastern United States. Skin effects and topography can create microclimates. Compared with arctic timberlines, alpine timberlines may receive fewer than half of the number of degree days based on air temperature, but because solar radiation intensities are greater at alpine than at arctic timberlines the number of degree days calculated from leaf temperatures may be similar.
Summer warmth sets the limit to which tree growth can occur, for while timberline conifers are frost-hardy during most of the year, they become sensitive to just 1 or 2 degrees of frost in mid-summer. A series of warm summers in the 1940s seems to have permitted the establishment of "significant numbers" of spruce seedlings above the previous treeline in the hills near Fairbanks, Alaska. Survival depends on a sufficiency of new growth to support the tree; the windiness of high-elevation sites is a potent determinant of the distribution of tree growth. Wind can mechanically damage tree tissues directly, including blasting with windborne particles, may contribute to the desiccation of foliage of shoots that project above snow cover. At the alpine timberline, tree growth is inhibited when excessive snow lingers and shortens the growing season to the point where new growth would not have time to harden before the onset of fall frost. Moderate snowpack, may promote tree growth by insulating the trees from extreme cold during the winter, curtailing water loss, prolonging a supply of moisture through the early part of the growing season.
However, snow accumulation in sheltered gullies in the Selkirk Mountains of southeastern British Columbia causes the timberline to be 400 metres lower than on exposed intervening shoulders. In a desert, the tree line marks; these tend to be called the "lower" tree line, occur below about 5,000 ft elevation in the desert of the southwestern United States. The desert tree line tends to be lower on pole-facing slopes than equator-facing slopes, because the increased shade on the former keeps them cooler and prevents moisture from evaporating as giving trees a longer growing season and more access to water. In some mountainous areas, higher elevations above the condensation line, or on equator-facing and leeward slopes, can result in low rainfall and increased exposure to solar radiation; this dries out the soil. Many south-facing ridges of the mountains of the Western U. S. have a lower treeline than the northern faces because of aridity. Different tree species have different tolerances to cold. Mountain ranges isolated by oceans or deserts may have restricted repertoires of tree species with gaps that are above the alpine tree line for some species yet below the desert tree line for others.
For example, several mountain ranges in the Great Basin of North America have lower belts of Pinyon Pines and Junipers separated by intermediate brushy but treeless zones from upper belts of Limber and Bristlecone Pines. On coasts and isolated mountains the tree line is much lower than in corresponding altitudes inland and in larger, more complex mountain systems, because strong winds reduce tree growth. In addition the lack of suitable soil, such as along talus slopes or exposed rock formations, prevents trees from gaining an adequate foothold and exposes them to drought and sun; the arctic tree line is the northernmost latitude in the Northern Hemisphere where tr
Desertification is a type of land degradation in which a dry area of land becomes a desert losing its bodies of water as well as vegetation and wildlife. It is caused by a variety of factors, such as through climate change and through the overexploitation of soil through human activity; when deserts appear automatically over the natural course of a planet's life cycle it can be called a natural phenomenon. Desertification is a significant global ecological and environmental problem with far reaching consequences on socio-economic and political conditions. Considerable controversy exists over the proper definition of the term "desertification" for which Helmut Geist has identified more than 100 formal definitions; the most accepted of these is that of the Princeton University Dictionary which defines it as "the process of fertile land transforming into desert as a result of deforestation, drought or improper/inappropriate agriculture". Desertification has been neatly defined in the text of the United Nations Convention to Combat Desertification as "land degradation in arid, semi-arid and dry sub-humid regions resulting from various factors, including climatic variations and human activities."Another major contribution to the controversy comes from the sub-grouping of types of desertification.
