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Indicator Value
Indicator value is a term that is used in the ecology of plants for two different indices. The older usage of the term refers to Ellenberg's indicator values from 1974, which are based on a simple ordinal classification of plants according to the position of their realized ecological niche along an environmental gradient.Ellenberg H. Zeigerwerte der Gefässpflanzen Mitteleuropas / H. Ellenberg // Scripta geobotanica. Göttingen, 1974. – Vol. 9. – 197 p. Since 1997, the term has also been used to refer to Dufrêne & Legendre's indicator value, which is a quantitative index measuring the statistical alliance of a species to any one of the classes in a classification of sites. According to Ellenberg Ellenberg's indicator values were the first model of bioindication proposed and applied to the flora of Central Europe, and they have a long tradition in interpretation and understanding of plant communities and their evolution. The latest edition of Ellenberg's indicator values appl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecology
Ecology () is the natural science of the relationships among living organisms and their Natural environment, environment. Ecology considers organisms at the individual, population, community (ecology), community, ecosystem, and biosphere levels. Ecology overlaps with the closely related sciences of biogeography, evolutionary biology, genetics, ethology, and natural history. Ecology is a branch of biology, and is the study of abundance (ecology), abundance, biomass (ecology), biomass, and distribution of organisms in the context of the environment. It encompasses life processes, interactions, and adaptations; movement of materials and energy through living communities; ecological succession, successional development of ecosystems; cooperation, competition, and predation within and between species; and patterns of biodiversity and its effect on ecosystem processes. Ecology has practical applications in fields such as conservation biology, wetland management, natural resource m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heinz Ellenberg
Heinz Ellenberg (1 August 1913 in Harburg (Elbe) – 2 May 1997 in Göttingen) was a German biologist, botanist and ecologist. Ellenberg was an advocate of viewing ecological systems through holistic means. He developed 9–point scales for rating European plant preferences for light, temperature, continentality (geographic region), nutrients, soil moisture, pH, and salinity. Life Ellenberg's father (a school teacher) died during World War I in 1914. From 1920 to 1932 Ellenberg studied in Hanover, where his interest in local flora and fauna was established, and where he came in contact with Reinhold Tüxen. In 1932 he moved to Montpellier, where he started his studies of ecology under the direction of Swiss ecologist Josias Braun-Blanquet. Later he studied botany, zoology, chemistry and geology in Heidelberg, Hanover and Göttingen, where he obtained a doctorate in Biology in 1938 in Göttingen under Franz Firbas. After completing his doctorate he worked at the centra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecological Niche
In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of Resource (biology), resources and competitors (for example, by growing when resources are abundant, and when predators, parasites and pathogens are scarce) and how it in turn alters those same factors (for example, limiting access to resources by other organisms, acting as a food source for predators and a consumer of prey). "The type and number of variables comprising the dimensions of an environmental niche vary from one species to another [and] the relative importance of particular environmental variables for a species may vary according to the geographic and biotic contexts". See also Chapter 2: Concepts of niches, pp. 7 ''ff'' A Grinnellian niche is determined by the habitat in which a species lives and its accompanying Behavioral ecology, behavioral adaptations. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Environmental Gradient
An environmental gradient, or climate gradient, is a change in Abiotic component, abiotic (non-living) factors through space (or time). Environmental gradients can be related to factors such as altitude, depth, temperature, soil humidity and precipitation. Often times, a multitude of Biotic component, biotic (living) factors are closely related to these gradients; as a result of a change in an environmental gradient, factors such as Abundance (ecology), species abundance, population density, Morphology (biology), morphology, Primary production, primary productivity, predation, and local adaptation may be impacted. Abiotic influence The species distribution along environmental gradients has been studied intensively due to large databases of species presence data (e.g. Global Biodiversity Information Facility, GBIF). The abiotic factors that environmental gradients consist of can have a direct ramifications on organismal survival. Generally, organismal distribution is tied t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Moisture
