|
Invasibility
Alien species, or species that are not native, invade habitats and alter ecosystems around the world. Invasive species are only considered invasive if they are able to survive and sustain themselves in their new environment. A habitat and the environment around it has natural flaws that make them vulnerable to invasive species. The level of vulnerability of a habitat to invasions from outside species is defined as its invasibility. One must be careful not to get this confused with invasiveness, which relates to the species itself and its ability to invade an ecosystem.Alpert, P., Bone, E., & Holzapfel, C. (2000). Invasiveness, invasibility and the role of environmental stress in the spread of non-native plants. ''Perspectives in Plant Ecology, Evolution and Systematics,'' ''3''(1), 52-66. doi:10.1078/1433-8319-00004 There are many factors, abiotic and biotic, that can raise or lower a habitat's invasibility, such as stress, disturbance, nutrient levels, climate, and pre-exist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biodiversity
Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic ('' genetic variability''), species ('' species diversity''), and ecosystem ('' ecosystem diversity'') level. Biodiversity is not distributed evenly on Earth; it is usually greater in the tropics as a result of the warm climate and high primary productivity in the region near the equator. Tropical forest ecosystems cover less than 10% of earth's surface and contain about 90% of the world's species. Marine biodiversity is usually higher along coasts in the Western Pacific, where sea surface temperature is highest, and in the mid-latitudinal band in all oceans. There are latitudinal gradients in species diversity. Biodiversity generally tends to cluster in hotspots, and has been increasing through time, but will be likely to slow in the future as a primary result of deforestation. It encompasses the evolutionary, ecological, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alien Plants At Cranny, Omagh - Geograph
Alien primarily refers to: * Alien (law), a person in a country who is not a national of that country ** Enemy alien, the above in times of war * Extraterrestrial life, life which does not originate from Earth ** Specifically, intelligent extraterrestrial beings; see List of alleged extraterrestrial beings ** For fictional extraterrestrial life, see Extraterrestrials in fiction * Introduced species, a species not native to its environment Alien(s), or The Alien(s) may also refer to: Science and technology * AliEn (ALICE Environment), a grid framework * Alien (file converter), a Linux program * Alien Technology, a manufacturer of RFID technology Arts and entertainment * ''Alien'' (franchise), a media franchise ** Alien (creature in ''Alien'' franchise) Films * ''Alien'' (film), a 1979 film by Ridley Scott ** ''Aliens'' (film), second film in the franchise from 1986 by James Cameron ** '' Alien 3'', third film in the franchise from 1992 by David Fincher ** '' Alien ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pine
A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family (biology), family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accepts 187 species names of pines as current, together with more synonyms. The American Conifer Society (ACS) and the Royal Horticultural Society accept 121 species. Pines are commonly found in the Northern Hemisphere. ''Pine'' may also refer to the lumber derived from pine trees; it is one of the more extensively used types of lumber. The pine family is the largest conifer family and there are currently 818 named cultivars (or Trinomial nomenclature, trinomials) recognized by the ACS. Description Pine trees are evergreen, coniferous resinous trees (or, rarely, shrubs) growing tall, with the majority of species reaching tall. The smallest are Siberian dwarf pine and Potosi pinyon, and the tallest is an tall ponderosa pine lo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grassland
A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur naturally on all continents except Antarctica and are found in most ecoregions of the Earth. Furthermore, grasslands are one of the largest biomes on earth and dominate the landscape worldwide. There are different types of grasslands: natural grasslands, semi-natural grasslands, and agricultural grasslands. They cover 31–69% of the Earth's land area. Definitions Included among the variety of definitions for grasslands are: * "...any plant community, including harvested forages, in which grasses and/or legumes make up the dominant vegetation." * "...terrestrial ecosystems dominated by herbaceous and shrub vegetation, and maintained by fire, grazing, drought and/or freezing temperatures." (Pilot Assessment of Global Ecosystems, 2000) * " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Caribbean Sea, and to the west and south by the Pacific Ocean. Because it is on the North American Plate, North American Tectonic Plate, Greenland is included as a part of North America geographically. North America covers an area of about , about 16.5% of Earth's land area and about 4.8% of its total surface. North America is the third-largest continent by area, following Asia and Africa, and the list of continents and continental subregions by population, fourth by population after Asia, Africa, and Europe. In 2013, its population was estimated at nearly 579 million people in List of sovereign states and dependent territories in North America, 23 independent states, or about 7.5% of the world's population. In Americas (terminology)#Human ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biomass (ecology)
The biomass is the mass of living biological organisms in a given area or ecosystem at a given time. Biomass can refer to ''species biomass'', which is the mass of one or more species, or to ''community biomass'', which is the mass of all species in the community. It can include microorganisms, plants or animals. The mass can be expressed as the average mass per unit area, or as the total mass in the community. How biomass is measured depends on why it is being measured. Sometimes, the biomass is regarded as the natural mass of organisms ''in situ'', just as they are. For example, in a salmon fishery, the salmon biomass might be regarded as the total wet weight the salmon would have if they were taken out of the water. In other contexts, biomass can be measured in terms of the dried organic mass, so perhaps only 30% of the actual weight might count, the rest being water. For other purposes, only biological tissues count, and teeth, bones and shells are excluded. In some appl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Habitat Fragmentation
Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological processes that slowly alter the layout of the physical environment (suspected of being one of the major causes of speciation), and human activity such as land conversion, which can alter the environment much faster and causes the extinction of many species. More specifically, habitat fragmentation is a process by which large and contiguous habitats get divided into smaller, isolated patches of habitats. Definition The term habitat fragmentation includes five discrete phenomena: * Reduction in the total area of the habitat * Decrease of the interior: edge ratio * Isolation of one habitat fragment from other areas of habitat * Breaking up of one patch of habitat into several smaller patches * Decrease in the average size of each patch of hab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biological Dispersal
Biological dispersal refers to both the movement of individuals (animals, plants, fungi, bacteria, etc.) from their birth site to their breeding site ('natal dispersal'), as well as the movement from one breeding site to another ('breeding dispersal'). Dispersal is also used to describe the movement of propagules such as seeds and spores. Technically, dispersal is defined as any movement that has the potential to lead to gene flow. The act of dispersal involves three phases: departure, transfer, settlement and there are different fitness costs and benefits associated with each of these phases. Through simply moving from one habitat patch to another, the dispersal of an individual has consequences not only for individual fitness, but also for population dynamics, population genetics, and species distribution. Understanding dispersal and the consequences both for evolutionary strategies at a species level, and for processes at an ecosystem level, requires understanding on the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Propagule Pressure
Propagule pressure (also termed introduction effort) is a composite measure of the number of individuals of a species released into a region to which they are not native. It incorporates estimates of the absolute number of individuals involved in any one release event (propagule size) and the number of discrete release events (propagule number). As the number of releases or the number of individuals released increases, propagule pressure also increases. Propagule pressure can be defined as the quality, quantity, and frequency of invading organisms (Groom, 2006). Propagule pressure is a key element to why some introduced species persist while others do not (Lockwood, 2005). Species introduced in large quantities and consistent quantities prove more likely to survive, whereas species introduced in small numbers with only a few release events are more likely to go extinct (Lockwood, 2005). Propagule pressure is a composite measure to the number of individuals released into a non-native ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spartina Anglica
''Sporobolus anglicus'' (common cordgrass) is a species of cordgrass that originated in southern England in about 1870 and is a neonative species in Britain. It was reclassified as '' Sporobolus anglicus'' after a taxonomic revision in 2014,Peterson, PM , et al (2014) A molecular phylogeny and new subgeneric classification of Sporobolus (Poaceae: Chloridoideae: Sporobolinae), Taxon 63: 1212-1243. but ''Spartina anglica'' is still in common usage. It is an allotetraploid species derived from the hybrid ''Sporobolus × townsendii'', which arose when the European native cordgrass '' Sporobolus maritimus'' (Small Cordgrass) hybridised with the introduced American '' Sporobolus alterniflorus'' (Smooth Cordgrass). It is a herbaceous perennial plant growing tall, yellowish green in spring and summer, and turning light brown in autumn and winter. The leaves are long, and broad at the base, tapering to a point. It produces flowers and seeds on only one side of the stalk. The flowe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carcinus Maenas
''Carcinus maenas'' is a common littoral crab. It is known by different names around the world. In the British Isles, it is generally referred to as the shore crab, or green shore crab. In North America and South Africa, it bears the name european green crab. ''C. maenas'' is a widespread invasive species, listed among the 100 "world's worst alien invasive species". It is native to the north-east Atlantic Ocean and Baltic Sea, but has colonised similar habitats in Australia, South Africa, South America and both Atlantic and Pacific coasts of North America. It grows to a carapace width of , and feeds on a variety of mollusks, worms, and small crustaceans, potentially affecting a number of fisheries. Its successful dispersal has occurred by a variety of mechanisms, such as on ships' hulls, sea planes, packing materials, and bivalves moved for aquaculture. Description ''C. maenas'' has a carapace up to long and wide, but can be larger outside its native rang ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hemigrapsus Sanguineus
''Hemigrapsus sanguineus'', the Japanese shore crab or Asian shore crab, is a species of crab from East Asia. It has been introduced to several other regions, and is now an invasive species in North America and Europe. It was introduced to these regions by ships from Asia emptying their ballast tanks in coastal waters. Description ''H. sanguineus'' has a squarish carapace, in width, with three teeth along the forward sides; its pereiopods are marked with alternating light and dark bands. The males have a bulb-like structure at the base of the movable finger on their claws. Other distinguishing features include three spines on each side of the carapace. Adult sizes range from 35–42 mm width. These crabs are opportunistic omnivores that tend to favor other animals over algae. As crab density in an invaded area increases, so does the breadth of the species' diet, which suggests that competition alters selection of food. There currently is no mitigation against these cra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> North America")
