Our Natural Habitat

8/8/2019 Our Natural Habitat

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OUR NATURAL HABITAT

A HABITATis an ecological or environment area that is inhabited by a particular species. Itis the natural environment in which an organism lives, or the physical environment thatsurrounds a species population.

the term species population is preferred to organism because, while it is possible todescribe the habitat of a single black bear, we may not find any particular or individual bearbut the grouping of bears that comprise a breeding population and occupy a certainbiogeographical area. Further, this habitat could be somewhat different from the habitat ofanother group or population of black bears living elsewhere. Thus it is neither the speciesnor the individual for which the term habitat is typically used.

The term habitat was originally defined as the physical conditions that surrounds aspecies, or species population, or assemblage of species, or community. In ecology, the

habitat shared by many species is called a biotope. A biome is the set of flora and faunawhich live in a habitat and occupy a certain geography.

Habitat destruction is a major factor in causing a species population to decrease,eventually leading to its being endangered, or even to its extinction. Large scale landclearing usually results in the removal of native vegetation and habitat destruction.Bushfires and poor fire management, pest and weed invasion, cyclone and storm damagecan also destroy habitat.

Habitat is the environment in which human beings live, work, recreate and move about. Itis not just a dwelling place a house with four walls but it is sum total of all factors whichconstitute the total environment where human beings live, work and perform their essential

and day to day obligations.


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POLLUTION

Pollution is the effect of undesirable changes in our surroundings that have harmful effectson plants, animals and human beings. This occurs when only short-term economic gainsare made at the cost of long-term ecological benefits for humanity, no phenomenon hasled to grater ecological changes that has been made by mankind. During the last fewdecades we have contaminated our air, water and land on which life itself depends with a

variety of waste products.Pollutants include solid, liquid or gaseous substances present in greater than naturalabundance, produced due to human activity, which have a detrimental effect on ourenvironment. The nature and concentration of a pollutant determine the severity of itsdetrimental effects on human health. An average human requires about 12kg of air eachday, which is nearly 12-15 times greater than the amount of food we eat. So, even a smallconcentration of pollutants in the air becomes more significant in comparison to similarlevels present in food. Pollutants that enter water have the ability to spread to distantplaces, especially in the marine ecosystem.

From an ecological perspective, pollutants can be classified as follows;

Degradable or non-persistent pollutants: these can be rapidly broken down by naturalprocesses; e.g., domestic sewage, discarded vegetables, etc.

Slowly-degradable or persistent pollutants: these are pollutants that remain in theenvironment for many years in an unchanged condition and take decades or longer todegrade; e.g., DDT (pesticides) and most plastics.

Non-degradable pollutants: these cannot be degraded by natural processes. Once theyare released into the environment they are difficult to eradicate and continue toaccumulate; e.g., toxic elements like lead or mercury, and nuclear wastes.


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AIR POLLUTION

The air pollution occurs due to the presence of undesirable solid or gaseous particles inthe air, in quantities that are harmful to human health and the environment. The air maybecome polluted by natural causes such as volcanoes, which release ash, dust, sulphurand other gases, or by forest fires that are occasionally naturally caused by lightening.

Pollutants that are emitted directly from identifiable sources are produced both by naturalevents( e.g. dust storms and volcanic eruptions) and human activities ( emission fromvehicles, industries, etc.). these areprimary pollutants. The pollutants that are produced inthe atmosphere when certain chemical reactions take place among the primary pollutantsare called secondary pollutants; e.g., sulphuric acid, nitric acid, carbonic acid, etc.

Air pollution is basically the release of chemicals and particulates into the atmosphere.Common examples include carbon monoxide, sulfur dioxide, CFCs and nitrogen oxidesproduced by industry and motor vehicles.

COMES FROM MANY SOURCES

Smog hanging over cities is the most familiar and obvious form of air pollution. But there

are different kinds of pollution some visible, some invisible that contribute to globalwarming. Generally any substance that people introduce into the atmosphere that hasdamaging effects on living things and the environment is considered air pollution.

Carbon dioxide, a greenhouse gas, is the main pollutant that is warming Earth. Thoughthings emit carbon dioxide when they breathe, carbon dioxide is widely considered to be apollutant when associated with cars, planes, power plants, and other human activities likethe burning of fossil fuels such as gasoline and natural gas.