Spanning from the vague yet shortsighted view as the "man-made-desert" to the broader yet less focused type as the "Non-pattern-Desert". The earliest known discussion of the topic arose soon after the French colonization of West Africa, when the Comité d'Etudes commissioned a study on desséchement progressif to explore the prehistoric expansion of the Sahara Desert; the world's most noted deserts have been formed by natural processes interacting over long intervals of time. During most of these times, deserts have shrunk independent of human activities. Paleodeserts are large sand seas now inactive because they are stabilized by vegetation, some extending beyond the present margins of core deserts, such as the Sahara, the largest hot desert. Desertification has played a significant role in human history, contributing to the collapse of several large empires, such as Carthage and the Roman Empire, as well as causing displacement of local populations. Historical evidence shows that the serious and extensive land deterioration occurring several centuries ago in arid regions had three epicenters: the Mediterranean, the Mesopotamian Valley, the Loess Plateau of China, where population was dense.
Drylands occupy 40–41% of Earth’s land area and are home to more than 2 billion people. It has been estimated that some 10–20% of drylands are degraded, the total area affected by desertification being between 6 and 12 million square kilometres, that about 1–6% of the inhabitants of drylands live in desertified areas, that a billion people are under threat from further desertification; as of 1998, the then-current degree of southward expansion of the Sahara was not well known, due to a lack of recent, measurable expansion of the desert into the Sahel at the time. The impact of global warming and human activities are presented in the Sahel. In this area, the level of desertification is high compared to other areas in the world. All areas situated in the eastern part of Africa are characterized by a dry climate, hot temperatures, low rainfall. So, droughts are the rule in the Sahel region; some studies have shown that Africa has lost 650,000 km² of its productive agricultural land over the past 50 years.
The propagation of desertification in this area is considerable. Some statistics have shown that since 1900 the Sahara has expanded by 250 km to the south over a stretch of land from west to east 6,000 km long; the survey, done by the research institute for development, had demonstrated that this means dryness is spreading fast in the Sahelian countries. 70% of the arid area has deteriorated and water resources have disappeared, leading to soil degradation. The loss of topsoil means that plants cannot take root and can be uprooted by torrential water or strong winds; the United Nations Convention says that about six million Sahelian citizens would have to give up the desertified zones of sub-Saharan Africa for North Africa and Europe between 1997 and 2020. Another major area, being impacted by desertification is the Gobi Desert; the Gobi desert is the fastest moving desert on Earth. This has destroyed many villages in its path. Photos show that the Gobi Desert has expanded to the point the entire nation of Croatia could fit inside its area.
This is causing a major problem for the people of China. They will soon have to deal with the desert. Although the Gobi Desert itself is still a distance away from Beijing, reports from field studies state there are large sand dunes forming only 70 km outside the city; as the desertification takes place, the landscape may progress through different stages and continuously transform in appearance. On sloped terrain, desertification can create larger empty spaces over a large strip of land, a phenomenon known as "Brousse tigrée". A mathematical model of this phenomenon proposed by C. Klausmeier attributes this patterning to dynamics in plant-water interaction. One outcome of this observation suggests an optimal plan
Land reclamation known as reclamation, known as land fill, is the process of creating new land from oceans, riverbeds, or lake beds. The land reclaimed is known as reclamation land fill. In a number of other jurisdictions, including parts of the United States, the term "reclamation" can refer to returning disturbed lands to an improved state. In Alberta, for example, reclamation is defined by the provincial government as "The process of reconverting disturbed land to its former or other productive uses." In Oceania it is referred to as land rehabilitation. Land reclamation can be achieved with a number of different methods; the most simple method involves filling the area with large amounts of heavy rock and/or cement filling with clay and dirt until the desired height is reached. The process is called "infilling" and the material used to fill the space is called "infill". Draining of submerged wetlands is used to reclaim land for agricultural use. Deep cement mixing is used in situations in which the material displaced by either dredging or draining may be contaminated and hence needs to be contained.
Land dredging is another method of land reclamation. It is the removal of sediments and debris from the bottom of a body of water, it is used for maintaining reclaimed land masses as sedimentation, a natural process, fills channels and harbors naturally. Instances where the creation of new land was for the need of human activities. Notable examples include: Some of the coastlines of Saadiyat Island, in the UAE. Used for commercial purposes. Much of the coastlines of Mumbai, India, it took over 150 years to join the original Seven Islands of Bombay. These seven islands were lush, thickly wooded, dotted with 22 hills, with the Arabian Sea washing through them at high tide; the original Isle of Bombay was only 24 km long and 4 km wide from Dongri to Malabar Hill and the other six were Colaba, Old Woman's Island, Parel and Mazgaon.. Much of the coastlines of Mainland China, Hong Kong, North Korea and South Korea, it is estimated. Inland lowlands in the Yangtze valley, including the areas of important cities like Shanghai and Wuhan.
