Ecology is a Broad Biological Science and Can Thus Be Divide

8/13/2019 Ecology is a Broad Biological Science and Can Thus Be Divide

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Ecologyis a broad biological science and can thus be divided into manysub-disciplines using various criteria. For example, one such categorization, based on overall complexity (from the leastcomplex to the most), is:

Behavioral ecology, hich studies the ecological and evolutionary basis for animal behavior, focusing largely at

the level of the individual!

"opulation ecology (or autecology), hich deals ith the dynamics of populations ithin species, and the

interactions of these populations ith environmental factors! #ommunity ecology (or synecology) hich studies the interactions beteen species ithin an ecological

community!

$cosystem ecology,hich studies ho flos of energy and matter interact ith biotic elements of ecosystems!

$cologycan also be classified on the basis of:

the primary %inds of organism under study, e.g. animal ecology, plant ecology, insect ecology!

the biomes principally studied, e.g.forest ecology, grassland ecology,desert ecology,benthic ecology!

the geographic or climatic area, e.g. arctic ecology, tropical ecology

the spatial scale under consideration, e.g.molecular ecology,macroecology,landscape ecology!

&pecialized branches of ecology include, among others:

applied ecology, the practice of employing ecological principles and understanding to solve real orld problems

(includes agroecologyandconservation biology)!

biogeography, the study of the geographic distributions of species !

chemical ecology, hich deals ith the ecological role of biological chemicals used in a ide range of areas

including defense against predators and attraction of mates!

conservation ecology,hich studies ho to reduce the ris% of species extinction!

ecological succession, hich focuses on understanding directed vegetation change!

ecophysiology hich studies the interaction of physiological traits ith the abiotic environment!

ecotoxicology, hich loo%s at the ecological role of toxic chemicals (often pollutants,but also naturally occurringcompounds)!

evolutionary ecology or ecoevolution hich loo%s at evolutionary changes in the context of the populations and

communities in hich the organisms exist!

fire ecology,hich loo%s at the role of fire in the environment of plants and animals and its effect on ecological

communities!

functional ecology, the study of the roles, or functions, that certain species (or groups thereof) play in an

ecosystem!

global ecology, hich examines ecological phenomena at the largest possible scale, addressing

macroecological'uestions!

landscape ecology,hich studies the interactions beteen discrete elements of a landscape!

macroecology, the study of large scale phenomena!

marine ecology, and a'uatic ecology, here the dominant environmental milieu is ater! microbial ecology, the ecology of micro-organisms!

microecology, the study of small scale phenomena!

paleoecology,hich see%s to understand the relationships beteen species in fossil assemblages!

restoration ecology, hich attempts to understand the ecological basis needed to restore impaired or damaged

ecosystems!
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theoretical ecology, the development of ecological theory, usually ith mathematical, statistical andor computer

modeling tools!

urban ecology,the study of ecosystems in urban areas.

$cology also plays important roles in many inter-disciplinary fields:

ecological design and ecological engineering.

ecological economics.

human ecology andecological anthropology. social ecology,ecological healthandenvironmental psychology.

Finally, ecology has also inspired (and lent its name to) other non-biological disciplines such as

industrial ecology.

softare ecology andinformation ecology.

Ecologyis essentially the study of the or%ings of the planet $arth.

Ecology, or ecological science, is the scientific study of the distribution and abundance of living organisms and ho

these properties are affected by interactions beteen the organisms and their environment

Behavioral ecologyis the study of the ecological and evolutionary basis for animal behavior, and the roles of behaviorin enabling an animal to adapt to its environment (both intrinsic and extrinsic).

Behavioral ecology emerged from ethology after *i%o +inbergen (a seminal figure in the study of animal behavior),outlined the four causes of behavior.

Population ecologyis a maor subfield of ecologyone that deals ith the dynamics of species populations and hothese populations interact ith the environment. +he older term, autecologyrefers to the roughly same field of study,coming from the division of ecology into autecology.Community ecologyis the study of the distribution, abundance, demography, and interactions beteen populations of

coexisting species. t is part of the division of ecology %non as synecologythat studies the organization ofecosystems specifically at the level of the biotic community(or biocoenosis).Ecosystem ecologyis the study of the movement of energy and matter through ecosystems. t is one of thefundamental disciplines of ecology. $cosystem ecology operates at a scale above that of communities but it is definedmore by subect matter than by scale.

