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Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred
environment Environment most often refers to: __NOTOC__ * Natural environment, all living and non-living things occurring naturally * Biophysical environment, the physical and biological factors along with their chemical interactions that affect an organism or ...
(
habitat Ibex in an alpine habitat In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. ...
), causing
population fragmentation Population fragmentation is a form of population segregation. It is often caused by habitat fragmentation. Causes of Fragmentation Fragmentation can be the cause of natural forces or human actions, although in modern times, human activity is the ...
and
ecosystem decay Ecosystem decay is a term coined by Thomas Lovejoy to define the process of which species become extinct locally based on habitat fragmentation. This process is what led to the extinction of several species, including the Irish Elk. Ecosystem decay ...
. Causes of habitat fragmentation include
geological Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rock (geology), rocks of which it is composed, and the processes by which th ...
processes that slowly alter the layout of the physical environment (suspected of being one of the major causes of
speciation Speciation is the evolution Evolution is change in the Heredity, heritable Phenotypic trait, characteristics of biological populations over successive generations. These characteristics are the Gene expression, expressions of genes that are ...

speciation
), and human activity such as
land conversion Land development is altering the landscape in any number of ways such as: * Changing landforms from a natural or semi-natural state for a purpose such as agriculture or House, housing * subdivision (land), Subdividing real estate into Lot (real est ...
, which can alter the environment much faster and causes the
extinction Extinction is the termination of a kind of organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by ...

extinction
of many species. More specifically,
habitat Ibex in an alpine habitat In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. ...

habitat
fragmentation is a process by which large and contiguous habitats get divided into smaller, isolated patches of habitats.


Definition

The term habitat fragmentation includes five discrete phenomena: * Reduction in the total area of the habitat * Decrease of the interior:
edge Edge or EDGE may refer to: Technology Computing * Edge computing Edge computing is a distributed computing paradigm that brings computation and data storage closer to the sources of data. This is expected to improve response times and save bandw ...

edge
ratio * 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 "fragmentation ... not only causes loss of the amount of habitat but by creating small, isolated patches it also changes the properties of the remaining habitat" (van den Berg et al. 2001). Habitat fragmentation is the landscape level of the phenomenon, and patch level process. Thus meaning, it covers; the patch areas, edge effects, and patch shape complexity. In scientific literature, there is some debate whether the term "habitat fragmentation" applies in cases of
habitat loss Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat Ibex in an alpine habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are pr ...
, or whether the term primarily applies to the phenomenon of habitat being cut into smaller pieces without significant reduction in habitat area. Scientists who use the stricter definition of "habitat fragmentation" per se would refer to the loss of habitat area as "habitat loss" and explicitly mention both terms if describing a situation where the habitat becomes less connected and there is less overall habitat. Furthermore, habitat fragmentation is considered as an invasive threat to
biodiversity Biodiversity is the biological variety and Genetic variability, variability of life, life on Earth. Biodiversity is a measure of variation at the Genetics, genetic, species, and ecosystem level. Terrestrial biodiversity is usually greater near ...

biodiversity
, due to its implications of affecting large number of
species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individu ...

species
than
biological invasions Biology is the natural science that studies life and living organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Life#Biology, prope ...
,
overexploitation Overexploitation, also called overharvesting, refers to harvesting a renewable resource File:Global Vegetation.jpg, Global vegetation A renewable resource, also known as a flow resource, is a natural resource which will replenish to replace th ...

overexploitation
, or
pollution Pollution is the introduction of contaminant Contamination is the presence of a constituent, impurity, or some other undesirable element that spoils, corrupts, infects, makes unfit, or makes inferior a material, physical body, natural en ...

pollution
. Additionally, the effects of habitat fragmentation damage the ability for species, such as
native plant In biogeography Biogeography is the study of the distribution of species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A spec ...

native plant
s, to be able to effectively adapt to their changing environments. Ultimately, this prevents
gene flow In , gene flow (also known as gene migration or geneflow and flow) is the transfer of material from one to another. If the rate of gene flow is high enough, then two populations will have equivalent allele frequencies and therefore can be cons ...

gene flow
from one generation of
population Population typically refers the number of people in a single area whether it be a city or town, region, country, or the world. Governments typically quantify the size of the resident population within their jurisdiction by a process called a ...
to the next, especially for species living in smaller population sizes. Whereas, for species of larger populations have more
genetic mutations A tulip flower exhibiting a partially yellow petal due to a mutation in its genes In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical proce ...
which can arise and
genetic recombination Genetic recombination (also known as genetic reshuffling) is the exchange of genetic material between different organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, ph ...
impacts which can increase species survival in those environments. Overall, habitat fragmentation results in habitat disintegration and
habitat loss Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat Ibex in an alpine habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are pr ...
which both tie into destructing
biodiversity Biodiversity is the biological variety and Genetic variability, variability of life, life on Earth. Biodiversity is a measure of variation at the Genetics, genetic, species, and ecosystem level. Terrestrial biodiversity is usually greater near ...

biodiversity
as a whole.


