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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Edge effects | 2/2 | https://en.wikipedia.org/wiki/Edge_effects | reference | science, encyclopedia | 2026-05-05T07:18:03.896436+00:00 | kb-cron |
Introduction of invasives/exotics Agriculture Higher severity and frequency of fires Companion animals (pets) acting as predators and competitors Trails Pollution, erosion Loss of foraging habitats Habitat fragmentation Deforestation and land use
== 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. "In studies of Amazon forest fragments, micro-climate effects were evident up to 100m (330ft.) into the forest interior." 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.
=== 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 lighter 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.
== Alternative definitions of edge effect == 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 == Ecotone Habitat fragmentation Landscape ecology Ruderal species Spatial ecology Woodland edge Deforestation
== References ==
== External links ==