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Other greenhouse gases include methane which comes from such sources as swamemitted by livestock and chlorofluorocarbons, which were used in refrigerants aerosolpropellants until they were banned because of their deteriorating effect on the Earth.

Another pollutant associated with climate change is sulfur dioxide, a component of smog.Sulphur dioxide and closely related chemicals are known primarily as a cause of acid rain.

TOXIC AIR POLLUTANTS

Toxic air pollutants, also known as hazardous air pollutants, are those pollutants that areknown or suspected to cause cancer or other serious health effects, such as reproductiveeffects or birth defects, or adverse environmental effects. Examples of toxic air pollutantsinclude benzene, which is found in gasoline; perchlorethlyene, which is emitted from somedry cleaning facilities; and methylene chloride, which is used as a solvent and paintstripper by a number of industries.

People exposed to toxic air pollutants at sufficient concentrations and durations may havean increased chance of getting cancer or experiencing other serious health effects. Thesehealth effects can include damage to the immune system, as well as neurological,reproductive, developmental, respiratory and other health problems.


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EFFECTS OF AIR POLLUTION ON HEALTH

Prolonged smoking or exposure to air pollutants contributes to diseasessuch as lung cancer, asthma, chronic bronchitis and emphysema. Elderly people,

infants, pregnant women and people with heart disease, asthma or otherrespiratory diseases are especially vulnerable to air pollution.

Exposure to air containing even 0.001% of carbon monoxide for severalhours can cause collapse , coma and even death. As carbon monoxide remainsattached to the hemoglobin in the blood for a long time, it accumulates and reducesthe oxygen-carrying capacity of blood. This impairs perception and thinking, slowsreflexes and causes headaches, drowsiness, dizziness and nausea.

Sulfur dioxide irritates the respiratory tissues; chronic exposure to it causesa condition similar to bronchitis. It also reacts with water, oxygen and other materialin the air to form sulfur-containing acids.

Nitrogen oxides can irritate the lungs, aggravate asthma or chronic

bronchitis and also increase our susceptibility to respiratory infections, likeinfluenza or common colds.

Many volatile organic compounds and toxic particulates can causemutations, reproductive problems or cancer. The repeated inhalation of ozone, acomponent of photochemical smog, causes coughing, chest pain, breathlessnessand irritation of the eye, nose and the throat.


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WATER POLLUTION

Comprising over 70% of the Earths surface, water is undoubtedly the most preciousnatural resource that exists on our planet. Without the seemingly invaluable compoundcomprised of hydrogen and oxygen, life on Earth would be non-existent. Although we ashumans recognize this fact, we disregard it by polluting our rivers, lakes and oceans.Subsequently, we are slowly but surely harming our planet to the point where organismsare dying at a very alarming rate. In addition to innocent organisms dying off, our drinking

water has become greatly affected as is our ability to use water for recreational purposes.

Water pollution occurs when a body of water is adversely affected due to the addition oflarge amounts of materials to the water. When it is unfit for its intended use, water isconsidered polluted.

CAUSES OF WATER POLLUTION

Many causes of pollution including sewage and fertilizers contain nutrients such as nitratesand phosphates. In excess levels, nutrients over stimulate the growth of aquatic plants andalgae. Excessive growth of these types of organisms consequently clogs our waterways,

use up dissolved oxygen as they decompose, and block light to deeper waters. This, inturn, proves very harmful to aquatic organisms as it affects he respiration ability or fish andother invertebrates that reside in water.

Pollution is also caused when silt and other suspended solids, such as soil, washoffplowed fields, construction and logging sites, urban areas, and eroded river banks when itrains. Under natural conditions, lakes, rivers and other water bodies undergoEutrophication, an aging process that slowly fills in the water body with sediments andorganic matter. When these sediments enter various bodies of water, fish respirationbecomes impaired, plant productivity and water depth becomes reduced, and aquaticorganisms and their environments become suffocated.


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Many types of fish and bottom-dwelling animals cannot survive when levels of dissolvedoxygen drop below two to five parts per million. When this occurs, it kills aquatic organismsin large numbers which leads to disruptions in the food chain.

Pathogens are another type of pollution that prove very harmful. They can cause manyillnesses that range from typhoid and dysentery to minor respiratory and skin diseases.Pathogens include such organisms as bacteria, viruses, and protozoan. These pollutantsenter waterways through untreated sewage, storm drains, septic tanks, runoff from farms,and particularly boats that dump sewage.

