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Ideas: link to landscape ecology.

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= Patch dynamics = From Wikipedia, the free encyclopedia

This article is about ecosystems. For the use of the term in physics, see Patch dynamics (physics). Patch dynamics is a conceptual approach to ecosystem and habitat analysis that emphasizes the heterogeneity, or landscape diversity and dissimilarity, within a system. As such, it posits that each area of an ecosystem consists of a mosaic of small sub-ecosystems.[1] Not to be confused with gap dynamics.

Contents
[hide]
 * 1History
 * 2Mosaics and connectivity
 * 3Conservation efforts
 * 4Patch Analysis
 * 5See also
 * 6References

History [edit source | edit]
Historically, due to the short time scale of human observation, mosaic landscapes were perceived to be static patterns of human population mosaics.[2] This focus centered around the idea that one could understand the status of a particular population, community, or ecosystem by studying a particular patch within a mosaic. However, this perception ignored the conditions that interact with and connect patches. In 1979, F. Herbert Bormann and Gene Likens coined the phrase "shifting mosaic" to describe the theory that landscapes change and fluctuate and are, in fact, dynamic.

Simon Paine and Robert Levin's 1981 paper titled "Intertidal Landscapes: Disturbance and The Dynamics of Pattern" was one of the first to significantly highlight the importance of disturbance in maintaining patch diversity. Their definition of patches refers to the location of mussels, but provides evidence that different local disturbance regimes can drive different community assemblages, thus promoting diversity.

Stewart Pickett and Peter White co-wrote "The Ecology of Natural Disturbance and Patch Dynamics" and published it in 1985. This book highlighted that disturbance is a natural feature in many landscapes. In addition, the two authors called attention to the fact that many species have evolved traits and strategies to survive and even thrive in disturbed environments.

Mosaics and connectivity [edit source | edit]
A habitat patch is any discrete area with a definite shape, spatial and configuration used by a species for breeding or obtaining other resources (citation). Mosaics are the patterns within landscapes that are composed of smaller patches, such as individual forest stands, shrubland patches, farms, or towns . These two concepts, when applied together, can provide a functional understanding of the patch dynamics concept, as patch dynamics also refers to changes in the structure, function, and composition of individual patches, which can affect the rate of nutrient cycling[citation needed].

Patches are also linked, as, although physically separated from one another, migration can occur from patch to patch and this process maintains the population of some patches. Such migration is one possible mechanism by which some plant species spread, implying that ecological systems within landscapes are open, rather than closed and isolated. (Pickett, 2006) Agriculture, fire, logging, and reforestation can all contribute to this process of colonization and can effectively change the shape of the patch.

Conservation efforts [edit source | edit]
Diverse patches of habitat created by natural disturbance regimes are critical to the maintenance of biodiversity, and recognizing the patch dynamics within a system can be an important aspect of conservation efforts when attempting to preserve certain ecological processes and/or regional biodiversity. Understanding how a patch changes and predicting how external forces may affect the patch, then, become key features when attempting to conserve certain aspects of patch-mosaic landscapes and the ecological roles they fulfill[citation needed]. These externalities include natural effects, such as land use, disturbance, restoration, and succession, as well as the effects of human activities.

Patch analysis [edit source | edit]
When discussing patch dynamics, scale is vital, as different processes occur at play at different sizes. When measuring a patch, size, shape, and the perimeter-to-area ratio are all important metrics. Furthermore, the number of patches, patch diversity, heterogeneity, and gaps are mosaic measurements used to assess landscape structure. Spatially hierarchical approaches attempt to account for these different spatial scales that work together to produce the observed landscape patterns. Patch-mosaic models, then, are spatial analysis tools that allow researchers to understand generalized spatial heterogeneity and landscape structure in order to design effective experiments and they are often used for management decisions, but do so under the assumption that there are distinct boundaries between patches and homogeneous environmental variables within patches.

See also [edit source | edit]

 * Conservation biology
 * Edge effect
 * Forest dynamics
 * Habitat conservation
 * Habitat corridor
 * Habitat fragmentation
 * Island biogeography
 * Landscape ecology
 * Spatial ecology