Causes


Natural causes

Evidence of
habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat Ibex in an alpine habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are pr ...
through natural processes such as
volcanism Volcanism (or volcanicity) is the phenomenon of eruption of molten rock (magma) onto the Earth#Surface, surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics and volcanic gases erupt through a break in the surface called ...
, fire, and
climate change Contemporary climate change includes both the global warming caused by humans, and its impacts on Earth's weather patterns. There have been previous periods of climate change, but the current changes are more rapid than any known even ...
is found in the fossil record. For example, habitat fragmentation of tropical rainforests in Euramerica 300 million years ago led to a great loss of amphibian diversity, but simultaneously the drier climate spurred on a burst of diversity among reptiles.


Human causes

Habitat fragmentation is frequently caused by humans when
native plant In biogeography Biogeography is the study of the distribution of species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A spec ...

native plant
s are cleared for human activities such as
agriculture Agriculture is the science, art and practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary Image:Family watching television 1958.jpg, Exercise trends, Increases in sedentary behaviors su ...

agriculture
,
rural developmentRural development is the process of improving the quality of life and economic well-being Well-being, also known as ''wellness'', ''prudential value'' or ''quality of life'', refers to what is intrinsically valuable relative ''to'' someone. So th ...
,
urbanization Urbanization (or urbanisation) refers to the population shift from rural File:Rural landscape in Finland.jpg, A rural landscape in Lappeenranta, South Karelia, Finland. 15 July 2000. In general, a rural area or a countryside is a geographi ...
and the creation of
hydroelectric Hydroelectricity, or hydroelectric power, is electricity produced from hydropower Hydropower (from el, ὕδωρ, "water"), also known as water power, is the use of falling or fast-running water Water (chemical formula H2O) is a ...
reservoirs. 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 cropland, pasture, pavement, or even barren land. The latter is often the result of
slash and burn Slash-and-burn agriculture is a farming method that involves the cutting and burning of plants in a forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating ...
farming in
tropical forest The tropics are the region of Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. The remaining 70.8% i ...

tropical forest
s. In the wheat belt of central-western
New South Wales New South Wales (abbreviated as NSW) is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspape ...
,
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

Australia
, 90% of the native vegetation has been cleared and over 99% of the
tall grass prairie The tallgrass prairie is an ecosystem native to central North America. Natural and Anthropogenic hazard#Fire, anthropogenic fire, as well as grazing by large mammals (primarily bison), were historically agents of periodic disturbance, which regulat ...
of
North America North America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continen ...

North America
has been cleared, resulting in extreme habitat fragmentation.


Endogenous vs. exogenous

There are two types of processes that can lead to habitat fragmentation. There are exogenous processes and endogenous processes. Endogenous is a process that develops as a part of species biology so they typically include changes in biology, behavior, and interactions within or between species. Endogenous threats can result in changes to breeding patterns or migration patterns and are often triggered by exogenous processes. Exogenous processes are independent of species biology and can include habitat degradation, habitat subdivision or habitat isolation. These processes can have a substantial impact on endogenous processes by fundamentally altering species behavior. Habitat subdivision or isolation can lead to changes in dispersal or movement of species including changes to seasonal migration. These changes can lead to a decrease in a density of species, increased competition or even increased predation.