FORMS OF WATER POLLUTION

There are three forms of water pollution namelypetroleum, radioactive substances, andheat. Petroleum often pollutes water bodies in the form of oil, resulting from oil spills.These large-scale accidental discharges of petroleum are an important cause of pollutionof pollution along shore lines. Radioactive substances are produced in the form of wastefrom nuclear power plants, and from the industrial, medical, and scientific use ofradioactive materials. Specific forms of waste are uranium and thorium mining and refining.The last form of water pollution is heat. Heat is a pollutant because increasedtemperatures result in the deaths of many aquatic organisms. These decreases intemperatures are caused when a discharge of cooling water by factories and power plantoccurs.


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GLOBAL WATER POLLUTION

Estimates suggest that nearly 1.5 billion people lack safe drinking water and that at least 5million deaths per year can be attributed to waterborne diseases. With over 70 percent ofthe plant covered by oceans, people have long acted as if these very bodies of water couldserve as a limitless dumping ground for wastes. Raw sewage, garbage, garbage, and oilspills have begun to overwhelm the diluting capabilities of the oceans, and most coastalwaters are now polluted. Beaches around the world are closed regularly, often because ofhigh amounts of bacteria from sewage disposal, and marine wildlife is beginning to suffer.

Clearly, the problems associated with water pollution have the capabilities to disrupt life onour planet to a great extent. But the government alone cannot solve the entire problem. Itis ultimately up to us, to be informed, responsible and involved when it comes to theproblems we face with our water.


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NOISE POLLUTION

Noise may not seem as harmful as the contamination of air or water, but it is a pollutionproblem that affects human health and can contribute to a general deterioration of

environmental quality.

Noise is undesirable and unwanted sound. Not all sound is noise. What may beconsidered as music to one person may be noise t another! It is not a substance that can

accumulate in the environment like most other pollutants. Sound is measured in a unitcalled the decibel.

There are several sounds of noise pollution that contribute to both indoor and outdoornoise pollution. Noise emanating from factories, vehicles, and playing of loudspeakersduring various festivals can contribute to outdoor noise pollution, while loudly played radioor music systems, and other electronic gadgets can contribute to indoor noise pollution.

The difference between sound and noise is often subjective and a matter of personalopinion. There are, however, some very harmful effects caused by exposure to high soundlevels. These effects can range in severity from being annoying to being extremely painfuland hazardous.

EFFECTS OF NOISE POLLUTION ON PHYSICAL HEALTH

The most direct harmful effect of excessive noise is physical damage to the ear and thetemporary or permanent hearing loss often called a temporary threshold shifts (TTS).People suffering from the condition are unable to detect weak sounds. Permanent loss,usually called noise-induced permanent threshold shift (NIPTS) represents a loss ofhearing ability from which there is no recovery.

Temporary effects are noticed at sound levels between 80 and 130 db. About 50% of thepeople exposed to 95 db sound levels at work will develop NIPTS and most people.exposed to more than 105 db will experience permanent hearing loss to some degree. Asound level of 150 db or more can physically rupture the human eardrum.


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EFFECTS OF NOISE POLLUTION ON MENTAL HEALTH

Noise can cause emotional or psychological effects such as irritability,anxiety and stress.

Lack of concentration and mental fatigue are significant health effects ofnoise.

As noise interferes with normal auditory communication, it may maskauditory warning signals and hence increases the rate of accidents especially inindustries.

Noise can lead to lowered worker efficiency and productivity and higher

accident rates on the job.


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LAND POLLUTION

Land pollution basically is about contaminating the land surface of the Earth throughdumping urban waste matter indiscriminately, dumping of industrial waste, mineralexploitation, and misusing the soil by harmful agricultural practices. Land pollutionincludes visible litter and waste along with the soil.

Land pollution comprises of: Solid waste and Soil pollution

Solid waste : solid matter that are created by human or animal activities, and whichare disposed because they are hazardous or useless are known as solid waste. Mostof the solid wastes, like paper, plastic containers, bottles, cans, and even used carsand electronic goods are not biodegradable, which means they do not get brokendown through inorganic or organic processes. Thus, when they accumulate they posea health threat to people, plus, decaying wastes also attract household pests andresult in urban areas becoming unhealthy, dirty, and unsightly places to reside in.