$cosystem ecology deals ith locally defined ecosystems hich exchange matter and energy ith their surroundings.n ecology, an ecosystemis a naturally occurring assemblage of organisms (plant, animal and other living organismsalso referred to as a biotic communityor biocoenosis) living together ith their environment (or biotope), functioningas a loose unit.

+he term ecosystem first appeared in a /012 publication by the British ecologist 3rthur +ansley (+ansley, /012).

Ecologyis essentially the study of the or%ings of the planet $arth.

Ecology, or ecological science, is the scientific study of the distribution and abundance of living organisms and hothese properties are affected by interactions beteen the organisms and their environment.Forest ecologyis the scientific study of patterns and processes in forests. +he management of forests is %non asforestry.

Forest ecology is one branch of a biotically-oriented classification of types of ecological study (as opposed to aclassification based on organizational level or complexity (e.n ecology, desert ecologyis the sum of the interactions beteen both biotic and abiotic factors of the desert biomes.

+he biotic factors of desert ecology include the interactions of plant, animal, and bacterial populations in a desertcommunity. &ome of the abiotic factors include latitude and longitude, soil, and climate. $ach of these factors havecaused adaptations to the particular environment of the region.Molecular ecologyis a field of microbiology interested in the presence of certain genes in the environment.
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t stems from the fact that many microorganisms are not easily obtainable as cultured strains in the laboratory, hichould allo for indentification and characterisation. t also stems from the development of "#4, hich allos for rapidamplification of genetic material.......Macroecologyis the subfield of ecology hich deals ith the study of relationships beteen organisms and theirenvironment at large spatial scales to characterise and explain statistical patterns of abundance, distribution anddiversity. +he term as coined by 5ames Bron of the 6niversity of *e 7exico and Brian 7aurer of 7ichigan &tate6niversity in a /080 paper in Science.......Landscape ecologyis a subdiscipline of ecology and geography that is the study of spatial variation in interested in

the of elements in the landscape (such as fields, hedgeros, oodlots, rivers or tons) and ho their distributionaffects the distribution and flo of energy and individuals in the environment (hich, in turn, may influence thedistribution of the elements themselves).Applied ecologyis a subfield ithin ecology hich considers the application of the science of ecology to real-orld(usually management) 'uestions.

3spects of applied ecology include:

4estoration ecology

4angeland management

nvasive species management

#onservation biology

9abitat management Biodiversity conservation

"rotected areas management

3gro-ecosystem management

Agroecologyis the science of applying ecological concepts and principles to the design, development, andmanagement of sustainable agricultural systems.

3groecology loo%s at both the socio-economic impacts and the environmental impacts of agricultural systems, andta%es a critical vie of modern industrial agricultural tecni'ues.

Conservation biologyis the study and preservation of habitat for the purpose of conserving biodiversity.

+he term conservation biology refers to the science and sometimes is used to encompass also the application of thisscience. n simple terms, conservation biology is scientific study of the phenomena that affect the maintenance, loss,and restoration of biological diversity.

Biogeographyis the science hich deals ith 'uestions of species patterns of distribution and the process thatresulted in such patterns. +he patterns of species distribution at this level can usually be explained through acombination of historical factors - speciation, extinction, continentalChemical ecologyis the study of the chemicals involved in the interactions of living organisms. t focuses on theproduction of and response to signaling molecules, toxins, and other organic compounds.

Related fields

3nalytical chemistry

Biochemistry

$cology

;enetics

Conservation ecologycovers a very ide range of subects, basically, any part of ecology that has a bearing onconservation. +he terms Ecologyand Conservationare fre'uently used interchangeably, but, although ecologists arefre'uently also conservationists, this does not necessarily have to be the case.


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Ecological succession, a fundamental concept in ecology, is the process by hich a natural community moves from asimpler level of organisation to a more complex community. &uccession is a natural process that occurs after someform or disturbance hich simplifies the system. $cological succession is usually differentiated into

Ecotoicologyis a discipline of ecology, hich loo%s at the ecological role of toxic chemicals (often pollutants, but alsonaturally occurring compounds).

