Search results
Results from the WOW.Com Content Network
Relative species abundance is a component of biodiversity and is a measure of how common or rare a species is relative to other species in a defined location or community. [1] Relative abundance is the percent composition of an organism of a particular kind relative to the total number of organisms in the area.
In ecology, local abundance is the relative representation of a species in a particular ecosystem. [1] It is usually measured as the number of individuals found per sample . The ratio of abundance of one species to one or multiple other species living in an ecosystem is referred to as relative species abundances . [ 1 ]
The Mean Species Abundance Index (MSA) calculates the trend in population size of a cross section of the species. It does this in line with the CBD 2010 indicator for species abundance. [10] The Biodiversity Intactness Index (BII) measures biodiversity change using abundance data on plants, fungi and animals worldwide.
The proportional abundance of the ith species in the jth subunit is |. These proportional abundances are weighted by the proportion of data that each subunit contributes to the dataset, p i j = m j / m {\displaystyle p_{ij}=m_{j}/m} , where m {\displaystyle m} is the total number of individuals in the dataset, and m j {\displaystyle m_{j}} is ...
Area-based counts, distance methods, and mark–recapture studies are the three general categories of methods for estimating abundance. Species evenness is combined with species richness , (the number of species in the community), in order to determine species diversity , which is an important measure of community structure.
Abundance (atom fraction) of the chemical elements in Earth's upper continental crust as a function of atomic number; [5] siderophiles shown in yellow. Graphs of abundance against atomic number can reveal patterns relating abundance to stellar nucleosynthesis and geochemistry.
The abundance of the chemical elements is a measure of the occurrences of the chemical elements relative to all other elements in a given environment. Abundance is measured in one of three ways: by mass fraction (in commercial contexts often called weight fraction), by mole fraction (fraction of atoms by numerical count, or sometimes fraction of molecules in gases), or by volume fraction.
The saprobic system is based on a survey of indicator organisms. For example, the abundance of Lymnaea stagnalis water snails and other organisms is estimated, and using a formula, the listed saprobic and tolerance values of the organisms allow the water quality grade — the saprobic index — to be computed.