Much of the coastline of Karachi, Pakistan. The shore of Jakarta Bay. Land is reclaimed to create new housing areas and real estate properties, for the expanding city of Jakarta. So far, the largest reclamation project in the city is the creation of "Golf Island", still ongoing. A part of the Hamad International Airport in Qatar, around 36 square kilometres; the entire island of The Pearl-Qatar situated in Qatar. Haikou Bay, Hainan Province, where the west side of Haidian Island is being extended, off the coast of Haikou City, where new land for a marina is being created; the Cotai Strip in Macau, where most of the major casinos are located Nagoya Centrair Airport, Japan Incheon International Airport, Korea Beirut Central District, Lebanon The southern Chinese city of Shenzhen The shore of Manila Bay in the Philippines along Metro Manila, has attracted major developments such as the Mall of Asia Complex, Entertainment City and the Cultural Center of the Philippines Complex. The city-state of Singapore, where land is in short supply, is famous for its efforts on land reclamation.
The Palm Islands, The World and hotel Burj al-Arab off Dubai in the United Arab Emirates The Yas Island in Abu Dhabi, UAE. Hulhumalé Island, Maldives, it is one of the six divisions of Malé City. Giant Sea Wall Jakarta Colombo International Financial City, Sri Lanka Airport of Nice, France Large parts of the Netherlands Almost half of the microstate of Monaco Parts of Dublin, Ireland Most of Belfast Harbour and areas of Belfast, Northern Ireland Parts of Saint Petersburg, such as the Marine Facade Helsinki Barceloneta area, Barcelona, in Spain The port of Zeebrugge in Belgium The southwestern residential area in Brest, Belarus Majority of left-bank and some right-bank residential areas of Kiev were built on a reclaimed fens and floodplains of the Dnieper river. Most of Fontvieille, Monaco Parts surrounding Port Hercules in La Condamine, Monaco The airport peninsula, the industrial area of Cornigliano, the PSA container terminal and other parts of the port in Genoa, Italy The Fens in East Anglia Venice, Italy Rione Orsini, part of Borgo Santa Lucia, Naples A big part of Kavala, city in Greece Fucine Lake, ItalyWaterfront Centre, Jersey The Foreshore in Cape Town The Hassan II Mosque in Morocco is built on reclaimed land.
The Eko Atlantic in Lagos, Nigeria. Large parts of Rio de Janeiro, most notably several blocks in the new docks area, the entire Flamengo Park and the neighborhood of Urca Parts of Florianópolis. Parts of New Orleans Parts of Montevideo, Rambla Sur and several projects still going on in Montevideo's Bay. Much of the urbanized area adjacent to San Francisco Bay, including most of San Francisco's waterfront and Financial District, San Francisco International Airport, the Port of Oakland, large portions of the city of Alameda has been reclaimed from the bay. Mexico City. Parts of Panama City urban and street development are based on reclaimed land, using material extracted from Panama Canal excavations; the Chicago shoreline The Northwestern University Lakefill, part of the campus of Northwestern University in Evanston, Illinois Back Bay, Massachusetts Battery Park City, Ma
Chloroplasts are organelles that conduct photosynthesis, where the photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, stores it in the energy-storage molecules ATP and NADPH while freeing oxygen from water in plant and algal cells. They use the ATP and NADPH to make organic molecules from carbon dioxide in a process known as the Calvin cycle. Chloroplasts carry out a number of other functions, including fatty acid synthesis, much amino acid synthesis, the immune response in plants; the number of chloroplasts per cell varies from one, in unicellular algae, up to 100 in plants like Arabidopsis and wheat. A chloroplast is a type of organelle known as a plastid, characterized by its two membranes and a high concentration of chlorophyll. Other plastid types, such as the leucoplast and the chromoplast, contain little chlorophyll and do not carry out photosynthesis. Chloroplasts are dynamic—they circulate and are moved around within plant cells, pinch in two to reproduce.