Implications


Habitat and biodiversity loss

One of the major ways that habitat fragmentation affects
biodiversity Biodiversity is the biological variety and Genetic variability, variability of life, life on Earth. Biodiversity is a measure of variation at the Genetics, genetic, species, and ecosystem level. Terrestrial biodiversity is usually greater near ...

biodiversity
is by reducing the amount of suitable habitat available for organisms. Habitat fragmentation often involves both
habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat Ibex in an alpine habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are pr ...
and the subdivision of previously continuous habitat. Plants and other sessile organisms are disproportionately affected by some types of habitat fragmentation because they cannot respond quickly to the altered spatial configuration of the habitat. Habitat loss, which can occur through the process of habitat fragmentation, is considered to be the greatest threat to species. But, the effect of the configuration of habitat patches within the landscape, independent of the effect of the amount of habitat within the landscape (referred to as fragmentation per se), has been suggested to be small. A review of empirical studies found that, of the 381 reported significant effect of habitat fragmentation per se on species occurrences, abundances or diversity in the scientific literature, 76% were positive whereas 24% were negative. Despite these results, the scientific literature tends to emphasize negative effects more than positive effects. Positive effects of habitat fragmentation per se imply that several small patches of habitat can have higher conservation value than a single large patch of equivalent size. Land sharing strategies could therefore have more positive impacts on species than land sparing strategies. Area is the primary determinant of the number of species in a fragment and the relative contributions of demographic and genetic processes to the risk of global population extinction depend on habitat configuration, stochastic environmental variation and species features. 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. Population dynamics of subdivided populations tend to vary
asynchronous Asynchrony is the state of not being in synchronization. Asynchrony or asynchronous may refer to: Electronics and computing * Asynchrony (computer programming), the occurrence of events independent of the main program flow, and ways to deal with ...
ly. 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
immigrants Immigration is the international movement of people to a destination country A country is a distinct territorial body or political entity A polity is an identifiable political entity—any group of people who have a collective ident ...
by some barrier are less likely to be repopulated than adjoining fragments. Even small species such as the Columbia spotted frog are reliant on the
rescue effectThe rescue effect is a phenomenon which was first described by Brown & Kodric-Brown,Brown JH, Kodric-Brown A. 1977 Turnover rates in insular biogeography: effect of immigration on extinction. Ecology 58, 445– 449. (doi:10.2307/ 1935620) and is com ...
. 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 journey is necessary for survival. Additionally, habitat fragmentation leads to
edge effect In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms ...

edge effect
s. 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 BBQ. Fire is the rapid oxidation of a material in the exothermic chemical process of combustion, releasing heat, light, and various reaction Product (chemistry), products. Fire is hot because the conversion of the weak double bond in molecula ...

Fires
become more likely in the area as humidity drops and temperature and wind levels rise. Exotic and pest species may establish themselves 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 that require interior habitat. The percentage preservation of contiguous habitats is closely related to both genetic and species biodiversity preservation. Generally a 10% remnant contiguous habitat will result in a 50%
biodiversity loss Biodiversity loss includes the extinction Extinction is the termination of a kind of organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells ...
. Much of the remaining terrestrial
wildlife Wildlife traditionally refers to undomesticated animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that functi ...

wildlife
habitat in many third world countries has experienced fragmentation through the development of urban expansion such as roads interfering with
habitat loss Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat Ibex in an alpine habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are pr ...
. Aquatic species’ habitats have been fragmented by
dam A dam is a barrier that stops or restricts the flow of surface water An example of surface water is Lake Kinney. Surface water is water Water is an Inorganic compound, inorganic, Transparency and translucency, transparent, tas ...

dam
s and water diversions. These fragments of habitat may not be large or connected enough to support species that need a large territory where they can find mates and food. The loss and fragmentation of habitats makes it difficult for migratory species to find places to rest and feed along their migration routes.


Informed conservation

Habitat fragmentation is often a cause of species becoming
threatened Threatened Species are any species (including animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume org ...
or
endangered An endangered species is a species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group ...

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 contiguous piece of land. In rare cases, a
conservation reliant species Conservation-reliant species are animal or plant species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined a ...
may gain some measure of disease protection by being distributed in isolated habitats, and when controlled for overall habitat loss some studies have shown a positive relationship between species richness and fragmentation; this phenomenon has been called the habitat amount hypothesis, though the validity of this claim has been disputed. The ongoing debate of what size fragments are most relevant for conservation is often referred to as SLOSS (Single Large or Several Small). One solution to the problem of habitat fragmentation is to link the fragments by preserving or planting corridors of native vegetation. In some cases, a bridge or underpass may be enough to join two fragments. This has the potential to mitigate the problem of isolation but not the loss of interior habitat. Wildlife corridors can help animals to move and occupy new areas when food sources or other natural resources are lacking in their core habitat, and animals can find new mates in neighbouring regions so that
genetic diversity Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species, it ranges widely from the number of species to differences within species In biology, a species is the basic unit of biological classificati ...
can increase. Species that relocate seasonally can do so more safely and effectively when it does not interfere with human development barriers. Another mitigation measure is the enlargement of small remnants 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
metapopulation A metapopulation consists of a group of spatially separated populations of the same species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiv ...

metapopulation
s
island biogeography Insular biogeography or island biogeography is a field within biogeography Biogeography is the study of the distribution of species and ecosystems in geography, geographic space and through evolutionary history of life, geological time. Organis ...
.


