Ecology (Part-1) PDF

ECOLOGY (Part-1)  Introduction  Greek word “Oikos” meaning “home” and “logos” meaning “study”  Ecology: The study of organisms in their natural habitat interacting with their surroundings  Ecosystem: A self-regulating group of biotic communities...

ECOLOGY (Part-1)  Introduction  Greek word “Oikos” meaning “home” and “logos” meaning “study”  Ecology: The study of organisms in their natural habitat interacting with their surroundings  Ecosystem: A self-regulating group of biotic communities of species interacting with one another and with their non-living environment exchanging energy and matter  An ecosystem is an integrated unit consisting of interacting plants, animals and microorganisms whose survival depends upon the maintenance and regulation of their This PPT should biotic be used and as reference only.abiotic Reading booksstructures and functions. (mentioned in syllabus) is mandatory for the preparation of  Classification of ecosystem  Natural ecosystem  Aquatic o Fresh water Running water Standing water o Marine  Terrestrial o Grassland o Forest o Desert  Artificial / Engineered ecosystem This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  Structural unit  Biotic o The plants, animals and microorganisms present in an ecosystem form the biotic component. o These organisms have different nutritional behaviour and status in the ecosystems and are accordingly known as Producers or Consumers, based on how do they get their food This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of   Producers o They are mainly the green plants, which can synthesize their food themselves by making use of carbon dioxide present in the air and water in the presence of sunlight by involving chlorophyll, the green pigment present in the leaves, through the process of photosynthesis.  Photo-autotrophs- (auto=self; troph=food, photo=light)  Chemo-autotrophs (Nitrosomonas, Iron bacteria, Methanogens) o There are some microorganisms also which can produce organic matter to some extent through oxidation of certain chemicals in the absence of sunlight. o For instance in the ocean depths, where there is no sunlight, chemoautotrophic sulphur bacteria make use of the heat generated by the decay of radioactive elements present in the earth core and released in ocean depths. o They use this heat to convert dissolved hydrogen sulphide (H 2S) and carbon dioxide This PPT should be used as reference only. Reading books (mentioned(CO 2) intoisorganic in syllabus) mandatory compounds. for the preparation of   Consumers- All organisms which get their organic food by feeding upon other organisms are called consumers.  Herbivores- They feed directly on producers and hence also known as primary consumers. e.g. rabbit, insect, man.  Carnivores – They feed on other consumers. If they feed on herbivores they are called secondary consumers (e.g. frog)  if they feed on other carnivores (snake, big fish etc.) they are known as tertiary carnivores/consumers.  Omnivores - They feed on both plants and animals. e.g. humans, rat, fox, many birds.  Detritivores - They feed on the parts of dead organisms, wastes of living organisms, their cast-offs and partially decomposed matter e.g. beetles, termites, ants, crabs, earthworms etc. This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of   Decomposers o They derive their nutrition by breaking down the complex organic molecules to simpler organic compounds and ultimately into inorganic nutrients. o Various bacteria and fungi are decomposers. This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  Structural unit  Abiotic  The physical and chemical components of an ecosystem constitute its abiotic structure. It includes climatic factors, edaphic (soil) factors, geographical factors, energy, nutrients and toxic substances.  Physical  Climatic (Sunlight, temperature, humidity, rainfall, wind)  Edaphic (soil type, soil moisture, soil reaction)  Geographic (Latitude, longitude, Altitude)  Chemical  Major nutrients  Trace elements  Pollutants  Organic substances This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  FUNCTIONAL ATTRIBUTES Every ecosystem performs under natural conditions in a systematic way. It receives energy from the sun and passes it on through various biotic components and in fact, all life depends upon this flow of energy. Besides energy, various nutrients and water are also required for life processes which are exchanged by the biotic components within themselves and with their abiotic components within or outside the ecosystem. The major functional attributes of an ecosystems are as follows: (i) Food chain, food webs and trophic structure (ii) Energy flow (iii) Cycling of nutrients (Biogeochemical cycles) (iv) Primary and Secondary production (v) Ecosystem development and regulation This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  Food chain  Food chain is a series of groups of organisms called trophic levels, in which, there is repeated eating and eaten by so as to transfer food energy. The sequence of eating and being eaten in an ecosystem is known as food chain. All organisms, living or dead, are potential food for some other organism and thus, there is essentially no waste in the functioning of a natural ecosystem. Trophic Levels This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  Some common examples of simple food chains are:  Grass → grasshopper → Frog → Snake → Hawk (Grassland ecosystem)  Phytoplanktons → water fleas → small fish → Tuna (Pond ecosystem)  Lichens → reindeer → Man (Arctic tundra)  Each organism in the ecosystem is assigned a feeding level or trophic level depending on its nutritional status.  