Their behavior is influenced by environmental factors like light color and intensity. Chloroplasts, like mitochondria, contain their own DNA, thought to be inherited from their ancestor—a photosynthetic cyanobacterium, engulfed by an early eukaryotic cell. Chloroplasts cannot be made by the plant cell and must be inherited by each daughter cell during cell division. With one exception, all chloroplasts can be traced back to a single endosymbiotic event, when a cyanobacterium was engulfed by the eukaryote. Despite this, chloroplasts can be found in an wide set of organisms, some not directly related to each other—a consequence of many secondary and tertiary endosymbiotic events; the word chloroplast is derived from the Greek words chloros, which means green, plastes, which means "the one who forms". The first definitive description of a chloroplast was given by Hugo von Mohl in 1837 as discrete bodies within the green plant cell. In 1883, A. F. W. Schimper would name these bodies as "chloroplastids".
In 1884, Eduard Strasburger adopted the term "chloroplasts". Chloroplasts are one of many types of organelles in the plant cell, they are considered to have originated from cyanobacteria through endosymbiosis—when a eukaryotic cell engulfed a photosynthesizing cyanobacterium that became a permanent resident in the cell. Mitochondria are thought to have come from a similar event, where an aerobic prokaryote was engulfed; this origin of chloroplasts was first suggested by the Russian biologist Konstantin Mereschkowski in 1905 after Andreas Schimper observed in 1883 that chloroplasts resemble cyanobacteria. Chloroplasts are only found in plants and the amoeboid Paulinella chromatophora. Cyanobacteria are considered the ancestors of chloroplasts, they are sometimes called blue-green algae though they are prokaryotes. They are a diverse phylum of bacteria capable of carrying out photosynthesis, are gram-negative, meaning that they have two cell membranes. Cyanobacteria contain a peptidoglycan cell wall, thicker than in other gram-negative bacteria, and, located between their two cell membranes.
Like chloroplasts, they have thylakoids within. On the thylakoid membranes are photosynthetic pigments, including chlorophyll a. Phycobilins are common cyanobacterial pigments organized into hemispherical phycobilisomes attached to the outside of the thylakoid membranes. Somewhere around 1 to 2 billion years ago, a free-living cyanobacterium entered an early eukaryotic cell, either as food or as an internal parasite, but managed to escape the phagocytic vacuole it was contained in; the two innermost lipid-bilayer membranes that surround all chloroplasts correspond to the outer and inner membranes of the ancestral cyanobacterium's gram negative cell wall, not the phagosomal membrane from the host, lost. The new cellular resident became an advantage, providing food for the eukaryotic host, which allowed it to live within it. Over time, the cyanobacterium was assimilated, many of its genes were lost or transferred to the nucleus of the host. From genomes that originally contained over 3000 genes only about 130 genes remain in the chloroplasts of contemporary plants.
Some of its proteins were synthesized in the cytoplasm of the host cell, imported back into the chloroplast. Separately, somewhere around 500 million years ago, it happened again and led to the amoeboid Paulinella chromatophora; this event is called endosymbiosis, or "cell living inside another cell with a mutual benefit for both". The external cell is referred to as the host while the internal cell is called the endosymbiont. Chloroplasts are believed to have arisen after mitochondria, since all eukaryotes contain mitochondria, but not all have chloroplasts; this is called serial endosymbiosis—an early eukaryote engulfing the mitochondrion ancestor, some descendants of it engulfing the chloroplast ancestor, creating a cell with both chloroplasts and mitochondria. Whether or not primary chloroplasts came from a single endosymbiotic event, or many independent engulfments across various eukaryotic lineages, has long been debated, it is now held that organisms with primary chloroplasts share a single ancestor that took in a cyanobacterium 600–2000 million years ago.