Soil pollution : soil pollution is chiefly caused by chemicals in pesticides, such aspoisons that are used to kill agricultural pests like insects and herbicides that are usedto get rid of weeds. Hence, soil pollution results from:

Unhealthy methods of soil management

Harmful practices of irrigation methods


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Land pollution is caused by farms because they allow manure to collect, whichLeaches into the nearby land area. Chemicals that are used for purposes like sheepdipping also cause serious land pollution as do diesel oil spillages.

Land pollution can affect wildlife, plants and humans in a number of ways, such as:

Cause problems in the respiratory system

Cause problems on the skin

Lead to birth defects

Cause various kinds of cancers

The toxic materials that pollute the soil can get into the human body directly by:

Coming into contact with the skin

Being washed into water sources like reservoirs and rivers

Eating fruits and vegetables that have been grown in polluted soil

Breathing in polluted dust or particles


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GRASSLANDSGrasslands cover areas where rainfall is usually low and/or the soil depth and quality ispoor. The low rainfall prevents the growth of a large number of trees and shrubs, but issufficient to support the growth of grass cover during the monsoon.

A variety of grasses, herbs, and several species of insects, birds and mammals haveevolved so that they are adopted to these wide-open grass-covered areas. These animalsare able to live in conditions where food is plentiful after the rains, so that they can storethis as fat that they use during the dry period when there is very little to eat. Man began touse these grasslands as pastures to fed livestock when animals were domesticated and,thus, became a pastoralist in ancient times.

In India, grasslands form a variety of ecosystems that are located in different climaticconditions ranging from near-desert conditions, to patches of shola grasslands that occuron hill-slopes alongside the extremely moist evergreen forests in south. In the Himalayanmountains, there are the high cold Himalayan pastures. There are tracts of tall elephantgrass in the low-lying terrain belt south of the Himalayan foothills. There are semi-aridgrasslands in western India, parts of central India, and in Deccan Plateau.

Grasslands are not restricted only to low rainfall areas. Certain grasslands types formwhen clearings are made in different forest types. Some are located on the higher, steephill-slopes with patches of forest that occur along the stream and in depressions.

The grasses are the major producers of biomass. Each grassland ecosystem has a widevariety of species of grasses and herbs. Some grass and herbs species are more sensitiveto excessive grazing and are suppressed if the area is over-grazed. Others are destroyedby repeated fires and cannot regenerate. Thus over-used or frequently burnt grasslandsare degraded and are poor in plants species diversity.

On the basis of a visit to a local site, I have observed various aspects of our natural habitat

that are discussed in the following pages.


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GUIDELINES TO LOOK FOR ON GRASSLAND:-

Utilizationpatternofthegrassland : ----

The grassland that I visited was spread in a vast area and was used for avariety of purposes. A patch of it was used as a nursery by the farmer whileanother patch was used for farming. Cattle grazing was also conducted sincethe grass-cover was quite thick and good. Burning of grass is done periodically.

Grasslandcarryingcapacity : ----

The carrying capacity of the grassland was quite enormous as the grass

was very good, fresh and in ample quantity that can easily feed a largecattle.

Documentinggrasslanddegradation : ----

The feedback from the localities indicate that there has been no definitechange in the landuse of the site. Though a patch of the area wasdegraded a few years ago and has remained in the same condition tillnow, it has no effect on the rest of the area. The grazing, farming, etc.continues as before.

Products of use that come from that grassland :----

FlowersCottonFodderHayFruitsVegetablesHerbs


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OBSEVATIONS ON THE SITE THAT SHOULD BERECORDED:-

Identifythetypeofgrassland : ----

The grassland visited was a SEMI-ARID region.

Qualitativeaspects : ----

A variety of living organisms as well as non-living things were discovered at thesite. Trees like neem, jatropa, eucalyptus, peepal, seesam, rubber, etc. were foundalong with shrubs like zyzipus, challotropist, etc. Animals like rats, dogs, squirrels,

cats, rabbits, cows, buffalos, sheep, chickens, etc. were seen. A wide variety ofinsects was also seen like mosquitoes, flies, bees, etc.

Whatchangesoccurseasonally : ----

Seasonal changes are inevitable. During the summers though the humidity is on ahigh, the farm is benefited. Rainfall also helps in a good harvest and productivity. Inwinters the chill affects the plants as well as the animals. They prefer being cozy intheir sheds or holes. The kind of crops, the harvest, the output, the animal life, thesoil texture and many more aspects depend solely on the season weather.