Genetic risks

As the remaining habitat patches are smaller, they tend to support smaller populations of fewer species. Small populations are at an increased risk of a variety of genetic consequences that influence their long-term survival. Remnant populations often contain only a subset of the genetic diversity found in the previously continuous habitat. In these cases, processes that act upon underlying genetic diversity, such as
adaptation In , adaptation has three related meanings. Firstly, it is the dynamic evolutionary process that fits s to their environment, enhancing their . Secondly, it is a state reached by the population during that process. Thirdly, it is a or adapti ...

adaptation
, have a smaller pool of fitness-maintaining alleles to survive in the face of environmental change. However in some scenarios, where subsets of genetic diversity are partitioned among multiple habitat fragments, almost all original genetic diversity can be maintained despite each individual fragment displaying a reduced subset of diversity.


Gene Flow and Inbreeding

Gene flow In population genetics Population genetics is a subfield of that deals with genetic differences within and between s, and is a part of . Studies in this branch of examine such phenomena as , , and . Population genetics was a vital ingredient ...

Gene flow
occurs when individuals of the same species exchange genetic information through reproduction. Populations can maintain genetic diversity through
migration Migration, migratory, or migrate may refer to: Human migration * Human migration, physical movement by humans from one region to another ** International migration, when peoples cross state boundaries and stay in the host state for some minimum len ...
. When a habitat becomes fragmented and reduced in area, gene flow and migration are typically reduced. Fewer individuals will migrate into the remaining fragments, and small disconnected populations that may have once been part of a single large population will become reproductively isolated. Scientific evidence that gene flow is reduced due to fragmentation depends on the study species. While trees that have long-range pollination and dispersal mechanisms may not experience reduced gene flow following fragmentation, most species are at risk of reduced gene flow following habitat fragmentation. Reduced gene flow, and reproductive isolation can result in
inbreeding Inbreeding is the production of offspring In biology, offspring are the young creation of living organisms, produced either by a Asexual reproduction, single organism or, in the case of sexual reproduction, two organisms. Collective offspri ...
between related individuals. Inbreeding does not always result in negative fitness consequences, but when inbreeding is associated with fitness reduction it is called
inbreeding depression Inbreeding depression is the reduced biological fitness Fitness (often denoted w or ω in population genetics models) is the quantitative representation of natural and sexual selection File:Sexual Selection with Peafowl.gif, 250px, Sexual se ...
. Inbreeding becomes of increasing concern as the level of
homozygosity Zygosity (the noun, zygote A zygote (from Greek ζυγωτός ''zygōtos'' "joined" or "yoked", from ζυγοῦν ''zygoun'' "to join" or "to yoke") is a eukaryotic cell formed by a fertilization event between two gamete A gamete ( /ˈɡ ...
increases, facilitating the expression of deleterious alleles that reduce the fitness. Habitat fragmentation can lead to inbreeding depression for many species due to reduced gene flow. Inbreeding depression is associated with conservation risks, like local extinction.


Genetic drift

Small populations are more susceptible to
genetic drift Genetic drift (allelic drift or the Sewall Wright effect) is the change in the frequency of an existing gene In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical stru ...

genetic drift
. Genetic drift is random changes to the genetic makeup of populations and leads to reductions in genetic diversity. The smaller the population is, the more likely genetic drift will be a driving force of evolution rather than natural selection. Because genetic drift is a random process, it does not allow species to become more adapted to their environment. Habitat fragmentation is associated with increases to genetic drift in small populations which can have negative consequences for the genetic diversity of the populations. However, research suggests that some tree species may be resilient to the negative consequences of genetic drift until population size is as small as ten individuals or less.