Pollutantsare substances hich directly or indirectly damage us or the environment. 7any of the compounds hichare dangerous to the environment can also be harmful to us in the long-term and come from nuclear-fossil sources, li%epetroleum.

"ollutants can cause the destruction of areas of the environment hich are protective to us.

Evolutionary ecologylies at the intersection of ecology and evolutionary biology. t approaches the study of ecology ina ay that explicitly considers the evolutionary histories of species and the interactions beteen them. #onversely, itcan be seen as an approach to the study of evolution that incorporates an understanding of the interactions beteenthe species under consideration.

Fire is a component of the environment. Fire ecology is the study of the interaction of fire ith living things.

+he effects of fire are due to a complex combination of:-

/. the fre'uency of fire


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obectives of restoration studies and proects are defined by the reference state hich is selected.

Ecology, or ecological science, is the scientific study of the distribution and abundance of living organismsand hothese properties are affected by interactionsbeteen the organisms and their environment. +he environment of anorganism includes both the physical properties, hich can be described as the sum of local abiotic factors li%e climateandgeology,as ell as the other organisms that share its habitat. +he term oekologieas coined in /8>>by the;erman biologist$rnst 9aec%el! the ord is derived from the ;ree%oikos(household) and logos (study)?therefore,ecology means the study of the household of nature.

!cope

$cology is usually considered a branch of biology,the general science that studies living beings.@rganisms can bestudied at many different levels, from proteins and nucleic acids(in biochemistryand molecular biology), to cells(incellular biology), to individuals (inbotany,zoology,and other similar disciplines), and finally at the level of populations,communities, and ecosystems, to the biosphereas a hole! these latter strata are the primary subects of ecologicalin'uiries. $cology is a multi-disciplinary science. Because of its focus on the higher levels of the organization of life onearth and on the interrelations beteen organisms and their environment, ecology dras heavily on many otherbranches of science, especially geologyandgeography, meteorology,pedology,chemistry, and physics. +hus, ecologyis said to be a holistic science, one that over-arches older disciplines such as biology hich in this vie become sub-disciplines contributing to ecological %noledge.

3griculture, fisheries, forestry, medicine and urban development are among human activites that ould fall ithinArebbs= (/0


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"opulation ecology (or autecology), hich deals ith the dynamics ofpopulationsithin species, and the

interactions of these populations ith environmental factors!

#ommunity ecology (or synecology) hich studies the interactions beteen species ithin an ecological

community!

Dandscape ecology,hich studies the interactions beteen discrete elements of a landscape!

$cosystem ecology,hich studies the flos of energy and matter through ecosystems!

;lobal ecology, hich loo%s at ecological 'uestions at the global level, often as%ing macroecological'uestions.

$cology can also be sub-divided on the basis of target groups:

3nimal ecology, plant ecology, insect ecology!

$cology can also be sub-divided from the perspective of the studied biomes:

3rctic ecology (orpolar ecology), tropical ecology, desert ecology

(temperatezone ecologycould also exist as a distinct sub-field, but ecology as a hole has an overhelminglytemperate bias, so the sub-field is redundant).

&panning all of the above is: $volutionary ecology.

#istory of ecology

Main article: History of ecology

Fundamental principles of ecology

Biosphere and biodiversity

Main articles:Biosphere, Biodiversity,6nified neutral theory of biodiversity

For modern ecologists, ecology can be studied at several levels: populationlevel (individuals of the same species),biocoenosislevel (or community of species), ecosystemlevel, and biospherelevel.

+he outer layer of the planet $arth can be divided into several compartments: the hydrosphere(or sphere of ater), thelithosphere(or sphere of soils and roc%s), and the atmosphere(or sphere of the air). +he biosphere(or sphere of life),sometimes described as the fourth envelope, is all living matter on the planet or that portion of the planet occupied bylife. t reaches ell into the other three spheres, although there are no permanent inhabitants of the atmosphere.4elative to the volume of the $arth, the biosphere is only the very thin surface layer hich extends from //,EEE metersbelo sea level to /2,EEE meters above.

t is thought that life first developed in the hydrosphere, at shallo depths, in the photic zone. 7ulticellular organisms

then appeared and colonized benthic zones.+errestrial life developed later, after theozone layerprotecting livingbeings from 6 rays formed. Giversification of terrestrial species is thought to be increased by the continents driftingapart, or alternately, colliding. Biodiversity is expressed at the ecological level (ecosystem), population level(intraspecific diversity), species level (specific diversity), and genetic level. 4ecently technology has alloed thediscovery of the deep ocean vent communities. +his remar%able ecological system is not dependant on sunlight butbacteria, utilising the chemistry of the hot volcanic vents, are at the base of its food chain.

