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Encyclopedia > Habitat fragmentation

Habitat fragmentation is a process of environmental change important in evolution and conservation biology. As the name implies, it describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat). Habitat fragmentation can be caused by geological processes that slowly alter the layout of the physical environment or by human activity such as land conversion, which can alter the environment on a much faster time scale. The former is suspected of being one of the major causes of speciation. The latter is causative in extinctions of many species. This article does not cite any references or sources. ... This article is about evolution in biology. ... This article or section is in need of attention from an expert on the subject. ... Habitat (which is Latin for it inhabits) is the place where a particular species live and grow. ... Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history, and the processes that shape it. ... Charles Darwins first sketch of an evolutionary tree from his First Notebook on Transmutation of Species (1837) Speciation is the evolutionary process by which new biological species arise. ... The Dodo, shown here in illustration, is an often-cited[1] example of modern extinction. ...

Fragmentation and destruction of Great Ape habitat in Central Africa, from the GLOBIO and GRASP projects.

Habitat fragmentation is frequently caused by humans when native vegetation is cleared for human activities such as agriculture, rural development or urbanization. Habitats which were once continuous become divided into separate fragments. After intensive clearing, the separate fragments tend to be very small islands isolated from each other by crop land, pasture, pavement, or even barren land. The latter is often the result of slash and burn farming in tropical forests. In the wheatbelt of central western New South Wales, Australia 90% of the native vegetation has been cleared and over 99% of the Tallgrass prairie of North America has been cleared, resulting in extreme habitat fragmentation. Image File history File links Scenarios for the reduction and fragmentation of Great Ape Habitat in Central Africa 2002-2032. ... Image File history File links Scenarios for the reduction and fragmentation of Great Ape Habitat in Central Africa 2002-2032. ... Genera Subfamily Ponginae Pongo - Orangutans Gigantopithecus (extinct) Sivapithecus (extinct) Subfamily Homininae Gorilla - Gorillas Pan - Chimpanzees Homo - Humans Paranthropus (extinct) Australopithecus (extinct) Sahelanthropus (extinct) Ardipithecus (extinct) Kenyanthropus (extinct) Pierolapithecus (extinct) (tentative) The Hominids (Hominidae) are a biological family which includes humans, extinct species of humanlike creatures and the other great apes... Vegetation is a general term for the plant life of a region; it refers to the ground cover provided by plants, and is, by far, the most abundant biotic element of the biosphere. ... Subdivision is the act of dividing up land into smaller pieces that are easier to sell, usually via a plat. ... Look up continuum in Wiktionary, the free dictionary. ... Assarting in Finland in 1892 Slash and burn (a specific practice that may be part of shifting cultivation or swidden-fallow agriculture) is an agricultural procedure widely used in forested areas. ... Tropical and subtropical moist broadleaf forests, also known as tropical rain forests, are a tropical and subtropical biome. ... Capital Sydney Government Constitutional monarchy Governor Professor Marie Bashir Premier Morris Iemma (ALP) Federal representation  - House seats 50  - Senate seats 12 Gross State Product (2004-05)  - Product ($m)  $305,437 (1st)  - Product per capita  $45,153/person (4th) Population (End of March 2006)  - Population  6,817,100 (1st)  - Density  8. ... Prairie grasses The tallgrass prairie is an ecosystem native to central North America, with fire as its primary periodic disturbance. ... World map showing North America A satellite composite image of North America. ...


The term habitat fragmentation can be considered to include six discrete processes:

  • Reduction in the total area of the habitat
  • Increase in the amount of edge
  • Decrease in the amount of interior habitat
  • Isolation of one habitat fragment from other areas of habitat
  • Breaking up of one patch of habitat into several smaller patches
  • Decrease in the average size of each patch of habitat

Contents

An edge effect is the effect of the juxtaposition of contrasting environments on an ecosystem. ...

Habitat destruction

One of the major ways that habitat fragmentation affects biodiversity is due to reduction in the amount of available habitat for plants and animals. Habitat fragmentation invariably involves some amount of habitat destruction. Plants and sessile animals in these areas are usually directly destroyed. Mobile animals (especially birds and mammals) retreat into remnant patches of habitat. This can lead to crowding effects and increased competition. Habitat destruction is a process of land use change in which one habitat-type is removed and replaced with some other habitat-type. ...


The remaining habitat fragments are smaller than the original habitat. Species that can move between fragments may use more than one fragment. Species which cannot move between fragments must make do with what is available in the single fragment in which they ended up. Since one of the major causes of habitat destruction is agricultural development, habitat fragments are rarely representative samples of the initial landscape.


Reduced viability

Habitat fragmented by numerous roads near the Indiana Dunes National Lakeshore is shown in this photo.
Habitat fragmented by numerous roads near the Indiana Dunes National Lakeshore is shown in this photo.