= Genetic consequences of habitat fragmentation for plant populations

= Habitat fragmentation decreases the size and increases plant populations' spatial isolation. With
genetic variation thumb File:Genetic Variation and Inheritance.svg, Parents have similar gene coding in this specific situation where they reproduce and variation in the offspring is seen. Offspring containing the variation also reproduce and passes down traits t ...

genetic variation
and increased methods of inter-population
genetic divergenceGenetic divergence is the process in which two or more populations of an ancestral species accumulate independent genetic changes (mutations Image:Darwin Hybrid Tulip Mutation 2014-05-01.jpg, A tulip flower exhibiting a partially yellow petal due ...
due to increased effects of , elevating
inbreeding Inbreeding is the production of offspring In biology, offspring are the young creation of living organisms, produced either by a Asexual reproduction, single organism or, in the case of sexual reproduction, two organisms. Collective offspri ...
and reducing gene flow within plant species. While genetic variation may decrease with remnant population size, not all fragmentation events lead to genetic losses and different types of genetic variation. Rarely, fragmentation can also increase gene flow among remnant populations, breaking down local genetic structure.


Adaptation

In order for populations to evolve in response to natural selection, they must be large enough that natural selection is a stronger evolutionary force than genetic drift. Recent studies on the impacts of habitat fragmentation on adaptation in some plant species have suggested that organisms in fragmented landscapes may be able to adapt to fragmentation. However, there are also many cases where fragmentation reduces adaptation capacity because of small population size.


Examples of impacted species

Some species that have experienced genetic consequences due to habitat fragmentation are listed below: * '' Macquaria australasica'' *''
Fagus sylvatica Beech (''Fagus'') is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology Biology is the natural science that studies life and living organisms, includin ...

Fagus sylvatica
'' *''
Betula nana ''Betula nana'', the dwarf birch, is a species of birch A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the b ...

Betula nana
'' *'' Rhinella ornata'' *'''' *''
Uta stansburiana The common side-blotched lizard (''Uta stansburiana'') is a species of side-blotched lizard in the family In human society, family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity ...
'' *'' Plestiodon skiltonianus'' *''
Sceloporus occidentalis The western fence lizard (''Sceloporus occidentalis'') is a common lizard of Arizona, California, Idaho, Nevada, Oregon, Utah, Washington (state), Washington, Northern Mexico, and the surrounding area. As the ventral abdomen of an adult is chara ...

Sceloporus occidentalis
'' *'' Chamaea fasciata''


Effect on animal behaviours

Although the way habitat fragmentation affects the genetics and extinction rates of species has been heavily studied, fragmentation has also been shown to affect species' behaviours and cultures as well. This is important because social interactions can determine and have an effect on a species' fitness and survival. Habitat fragmentation alters the resources available and the structure of habitats, as a result, alters the behaviours of species and the dynamics between differing species. Behaviours affected can be within a species such as reproduction, mating, foraging, species dispersal, communication and movement patterns or can be behaviours between species such as predator-prey relationships. In addition, when animals happen to venture into unknown areas in between fragmented forests or landscapes, they can supposedly come into contact with humans which puts them at a great risk and further decreases their chances of survival.


Predation behaviours

Habitat fragmentation due to anthropogenic activities has been shown to greatly affect the predator-prey dynamics of many species by altering the number of species and the members of those species. This affects the natural predator-prey relationships between animals in a given community and forces them to alter their behaviours and interactions, therefore resetting the so-called "behavioral space race". The way in which fragmentation changes and re-shapes these interactions can occur in many different forms. Most prey species have patches of land that are a refuge from their predators, allowing them the safety to reproduce and raise their young. Human introduced structures such as roads and pipelines alter these areas by facilitating predator activity in these refuges, increasing predator-prey overlap. The opposite could also occur in the favour of prey, increasing prey refuge and subsequently decreasing predation rates. Fragmentation may also increase predator abundance or predator efficiency and therefore increase predation rates in this manner. Several other factors can also increase or decrease the extent to which the shifting predator-prey dynamics affect certain species, including how diverse a predators diet is and how flexible habitat requirements are for predators and prey. Depending on which species are affected and these other factors, fragmentation and its effects on predator-prey dynamics may contribute to species extinction. In response to these new environmental pressures, new adaptive behaviours may be developed. Prey species may adapt to increased risk of predation with strategies such as altering mating tactics or changing behaviours and activities related to food and foraging.


= Boreal woodland caribous

= In the boreal woodland caribous of British Columbia, the effects of fragmentation are demonstrated. The species refuge area is peatland bog which has been interrupted by linear features such as roads and pipelines. These features have allowed their natural predators, the wolf, and the black bear to more efficiently travel over landscapes and between patches of land. Since their predators can more easily access the caribous' refuge, the females of the species attempt to avoid the area, affecting their reproductive behaviours and offspring produced.


