A wildfire or wildland fire is a fire in an area of combustible vegetation occurring in rural areas. Depending on the type of vegetation present, a wildfire can be classified more as a brush fire, desert fire, forest fire, grass fire, hill fire, peat fire, vegetation fire, or veld fire. Fossil charcoal indicates that wildfires began soon after the appearance of terrestrial plants 420 million years ago. Wildfire's occurrence throughout the history of terrestrial life invites conjecture that fire must have had pronounced evolutionary effects on most ecosystems' flora and fauna. Earth is an intrinsically flammable planet owing to its cover of carbon-rich vegetation, seasonally dry climates, atmospheric oxygen, widespread lightning and volcanic ignitions. Wildfires can be characterized in terms of the cause of ignition, their physical properties, the combustible material present, the effect of weather on the fire. Wildfires can cause damage to property and human life, although occurring wildfires may have beneficial effects on native vegetation and ecosystems that have evolved with fire.
High-severity wildfire creates complex early seral forest habitat, which has higher species richness and diversity than unburned old forest. Many plant species depend on the effects of fire for reproduction. Wildfires in ecosystems where wildfire is uncommon or where non-native vegetation has encroached may have negative ecological effects. Wildfire behavior and severity result from a combination of factors such as available fuels, physical setting, weather. Analyses of historical meteorological data and national fire records in western North America show the primacy of climate in driving large regional fires via wet periods that create substantial fuels, or drought and warming that extend conducive fire weather. Strategies for wildfire prevention and suppression have varied over the years. One common and inexpensive technique is controlled burning: intentionally igniting smaller fires to minimize the amount of flammable material available for a potential wildfire. Vegetation may be burned periodically to maintain high species diversity and limit the accumulation of plants and other debris that may serve as fuel.
Wildland fire use is the cheapest and most ecologically appropriate policy for many forests. Fuels may be removed by logging, but fuels treatments and thinning have no effect on severe fire behavior when under extreme weather conditions. Wildfire itself is "the most effective treatment for reducing a fire's rate of spread, fireline intensity, flame length, heat per unit of area", according to Jan Van Wagtendonk, a biologist at the Yellowstone Field Station. Building codes in fire-prone areas require that structures be built of flame-resistant materials and a defensible space be maintained by clearing flammable materials within a prescribed distance from the structure. Three major natural causes of wildfire ignitions exist: dry climate lightning volcanic eruptionThe most common direct human causes of wildfire ignition include arson, discarded cigarettes, power-lines arcs, sparks from equipment. Ignition of wildland fires via contact with hot rifle-bullet fragments is possible under the right conditions.
Wildfires can be started in communities experiencing shifting cultivation, where land is cleared and farmed until the soil loses fertility, slash and burn clearing. Forested areas cleared by logging encourage the dominance of flammable grasses, abandoned logging roads overgrown by vegetation may act as fire corridors. Annual grassland fires in southern Vietnam stem in part from the destruction of forested areas by US military herbicides and mechanical land-clearing and -burning operations during the Vietnam War; the most common cause of wildfires varies throughout the world. In Canada and northwest China, lightning operates as the major source of ignition. In other parts of the world, human involvement is a major contributor. In Africa, Central America, Mexico, New Zealand, South America, Southeast Asia, wildfires can be attributed to human activities such as agriculture, animal husbandry, land-conversion burning. In China and in the Mediterranean Basin, human carelessness is a major cause of wildfires.
In the United States and Australia, the source of wildfires can be traced both to lightning strikes and to human activities. Coal seam fires burn in the thousands around the world, such as those in Burning Mountain, New South Wales, they can flare up unexpectedly and ignite nearby flammable material. The spread of wildfires varies based on the flammable material present, its vertical arrangement and moisture content, weather conditions. Fuel arrangement and density is governed in part by topography, as land shape determines factors such as available sunlight and water for plant growth. Overall, fire types can be characterized by their fuels as follows: Ground fires are fed by subterranean roots and other buried organic matter; this fuel type is susceptible to ignition due to spotting. Ground fires burn by smoldering, can burn for days to months, such as peat fires in Kalimantan and Eastern Sumatra, which resulted from a riceland creation project that unintentionally drained and dried the peat.
Crawling or surface fires are fueled by low-lying vegetation on the forest floor such as leaf and timber litter, debris and low-lying shrubbery. This kind of fire burns at a lower temperature than crown fires and may spread
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
Poa foliosa is a species of tussock grass known as muttonbird poa. It is native to the subantarctic islands of New Australia. Poa foliosa is a dioecious grass growing as densely clumped tussocks up to 2 m in height; the tussocks arise from short, woody stolons, with the shoots covered at the base by the fibrous remnants of sheaths. The leaf-blades are 150–400 mm long and 3–6 mm wide; the plant flowers from October to December, fruits from November to April. In New Zealand the grass is found on the north-eastern Titi, or Muttonbird, Islands, as well as on the Solander, Antipodes and Campbell Islands, it is found on Australia’s Macquarie Island. The habitat is coastal and subcoastal near seabird colonies. On Macquarie Island’s coastal terraces and slopes it grows in mixed stands with Stilbocarpa polaris where the drainage is good, along the borders of streams, it forms a tall tussock grassland along the beaches above the high-water mark, as well as patchily on the island’s plateau in sheltered and exposed sites.
