Edge effects

In ecology, edge effects are changes in population or community structures that occur at the boundary of two or more habitats.[1] Areas with small habitat fragments exhibit especially pronounced edge effects that may extend throughout the range. As the edge effects increase, the boundary habitat allows for greater biodiversity.

Edge Effect
Edges arise where two habitat types come into contact as here in Pennsylvania, United States.

Types

  • Inherent – Natural features stabilize the border location.
  • Induced – Transient natural disturbances (e.g., fire or flood) or human related activities, subject borders to successional changes over time.
  • Narrow – One habitat abruptly ends and another begins (e.g., an agricultural field.)
  • Wide (ecotone) – A large distance separates the borders of two clearly and purely definable habitats based upon their physical conditions and vegetation, and in between there exists a large transition region.
  • Convoluted – The border is non-linear.
  • Perforated – The border has gaps that host other habitats.

Height can create borders between patches as well.[2]

Biodiversity

Environmental conditions enable certain species of plants and animals to colonize habitat borders. Plants that colonize tend to be shade-intolerant and tolerant of dry conditions, such as shrubs and vines. Animals that colonize tend to be those that require two or more habitats, such as white-tailed and mule deer, elk, cottontail rabbits, blue jays, and robins.[3] Some animals travel between habitats, while edge species are restricted to edges. Larger patches include more individuals and therefore have increased biodiversity. The width of the patch also influences diversity: an edge patch must be more pronounced than just a stark border in order to develop gradients of edge effects.

Animals traveling between communities can create travel lanes along borders, which in turn increases light reaching plants along the lanes and promotes primary production. As more light reaches the plants, greater numbers and sizes can thrive. Increased primary production can increase numbers of herbivorous insects, followed by nesting birds and so on up the trophic levels.

In the case of wide and/or overgrown borders, some species can become restricted to one side of the border despite having the ability to inhabit the other. Sometimes, the edge effects result in abiotic and biotic conditions which diminish natural variation and threaten the original ecosystem. Detrimental edge effects are also seen in physical and chemical conditions of border species. For instance, fertilizer from an agricultural field could invade a bordering forest and contaminate the habitat. The three factors affecting edges can be summarized:

  • Abiotic effect—Changes in the environmental conditions that result from the proximity to a structurally dissimilar matrix
  • Direct biological effects—Changes in species abundance and distribution caused directly by physical conditions near the edge
  • Indirect biological effects which involve changes in species interactions such as predation, brood parasitism, competition, herbivory, and biotic pollination and seed dispersal[4]

Human effects

Human activity creates edges through development and agriculture. Often, the changes are detrimental to both the size of the habitat and to species. Examples of human impacts include:

Examples

When edges divide any natural 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. In 1971, Odum wrote, '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.'. In a forest where the adjacent land has been cut, creating an open/forest boundary, sunlight and wind penetrate to a much greater extent, drying out the interior of the forest close to the edge and encouraging growth of opportunistic species there. Air temperature, vapor pressure deficit, soil moisture, light intensity and levels of photosynthetically active radiation (PAR) all change at edges.

Amazon rainforest

One study estimated that the amount of Amazon Basin area modified by edge effects exceeded the area that had been cleared.[5] "In studies of Amazon forest fragments, micro-climate effects were evident up to 100m (330ft.) into the forest interior."[6] The smaller the fragment, the more susceptible it is to fires spreading from nearby cultivated fields. Forest fires are more common close to edges due to increased light availability that leads to increased desiccation and increased understory growth. Increased understory biomass provides fuel that allows pasture fires to spread into the forests. Increased fire frequency since the 1990s is among the edge effects that are slowly transforming Amazonian forests. The changes in temperature, humidity and light levels promote invasion of non-forest species, including invasive species. The overall effect of these fragment processes is that all forest fragments tend to lose native biodiversity depending on fragment size and shape, isolation from other forest areas, and the forest matrix.[6]

North America

The amount of forest edge is orders of magnitude greater now in the United States than when the Europeans first began settling North America. Some species have benefited from this fact, for example, the brown-headed cowbird, which is a brood parasite that lays its eggs in the nests of songbirds nesting in forest near the forest boundary. Another example of a species benefiting from the proliferation of forest edge is poison ivy.

