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In biology, agricultural science, physiology, and ecology, a limiting factor is one that controls a process, such as organism growth or species population size or distribution. The availability of food, predation pressure, or availability of shelter are examples of factors that could be limiting for a species population in a specific area. The concept is based upon Liebig's Law of the Minimum put forth by German geochemist, Justus von Liebig, in 1840. It can be easy to conceive how a limiting resource (say, food) controls a process (say, growth) by running low or running out. However, some biological and ecological processes are controlled by too much of a factor (such as heat) rather than too little. Or, processes may be controlled by complex interactions of factors (Shelford, 1952). Walter Taylor (1934) proposed the following broad, restatement of the law of the minimum:
- "The functioning of an organism is controlled or limited by that essential environmental factor or combination of factors present in the least favorable amount. The factors may not be continuously effective but only at some critical period during the year or perhaps only during some critical year in a climatic cycle."
Types
The most basic types of limiting factors for plants are physical barriers, sunlight, water, temperature and soil.
Plant nutrients
A limiting nutrient is a chemical (nutrient) necessary for plant growth, but available in a concentration insufficient to support continued growth. Once the limiting nutrient is exhausted, plant growth ceases. In the case of algae in an aquatic ecosystem, populations stop expanding. If a limiting nutrient is introduced to a population, growth will be promoted until limitation by that or another nutrient or some other limiting factor occurs. It is usually the case—although not always—that in marine ecosystems it is nitrogen, and in fresh water ecosystems it is phosphorus, that are limiting. When neither is limiting, eutrophication can result.
Although nitrogen (N) is limiting to production in most ecosystems, especially estuaries and coastal ecosystems, phosphorus (P) can also be a limiting nutrient in some coastal systems and most freshwater systems (Carpenter et al., 1998). It has been shown, though, that carbon (C), silica (Si), and iron (Fe) may also be limiting nutrients in marine ecosystems (Sundareshwar et al., 2003).
For example, in an aquarium, some limiting factors can be the size and the amount of dissolved carbon dioxide and oxygen is important, especially for the marine organisms. Other factors, such as lighting and the photosynthetic algae are significant as well.
References
- Carpenter S. R., N. F. Caraco, D. L. Correll, R. W. Howarth, A. N. Sharpley, and V. H. Smith. (1998). Nonpoint pollution of surface waters with phosphorus and nitrogen. Ecological Applications 8:559-568.
- Taylor, W. A. (1934). Significance of extreme or intermittant conditions in distribution of species and management of natural resources, with a restatement of Liebig's law of the minimum. Ecology, 15: 374-379.
- Shelford, V. E. (1952). Paired factors and master factors in environmental relations. Illinois Acad. Sci. Trans., 45: 155-160
- Sundareshwar P.V., J.T. Morris, E.K. Koepfler, and B. Fornwalt. (2003). Phosphorus limitation of coastal ecosystem processes. Science 299:563-565.
"Limiting factor"