The upland grasslands are an important habitat for burrow-nesting petrels and mice. Where rabbit grazing is controlled, Poa foliosa tall tussock grassland becomes more widespread. Clayton, W. D.. T.. "Poa foliosa". GrassBase. Royal Botanic Gardens, Kew. Retrieved 2011-01-03. "Macquarie Island flora". Australian Antarctic Division. 2010-08-12. Retrieved 2011-01-03. "Poa foliosa". New Zealand Plant Conservation Network. Retrieved 2011-01-03
In physical geography, a dune is a hill of loose sand built by aeolian processes or the flow of water. Dunes occur in different sizes, formed by interaction with the flow of air or water. Most kinds of dunes are longer on the stoss side, where the sand is pushed up the dune, have a shorter "slip face" in the lee side; the valley or trough between dunes is called a slack. A "dune field" or erg is an area covered by extensive dunes. Dunes occur along some coasts; some coastal areas have one or more sets of dunes running parallel to the shoreline directly inland from the beach. In most cases, the dunes are important in protecting the land against potential ravages by storm waves from the sea. Although the most distributed dunes are those associated with coastal regions, the largest complexes of dunes are found inland in dry regions and associated with ancient lake or sea beds. Dunes can form under the action of water flow, on sand or gravel beds of rivers and the sea-bed; the modern word "dune" came into English from French c.
1790, which in turn came from Middle Dutch dūne. Dunes are made of sand-sized particles, may consist of quartz, calcium carbonate, gypsum, or other materials; the upwind/upstream/upcurrent side of the dune is called the stoss side. Sand is pushed or bounces up the stoss side, slides down the lee side. A side of a dune that the sand has slid down is called a slip face; the Bagnold formula gives the speed. Five basic dune types are recognized: crescentic, star and parabolic. Dune areas may occur in three forms: simple and complex. Barchan dunes are crescent-shaped mounds which are wider than they are long; the lee-side slipfaces are on the concave sides of the dunes. These dunes form under winds that blow from one direction, they form separate crescents. When the sand supply is greater, they may merge into barchanoid ridges, transverse dunes; some types of crescentic dunes move more over desert surfaces than any other type of dune. A group of dunes moved more than 100 metres per year between 1954 and 1959 in China's Ningxia Province, similar speeds have been recorded in the Western Desert of Egypt.
The largest crescentic dunes on Earth, with mean crest-to-crest widths of more than three kilometres, are in China's Taklamakan Desert. See lunettes and parabolic dues, for dunes similar to crescent-shaped ones. Abundant barchan dunes may merge into barchanoid ridges, which grade into linear transverse dunes, so called because they lie transverse, or across, the wind direction, with the wind blowing perpendicular to the ridge crest. Seif dunes are linear dunes with two slip faces; the two slip faces make them sharp-crested. They are called seif dunes after the Arabic word for "sword", they may be more than 160 kilometres long, thus visible in satellite images. Seif dunes are associated with bidirectional winds; the long axes and ridges of these dunes extend along the resultant direction of sand movement. Some linear dunes merge to form Y-shaped compound dunes. Formation is debated. Bagnold, in The Physics of Blown Sand and Desert Dunes, suggested that some seif dunes form when a barchan dune moves into a bidirectional wind regime, one arm or wing of the crescent elongates.
Others suggest. In the sheltered troughs between developed seif dunes, barchans may be formed, because the wind is constrained to be unidirectional by the dunes. Seif dunes are common in the Sahara, they range up to 300 km in length. In the southern third of the Arabian Peninsula, a vast erg, called the Rub' al Khali or Empty Quarter, contains seif dunes that stretch for 200 km and reach heights of over 300 m. Linear loess hills known; these hills appear to have been formed during the last ice age under permafrost conditions dominated by sparse tundra vegetation. Radially symmetrical, star dunes are pyramidal sand mounds with slipfaces on three or more arms that radiate from the high center of the mound, they tend to accumulate in areas with multidirectional wind regimes. Star dunes grow upward rather than laterally, they dominate the Grand Erg Oriental of the Sahara. In other deserts, they occur around the margins of the sand seas near topographic barriers. In the southeast Badain Jaran Desert of China, the star dunes are up to 500 metres tall and may be the tallest dunes on Earth.
