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Population density is the number of people per unit of area, usually transcribed as "per square kilometer" or square mile, and which may include or exclude, for example, areas of water or glaciers. Commonly this is calculated for a county, city, country, another territory or the entire world. The world's population is around 8,000,000,000 [3 ...
Definition and concepts. Plant density is defined as the number of plants present per unit area of ground. In nature, plant densities can be especially high when seeds present in a seed bank germinate after winter, or in a forest understory after a tree fall opens a gap in the canopy. Due to competition for light, nutrients and water ...
Species richness is the number of different species represented in an ecological community, landscape or region. [1] Species richness is simply a count of species, and it does not take into account the abundances of the species or their relative abundance distributions. Species richness is sometimes considered synonymous with species diversity ...
The Demography of the World Population from 1950 to 2100. Data source: United Nations — World Population Prospects 2017. Demography (from Ancient Greek δῆμος (dêmos) 'people, society' and -γραφία (-graphía) 'writing, drawing, description') [1] is the statistical study of human populations: their size, composition (e.g., ethnic group, age), and how they change through the ...
In biology, the range of a species is the geographical area within which that species can be found. Within that range, distribution is the general structure of the species population, while dispersion is the variation in its population density. Range is often described with the following qualities:
A population is defined as a group of interacting organisms of the same species. A demographic structure of a population is how populations are often quantified. The total number of individuals in a population is defined as a population size, and how dense these individuals are is defined as population density.
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]
Negative density-dependence, or density-dependent restriction, describes a situation in which population growth is curtailed by crowding, predators and competition. [citation needed] In cell biology, it describes the reduction in cell division. When a cell population reaches a certain density, the amount of required growth factors and nutrients ...