Communication behaviours

Fragmentation affecting the communication behaviours of birds has been well studied in Dupont's Lark. The Larks primarily reside in regions of Spain and are a small passerine bird which uses songs as a means of cultural transmission between members of the species. The Larks have two distinct vocalizations, the song, and the territorial call. The territorial call is used by males to defend and signal territory from other male Larks and is shared between neighbouring territories when males respond to a rivals song. Occasionally it is used as a threat signal to signify an impending attack on territory. A large song repertoire can enhance a male's ability to survive and reproduce as he has a greater ability to defend his territory from other males, and a larger number of males in the species means a larger variety of songs being transmitted. Fragmentation of the Dupont's Lark territory from agriculture, forestry and urbanization appears to have a large effect on their communication structures. Males only perceive territories of a certain distance to be rivals and so isolation of territory from others due to fragmentation leads to a decrease in territorial calls as the males no longer have any reason to use it or have any songs to match.
Human Humans (''Homo sapiens'') are the most abundant and widespread species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A speci ...

Human
s have also brought on varying implications into ecosystems which in turn affect animal behaviour and responses generated. Although there are some species which are able to survive these kinds of harsh conditions, such as, cutting down wood in the forests for
pulp and paper Image:InternationalPaper6413.jpg, frame, International Paper is the world's largest pulp and paper maker. The pulp and paper industry comprises companies that use wood as raw material and produce Pulp (paper), pulp, paper, paperboard and other cell ...
industries, there are animals which can survive this change but some that cannot. An example includes, varying
aquatic insect Aquatic insects or water insects live some portion of their life cycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia *Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduc ...
s are able to identify appropriate ponds to lay their eggs with the aid of
polarized light Polarization (also Also or ALSO may refer to: *Advanced Life Support in Obstetrics Advanced Life Support in Obstetrics (ALSO) is a program that was developed by the American Academy of Family Physicians (AAFP). This course helps physicians, ce ...
to guide them, however, due to
ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...

ecosystem
modifications caused by humans they are led onto artificial structures which emit artificial light which are induced by dry asphalt dry roads for an example.


Effect on microorganisms

While habitat fragmentation is often associated with its effects on large plant and animal populations and biodiversity, due to the interconnectedness of ecosystems there are also significant effects that it has on the
microbiota Microbiota are the range of microorganisms that may be commensalism, commensal, symbiotic, or pathogenic found in and on all multicellular organisms, including plants. Microbiota include bacteria, archaea, protists, fungus, fungi, and viruses, ...
of an environment. Increased fragmentation has been linked to reduced populations and diversity of fungi responsible for decomposition, as well as the insects they are host to. This has been linked to simplified food webs in highly fragmented areas compared to old growth forests. Furthermore, edge effects have been shown to result in significantly varied microenvironments compared to interior forest due to variations in light availability, presence of wind, changes in precipitation, and overall moisture content of leaf litter. These microenvironments are often not conducive to overall forest health as they enable generalist species to thrive at the expense of specialists that depend on specific environments.


Forest fragmentation

Forest fragmentation is a form of habitat fragmentation where forests are reduced (either naturally or man-made) to relatively small, isolated patches of forest known as forest fragments or forest remnants. The intervening matrix that separates the remaining woodland patches can be natural open areas,
farmland Agricultural land is typically land ''devoted to'' agriculture Agriculture is the science, art and practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary Image:Family watching televis ...

farmland
, or developed areas. Following the principles of
island biogeography Insular biogeography or island biogeography is a field within biogeography Biogeography is the study of the distribution of species and ecosystems in geography, geographic space and through evolutionary history of life, geological time. Organis ...
, remnant woodlands act like islands of forest in a sea of pastures, fields, subdivisions, shopping malls, etc. These fragments will then begin to undergo the process of
ecosystem decay Ecosystem decay is a term coined by Thomas Lovejoy to define the process of which species become extinct locally based on habitat fragmentation. This process is what led to the extinction of several species, including the Irish Elk. Ecosystem decay ...
. Forest fragmentation also includes less subtle forms of discontinuities such as utility right-of-ways (ROWs). Utility ROWs are of ecological interest because they have become pervasive in many forest communities, spanning areas as large as 5 million acres in the United States. Utility ROWs include electricity transmission ROWs, gas pipeline and telecommunication ROWs. Electricity transmission ROWs are created to prevent vegetation interference with transmission lines. Some studies have shown that electricity transmission ROWs harbor more plant species than adjoining forest areas, due to alterations in the microclimate in and around the corridor. Discontinuities in forest areas associated with utility right-of-ways can serve as biodiversity havens for native bees and grassland species, as the right-of-ways are preserved in an early successional stage. Forest fragmentation reduces food resources and
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habitat
sources for animals thus splitting these species apart. Thus, making these animals become much more susceptible to effects of
predation Predation is a biological interaction In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical en ...

predation
and making them less likely to perform
interbreeding In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechani ...
- lowering genetic diversity.


