Edge effect
The edge effect in ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...

 is the effect of the juxtaposition or placing side by side of contrasting environments
Natural environment
The natural environment encompasses all living and non-living things occurring naturally on Earth or some region thereof. It is an environment that encompasses the interaction of all living species....

 on an ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....


This term is commonly used in conjunction with the boundary between natural habitats
Habitat (ecology)
A habitat is an ecological or environmental area that is inhabited by a particular species of animal, plant or other type of organism...

, especially forests, and disturbed or developed land. Edge effects are especially pronounced in small habitat fragments
Habitat fragmentation
Habitat fragmentation as the name implies, describes the emergence of discontinuities in an organism's preferred environment , causing population fragmentation...

 where they may extend throughout the patch. Increasing edge effects allows more habitat structure to increase biodiversity within the area.


When edges are expanded into any natural
Nature, in the broadest sense, is equivalent to the natural world, physical world, or material world. "Nature" refers to the phenomena of the physical world, and also to life in general...

 ecosystem, and the area outside the boundary is a disturbed or unnatural system, the natural ecosystem can be seriously affected for some distance in from the edge. "Eugene P. Odum, professor of zoology, 1971: 'The tendency for increased variety and diversity at community junctions is known as the edge effect.... It is common knowledge that the density of songbirds is greater on estates, campuses and similar settings...as compared with tracts of uniform forest.'" quoted in William T. Vollmann, "Another Roadside Attraction," New York Times Book Review, at 9, February 21, 2010. In the case of a forest where the adjacent land has been cut, creating an open/forest boundary, sunlight
Sunlight, in the broad sense, is the total frequency spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the Earth's atmosphere, and solar radiation is obvious as daylight when the Sun is above the horizon.When the direct solar radiation is not blocked...

 and wind
Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space...

 penetrate to a much greater extent, drying out the interior of the forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...

 close to the edge and encouraging growth of opportunistic species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 at the edge. Air temperature, vapor pressure deficit, soil moisture
Water content
Water content or moisture content is the quantity of water contained in a material, such as soil , rock, ceramics, fruit, or wood. Water content is used in a wide range of scientific and technical areas, and is expressed as a ratio, which can range from 0 to the value of the materials' porosity at...

, light intensity and levels of photosynthetically active radiation
Photosynthetically active radiation
Photosynthetically active radiation, often abbreviated PAR, designates the spectral range of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis. This spectral region corresponds more or less with the range of light visible to...

 (PAR) all change at edges.

Amazon Rainforest

It has been estimated that the amount of Amazonian
Amazon Basin
The Amazon Basin is the part of South America drained by the Amazon River and its tributaries that drains an area of about , or roughly 40 percent of South America. The basin is located in the countries of Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, and Venezuela...

 area modified by edge effects exceeded the area that had been cleared. Forest fires are more common close to edges as a consequence of increased desiccation at edges and increased understory
Understory is the term for the area of a forest which grows at the lowest height level below the forest canopy. Plants in the understory consist of a mixture of seedlings and saplings of canopy trees together with understory shrubs and herbs...

 growth present because of increased light availability. Increased understory biomass
Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....

 provides fuel that allows pasture fires to spread into the forests. Increased fire frequency since the 1990s are among the edge effects which are slowly transforming Amazonian forests.

North America

The amount of forest edge is also orders of magnitude greater now in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 than when the European
European ethnic groups
The ethnic groups in Europe are the various ethnic groups that reside in the nations of Europe. European ethnology is the field of anthropology focusing on Europe....

s first began settling North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. Some species have benefited from this fact, for example the Brown-headed Cowbird
Brown-headed Cowbird
The Brown-headed Cowbird is a small brood parasitic icterid of temperate to subtropical North America. They are permanent residents in the southern parts of their range; northern birds migrate to the southern United States and Mexico in winter, returning to their summer habitat around March or...

, which is a brood parasite
Brood parasite
Brood parasites are organisms that use the strategy of brood parasitism, a kind of kleptoparasitism found among birds, fish or insects, involving the manipulation and use of host individuals either of the same or different species to raise the young of the brood-parasite...

 that lays its eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

 in the nest
Bird nest
A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American Robin or Eurasian Blackbird, or the elaborately woven hanging nest of the...

s of songbird
A songbird is a bird belonging to the suborder Passeri of the perching birds . Another name that is sometimes seen as scientific or vernacular name is Oscines, from Latin oscen, "a songbird"...

s nesting in forest near the forest boundary. Thus, the more edge in relation to the forest interior, the more cowbirds and the fewer songbirds as a result.