In the grassland food chain, grasshopper occupies the Ist trophic level, frog the IInd and snake and hawk occupy the IIIrd and the IVth trophic levels, respectively.  The decomposers consume the dead matter of all these trophic levels. This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  Types of Food Chain  Grazing food chain-It starts with green plants (primary producers) and culminates in carnivores  Grass  Rabbit  Fox  Algae  Water flea  Small fish  Big fish  Detrius food chain- It starts with dead organic matter which the detritivores and decomposers consume. Partially decomposed dead organic matter and even the decomposers are consumed by detritivores and their predators.  Dead organic matter  Fungi  Bacteria This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  o A large quantity of leaf material falls in the form of litter into the water. o The leaf fragments are eaten by saprotrophs. (Saprotrophs are those organisms which feed on dead organic matter). o These fallen leaves are colonized by small algae, which are also consumed by the saprotrophs or detritivores consisting of crabs, mollusks, shrimps, insect larvae, nematodes and fishes. o The detritivores are eaten by small carnivorous fishes, which is turn are eaten by large carnivorous fishes. Leaf litter → algae → crabs → small carnivorous fish → large carnivorous fish (Mangrove ecosystem) Dead organic matter → fungi → bacteria (Forest ecosystem) o Thus the grazing food chain derives its energy basically from plant energy while in the This PPT should be used as reference only. Reading books detritus (mentioned foodischain in syllabus) it isforobtained mandatory primarily the preparation of from plant biomass, secondarily from microbial  Food Web  Food web: A network of food chain.  Food web is an important conceptual tool for illustrating the feeding relationships among species within a community, revealing species interactions and community structure, and understanding the dynamics of energy transfer in an ecosystem.  In a linear food chain, if one species becomes extinct or one species suffers then the species in the subsequent trophic levels are also affected.  In a food web, on the other hand, there are a number of options available at each trophic level.  So if one species is affected, it does not affect other trophic levels so seriously. This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of   Significance of food chain and Food web  Energy flow  Nutrient cycles  Ecological balance (population size regulation)- The food chains also help in maintaining and regulating the population size of different animals and thus, help maintain the ecological balance.  Biomagnification  The process by which a compound (such as a pollutant or pesticide) increases its concentration in the tissues of organisms as it travels up the food chain This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  Case Study A build-up of DDT concentration : A striking case of biomagnification of DDT (a broad range insecticide) was observed when some birds like Osprey were found to suffer a sharp decline in their population. The young ones of these birds were found to hatch out in premature condition leading to their death. This was later found to be due to bio-magnification of DDT through the food chain. DDT sprayed for pest control was in very low concentration, but its concentration increased along the food chain through phytoplanktons to zooplanktons and then to fish which was eaten by the birds. The concentration of DDT was magnified several thousand times in the birds which caused thinning of shells in the birds eggs, causing death of the young ones. This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  Ecological pyramids  Graphic representation of trophic structure and function of an ecosystem, starting with producers at the base and successive trophic levels forming the apex is knows as an ecological pyramid. This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  Ecological pyramids  Pyramid of number - It represents the number of individual organisms at each trophic level. This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  Ecological pyramids Grassla Forest Parasitic food nd chain This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  Ecological pyramids  Pyramid of biomass  It is based upon the total biomass (dry matter) at each trophic level in a food chain.  The pyramid of biomass in a forest is upright in contrast to its pyramid of numbers.  This is because the producers (trees) accumulate a huge biomass while the consumers total biomass feeding on them declines at higher trophic levels, resulting in broad base and narrowing top. This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  Ecological pyramids  Pyramid of energy  The amount of energy present at each trophic level is considered for this type of pyramid.  