Area is the primary determinant of the number of species in a fragment[1]. The size of the fragment will influence the number of species which are present when the fragment was initially created, and will influence the ability of these species to persist in the fragment. Small fragments of habitat can only support small populations of plants and animals and small populations are more vulnerable to extinction. Minor fluctuations in climate, resources, or other factors that would be unremarkable and quickly corrected in large populations can be catastrophic in small, isolated populations. Thus fragmentation of habitat is an important cause of species extinction.[1] Population dynamics of subdivided populations tend to vary asynchronously. In an unfragmented landscape a declining population can be "rescued" by immigration from a nearby expanding population. In fragmented landscapes, the distance between fragments may prevent this from happening. Additionally, unoccupied fragments of habitat that are separated from a source of colonists by some barrier are less likely to be repopulated than adjoining fragments[citation needed]. Even small species such as the Columbia spotted frog are reliant on the rescue effect. Studies showed 25% of juveniles travel a distance over 200m compared to 4% of adults. Of these, 95% remain in their new locale, demonstrating that this is no mere wanderlust, but a costly journey that has an adaptive payoff for species survival. High dispersal in other amphibians indicate that it is crucial to the endangerement of rare species in the class[2]. Image File history File linksMetadata No higher resolution available. ... Image File history File linksMetadata No higher resolution available. ... Indiana Dunes National Lakeshore, a U.S. national lakeshore authorized by Congress in 1966, is located in Northwest Indiana. ... Divisions Green algae Chlorophyta Charophyta Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta—liverworts Anthocerotophyta—hornworts Bryophyta—mosses Vascular plants (tracheophytes) †Rhyniophyta—rhyniophytes †Zosterophyllophyta—zosterophylls Lycopodiophyta—clubmosses †Trimerophytophyta—trimerophytes Pteridophyta—ferns and horsetails Seed plants (spermatophytes) †Pteridospermatophyta—seed ferns Pinophyta—conifers Cycadophyta—cycads Ginkgophyta—ginkgo Gnetophyta—gnetae Magnoliophyta—flowering plants... “Animalia” redirects here. ... Asynchrony is the state of not being synchronized. ... This is a biological article: For a territory administered by another territory see: Colony For a group attempting to affiliate with a Fraternity or Sorority see: Colony (fraternity) In biology, a colony (from Latin colonia) refers to several individual organisms of the same species living closely together, usually for mutual... Binomial name Rana luteiventris Thompson, 1913 The Columbia Spotted Frog (Rana luteiventris) is a North American species of frog. ... A class is the rank in the scientific classification of organisms in biology below Phylum and above Order. ...


Additionally, habitat fragmentation leads to edge effects. Microclimatic changes in light, temperature, and wind can alter the ecology around the fragment, and in the interior and exterior portions of the fragment. Fires become more likely in the area as humidity drops and temperature and wind levels rise. Exotic and pest species can establish themselves more easily in such disturbed environments, and the proximity of domestic animals often upsets the natural ecology. Also, habitat along the edge of a fragment has a different climate and favours different species from the interior habitat. Small fragments are therefore unfavourable for species which require interior habitat. An edge effect is the effect of the juxtaposition of contrasting environments on an ecosystem. ... A wildfire, also known as a wildland fire, forest fire, vegetation fire, grass fire, peat fire (gambut in Indonesia), bushfire (in Australasia), or hill fire, is an uncontrolled fire often occurring in wildland areas, but which can also consume houses or agricultural resources. ...


Conservation implications

Habitat fragmentation is often a cause of species becoming threatened or endangered. The existence of viable habitat is critical to the survival of any species, and in many cases the fragmentation of any remaining habitat can lead to difficult decisions for conservation biologists. Given a limited amount of resources available for conservation is it preferable to protect the existing isolated patches of habitat or to buy back land to get the largest possible continuous piece of land. This ongoing debate is often referred to as SLOSS (Single Large or Several Small). The SLOSS Debate was a debate in ecology and conservation biology during the 1970s and 1980s as to whether a Single Large or Several Small (SLOSS) reserves was a superior means of conserving biodiversity in a fragmented habitat. ...


One popular solution to the problem of habitat fragmentation is to link the fragments by planting corridors of native vegetation. This has the potential to solve the problem of isolation but not the loss of interior habitat. In some cases a threatened species may gain some measure protection from disease by being distributed in isolated habitats.


Another solution is to enlarge small remnants in order to increase the amount of interior habitat. This may be impractical since developed land is often more expensive and could require significant time and effort to restore.


The best solution is generally dependent on the particular species or ecosystem that is being considered. More mobile species, like most birds, do not need connected habitat while some smaller animals, like rodents, may be more exposed to predation in open land. These questions generally fall under the headings of metapopulations or island biogeography. A metapopulation consists of a group of spatially separated populations of the same species which interact at some level. ... The study of island biogeography is a field within biogeography that attempts to establish and explain the factors that affect the species diversity of a particular community. ...


See also

The endangered Smiths blue butterfly. ... A wildlife corridor is the artificial joining of fragmented habitats. ... Extinction Vortices are a means through which conservation biologists, geneticists and ecologists can understand the dynamics of and categorize extinctions in the context of their causes. ...

References

  1. ^ a b Rosenzweig, Michael L. (1995). Species diversity in space and time. Cambridge: Cambridge University Press. 
  2. ^ Funk, W.C., A.E. Greene, P.S. Corn & F.W. Allendorf. (2005) "High dispersal in a frog species suggests that it is vulnerable to habitat fragmentation." Biol. Lett. 1(1): 13-6.

Michael Rosenzweig is an ecologist at the University of Arizona who has developed and popularized the concept of Reconciliation Ecology. ... The headquarters of the Cambridge University Press, in Trumpington Street, Cambridge. ... There are very few or no other articles that link to this one. ...

External links

  • GLOBIO, an ongoing programme to map the past, current and future impacts of human activities on the natural environment, specifically highlighting larger wilderness areas and their fragmentation

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Spartanburg SC | GoUpstate.com | Spartanburg Herald-Journal (1011 words)
Habitat fragmentation is a process of environmental change important in evolution and conservation biology.
Habitat fragmentation can be caused by geological processes that slowly alter the layout of the physical environment or by human activity such as land conversion, which can alter the environment on a much faster time scale.
Habitat fragmentation is frequently caused by humans when native vegetation is cleared for human activities such as agriculture, rural development or urbanization.
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