Another example of a species benefiting from the proliferation of forest edge is poison ivy. Dragonflies
A dragonfly is a winged insect belonging to the order Odonata, the suborder Epiprocta or, in the strict sense, the infraorder Anisoptera . It is characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body...

 eat mosquito
Mosquitoes are members of a family of nematocerid flies: the Culicidae . The word Mosquito is from the Spanish and Portuguese for little fly...

es, but have a more difficult time than mosquitoes do at surviving around the edges of human habitation. Thus, trails and hiking areas near human settlements often have more mosquitoes than do deep forest habitats. Grass
Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...

es, huckleberries
Huckleberry is a common name used in North America for several species of plants in two closely related genera in the family Ericaceae:* Vaccinium* GaylussaciaHuckleberry may also refer to:-Plants:...

, flowering currant
Ribes sanguineum
Ribes sanguineum is a species of currant native to western coastal North America from central British Columbia south to central California.-Description:...

s and shade-intolerant trees such as the Douglas-fir
Douglas-fir is one of the English common names for evergreen coniferous trees of the genus Pseudotsuga in the family Pinaceae. Other common names include Douglas tree, and Oregon pine. There are five species, two in western North America, one in Mexico, and two in eastern Asia...

 all do well in edge habitats.

In the case of developed lands juxtaposed to wild lands, problems with invasive exotics often result. Species such as Kudzu
Kudzu is a plant in the genus Pueraria in the pea family Fabaceae, subfamily Faboideae. It is a climbing, coiling, and trailing vine native to southern Japan and southeast China. Its name comes from the Japanese name for the plant, . It is a weed that climbs over trees or shrubs and grows so...

, Japanese Honeysuckle
Japanese Honeysuckle
The Japanese Honeysuckle is a species of honeysuckle native to eastern Asia including China , Japan, and Korea. It is a twining vine able to climb up to high or more in trees, with opposite, simple oval leaves long and broad...

 and Multiflora Rose
Multiflora Rose
Rosa multiflora is a species of rose native to eastern Asia, in China, Japan and Korea....

 have done damage to localized natural ecosystems. Beneficially, the open spots and edges provide places for species that thrive where there is more light and vegetation that is close to the ground. Deer and elk benefit particularly as their principal diet is that of grass and shrubs which are only found on the edges of forested areas.

Effects on succession

Edge effects also apply to succession
Ecological succession
Ecological succession, is the phenomenon or process by which a community progressively transforms itself until a stable community is formed. It is a fundamental concept in ecology, and refers to more or less predictable and orderly changes in the composition or structure of an ecological community...

, that is where vegetation is spreading outwards rather than being encroached upon. Here different species will be more suited to the edges or central sections of the vegetation, resulting in a varied distribution. Edges themselves also vary with orientation - for example edges on the north or south will receive less or more sun than the opposite side (depending on hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...

), resulting in differing vegetation patterns.

Other usage

The phenomenon of increased variety of plants as well as animals at the community junction (ecotone
An ecotone is a transition area between two biomes but different patches of the landscape, such as forest and grassland. It may be narrow or wide, and it may be local or regional...

) is also called the Edge effect and is essentially due to a locally broader range of suitable environmental conditions or ecological niches.

Edge effects in biological assays refer to artifacts appearing in data which are caused by the position of the wells on a screening plate rather than a biological effect.

Edge effect in scanning electron microscopy is a phenomenon where a larger number of secondary and/or backscattered electrons are generated on a surface that is not purely horizontal. As the angle relative to horizontal increases, so does the surface area hit by the beam of electrons and therefore the strength of the detected signal increases.

See also

  • Ecotone
    An ecotone is a transition area between two biomes but different patches of the landscape, such as forest and grassland. It may be narrow or wide, and it may be local or regional...

  • Habitat fragmentation
    Habitat fragmentation
    Habitat fragmentation as the name implies, describes the emergence of discontinuities in an organism's preferred environment , causing population fragmentation...

  • Landscape ecology
    Landscape ecology
    Landscape ecology is the science of studying and improving relationships between urban development and ecological processes in the environment and particular ecosystems...

  • Ruderal species
    Ruderal species
    A ruderal species is a plant species that is first to colonize disturbed lands. The disturbance may be natural , or due to human influence – constructional , or agricultural .Ruderal species typically dominate the disturbed area...

  • Spatial ecology
    Spatial ecology
    Spatial ecology is a specialization of ecologyand geography that is concerned with the identification of spatial patterns and their relationships to ecological events. In spatial ecology, ecological events can be explained through the detection of patterns at a given spatial scale; local,...

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