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FINDINGS ON THE SITE THAT SHOULD BE RECORDEDTHROUGH INTERVIEWS

Whousesitandtowhatextent : ----

Mostly the farmers and localities use the grassland for their own sustainence.Farmers use it for a variety of purposes like for fuelwood, cattle grazing, cropproduction, fodder, source of income, etc.

Estimate the extent of free grazing by cattle, sheep, goats, and theirproportion : -----

The extent of grazing can be estimated from the fact that a very large flock of dairyanimals graze on the field regularly and still a considerable amount is left for sale.Whatistheproductivityofthegrassland : -----

According to the local people the fodder collection is more than enough for theirown livestock. They get quite a large portion to sell in the market. The sale offodder adds to the revenue of the farm and helps in making more developments.

Is the utilization sustainable or unsustainable :----

The utilization is very much sustainable as the soil is of excellent texture and thefodder collection is being done since a very long time. The flora and fauna hasbeen in a very good shape and the shepherd says the cattle is also happy.


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LOCAL POLLUTED SITE

Pollution occurs from a variety of sources and affects different aspects of our environmentand thus our lives and our health. I visited a local SEMIARIDDOMESTICAREA andobserved the following aspects : ----

Thetype of land or water used in the area : -----

The type of soil used is quite fertile and productive. But the water is used from a verysmall lake that is polluted. The colour of the water is blackish brown with weeds grownat the corners and a large amount of waste dumped. The water being used is certainlyof poor quality and may affect the locals.

Identify what is being polluted :----

AIR : - The air around the site is being ruined to no bounds as poisonous gasesare being emited from a nearby factory. These gases contain chemicals thatcontaminates the air and causes serious air pollution affecting the lives andhealth of the local people.

WATER : - A small pond like water body that is m deep on the site is beingpolluted because a lot of waste is being dumped into it. All sorts of garbage likeplastic bottles, aluminium cans, pieces of cloth, dried plants, thermacol, sticks,chemicals, polythene bags, paper, etc. is lying in it. All in all the pond is a horriblesight to look at and gives an unbearable odour create water pollution.

SOIL : - the soil though in a considerably good shape is being polluted. The farmerat times uses low quality pestcides and fertilizers thus damaging the fertility of the

soil. Often the grass is burnt which further destroys the nutrients in it. Hence, soilerosion in traces can also be seen.

PLANTS : - the plants that grow at the outskirts of the field are regularly wateredby the water from that sulking pond and the poisonous chemicals from the factoryalso play their role in affecting them. The polluted air does the most of destructionwork for the flora of the site since it consists of gases not suitable for the health ofthe plants.


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The health aspect associated with the pollutants : ----

The health of all, the localities, people living on the site, plants, animals and soil isbeing detorieted. The impurities in the environment affect the well-being of one and all.Chemicals in the air and water, garbage dump, wrong elements in soil, weeds,bacteria, etc. all help in destroying the natural habitat of the site.

Effects of the pollution on their lives : ----

The effects of pollution on the lives of local people are adverse. On drinkingwater from the dirty pond many children have taken ill and are serious. The fruitsand vegetables grown for the sustanence of the farmer also contain a hint ofharmful chemical sand fatal poisonous elements. The people inhale the air that

contains huge quantity of poison and endangering substances. Even a lot ofnoise pollution is created by the factory which disturbs the daily life of the localpeople.


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SOLID WASTE

Pollution caused due to solid waste can be seen at various places like:

Garbagedumps : - Garbage is a source of various diseases. The improperhandling of organic waste leads to a large population of flies, cockroaches andrats that are responsible for the spread of diseases. Products like plastics arenot degraded in nature and hence remain for a long time in the environment,thus adding to the ned for more dumps. For many years, waste has also beendumped into oceans, rivers or on land.

Households : - The garbage generated in our homes is termed as'domestic waste'. Domestic waste is further classified as kitchen waste, which isdegradable, wet waste and non-biodegradable recyclable home waste, whichconsists of plastics, glass and metal.

Agriculture : - Agricultural waste consists of biomass, including farmresidues such as rice husk, straw, bagasse, etc. this biomass could beeffectively used for generating power or producing paper. Waste material fromfields includes fertilizers and pesticides that are a serious hazard.