+he biosphere contains great 'uantities of elements such as carbon,nitrogenand oxygen.@ther elements, such asphosphorus,calcium, and potassium,are also essential tolife,yet are present in smaller amounts. 3t the ecosystemand biosphere levels, there is a continual recycling of all these elements, hich alternate beteen the mineral andorganic states.

Hhile there is a slight input of geothermal energy, the bul% of the functioning of the ecosystem is based on the input of

solar energy. "lants and photosynthetic microorganisms convert lightinto chemical energy by the process ofphotosynthesis, hich creates glucose(a simple sugar) and releases free oxygen. ;lucose thus becomes thesecondary energy source hich drives the ecosystem. &ome of this glucose is used directly by other organisms forenergy. @ther sugar molecules can be converted to other molecules such as amino acids. "lants use some of thissugar, concentrated in nectarto entice pollinators to aid them in reproduction.
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#ellular respirationis the process by hich organisms (li%e mammals) brea% the glucose bac% don into itsconstituents, aterandcarbon dioxide, thus regaining the stored energy the sun originally gave to the plants. +heproportion of photosynthetic activity of plants and other photosynthesizers to the respiration of other organismsdetermines the specific composition of the $arth=s atmosphere, particularly its oxygen level. ;lobal air currentsmix theatmosphere and maintain nearly the same balance of elements in areas of intense biological activity and areas of slightbiological activity.

Hater is also exchanged beteen the hydrosphere, lithosphere, atmosphere and biosphere in regular cycles. +heoceans are large tan%s, hich store ater, ensure thermal and climatic stability, as ell as the transport of chemicalelements than%s to large oceanic currents.

For a better understanding of ho the biosphere or%s, and various dysfunctions related to human activity, 3mericanscientists simulated the biosphere in a small-scale model, called Biosphere .

$he ecosystem concept

Main article:$cosystem

+he first principle of ecology is that each living organism has an ongoing and continual relationship ith every otherelement that ma%es up its environment. 3n ecosystemcan be defined as any situation here there is interactionbeteen organisms and their environment.

+he ecosystem is composed of to entities, the entirety of life (called the biocoenosis) and the medium that life exists in(the biotope). Hithin the ecosystem, species are connected and dependent upon one another in the food chain, andexchange energyand matterbeteen themselves and ith their environment.

+he concept of an ecosystem can apply to units of variable size, such as a pond, a field, or a piece of deadood. 3 unitof smaller size is called a microecosystem. For example, an ecosystem can be a stone and all the life under it. 3mesoecosystemcould be a forest, and a macroecosystema hole ecoregion, ith itsatershed.

+he main 'uestions hen studying an ecosystem are:

9o could the colonization of a barren area be carried outI

Hhat are the ecosystems dynamics and changes

9o does an ecosystem interact at local, regional and global scale

s the current state stableI Hhat is the value of an ecosystemI 9o does the interaction of ecological systems provide benefit to humans,

especially in the provision of healthy aterI

$cosystems are often classified by reference to the biotopes concerned. +he folloing ecosystems may be defined:

3s continental ecosystems (or terrestrial), such as forest ecosystems, meado ecosystems (meados, steppes,

savannas), or agro-ecosystems (agricultural systems).

3s ecosystems of inland aters, such as lentic ecosystems (la%es, ponds) or lotic ecosystems (rivers)

3s oceanic ecosystems (seas, oceans).

3nother classification can be done by reference to its communities (for example a human ecosystem).

"ynamics and stability

Main articles:biogeochemistry,9omeostasis,"opulation dynamics

Ecological factorshich can affect dynamic change in a populationorspeciesin a given ecology orenvironmentareusually divided into to groups: abiotic and biotic.

