||This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations. (January 2010)|
Patch dynamics is a conceptual approach to ecosystem and habitat analysis that emphasizes dynamics of heterogeneity within a system (i.e. that each area of an ecosystem is made up of a mosaic of small 'sub-ecosystems').
Diverse patches of habitat created by natural disturbance regimes are seen as critical to the maintenance of this diversity (ecology). A habitat patch is any discrete area with a definite shape, spatial and configuration used by a species for breeding or obtaining other resources. Mosaics are the patterns within landscapes that are composed of smaller elements, such as individual forest stands, shrubland patches, highways, farms, or towns.
Patches and mosaics
Historically, due to the short time scale of human observation, mosaic landscapes were perceived to be static|date=January 2010}patterns of human population mosaics}. This focus centered around the idea that the status of a particular population, community, or ecosystem could be understood by studying a particular patch within a mosaic. However, this perception ignored the conditions that interact with, and connect patches. In 1979, Bormann and Likens coined the phrase shifting mosaic to describe the theory that landscapes change and fluctuate, and are in fact dynamic. This is related to the battle of cells that occurs in a Petri dish.
Patch dynamics refers to the concept that landscapes are dynamic. There are three states that a patch can exist in: potential, active, and degraded. Patches in the potential state are transformed into active patches through colonization of the patch by dispersing species arriving from other active or degrading patches. Patches are transformed from the active state to the degraded state when the patch is abandoned, and patches change from degraded to potential through a process of recovery.
Logging, fire, farming, and reforestation can all contribute to the process of colonization, and can effectively change the shape of the patch. Patch dynamics also refers to changes in the structure, function, and composition of individual patches that can, for example, effect the rate of nutrient cycling.
Patches are also linked, although separated from other patches, migration occurs from one patch to another[vague]. This migration maintains the population of some patches, and can be the mechanism by which some plant species spread. This implies that ecological systems within landscapes are open, rather than closed and isolated. (Pickett, 2006)
Recognizing the patch dynamics within a system is needed for conservation (ecology) efforts to succeed. Successful conservation includes understanding how a patch changes and predicting how they will be affected by external forces. These externalities include natural effects, such as land use, disturbance, restoration, and succession, and the effects of human activities. In a sense, conservation is the active maintenance of patch dynamics (Pickett, 2006).
- Conservation biology
- Edge effect
- Habitat conservation
- Habitat corridor
- Habitat fragmentation
- Island biogeography
- Landscape ecology
- Spatial ecology
- Pickett, Steward T.A.; White, P.S. (1985). The Ecology of Natural Disturbance and Patch Dynamics. Academic Press. ISBN 0123960215.
- Forman, R.T.T. 1995. Land Mosaics: The Ecology of Landscapes and Regions. Cambridge University Press, Cambridge, UK.
- Groom, Martha J., Meffe, Gary K., Carroll, Ronald. 2006. Principles of Conservation Biology, Third Edition. Mosaics and Patch Dynamics by Steward T.A. Pickett