It has been proposed. The exception is the amoeboid Paulinella chromatophora, which descends from an ancestor that took in a Prochlorococcus cyanobacterium 90–500 million years ago; these chloroplasts
Arizona is a state in the southwestern region of the United States. It is part of the Western and the Mountain states, it is the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona shares the Four Corners region with Utah and New Mexico. Arizona is the 48th state and last of the contiguous states to be admitted to the Union, achieving statehood on February 14, 1912, coinciding with Valentine's Day. Part of the territory of Alta California in New Spain, it became part of independent Mexico in 1821. After being defeated in the Mexican–American War, Mexico ceded much of this territory to the United States in 1848; the southernmost portion of the state was acquired in 1853 through the Gadsden Purchase. Southern Arizona is known for its desert climate, with hot summers and mild winters. Northern Arizona features forests of pine, Douglas fir, spruce trees. There are ski resorts in the areas of Flagstaff and Tucson. In addition to the Grand Canyon National Park, there are several national forests, national parks, national monuments.
About one-quarter of the state is made up of Indian reservations that serve as the home of 27 federally recognized Native American tribes, including the Navajo Nation, the largest in the state and the United States, with more than 300,000 citizens. Although federal law gave all Native Americans the right to vote in 1924, Arizona excluded those living on reservations in the state from voting until the state Supreme Court ruled in favor of Native American plaintiffs in Trujillo v. Garley; the state's name appears to originate from an earlier Spanish name, derived from the O'odham name alĭ ṣonak, meaning "small spring", which applied only to an area near the silver mining camp of Planchas de Plata, Sonora. To the European settlers, their pronunciation sounded like "Arissona"; the area is still known as alĭ ṣonak in the O'odham language. Another possible origin is the Basque phrase haritz ona, as there were numerous Basque sheepherders in the area. A native Mexican of Basque heritage established the ranchería of Arizona between 1734 and 1736 in the current Mexican state of Sonora, which became notable after a significant discovery of silver there, c.
1737. There is a misconception. For thousands of years before the modern era, Arizona was home to numerous Native American tribes. Hohokam and Ancestral Puebloan cultures were among the many that flourished throughout the state. Many of their pueblos, cliffside dwellings, rock paintings and other prehistoric treasures have survived, attracting thousands of tourists each year; the first European contact by native peoples was with Marcos de Niza, a Spanish Franciscan, in 1539. He explored parts of the present state and made contact with native inhabitants the Sobaipuri; the expedition of Spanish explorer Coronado entered the area in 1540–1542 during its search for Cíbola. Few Spanish settlers migrated to Arizona. One of the first settlers in Arizona was José Romo de Vivar. Father Kino was the next European in the region. A member of the Society of Jesus, he led the development of a chain of missions in the region, he converted many of the Indians to Christianity in the Pimería Alta in the 1690s and early 18th century.
Spain founded presidios at Tubac in 1752 and Tucson in 1775. When Mexico achieved its independence from the Kingdom of Spain and its Spanish Empire in 1821, what is now Arizona became part of its Territory of Nueva California known as Alta California. Descendants of ethnic Spanish and mestizo settlers from the colonial years still lived in the area at the time of the arrival of European-American migrants from the United States. During the Mexican–American War, the U. S. Army occupied the national capital of Mexico City and pursued its claim to much of northern Mexico, including what became Arizona Territory in 1863 and the State of Arizona in 1912; the Treaty of Guadalupe Hidalgo specified that, in addition to language and cultural rights of the existing inhabitants of former Mexican citizens being considered as inviolable, the sum of US$15 million dollars in compensation be paid to the Republic of Mexico. In 1853, the U. S. acquired the land south below the Gila River from Mexico in the Gadsden Purchase along the southern border area as encompassing the best future southern route for a transcontinental railway.
What is now known as the state of Arizona was administered by the United States government as part of the Territory of New Mexico until the southern part of that region seceded from the Union to form the Territory of Arizona. This newly established territory was formally organized by the Confederate States government on Saturday, January 18, 1862, when President Jefferson Davis approved and signed An Act to Organize the Territory of Arizona, marking the first official use of the name "Territory of Arizona"; the Southern territory supplied the Confederate government with men and equipment. Formed in 1862, Arizona scout companies served with the Confederate States Army duri
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