Industries : - Industrial solid waste includes material from various industriesor mines. Industries produce solid waste during the manufacturing processes.Some of these are chemicals that have serious environmental ill-effects, asthey are toxic.The waste generated during mining is non-biodegradable; it remains in theenvironment nearly indefinitely.

Hospitals : - The waste generated from hospitals contains cotton dressingsand bandages with blood or other tissue fluids and pus, all of which can containpathogens. It can spread bacteria, fungi and viruses. Used needles, syringes,bottles, plastic bags, operation theatre waste, such as tissues, blood and plasticdisposable equipment all need very careful disposal.


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While visiting a local garbage dump site, following was observed:--

The area covered : ----

The area covered is a small patch of land that has a bit of dairy farmingbeing conducted on it. At the far end is a land used for dumping garbageand waste. That part becomes a lot stinky and unhygienic.

Hours spent on collecting the waste : ----

On alternate days the sweepers from municipal corporation collect thewaste from the land. A total of six or seven hours approximately are spenton the waste collection.

The types of waste collected : ----

The waste collected from there mostly consists of plastic bottles, jute bags,dry weeds, sticks, cattle waste, etc.

The problems faced while collecting waste : ----

Since the waste collected on alternate days, the amount of waste is quitelarge and at times becomes unmanageable. The odour of the garbage alsoacts as a disturbing factor for the sweepers. The localities face a lot ofproblems because with the garbage come a lot of flies and diseases that

affect their daily lives.

What is done with the waste collected : ----

The garbage so collected is segregated and sent for recycling. But the restthat cannot be recycled is dumped in the city garbage yard. There arevarious types of treatments that can be conducted to recycle the waste like :

APIoil-water separators

Sedimentation (water treatment)

Dissolved air flotation

Activated sludge biotreaters

Biofilters


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LIST OF GARBAGE DUMP MOSTLY FOUND

Polybags

Thermacol

Water reed

Polysterene cups

Packets of chips

Cloth

Plastic

Notebooks

Sticks

Holi colours

Pet bottles

Jute bags

Cardboard

Leather

Fruit and vegetable peels

Cans

Stones


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Observations found while examining the polluted water body on the site : ----

Industrial units near the site :----

There are three factories just adjacent to the lake. One of them is achemical manufacturer, another a textile factory and the third a bath-fittingmanufacturer.

Is the industrial wastewater discharged in the site : ----

All the units use the water body as their dump yard and dispose all the waste.The waste from the chemical factory affects the water adversely.

The colour and odour: ----

The colour and odour of the water is not in a good shape. A blackish grayishtinge in the water is visible and the smell is unbearable because of the

chemicals and garbage dumped.

Sources of water contamination from the agricultural land on whichfertilizers are used : ----

The agricultural site also plays its role in the contamination of the water. All thedried weeds and sticks are dumped into the lake which contain large amount ifpesticides and fertilizers. This contaminates the water very badly.

Plants, birds and animals found nearby : ----

The plants mostly found near the water body are small weeds and shrubs thatgrew automatically. Rats, mosquitoes, chamelions, ladybirds, bees, flies, grass-hoppers, lizards, vasps, snakes, dogs, cats, buffalloos, cows, rabbits, etc. arefound on the site. Birds like eagles, sparrows, butterflies, crows, etc. can beseen.


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SIMPLE ECOSYSTEMS

A limited space within which living beings interact with nonliving matter at ainterdependence to form an environment unit is called an ecosystem.An ecosystem is a natural unit consisting of all plants, animals and micro-organisms in anarea functioning together with all of the non-living physical factors of the environment.

Central to the ecosystem concept is the idea that living organisms are continually engagedin a set of relationships with every other element constituting the environment in whichthey exist. The human ecosystem concept is then grounded in the deconstruction of thehuman/nature dichotomy, and the emergent premise that all species are ecologically

integrated with each other, as well as with the abiotic constituents of their biotope.A system as small as a household or university, or as large as a nation state, may then besuitable discussed as a human ecosystem.

Introduction of new elements, whether biotic or abiotic, into an ecosystem tend to have adisruptive effect. In some cases, this can lead to ecological collapse or trophic cascadingand the death of many species belonging to the ecosystem in question. Under thisdeterministic vision, the abstract notion of ecological health attempts to measure therobustness and recovery capacity for an ecosystem.

