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Grindelia Fraxino-pratensis
''Grindelia fraxinipratensis'', common name Ash Meadows gumweed, is a North American species of flowering plants in the family Asteraceae. It is native to the southwestern United States, in Mojave Desert regions in Nye County in Nevada and Inyo County in California. Some of the Nevada populations (including the type locality) lie inside the Nevada Test Site of the United States Atomic Energy Commission Some sources spell the name as ''G. fraxino-pratensis''. ''Grindelia fraxinipratensis'' is the accepted spelling according to the International Code of Nomenclature. ''Grindelia fraxinipratensis'' grows in meadows and on the borders of woodlands. It is a biennial or perennial herb growing tall, erect in form, brown or reddish, and hairless and oily. It grows from a thick underground caudex atop a woody taproot. The dark green leaves are up to long, widely lance-shaped or oblong, sometimes toothed near the tips, and studded with visible resin glands. The inflorescence bears o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asteraceae
The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae were first described in the year 1740. The number of species in Asteraceae is rivaled only by the Orchidaceae, and which is the larger family is unclear as the quantity of extant species in each family is unknown. Most species of Asteraceae are annual, biennial, or perennial herbaceous plants, but there are also shrubs, vines, and trees. The family has a widespread distribution, from subpolar to tropical regions in a wide variety of habitats. Most occur in hot desert and cold or hot semi-desert climates, and they are found on every continent but Antarctica. The primary common characteristic is the existence of sometimes hundreds of tiny individual florets which are held together by protective involucres in flower heads, or more technicall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amargosa Valley
The Amargosa Valley is the valley through which the Amargosa River flows south, in Nye County, southwestern Nevada and Inyo County in the state of California. The south end is alternately called the "Amargosa River Valley'" or the "Tecopa Valley." Its northernmost point is around Beatty, Nevada and southernmost is Tecopa, California, where the Amargosa River enters into the Amargosa Canyon. Geography The Amargosa Valley ("the Valley") is located within the Basin and Range Province ("the Province") which is characterized by abrupt changes in elevation, alternating between narrow faulted mountain chains and flat arid valleys or basins. As is typical of the Province, the Valley is long from north to south and narrow from east to west. It lies to the east of Death Valley, separated from it by the Amargosa Range and Funeral Mountains. The Valley lies within the Mohave Desert region of the Province. The more narrowly bounded Amargosa Desert forms the eastern portion of the Valley. H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Table
The water table is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with water. It can also be simply explained as the depth below which the ground is saturated. The water table is the surface where the water pressure head is equal to the atmospheric pressure (where gauge pressure = 0). It may be visualized as the "surface" of the subsurface materials that are saturated with groundwater in a given vicinity. The groundwater may be from precipitation or from groundwater flowing into the aquifer. In areas with sufficient precipitation, water infiltrates through pore spaces in the soil, passing through the unsaturated zone. At increasing depths, water fills in more of the pore spaces in the soils, until a zone of saturation is reached. Below the water table, in the phreatic zone (zone of saturation), layers of permeable rock that yield groundwater are called aquifers. In less permeable soils, such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wetland
A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The primary factor that distinguishes wetlands from terrestrial land forms or Body of water, water bodies is the characteristic vegetation of aquatic plants, adapted to the unique anoxic hydric soils. Wetlands are considered among the most biologically diverse of all ecosystems, serving as home to a wide range of plant and animal species. Methods for assessing wetland functions, wetland ecological health, and general wetland condition have been developed for many regions of the world. These methods have contributed to wetland conservation partly by raising public awareness of the functions some wetlands provide. Wetlands occur naturally on every continent. The water in wetlands is either freshwater, brackish or seawater, saltwater. The main w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peat
Peat (), also known as turf (), is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. The peatland ecosystem covers and is the most efficient carbon sink on the planet, because peatland plants capture carbon dioxide (CO2) naturally released from the peat, maintaining an equilibrium. In natural peatlands, the "annual rate of biomass production is greater than the rate of decomposition", but it takes "thousands of years for peatlands to develop the deposits of , which is the average depth of the boreal orthernpeatlands", which store around 415 gigatonnes (Gt) of carbon (about 46 times 2019 global CO2 emissions). Globally, peat stores up to 550 Gt of carbon, 42% of all soil carbon, which exceeds the carbon stored in all other vegetation types, including the world's forests, although it covers just 3% of the land's surface. ''Sphagnum'' moss, also called peat moss, is one of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Threatened Species
Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensation'', a mathematical measure of biomass related to population growth rate. This quantitative metric is one method of evaluating the degree of endangerment. IUCN definition The International Union for Conservation of Nature (IUCN) is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories, depending on the degree to which they are threatened: *Vulnerable species *Endangered species * Critically endangered species Less-than-threatened categories are near threatened, least concern, and the no longer assigned category of conservation dependent. Species which have not been evaluated (NE), or do not have sufficient data ( data deficient) also are not considered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distichlis Spicata
''Distichlis spicata'' is a species of grass known by several common names, including seashore saltgrass, inland saltgrass, and desert saltgrass. This grass is native to the Americas, where it is widespread. It can be found on other continents as well, where it is naturalized. It is extremely salt tolerant.Mojave Desert Wildflowers, Pam MacKay, 2nd ed. 2013, p 284 Distribution and habitat ''Distichlis spicata'' thrives along coastlines and on salt flats and disturbed soils, as well as forest, woodland, montane, and desert scrub habitats. It can form dense monotypic stands, and it often grows in clonal colonies. Non-clonal populations tend to be skewed toward a majority of one sex or the other. The grass forms sod with its hearty root system. Its rhizomes have sharp points which allow it to penetrate hard soils and aerenchymous tissues, which allow it to grow underwater and in mud. This plant grows easily in salty and alkaline soils, excreting salts from its tissues via salt g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spring (hydrosphere)
A spring is a point of exit at which groundwater from an aquifer flows out on top of Earth's crust (pedosphere) and becomes surface water. It is a component of the hydrosphere. Springs have long been important for humans as a source of fresh water, especially in arid regions which have relatively little annual rainfall. Springs are driven out onto the surface by various natural forces, such as gravity and hydrostatic pressure. Their yield varies widely from a volumetric flow rate of nearly zero to more than for the biggest springs. Formation Springs are formed when groundwater flows onto the surface. This typically happens when the groundwater table reaches above the surface level. Springs may also be formed as a result of karst topography, aquifers, or volcanic activity. Springs also have been observed on the ocean floor, spewing hot water directly into the ocean. Springs formed as a result of karst topography create karst springs, in which ground water travels throu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkali Soil
Alkali, or Alkaline, soils are clay soils with high pH (greater than 8.5), a poor soil structure and a low infiltration capacity. Often they have a hard calcareous layer at 0.5 to 1 metre depth. Alkali soils owe their unfavorable physico-chemical properties mainly to the dominating presence of sodium carbonate, which causes the soil to swellManaging irrigation water quality, Oregon State University, USA Retrieved on 2012-10-04. and difficult to clarify/settle. They derive their name from the group of elements, to which |
Saline Soil
Soil salinity is the salt content in the soil; the process of increasing the salt content is known as salinization. Salts occur naturally within soils and water. Salination can be caused by natural processes such as mineral weathering or by the gradual withdrawal of an ocean. It can also come about through artificial processes such as irrigation and road salt. Natural occurrence Salts are a natural component in soils and water. The ions responsible for salination are: Na+, K+, Ca2+, Mg2+ and Cl−. Over long periods of time, as soil minerals weather and release salts, these salts are flushed or leached out of the soil by drainage water in areas with sufficient precipitation. In addition to mineral weathering, salts are also deposited via dust and precipitation. Salts may accumulate in dry regions, leading to naturally saline soils. This is the case, for example, in large parts of Australia. Human practices can increase the salinity of soils by the addition of salts in i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clay
Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay particles, but become hard, brittle and non–plastic upon drying or firing. Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impurities, such as a reddish or brownish colour from small amounts of iron oxide. Clay is the oldest known ceramic material. Prehistoric humans discovered the useful properties of clay and used it for making pottery. Some of the earliest pottery shards have been dated to around 14,000 BC, and clay tablets were the first known writing medium. Clay is used in many modern industrial processes, such as paper making, cement production, and chemical filtering. Between one-half and two-thirds of the world's population live or work in buildings made with clay, often ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amargosa Desert
The Amargosa Desert is located in Nye County in western Nevada, United States, along the California–Nevada border, comprising the northeastern portion of the geographic Amargosa Valley, north of the Ash Meadows National Wildlife Refuge. The desert is named after the Amargosa River, which was named after the Spanish word for bitter because of the bitter taste of the water. Geography The Amargosa Desert lies at an elevation of about , and includes Crater Flat and the community of Amargosa Valley, Nevada, (formerly Lathrop Wells), which lies at the southern end of the desert. The desert lies between the Funeral Mountains and Death Valley to the west, and Yucca Mountain and the Nellis Air Force Range to the east. Natural history The Amargosa Desert is an arid desert habitat and an ecotone between the northern Great Basin and southern Mojave Desert ecosystems and biogeography regions. The seasonal Amargosa River course runs through the desert, with the rare Shoshone pupfish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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