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Xerosere
Xerosere is a plant succession that is limited by water availability. It includes the different stages in a ''xerarch succession''. Xerarch succession of ecological communities originated in extremely dry situation such as sand deserts, sand dunes, salt deserts, rock deserts etc. A xerosere may include lithoseres (on rock) and psammoseres (on sand). Stages Bare rocks Bare rocks are produced when glaciers recede or volcanoes erupt. Erosion of these rocks is brought by rain water and wind loaded with soil particles. The rain water combines with atmospheric carbon dioxide that corrodes the surface of the rocks and produce crevices. Water enters these crevices, freezes and expands to separate boulders. These boulders move down under the influence of gravity and wear particles from the rocks. Also when the wind loaded with soil particles strikes against the rocks, it removes soil particles. All these processes lead to formation of a little soil at the surface of these bare ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithosere
A lithosere (a sere originating on rock) is a plant succession that begins life on a newly exposed rock surface, such as one left bare as a result of glacial retreat, tectonic uplift as in the formation of a raised beach, or volcanic eruptions. For example, the lava fields of Eldgjá in Iceland where Laki and Katla fissures erupted in the year 935 and the solidified lava has, over time, begun to form a lithosere. Pioneer species are the first organisms that colonise an area, of which lithoseres are an example. They will typically be very hardy (''i.e.'', they will be xerophyte A xerophyte (from Greek ξηρός ''xeros'' 'dry' + φυτόν ''phuton'' 'plant') is a species of plant that has adaptations to survive in an environment with little liquid water, such as a desert such as the Sahara or places in the Alps or th ...s, wind-resistant or cold-resistant). In the case of a lithosere the pioneer species will be cyanobacteria and algae, which create their own food and water— ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Psammosere
A psammosere is a seral community, an ecological succession that began life on newly exposed coastal sand. Most common psammoseres are sand dune systems. In a psammosere, the organisms closest to the sea will be pioneer species: Halophyte, salt-tolerant species such as Littoral zone, littoral algae and Salicornia, glasswort with marram grass stabilising the dunes. Progressing inland many characteristic features change and help determine the natural succession of the dunes. For instance, the drainage slows down as the land becomes more compact and has better soils, and the pH drops as the proportion of seashell fragments reduces and the amount of humus increases. Sesuvium portulacastrum, Sea purslane, sea lavender, meadow grass and Calluna, heather eventually grade into a typical non-maritime terrestrial eco-system. The first trees (or pioneer trees) that appear are typically fast-growing trees such as birch, willow or rowan. In turn these will be replaced by slow-growing, larger tre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Succession
Ecological succession is the process of change in the species structure of an ecological community over time. The time scale can be decades (for example, after a wildfire) or more or less. Bacteria allows for the cycling of nutrients such as carbon, nitrogen and sulphur. The community begins with relatively few pioneering plants and animals and develops through increasing complexity until it becomes stable or self-perpetuating as a climax community. The "engine" of succession, the cause of ecosystem change, is the impact of established organisms upon their own environments. A consequence of living is the sometimes subtle and sometimes overt alteration of one's own environment. Succession is a process by which an ecological community undergoes more or less orderly and predictable changes following a disturbance or the initial colonization of a new habitat. Succession may be initiated either by formation of new, unoccupied habitat, such as from a lava flow or a severe landslid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grimmia
''Grimmia'' is a genus of mosses (Bryophyta), originally named by Jakob Friedrich Ehrhart in honour of Johann Friedrich Carl Grimm, a physician and botanist from Gotha, Germany. Geographic distribution Although predominantly occurring in the moderate zones, representatives of the cosmopolitan genus ''Grimmia'' may be found in all parts of the world, from Alaska to the most southern point of Chile, and from Siberia to South Africa, though in tropic regions, e.g. Hawaii and Indonesia, ''Grimmia'' species only occur high up in the mountains. Identification ''Grimmia'' is a notoriously difficult genus in terms of identification, and in the majority of herbaria a considerable number of species was found misidentified. The American bryologist Geneva Sayre (1911–1992), who worked for many years on a monograph of the North American ''Grimmias'', indicated in an original way these difficulties, as she said: "it contains an ambigua, a varia, a decipiens, a controversa, a rev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhus
Sumac ( or ), also spelled sumach, is any of about 35 species of flowering plants in the genus ''Rhus'' and related genera in the cashew family (Anacardiaceae). Sumacs grow in subtropical and temperate regions throughout the world, including East Asia, Africa, and North America. Sumac is used as a spice, as a dye, and in medicine. Description Sumacs are dioecious shrubs and small trees in the family Anacardiaceae that can reach a height of . The leaves are usually pinnately compound, though some species have trifoliate or simple leaves. The flowers are in dense panicles or spikes long, each flower very small, greenish, creamy white or red, with five petals. The fruits are reddish, thin-fleshed drupes covered in varying levels of hairs at maturity and form dense clusters at branch tips, sometimes called sumac bobs. Sumacs propagate both by seed ( spread by birds and other animals through their droppings), and by new shoots from rhizomes, forming large clonal colonies. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Festuca