Abiotic factorsare geological, geographical, hydrologicaland climatological parameters. 3 biotopeis anenvironmentally uniform region characterized by a particular set of abiotic ecological factors. &pecific abiotic factorsinclude:

Hater, hich is at the same time an essential element to life and a milieu

3ir, hich provides oxygen, nitrogen, and carbon dioxide to living species and allos the dissemination of pollen

andspores
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&oil, at the same time source of nutriment and physical support

o &oilp9,salinity, nitrogen and phosphorus content, ability to retain ater, and density are all influential

o +emperature, hich should not exceed certain extremes, even if tolerance to heat is significant for some species

o Dight, hich provides energy to the ecosystem through photosynthesis

o *atural disasters can also be considered abiotic

Biocenose, or community, is a group of populations of plants, animals, micro-organisms. $ach population is the resultof procreationsbeteen individuals of same species and cohabitationin a given place and for a given time. Hhen apopulation consists of an insufficient number of individuals, that population is threatened ith extinction! the extinctionof a species can approach hen all biocenoses composed of individuals of the species are in decline. n smallpopulations, consanguinity (inbreeding)can result in reduced genetic diversitythat can further ea%en the biocenose.

Biotic ecological factorsalso influence biocenose viability! these factors are considered as either intraspecific andinterspecific relations.

%ntraspecific relationsare those hich are established beteen individuals of the same species, forming apopulation. +hey are relations of co-operationor competition, ith division of the territory, and sometimesorganization in hierarchical societies.

%nterspecific relations interactions beteen different speciesare numerous, and usually describedaccording to their beneficial, detrimental or neutral effect (for example, mutualism(relation JJ) or competition(relation --)). +he most significant relation is the relation of predation(to eat or to be eaten), hich leads to theessential concepts in ecology of food chains(for example, the grass is consumed by the herbivore, itselfconsumed by a carnivore, itself consumed by a carnivore of larger size). 3 high predator to prey ratio can have anegative influence on both the predator and prey biocenoses in that lo availability of food and high death rateprior to sexual maturity can decrease (or prevent the increase of) populations of each, respectively. &electivehunting of species by humans hich leads to population decline is one example of a high predator to prey ratioin action. @ther interspecific relations includeparasitism, infectious diseaseand competition for limitingresources, hich can occur hen to species share the same ecological niche.

+he existing interactions beteen the various living beings go along ith a permanent mixing of mineral and organicsubstances, absorbed by organisms for their groth, their maintenance and their reproduction, to be finally reected asaste. +hese permanent recyclings of the elements (in particular carbon,oxygenandnitrogen) as ell as the aterarecalled biogeochemical cycles. +hey guarantee a durable stability of the biosphere (at least hen unchec%ed humaninfluence and extreme eatheror geological phenomena are left aside). +his self-regulation, supported by negativefeedbac%controls, ensures the perenniality of the ecosystems. t is shon by the very stable concentrations of mostelements of each compartment. +his is referred to as homeostasis. +he ecosystem also tends to evolve to a state ofideal balance, reached after asuccessionof events, the climax (for example a pond can become a peat bog).

!patial relationships and subdivisions of land

Main articles:Biome,ecozone

$cosystems are not isolated from each other, but are interrelated. For example, atermay circulate beteenecosystems by the means of a riveror ocean current. Hater itself, as a li'uid medium, even defines ecosystems. &omespecies, such as salmonor freshater eelsmove beteen marine systems and fresh-ater systems. +heserelationships beteen the ecosystems lead to the concept of a biome.

3biomeis a homogeneous ecological formation that exists over a vast region, such as tundraorsteppes.+hebiospherecomprises all of the $arth=s biomes -- the entirety of places here life is possible -- from the highestmountains to the depths of the oceans.

Biomes correspond rather ell to subdivisions distributed along the latitudes, from the e'uatortoards the poles, ithdifferences based on to the physical environment (for example, oceans or mountain ranges) and to the climate.+heir

variation is generally related to the distribution of species according to their ability to tolerate temperature andordryness. For example, one may find photosyntheticalgaeonly in thephoticpart of the ocean (here light penetrates),hile conifers are mostly found in mountains.

