Limiting factors are environmental influences that prevent individual organisms, their populations, or multi-species communities from attaining as high a rate of productivity as they could potentially achieve under optimal conditions. Limiting factors can be a single environmental influence, or a complex of related ones. Oftentimes, limiting factors are divided into two categories: density-dependent and density-independent. Density-dependent factors that affect a population relate to population density, such as predation and the number of organisms per a given area. Density-independent factors are environmental factors affecting a population, such as temperature and oxygen supply.

Numerous environmental factors must be suitable if organisms are to persist and flourish. For example, temperature cannot be too hot or too cold, and nutrients must be available in appropriate amounts. The minimal requirement for a metabolically essential environmental factor is the least availability that will sustain organisms and ecological processes. On the other hand...