Soil moisture is the water content of the soil. It can be expressed in terms of volume or weight. Soil moisture measurement can be based on ''in situ'' probes (e.g., capacitance probes, neutron probes) or remote sensing methods. Water that enters a field is removed from a field by Surface runoff, runoff, drainage, evaporation or transpiration. Runoff is the water that flows on the surface to the edge of the field; drainage is the water that flows through the soil downward or toward the edge of the field underground; evaporative water loss from a field is that part of the water that evaporates into the atmosphere directly from the field's surface; transpiration is the loss of water from the field by its evaporation from the plant itself. Water affects soil formation, soil structure, structure, stability and erosion but is of primary concern with respect to Plant development, plant growth. Water is essential to plants for four reasons: # It constitutes 80–95% of the plant's proto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Salinity
Soil salinity is the salt (chemistry), salt content in the soil; the process of increasing the salt content is known as salinization (also called salination in American and British English spelling differences, American English). Salts occur naturally within soils and water. Salinization 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 Sodium_chloride#Road_salt, road salt. Natural occurrence Salt (chemistry), Salts are a natural component in soils and water. The ions responsible for salinization are: Sodium, Na+, Potassium, K+, Calcium, Ca2+, Magnesium, Mg2+ and Chlorine, Cl−. Over long periods of time, as soil minerals weathering, 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 precipitatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elias Landolt
Elias Landolt (1926–2013) was a Swiss geobotanist, known for his publications on Switzerland's native flora and Lemnoideae (popularly called duckweeds or water lenses). Life and career Landolt grew up in the Zürich district Enge. He was the eldest son of the lawyer, politician and later Zürich's mayor Emil Landolt and the great-grandson of his namesake Elias Landolt, a forest scientist. At ETH Zurich (ETHZ), Elias Landolt (the younger) studied natural science from 1945 to 1949 and received his doctorate there in 1953 under the professors Ernst Gäumann and Walo Koch with a dissertation on ''Ranunculus montanus'' (mountain buttercup). From 1953 to 1955, he was a postdoc in California, first at the Carnegie Institution for Science, Department of Plant Biology, Stanford, and then at Caltech in Pasadena. Returning to Zürich in 1955, Landolt joined the academic staff of ETHZ, where he worked until his retirement. In 1957 he completed his habilitation thesis ''Physiologische ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Statistical Significance
In statistical hypothesis testing, a result has statistical significance when a result at least as "extreme" would be very infrequent if the null hypothesis were true. More precisely, a study's defined significance level, denoted by \alpha, is the probability of the study rejecting the null hypothesis, given that the null hypothesis is true; and the p-value, ''p''-value of a result, ''p'', is the probability of obtaining a result at least as extreme, given that the null hypothesis is true. The result is said to be ''statistically significant'', by the standards of the study, when p \le \alpha. The significance level for a study is chosen before data collection, and is typically set to 5% or much lower—depending on the field of study. In any experiment or Observational study, observation that involves drawing a Sampling (statistics), sample from a Statistical population, population, there is always the possibility that an observed effect would have occurred due to sampling error al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permutation
In mathematics, a permutation of a set can mean one of two different things: * an arrangement of its members in a sequence or linear order, or * the act or process of changing the linear order of an ordered set. An example of the first meaning is the six permutations (orderings) of the set : written as tuples, they are (1, 2, 3), (1, 3, 2), (2, 1, 3), (2, 3, 1), (3, 1, 2), and (3, 2, 1). Anagrams of a word whose letters are all different are also permutations: the letters are already ordered in the original word, and the anagram reorders them. The study of permutations of finite sets is an important topic in combinatorics and group theory. Permutations are used in almost every branch of mathematics and in many other fields of science. In computer science, they are used for analyzing sorting algorithms; in quantum physics, for describing states of particles; and in biology, for describing RNA sequences. The number of permutations of distinct objects is factorial, us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Measurement Of Biodiversity
A variety of objective means exist to empirically measure biodiversity. Each measure relates to a particular use of the data, and is likely to be associated with the variety of genes. Biodiversity is commonly measured in terms of taxonomic richness of a geographic area over a time interval. In order to calculate biodiversity, species evenness, species richness, and species diversity are to be obtained first. ''Species evenness'' is the relative number of individuals of each species in a given area. ''Species richness'' is the number of species present in a given area. ''Species diversity'' is the relationship between species evenness and species richness. There are many ways to measure biodiversity within a given ecosystem. However, the two most popular are Shannon-Weaver diversity index, commonly referred to as Shannon diversity index, and the other is Simpsons diversity index. Although many scientists prefer to use Shannon's diversity index simply because it takes into account sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