Often, however, ecosystems have the ability to rebound from a disruptive agent. Thedifference between collapse or a gentle rebound is determined by two factors the toxicityof the introduced element and the resiliency of the original ecosystem.

An ecosystem results from the sum of myriad individual responses of organisms to stimuli

from non-living and living elements in the environment. The presence or absence ofpopulations merely depends on reproductive and dispersal success, and population levelsfluctuate in response to stochastic events. As the number of species in an ecosystem is


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higher, the number of stimuli is also higher. Given the great diversity among organisms onearth, most of the time, ecosystems only changed very gradually, as some species woulddisappear while others would move in.

ECOSYSTEM SERVICES

From an anthropological point of view many people see ecosystems as production unitsthat of goods and services. Among some of the most common goods produced byecosystems, is wood by forest ecosystems and grass for cattle by natural grasslands.Meat from wild animals has proved to be extremely successful under well-controlledmanagement schemes. Much less successful has been the discovery andcommercialization of substances of wild organisms for pharmaceutical purposes. Servicesderived from ecosystems are referred to as ecosystem services. They may include (1)

facilitating the enjoyment of nature, which may generate many forms of income andemployment in the tourism sector, often referred to as ecotourism, (2), water retention,thus facilitating a more evenly distributed release of wart, (3) soil protection, open airlaboratory for scientific research, etc.

A greater degree of species diversity or biological diversity popularly referred to asBiodiversity of an ecosystem may contribute to greater resilience of an ecosystem,because there are more species present at a location to respond to a factor of change andthus absorb or reduce its effects, thus reducing the effect before its structure isfundamentally changed to a different state.

The ecosystem concept fits into an ordered view of nature that was developed byscientists to simplify the study of the relationships between organisms and their physicalenvironment, a field known as ecology.

Any given place may have several different ecosystems that vary in size and complexity. Atropical island may have a rain forest ecosystem that covers hundreds of square miles, amangrove swamp ecosystem along the coast, and an underwater coral reef ecosystem.Ecosystem components are so interconnected that a change in anyone component of anecosystem will cause subsequent changes throughout the system.

HOW ECOSYSTEM WORK

The living portion of an ecosystem s best described in terms of feeding levels known astrophic levels known as trophic levels. Green plants make up the first trophic level and areknown as primary producers. Plants are able to convert energy from the sun into food in aprocess known as photosynthesis. In the second trophic level, the primary consumers known as herbivores are animals and insects that obtain their energy solely by eating the


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green plants.The third trophic level is composed of the secondary consumers, flesh eating orcarnivores animals that feed on herbivores. At the fourth level are the tertiary consumers,carnivores that feed on other carnivores. Finally, the fifth trophic level consists of thedecomposers, organisms such as fungi and bacteria that break down dead or dying matterinto nutrients that can be used again.

Some or all of these trophic levels combine to form what is known as a food web, theecosystems mechanism for circulating and recycling energy and materials.

In addition to the exchange of energy, ecosystems are characterized by several othercycles. Elements such as carbon and nitrogen travel throughout the biotic and bioticcomponents or an ecosystem in processes known as nutrient cycles. For example,nitrogen traveling in the air may be snatched by a tree-dwelling, or epiphytic, lichen hatconverts it to a form useful to plants. When rain drips through the lichen and falls to theground, or the lichen itself falls to the forest floor, the nitrogen from the raindrops or thelichen is leached into the soil to be used by plants and trees.

And nitrogen travel throughout the biotic and biotic components or an ecosystem inprocesses known as nutrient cycles.

Another process important to ecosystems is the water cycle, the movement of water fromocean to atmosphere to land and eventually back to the ocean. An ecosystem such as aforest or wetland plays a significant role in this cycle by storing, releasing, or filtering thewater as it passes through the system.

Every ecosystem is also characterized by a disturbance cycle, a regular cycle of eventssuch as fires, storms, floods and landslides that keeps the ecosystem in a constant state ofchange and adaptation. Some species even depend on the disturbance cycle for survival

or reproduction. For example, longleaf pine forests depend on frequent low intensity firesfor reproduction. The cones of the trees, which contain the reproductive structures, aresealed shut with a resin that melts away to release the seeds only under high heat.

Our Natural Habitat

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