''Festuca'' (fescue) is a genus of flowering plants belonging to the grass family Poaceae (subfamily Pooideae). They are evergreen or herbaceous perennial tufted grasses with a height range of and a cosmopolitan distribution, occurring on every continent except Antarctica. The genus is closely related to ryegrass (''Lolium''), and recent evidence from phylogenetic studies using DNA sequencing of plant mitochondrial DNA shows that the genus lacks monophyly. As a result, plant taxonomists have moved several species, including the forage grasses tall fescue and meadow fescue, from the genus ''Festuca'' into the genus ''Lolium'', or alternatively into the segregate genus '' Schedonorus''. Because the taxonomy is complex, scientists have not determined how many true species belong to the genus, but estimates range from more than 400 to over 640.Darbyshire, S. J. and L. E. Pavlick''Festuca''. Grass Manual. Flora of North America. Fescue pollen is a significant contributor t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aristida
''Aristida'' is a very nearly cosmopolitan genus of plants in the grass family. ''Aristida'' is distinguished by having three awns (bristles) on each lemma of each floret. The genus includes about 300 species found worldwide, often in arid warm regions. This genus is among those colloquially called three-awns wiregrasses, speargrasses and needlegrasses. The name ''Aristida'' is derived from the Latin "arista", meaning "awn". They are characteristic of semiarid grassland. The Wiregrass Region of North America is named for '' A. stricta''. Other locales where this genus is an important component of the ecosystem include the Carolina Bays, the sandhills of the Carolinas, and elsewhere, Mulga scrub in Australia, and the xeric grasslands around Lake Turkana in Africa. Local increases in the abundance of wiregrasses is a good indicator of overgrazing, as livestock avoid them. Description ''Aristida'' stems are ascending to erect, with both basal and cauline leaves. The le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perennial Plant
A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also widely used to distinguish plants with little or no woody growth (secondary growth in girth) from trees and shrubs, which are also technically perennials. Perennialsespecially small flowering plantsthat grow and bloom over the spring and summer, die back every autumn and winter, and then return in the spring from their rootstock or other overwintering structure, are known as herbaceous perennials. However, depending on the rigours of local climate (temperature, moisture, organic content in the soil, microorganisms), a plant that is a perennial in its native habitat, or in a milder garden, may be treated by a gardener as an annual and planted out every year, from seed, from cuttings, or from divisions. Tomato vines, for example, live several y ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biennial Plant
A biennial plant is a flowering plant that, generally in a temperate climate, takes two years to complete its biological life cycle. Life cycle In its first year, the biennal plant undergoes primary growth, during which its vegetative structures (leaves, stems, and roots) develop. Usually, the stem of the plant remains short and the leaves are low to the ground, forming a rosette. After one year's growing season, the plant enters a period of dormancy for the colder months. Many biennials require a cold treatment, or vernalization, before they will flower. During the next spring or summer, the stem of the biennial plant elongates greatly, or "bolts". The plant then flowers, producing fruits and seeds before it finally dies. There are far fewer biennials than either perennial plants or annual plants. Biennials do not always follow a strict two-year life cycle and the majority of plants in the wild can take 3 or more years to fully mature. Rosette leaf size has been found to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evaporation
Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidity affects rate of evaporation of water. When the molecules of the liquid collide, they transfer energy to each other based on how they collide. When a molecule near the surface absorbs enough energy to overcome the vapor pressure, it will escape and enter the surrounding air as a gas. When evaporation occurs, the energy removed from the vaporized liquid will reduce the temperature of the liquid, resulting in evaporative cooling. On average, only a fraction of the molecules in a liquid have enough heat energy to escape from the liquid. The evaporation will continue until an equilibrium is reached when the evaporation of the liquid is equal to its condensation. In an enclosed environment, a liquid will evaporate until the surrounding a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Humus
In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the Latin word for "earth" or "ground". In agriculture, "humus" sometimes also is used to describe mature or natural compost extracted from a woodland or other spontaneous source for use as a soil conditioner. It is also used to describe a topsoil horizon that contains organic matter (''humus type'', ''humus form'', or ''humus profile''). Humus has many nutrients that improve the health of soil, nitrogen being the most important. The ratio of carbon to nitrogen (C:N) of humus commonly ranges between eight and fifteen with the median being about twelve. It also significantly affects the bulk density of soil. Humus is amorphous and lacks the "cellular cake structure characteristic of plants, micro-organisms or animals". Description The prim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Milk Weed
''Asclepias'' is a genus of herbaceous, perennial, flowering plants known as milkweeds, named for their latex, a milky substance containing cardiac glycosides termed cardenolides, exuded where cells are damaged. Most species are toxic to humans and many other species, primarily due to the presence of cardenolides, although, as with many such plants, there are species that feed upon them (e.g. their leaves) and from them (e.g. their nectar). Most notable are monarch butterflies, who use and require certain milkweeds as host plants for their larvae. The genus contains over 200 species distributed broadly across Africa, North America, and South America. It previously belonged to the family Asclepiadaceae, which is now classified as the subfamily Asclepiadoideae of the dogbane family, Apocynaceae. The genus was formally described by Carl Linnaeus in 1753, who named it after Asclepius, the Greek god of healing. Flowers Members of the genus produce some of the most complex flow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