+hough this is a simplification of more complicated scheme, latitudeand altitudeapproximate a good representation ofthe distribution of biodiversityithin the biosphere. ery generally, the richness of biodiversity (as ell for animal than
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plant species) is decreasing most rapidly near the e'uator(as in Brazil)and less rapidly as one approaches the poles.

+he biosphere may also be divided into ecozone,hich are very ell defined today and primarily follo the continentalborders. +he ecozones are themselves divided into ecoregions, though there is not agreement on their limits.

Ecosystem productivity

n an ecosystem, the connections beteen species are generally related to foodand their role in the food chain. +hereare three categories of organisms:

Producers-- plants hich are capable of photosynthesis Consumers-- animals, hich can be primary consumers (herbivorous), or secondary or tertiary consumers

(carnivorous).

Decomposers-- bacteria, mushrooms hich degrade organic matter of all categories, and restore minerals to

the environment.

+hese relations form se'uences, in hich each individual consumes the preceding one and is consumed by the onefolloing, in hat are called food chainsor food netor%. n a food netor%, there ill be feer organisms at each levelas one follos the lin%s of the netor% up the chain.

+hese concepts lead to the idea ofbiomass(the total living matter in a given place), of primary productivity (the

increase in the mass of plants during a given time) and of secondary productivity (the living matter produced byconsumers and the decomposers in a given time).

+hese to last ideas are %ey, since they ma%e it possible to evaluate the load capacity -- the number of organismshich can be supported by a given ecosystem. n any food netor%, the energy contained in the level of the producersis not completely transferred to the consumers. +hus, from an energy point of vie, it is more efficient for humans to beprimary consumers (to get nourishment from grains and vegetables) than as secondary consumers (from herbivoressuch as beef and veal), and more still than as a tertiary consumer (from eating carnivores).

+he productivity of ecosystems is sometimes estimated by comparing three types of land-based ecosystems and thetotal of a'uatic ecosystems:

+he forests (/1 of the $arth=s land area) contain dense biomasses and are very productive. +he total production

of the orld=s forests corresponds to half of the primary production. &avannas, meados, and marshes (/1 of the $arth=s land area) contain less dense biomasses, but are

productive. +hese ecosystems represent the maor part of hat humans depend on for food.

$xtreme ecosystems in the areas ith more extreme climates -- deserts and semi-deserts, tundra, alpine

meados, and steppes -- (/1 of the $arth=s land area) have very sparse biomasses and lo productivity

Finally, the marine and fresh ater ecosystems (1C of $arth=s surface) contain very sparse biomasses (apart

from the coastal zones).

9umanity=s actions over the last fe centuries have seriously reduced the amount of the $arth covered by forests(deforestation), and have increased agro-ecosystems (agriculture). n recent decades, an increase in the areasoccupied by extreme ecosystems has occurred (desertification).

Ecological crisis

;enerally, an ecological crisisis hat occurs hen theenvironmentof life of a species or a population evolves in anunfavourable ay to its survival.

t may be that the environment 'uality degrades compared to the species needs, after a change of abiotic ecologicalfactor (for example, an increase of temperature, less significant rainfalls).t may be that the environment becomes unfavourable for the survival of a species (or a population) due to an increasepressure of predation(for example overfishing).Dastly, it may be that the situation becomes unfavourable to the 'uality of life of the species (or the population) due torise in the number of individuals (overpopulation).

$cological crises may be more or less brutal (occurring beteen a fe months to a fe million years). +hey can also beof natural or anthropic origin. +hey may relate to one uni'ue species or on the contrary, to a high number of species(see the article on $xtinction event).

Dastly, an ecological crisis may be local (as an oil spill) or global (a rise in the sea level related to global arming).
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3ccording to its degree of endemism, a local crisis ill have more or less significant conse'uences, from the death ofmany individuals to the total extinction of a species. Hhatever its origin, disappearance of one or several species oftenill involve a rupture in thefood chain, further impacting the survival of other species.

n the case of a global crisis, the conse'uences can be much more significant! some extinction events shoed thedisappearance of more than 0EK of existing species at that time. 9oever, it should be noted that the disappearance ofcertain species, such as the dinosaurs, by freeing an ecological niche, alloed the development and the diversificationof the mammals. 3n ecological crisis thus paradoxically favored biodiversity.