Implications

Forest fragmentation is one of the greatest threats to
biodiversity Biodiversity is the biological variety and Genetic variability, variability of life, life on Earth. Biodiversity is a measure of variation at the Genetics, genetic, species, and ecosystem level. Terrestrial biodiversity is usually greater near ...

biodiversity
in forests, especially in the tropics. The problem of
habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat Ibex in an alpine habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are pr ...
that caused the fragmentation in the first place is compounded by: * the inability of individual forest fragments to support viable populations, especially of large vertebrates * the local
extinction Extinction is the termination of a kind of organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by ...

extinction
of species that do not have at least one fragment capable of supporting a viable population *
edge effect In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms ...

edge effect
s that alter the conditions of the outer areas of the fragment, greatly reducing the amount of true forest interior habitat. The effect of fragmentation on the
flora Flora is all the plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular respiration, ca ...

flora
and
fauna Fauna is all of the animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular r ...

fauna
of a forest patch depends on a) the size of the patch, and b) its degree of isolation. Isolation depends on the distance to the nearest similar patch, and the contrast with the surrounding areas. For example, if a cleared area is reforested or allowed to regenerate, the increasing structural diversity of the
vegetation Vegetation is an assemblage of plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular re ...

vegetation
will lessen the isolation of the forest fragments. However, when formerly forested lands are converted permanently to pastures, agricultural fields, or human-inhabited developed areas, the remaining forest fragments, and the biota within them, are often highly isolated. Forest patches that are smaller or more isolated will lose species faster than those that are larger or less isolated. A large number of small forest "islands" typically cannot support the same biodiversity that a single contiguous forest would hold, even if their combined area is much greater than the single forest. However, forest islands in rural landscapes greatly increase their biodiversity. In the
Maulino forest Maulino forest ( es, Bosque Maulino) is a forest type naturally growing in the Chilean Coast Range of Central Chile from latitude 35°55 to 36°20 S. The chief tree species is ''Nothofagus glauca''. Other tree species include ''Nothofagus leonii'', ...
of Chile fragmentation appear to not affect overall plant diversity much, and tree diversity is indeed higher in fragments than in large continuous forests.
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in
Montreal Montreal ( ; officially Montréal, ) is the second-most populous city in Canada Canada is a country in the northern part of . Its extend from the to the and northward into the , covering , making it the world's . Its southern and w ...

Montreal
,
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Quebec
,
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Canada
released a university based newspaper statement stating that 70% of the world’s remaining forest stands within one kilometre of a forest edge putting biodiversity at an immense risk based on research conducted by international scientists. Reduced fragment area, increased isolation, and increased edge initiate changes that percolate through all ecosystems. Habitat fragmentation is able to formulate persistent outcomes which can also become unexpected such as an abundance of some species and the pattern that long temporal scales are required to discern many strong system responses.


Sustainable forest management

The presence of forest fragments influences the supply of various
ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...