Pyramid of energy gives the best representation of the trophic relationships and it is always upright. This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  Energy flow Universal energy flow model As the flow of energy takes place, there is a gradual loss of energy at every level, thereby resulting in less energy available at next trophic level as indicated by narrower pipes (energy flow) and smaller boxes (stored energy in biomass). The loss of energy is mainly the energy not utilized (NU). energy lost in locomotion, excretion etc. or it is the energy lost in respiration (R) which is for maintenance. The rest of the energy is used for production (P). This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  Energy flow Single channel energy flow model The flow of energy takes place in a unidirectional manner through a single channel of green plants or producers to herbivores and carnivores. This a model and illustrated the gradual decline in energy level due to loss of energy at each successive trophic level in a grazing food chain. This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  Energy flow  Double channel or Y- shaped energy flow model  In nature, both grazing food chain and detritus food chain operate in the same ecosystem.  In marine ecosystem where primary production in the open sea is limited and a major portion of it is eaten by herbivorous marine animals.  Therefore, very little primary production is left to be passed on to the dead or detritus compartment.  In a forest ecosystem the huge quantity of biomass produced cannot be all consumed by herbivores. This PPT should be used as reference only. Reading books (mentioned Rather,inasyllabus) large proportion of the is mandatory for thepreparation live biomass of  Nutrient cycles  Nutrients like carbon, nitrogen, sulphur, oxygen, hydrogen, phosphorus etc. move in circular paths through biotic and abiotic components and are therefore known as biogeochemical cycles.  The nutrients too move through the food chain and ultimately reach the detritus compartment (containing dead organic matter) where various micro-organisms carry out decomposition.  Various organically bound nutrients of dead plants and animals are converted into inorganic substances by microbial decomposition that are readily used up by plants This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of (primary producers) and the cycle starts afresh.  Nutrient cycles  Nitrogen Nitrogen is present in the atmosphere as N2 in large amount (78%) It is fixed either by the physical process of lightening or biologically by some bacteria and/or cyanobacteria (blue green algae) The nitrogen is taken up by plants and used in metabolism for biosynthesis of amino acids, proteins, vitamins etc. and passes through the food chain. After death of the plants and animals, the organic nitrogen in dead tissues is decomposed by several groups of ammonifying and nitrifying bacteria which convert them into ammonia, nitrites and nitrates, which are again used by plants. Some bacteria convert nitrates, into molecular nitrogen or N 2 which is released back into the atmosphere and the cycle goes on. This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  Nutrient cycles  Carbon  Carbon, in the form of carbon dioxide is taken up by green plants as a raw material for photosynthesis, through which a variety of carbohydrates and other organic substances are produced.  Through the food chain it moves and ultimately organic carbon present in the dead matter is returned to the atmosphere as carbon dioxide by microorganisms.  Respiration by all organisms produces carbon dioxide, while the latter is used up by plants.  In the recent years carbon dioxide levels have increased in the atmosphere due to burning of fossil fuels etc. – global warming This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  Nutrient cycles  Phosphorus  The reservoir of phosphorus lies in the rocks, fossils etc. which is excavated by man for using it as a fertilizer.  Farmers use the phosphate fertilizers indiscriminately and as a result excess phosphates are lost as run-off, which causes the problem of eutrophication or over nourishment of lakes leading to algal blooms.  A good proportion of phosphates moving with surface runoff reaches the oceans and are lost into the deep sediments.  Sea birds, playing an important role in phosphorus cycling.  Guano deposits on the coasts of Peru are very rich sources of P phosphorus This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  Production of biomass  Primary production  Biomass production using photosynthesis  Primary productivity of an ecosystem is defined as the rate at which radiant energy is converted into organic substances by photosynthesis or chemo-synthesis by the primary producers.  Primary production of an ecosystem depends upon the solar radiations, availability of water and nutrients and upon the type of the plants and their chlorophyll content.  Net primary production (NPP) and the respiratory loss (R) added to it gives the gross primary production (GPP).  NPP = GPP - R  Secondary production  Biomass production by consuming producers  The amount of organic matter stored by the herbivores or carnivores (in excess of respiratory loss) is known as secondary production.  The energy stored at consumer level for use by the next trophic level is thus defined as secondary production. This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of  To be continued… This PPT should be used as reference only. Reading books (mentioned in syllabus) is mandatory for the preparation of