&ometimes, an ecological crisis can be a specific and reversible phenomenon at the ecosystem scale. But moregenerally, the crises impact ill last. ndeed, it rather is a connected series of events, that occur till a final point. Fromthis stage, no return to the previous stable state is possible, and a ne stable state ill be set up gradually (seehomeorhesy).

Dastly, if an ecological crisis can cause extinction, it can also more simply reduce the 'uality of life of the remainingindividuals. +hus, even if the diversity of the human population is sometimes considered threatened (see in particularindigenous people), fe people envision human disappearance at short span. 9oever, epidemic diseases, famines,impact on health of reduction of air 'uality,food crises, reduction of living space, accumulation of toxic or nondegradable astes, threats on %eystone species(great apes, panda, hales) are also factors influencing the ell-beingof people.

Guring the past decades, this increasing responsibility of humanity in some ecological crises has been clearly observed.

Gue to the increases in technology and a rapidly increasing population, humans have more influence on their onenvironment than any otherecosystem engineer.

&ome usually 'uoted examples as ecological crises are:

"ermian-+riassic extinction event 2 million years ago

;lobal arming related to the ;reenhouse effect. Harming could involve flooding of the 3sian deltas (see also

ecorefugees), multiplication ofextreme eatherphenomena and changes in the nature and 'uantity of the foodresources (see ;lobal arming and agriculture). &ee also international Ayoto "rotocol.

@zone layer hole issue

Geforestation and desertification, ith disappearance of many species.

+henuclearmeltdon at#hernobylin/08>caused the death of many people and animals from cancer, and

caused mutations in a large number of animals and people. +he area around the plant is no abandonedbecause of the large amount of radiation generated by the meltdon.

&ature(also called the material 'orld, the material universe, the natural 'orld, and the natural universe) is allmatter and energy, especially in its essential form. *ature is the subect of scientific study, and the history of theconcept is lin%ed to the history of science.

Lifeis a multi-faceted concept. ifemay refer to the ongoing process of hich living things are a part, the periodbeteen the conception (or a point at hich the entity can be considered to be an individualized being) and death of anorganism, the condition of an entity that has been

%nteractionis a %ind of action hich occurs as to or more obects have an effect upon one another. +he idea of a to-ay effect is essential in the concept of interaction instead of a one-ay causal effect. #ombinations of many simpleinteractions can lead to surprising emergent phenomena. t has different tailored meanings in various sciences.

+he natural environmentcomprises all living and non-living things that occur naturally on $arth. n its purest sense, itis thus an environment that is not the result of human activity or intervention. +he natural environment may becontrasted to the built environment.

+he climate(ancient ;ree%: !"#$%) is the eather averaged over a long period of time. +he ntergovernmental "anel on

#limate #hange ("##) glossary definition is:

Climate in a narro& sense is usually defined as the 'average
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(eology(from ;ree% LM- (ge-, the earth) and NOLOP (logos, ord, reason)) is the science and study of the $arth,its composition, structure, physical properties, history, and the processes that shape it. t is one of the $arth sciences.;eologists have helped establish the age of the $arth at about C.#abitat(from the Datin for it inhabits) is the place here a particular species lives and gros. t is essentially theenvironmentat least the physical environmentthat surrounds (influences and is utilized by) a species population.He use species population instead of organism

Biologyis the study, or science, of life. t is concerned ith the characteristics and behaviors of organisms, hospecies and individuals come into existence, and the interactions they have ith each other and ith the environment.Biology encompasses a broad spectrum of academic fields that are often vieed as independent disciplines. 9oever,together they address the phenomenon of life over a ide range of scales.

n biology and ecology, an organism(in ;ree% organonQ instrument) is a complex adaptive system of organs thatinfluence each other in such a ay that they function as a more or less stable hole and have properties of life.

+he origin of life and the relationships beteen its maor lineages are controversial.

3 nucleic acidis a complex, high-molecular-eight biochemical macromolecule composed of nucleotide chains that

convey genetic information. +he most common nucleic acids are deoyribonucleic acid(G*3) and ribonucleic acid(4*3). *ucleic acids are found in all living cells and viruses.