Oval or circular mounds that lack a slipface. Dome dunes occur at the far upwind margins of sand seas. Fixed crescentic dunes that form on the leeward margins of playas and river valleys in arid and semiarid regions in response to the direction of prevailing winds, are known as lunettes, source-bordering dunes and clay dunes, they may be composed of clay, sand, or gypsum, eroded from the basin floor or shore, transported up the concave side of the dune, deposited on the convex side. Examples in Australia are up to 6.5 km long, 1 km wide, up to 50 metres high. They occur in southern and West Africa, in parts of the western United States Texas. U-shaped mounds of sand with convex noses trailed by elongated arms are parabolic dunes; these dunes are formed from blowout dunes where the erosion
Montane ecosystems refers to any ecosystem found in mountains. These ecosystems are affected by climate, which gets colder as elevation increases, they are stratified according to elevation. Dense forests are common at moderate elevations. However, as the elevation increases, the climate becomes harsher, the plant community transitions to grasslands or tundra; as elevation increases, the climate becomes cooler, due to a decrease in atmospheric pressure and the adiabatic cooling of airmasses. The change in climate by moving up 100 meters on a mountain is equivalent to moving 80 kilometers towards the nearest pole; the characteristic flora and fauna in the mountains tend to depend on elevation, because of the change in climate. This dependency causes life zones to form: bands of similar ecosystems at similar altitude. One of the typical life zones on mountains is the montane forest: at moderate elevations, the rainfall and temperate climate encourages dense forests to grow. Holdridge defines the climate of montane forest as having a biotemperature of between 6 and 12 °C, where biotemperature is the mean temperature considering temperatures below 0 °C to be 0 °C.
Above the elevation of the montane forest, the trees thin out in the subalpine zone, become twisted krummholz, fail to grow. Therefore, montane forests contain trees with twisted trunks; this phenomenon is observed due to the increase in the wind strength with the elevation. The elevation where trees fail to grow is called the tree line; the biotemperature of the subalpine zone is between 3 and 6 °C. Above the tree line the ecosystem is called the alpine zone or alpine tundra, dominated by grasses and low-growing shrubs; the biotemperature of the alpine zone is between 1.5 and 3 °C. Many different plant species live in the alpine environment, including perennial grasses, forbs, cushion plants and lichens. Alpine plants must adapt to the harsh conditions of the alpine environment, which include low temperatures, ultraviolet radiation, a short growing season. Alpine plants display adaptations such as rosette structures, waxy surfaces, hairy leaves; because of the common characteristics of these zones, the World Wildlife Fund groups a set of related ecoregions into the "montane grassland and shrubland" biome.
Climates with biotemperatures below 1.5 °C tend to consist purely of ice. Montane forests occur between the subalpine zone; the elevation at which one habitat changes to another varies across the globe by latitude. The upper limit of montane forests, the forest line or timberline, is marked by a change to hardier species that occur in less dense stands. For example, in the Sierra Nevada of California, the montane forest has dense stands of lodgepole pine and red fir, while the Sierra Nevada subalpine zone contains sparse stands of whitebark pine; the lower bound of the montane zone may be a "lower timberline" that separates the montane forest from drier steppe or desert region. Montane forests differ from lowland forests in the same area; the climate of montane forests is colder than lowland climate at the same latitude, so the montane forests have species typical of higher-latitude lowland forests. Humans can disturb montane forests through agriculture. On isolated mountains, montane forests surrounded by treeless dry regions are typical "sky island" ecosystems.
Montane forests in temperate climate are one of temperate coniferous forest or temperate broadleaf and mixed forest, forest types that are well known from northern Europe, northern United States, southern Canada. The trees are, however not identical to those found further north: geology and climate causes different related species to occur in montane forests. Montane forests around the world tend to be more species-rich than those in Europe, because major mountain chains in Europe are oriented east-west. Montane forests in temperate climate occur in Europe, in North America, south-western South America, New Zealand and Himalaya. Montane forests in Mediterranean climate are warm and dry except in winter, when they are wet and mild; these forests are mixed conifer and broadleaf forests, with only a few conifer species. Pine and Juniper are typical trees found in Mediterranean montane forests; the broadleaf trees show more variety and are evergreen, e.g. evergreen Oak. This type of forest is found in the Mediterranean Basin, North Africa and the southwestern US, Iran and Afghanistan.
In the tropics, montane forests can consist of broadleaf forest in addition to coniferous forest. One example of a tropical montane forest is a cloud forest, which gains its moisture from clouds and fog. Cloud forests exhibit an abundance of mosses covering the ground and vegetation, in which case they are referred to as mossy forests. Mossy forests develop on the saddles of mountains, where moisture introduced by settling clouds is more retained. Depending on latitude, the lower limit of montane rainforests on large mountains is between 1,500 and 2,500 metres while the upper limit is from 2,400 to 3,300 metres; the subalpine zone is the biotic zone below the tree line around the world. In tropical regions of Southeast Asia the tree line may be above 4,000 m, whereas in Scotland it may be as low as 450 m. Species that occur in this zone depend on the location of the zone on the Earth, for example, snow gum in Australia, or subalpine larch, mountain h
Poa sieberiana known as grey tussock-grass and snow grass, is a species of tussock grass, endemic to Australia. The species was formally described in 1827 by German botanist Kurt Sprengel in Systema Vegetabilium