Conversely, Dragonflies eat mosquitoes, but have more trouble than mosquitoes surviving around the edges of human habitation. Thus, trails and hiking areas near human settlements often have more mosquitoes than do deep forest habitats. Grasses, huckleberries, flowering currants and shade-intolerant trees such as the Douglas-fir all thrive in edge habitats.

In the case of developed lands juxtaposed to wild lands, problems with invasive exotics often result. Species such as kudzu, Japanese honeysuckle and multiflora rose have damaged 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 found only on the edges of forested areas.

Effects on succession

Edge effects also apply to succession, when vegetation spreads rather than losing to competitors. Different species are suited either to the edges or to central sections of the habitat, resulting in a varied distribution. Edges also vary with orientation: edges on the north or south receive less or more sun than the opposite side (depending on hemisphere and convex or concave relief), producing varying vegetation patterns.

Other usage

The phenomenon of increased variety of plants as well as animals at the community junction (ecotone) 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 in data that are caused by the position of the wells on a screening plate rather than a biological effect.

The edge effect in scanning electron microscopy is the phenomenon in which the number of secondary and/or backscattered electrons that escape the sample and reach the detector is higher at an edge than at a surface. The interaction volume spreads far below the surface, but secondary electrons can only escape when close to the surface (generally about 10 nm, although this depends on the material). However, when the electron beam impacts an area close to the edge, electrons that are generated below an impact point that is close to an edge but that is far below the surface may be able to escape through the vertical surface instead.

See also

References

  1. ^ Levin, Simon A. (2009). The Princeton Guide to Ecology. Princeton University Press. p. 780.
  2. ^ Smith, T.M.; Smith, R.L. (2009). "Elements of Ecology": 391–411.
  3. ^ "Ecotone". 2011.
  4. ^ Murcia, C. (1995). "Edge effects in fragmented forests:implications for conservation" (PDF). Tree. 20 (2): 58–62. doi:10.1016/S0169-5347(00)88977-6. PMID 21236953.
  5. ^ Skole, D. L.; C. Tucker (1994). "Tropical deforestation and habitat loss fragmentation in the Amazon: satellite data from 1978-1988". Science. 260 (5116): 1905–1910. doi:10.1126/science.260.5116.1905. hdl:10535/3304. PMID 17836720.
  6. ^ a b Corlett, Richard, T; Richard B. Primack (2011). Tropical Rain Forests an Ecological and Biogeographical Comparison (Second ed.). John Wiley & Sons Ltd, The atrium, Southern Fate, Chichester, West Sussex, PO19 8SQ: Wiley-Blackwell. pp. 266–267. ISBN 978-1-4443-3254-4.

External links

Ameagle, West Virginia

Ameagle is an unincorporated community in Raleigh County, West Virginia, United States. Ameagle is 6 miles (9.7 km) east-southeast of Whitesville. The community was named for the American Eagle Colliery.

Bacterivore

Bacterivores are free-living, generally heterotrophic organisms, exclusively microscopic, which obtain energy and nutrients primarily or entirely from the consumption of bacteria. Many species of amoeba are bacterivores, as well as other types of protozoans. Commonly, all species of bacteria will be prey, but spores of some species, such as Clostridium perfringens, will never be prey, because of their cellular attributes.

Biological Dynamics of Forest Fragments Project

The Biological Dynamics of Forest Fragments Project (BDFFP), originally called the Minimum Critical Size of Ecosystems Project is a large-scale ecological experiment looking at the effects of habitat fragmentation on tropical rainforest; it is one of the most expensive biology experiments ever run. The experiment, which was established in 1979 is located near Manaus, in the Brazilian Amazon. The project is jointly managed by the Smithsonian Institution and the Brazilian Institute for Research in the Amazon (INPA).