Biochemistrythe chemistry of life, a bridge beteen biology and chemistry that studies ho complex chemicalreactions give rise to life. t is a hybrid branch of chemistry hich specialises in the chemical processes in livingorganisms. +his article only discusses terrestrial biochemistry (carbon- and ater-based), as all the life forms e %noare on $arth.

Molecular biologyis the study of biology at a molecular level. +he field overlaps ith other areas of biology andchemistry, particularly genetics and biochemistry. 7olecular biology chiefly concerns itself ith understanding theinteractions beteen the various systems of a cell, including the interrelationship of G*3, 4*3 and protein synthesisand learning ho these interactions are regulated.

cellis the structural and functional unit of all living organisms, and are sometimes called the building bloc%s of life.&ome organisms, such as bacteria, are unicellular, consisting of a single cell. @ther organisms, such as humans, aremulticellular, (humans have an estimated /EE,EEE billion or /E/Ccells).

(or other meanings) see *otany +disambiguation,

Botanyis the scientific study of plant life. 3s a branch of biology, it is also sometimes referred to as plant science)s*orplant biology. Botany covers a ide range of scientific disciplines that study the groth, reproduction, metabolism,development, diseases, and evolution of plants.+oology(;ree% zoonQ animal and logosQ ord) is the biological discipline hich involves the study of animals.

#istory of ,oology

Main articles:9istory of zoology (before Garin), 9istory of zoology (since Garin)

Branches of biology relevant to ,oology

populationis the collection of peopleor organisms of a particular speciesliving in a given geographic area.

"opulation is studied in a ide variety of ays and disciplines. n population dynamics, size, age and sex structure,mortality, reproductive behaviour, and groth of a population are studied.n ecology, an ecosystemis a naturally occurring assemblage of organisms (plant, animal and other living organismsalso referred to as a biotic communityor biocoenosis) living together ith their environment (or biotope), functioningas a loose unit.


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+he term ecosystem first appeared in a /012 publication by the British ecologist 3rthur +ansley (+ansley, /012).

biosphere is that part of a planet=s outer shellincluding air, land, surface roc%s and aterithin hich life occurs,and hich biotic processes in turn alter or transform. From the broadest geophysiological point of vie, the biosphere isthe global ecological system integrating

+he natural environmentcomprises all living and non-living things that occur naturally on $arth. n its purest sense, itis thus an environment that is not the result of human activity or intervention. +he natural environment may becontrasted to the built environment.

For some, there

(eology(from ;ree% LM- (ge-, the earth) and NOLOP (logos, ord, reason)) is the science and study of the $arth,its composition, structure, physical properties, history, and the processes that shape it. t is one of the $arth sciences.;eologists have helped establish the age of the $arth at about C.(eographyis the study of the locational and spatial variation of both natural and human phenomena on $arth. +heord derives from the ;ree% ords -.or -/0%($arth) and -1%2/03(to describe and to rite).

Meteorologyis the scientific study of the atmosphere that focuses on eather processes and forecasting.7eteorological phenomena are observable eather events hich illuminate and are explained by the science ofmeteorology. +hose events are bound by the variables that exist in $arth=s atmosphere.

Pedology(pRdS=lTgy), (from 4ussian:pedologiya, from the ;ree%pedonQ soil, earth), is the study of soils and soilformation. t is the branch of soil science that deals ith soil genesis, morphology, classification and distribution.

&oil is not onlyChemistry(derived from the 3rabic ord chemia, alchemy, here alis 3rabic for the) is the science of matter thatdeals ith the composition, structure, and properties of substances and ith the transformations that they undergo. nthe study of matter, chemistry also investigates its interactions ith energy and itself (see physics, biology).Physics(from the ;ree%, UVWXYZP (physikos), natural, and U[WXP (physis), nature) is the science of the natural orlddealing ith the fundamental constituents of the universe, the forces they exert on one another, and the resultsproduced by these forces.Biodiversityor biological diversityis the diversity of and in living nature. +here are a number of definitions andmeasures of biodiversity.

Etymology

*iodiversityis a neologism and a portmanteau ord, from bioand diversity. +he term biological diversityas coined by+homas Doveoy in /08E, hile the ord biodiversityitself as coined by the entomologist $.

Ecology is a Broad Biological Science and Can Thus Be Divide

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