ecosystem
s in adjacent Agriculture, agricultural fields (Mitchell et al. 2014). Mitchell et al (2014), researched on six varying ecosystem factors such as crop production, decomposition, pesticide regulation, carbon storage, soil fertility, and water quality regulation in soybean fields through separate distances by nearby forest fragments which all varied in isolation and size across an agricultural landscape in Quebec, Quebec, Canada. Sustainable forest management can be achieved in several ways including by managing forests for ecosystem services (beyond simple provisioning), through government compensation schemes, and through effective regulation and legal frameworks. The only realistic method of conserving forests is to apply and practice sustainable forest management to risk further loss. There is a high industrial demand for wood, Pulp (paper), pulp, paper, and other resources which the forest can provide with, thus businesses which will want more access to the cutting of forests to gain those resources. The Rainforest Alliance, rainforest alliance has efficiently been able to put into place an approach to sustainable forest management, and they established this in the late 1980s. Their Conservation biology, conservation was deemed successful as it has saved over nearly half a billion acres of land around the world. A few approaches and measures which can be taken in order to conserve forests are methods by which erosion can be minimized, waste is properly disposed, conserve native tree species to maintain
genetic diversity Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species, it ranges widely from the number of species to differences within species In biology, a species is the basic unit of biological classificati ...
, and setting aside forestland (provides habitat for critical Species, wildlife species). Additionally, Wildfire, forest fires can also occur frequently and measures can also be taken to further prevent forest fires from occurring. For example, in Guatemala’s culturally and ecologically significant Petén Department, Petén region, researchers were able to find over a 20-year period, actively managed Forest Stewardship Council, FSC-certified forests experienced substantially lower rates of deforestation than nearby protected areas, and forest fires only affected 0.1 percent of certified land area, compared to 10.4 percent of protected areas. However, it must be duly noted that short term decisions regarding forest sector employment and harvest practices can have long-term effects on biodiversity. Planted forests become increasingly important as they supply approximately a quarter of global industrial roundwood production and are predicted to account for 50% of global output within two decades (Brown, 1998; Jaakko Poyry, 1999). Although there have been many difficulties, the implementation of forest certification has been quite prominent in being able to raise effective awareness and disseminating knowledge on a holistic concept, embracing economic, environmental and social issues, worldwide. While also providing a tool for a range of other applications than assessment of sustainability, such as e.g. verifying Carbon sink, carbon sinks.


Approaches to understanding habitat fragmentation

Two approaches are typically used to understand habitat fragmentation and its ecological impacts.


Species-oriented approach

The species-oriented approach focuses specifically on individual species and how they each respond to their environment and habitat changes with in it. This approach can be limited because it does only focus on individual species and does not allow for a broad view of the impacts of habitat fragmentation across species.


Pattern-oriented approach

The pattern-oriented approach is based on land cover and its patterning in correlation with species occurrences. One model of study for landscape patterning is the patch-matrix-corridor model developed by Richard Forman The pattern-oriented approach focuses on land cover defined by human means and activities. This model has stemmed from
island biogeography Insular biogeography or island biogeography is a field within biogeography Biogeography is the study of the distribution of species and ecosystems in geography, geographic space and through evolutionary history of life, geological time. Organis ...
and tries to infer causal relationships between the defined landscapes and the occurrence of species or groups of species within them. The approach has limitations in its collective assumptions across species or landscapes which may not account for variations amongst them.


Variegation Model

The other model is the variegation model. Variegated landscapes retain much of their natural vegetation but are intermixed with gradients of modified habitat This model of habitat fragmentation typically applies to landscapes that are modified by agriculture. In contrast to the fragmentation model that is denoted by isolated patches of habitat surrounded by unsuitable landscape environments, the variegation model applies to landscapes modified by agriculture where small patches of habitat remain near the remnant original habitat. In between these patches are a matrix of grassland that is often modified versions of the original habitat. These areas do not present as much of a barrier to native species.


See also

* Empty forest * Extinction vortex * Gene pool * Genetic erosion * Habitat conservation * Habitat corridor * Habitat destruction * Landscape connectivity * Landscape ecology * Patch dynamics * Reproductive isolation * Restoration ecology * Road kill * Wildlife corridor * Wildlife crossing


Bibliography

* Lindenmayer D.B & Fischer J (2013) ''Habitat Fragmentation and Landscape Change: An Ecological and Conservation Synthesis'' (Island Press)


References


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
Monash Virtual Laboratory
– Simulations of habitat fragmentation and population genetics online at Monash University's Virtual Laboratory.
Defragmentation in Belgium (Flanders) – Connecting nature, connecting people. Accessed: Jan 22, 2009Wildlife passages – De-Fragmentation in the Netherlands – How to evaluate their effectiveness? Accessed: Jan 22, 2009Landscape Fragmentation in Europe
The technical report from 2006 - the result of a collaboration between the Swiss Federal Office for the Environment (FOEN) and the European Environment Agency (EEA). Accessed: Feb 22, 2016
Kinver, Mark. (2013, September 26). "Forest fragmentation triggers 'ecological Armageddon'", BBC News.
{{DEFAULTSORT:Habitat Fragmentation Habitats, Fragmentation Habitat, Fragmentation Ecological connectivity Conservation biology Environmental conservation Sustainable forest management