The project was initiated in 1979 by Thomas Lovejoy to investigate the SLOSS debate. Initially named the Minimum Critical Size of Ecosystems Project, the project created forest fragments of sizes 1 hectare (2 acres), 10 hectares (25 acres), and 100 hectares (247 acres). Data were collected prior to the creation of the fragments and studies of the effects of fragmentation now exceed 25 years.

As of October 2010 562 publications and 143 graduate dissertations and theses had emerged from the project.

Byrrhidae

Byrrhidae, the pill beetles, is a family of beetles in the superfamily Byrrhoidea. These beetles are common in the forests of the Northern Hemisphere. They feed mainly on moss. Populations increase after wildfires.There are about 450 species in this family.Genera include:

Amphycyrta

Arctobyrrhus

Byrrhus

Chaetophora

Curimopsis

Cytilus

Eusomalia

Exomella

Lioligus

Lioon

Listemus

Morychus

Porcinolus

Sierraclava

Simplocaria

Caldor, California

For the United States-based retail store, see Caldor.

Caldor is an unincorporated community in El Dorado County, California. It lies at an elevation of 4442 feet (1354 m). Caldor was linked to Diamond Springs by the Diamond and Caldor Railway. The community was named for the California Door Company.

Circular convolution

The circular convolution, also known as cyclic convolution, of two aperiodic functions (i.e. Schwartz functions) occurs when one of them is convolved in the normal way with a periodic summation of the other function. That situation arises in the context of the circular convolution theorem. The identical operation can also be expressed in terms of the periodic summations of both functions, if the infinite integration interval is reduced to just one period.  That situation arises in the context of the discrete-time Fourier transform (DTFT) and is also called periodic convolution.  In particular, the DTFT of the product of two discrete sequences is the periodic convolution of the DTFTs of the individual sequences.

Let x be a function with a well-defined periodic summation, xT, where:

If h is any other function for which the convolution xTh exists, then the convolution xTh is periodic and identical to:

where to is an arbitrary parameter and hT is a periodic summation of h.

The second integral is called the periodic convolution of functions xT and hT and is sometimes normalized by 1/T. When xT is expressed as the periodic summation of another function, x, the same operation may also be referred to as a circular convolution of functions h and x.

Copiotroph

A copiotroph is an organism found in environments rich in nutrients, particularly carbon. They are the opposite to oligotrophs, which survive in much lower carbon concentrations.

Copiotrophic organisms tend to grow in high organic substrate conditions. For example, copiotrophic organisms grow in Sewage lagoons. They grow in organic substrate conditions up to 100x higher than oligotrophs.

Decomposer

Decomposers are organisms that break down dead or decaying organisms, and in doing so, they carry out the natural process of decomposition. Like herbivores and predators, decomposers are heterotrophic, meaning that they use organic substrates to get their energy, carbon and nutrients for growth and development. While the terms decomposer and detritivore are often interchangeably used, detritivores must ingest and digest dead matter via internal processes while decomposers can directly absorb nutrients through chemical and biological processes hence breaking down matter without ingesting it. Thus, invertebrates such as earthworms, woodlice, and sea cucumbers are technically detritivores, not decomposers, since they must ingest nutrients and are unable to absorb them externally.

Dominance (ecology)

Ecological dominance is the degree to which a taxon is more numerous than its competitors in an ecological community, or makes up more of the biomass.

Most ecological communities are defined by their dominant species.

In many examples of wet woodland in western Europe, the dominant tree is alder (Alnus glutinosa).

In temperate bogs, the dominant vegetation is usually species of Sphagnum moss.

Tidal swamps in the tropics are usually dominated by species of mangrove (Rhizophoraceae)

Some sea floor communities are dominated by brittle stars.

Exposed rocky shorelines are dominated by sessile organisms such as barnacles and limpets.

Feeding frenzy

In ecology, a feeding frenzy occurs when predators are overwhelmed by the amount of prey available. For example, a large school of fish can cause nearby sharks, such as the lemon shark, to enter into a feeding frenzy. This can cause the sharks to go wild, biting anything that moves, including each other or anything else within biting range. Another functional explanation for feeding frenzy is competition amongst predators. This term is most often used when referring to sharks or piranhas. It has also been used as a term within journalism.

Gustav Eberhard

Gustav E. Eberhard (10 August 1867 – 3 January 1940) German astrophysicist.

Eberhard published numerous investigations on spectroscopy and on photographic photogrametry.The photographic Eberhard effect (belonging to the edge effects family) is named after him and was published in 1926.

Habitat fragmentation

Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological processes that slowly alter the layout of the physical environment

(suspected of being one of the major causes of speciation),and human activity such as land conversion, which can alter the environment much faster and causes the extinction of many species.

Intraguild predation

Intraguild predation, or IGP, is the killing and sometimes eating of potential competitors. This interaction represents a combination of predation and competition, because both species rely on the same prey resources and also benefit from preying upon one another. Intraguild predation is common in nature and can be asymmetrical, in which one species feeds upon the other, or symmetrical, in which both species prey upon each other. Because the dominant intraguild predator gains the dual benefits of feeding and eliminating a potential competitor, IGP interactions can have considerable effects on the structure of ecological communities.

Katsunori Wakabayashi

Katsunori Wakabayashi (若林 克法, Wakabayashi Katsunori) is a physicist at the International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Japan. He is an authority and leading researcher in nanotechnology in the area of energy states of single wall carbon nanotubes (SWCN).

His research is notable for the edge effects of the nanographene materials, which is a part of the single layer graphene. He obtained his Ph.D in 2000 from University of Tsukuba in Japan. From 2000 to 2009 he was an Assistant Professor at Department of Quantum Matter in Hiroshima University, Japan. From 2009, he is an Independent Scientist at International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS) in Tsukuba, Japan. Beside the above primary research position, he was a visiting scholar at ETH-Zurich, Switzerland from 2003 to 2005, also had a concurrent position as PRESTO researcher in Japan Science and Technology Agency (JST).

Mackie line

In photographic science, a Mackie line is an adjacency or border effect created during development, at the border between areas of high and low densities.

During developing, developer remains relatively fresh in an area of low density as less developing takes place, and consequently, developer oxidation product concentration remains relatively low. At the border between high and low density areas the relatively fresh developer diffuses laterally into the high density area and causes there a continuation of development. The result is an increased border density of the high density area.The Mackie line effect belongs to the family of edge effects. Edge effects include: Gelatin-, Ross-, Fringe-, Eberhard- and Kostinsky effects.

Mesotrophic soil

Mesotrophic soils are soils with a moderate inherent fertility. An indicator of soil fertility is its base status, which is expressed as a ratio relating the major nutrient cations (calcium, magnesium, potassium and sodium) found there to the soil's clay percentage. This is commonly expressed in hundredths of a mole of cations per kilogram of clay, i.e. cmol (+) kg−1 clay.

Organotroph

An organotroph is an organism that obtains hydrogen or electrons from organic substrates. This term is used in microbiology to classify and describe organisms based on how they obtain electrons for their respiration processes. Some organotrophs such as animals and many bacteria, are also heterotrophs. Organotrophs can be either anaerobic or aerobic.

Antonym: Lithotroph, Adjective: Organotrophic.

Recruitment (biology)

In biology, especially marine biology, recruitment occurs when a juvenile organism joins a population, whether by birth or immigration, usually at a stage whereby the organisms are settled and able to be detected by an observer.There are two types of recruitment: closed and open.In the study of fisheries, recruitment is "the number of fish surviving to enter the fishery or to some life history stage such as settlement or maturity".

Woodland edge

A woodland edge or forest edge is the transition zone (ecotone) from an area of woodland or forest to fields or other open spaces. Certain species of plants and animals are adapted to the forest edge, and these species are often more familiar to humans than species only found deeper within forests. A classic example of a forest edge species is the white-tailed deer in North America.

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