Ecosystem_.pdf

NOTES Ecosystem © 2022, Aakash BYJU'S. All rights reserved Key Takeaways Types of ecosystem 1 Based on location Based on human interference 2 Ecosystem components Abiotic Biotic Ecosystem structure © 2022, Aakash BYJU'S. All rights reserved 3 Ecosystem functions 4 Productivity Decomposition Nutrient...

NOTES Ecosystem © 2022, Aakash BYJU'S. All rights reserved Key Takeaways Types of ecosystem 1 Based on location Based on human interference 2 Ecosystem components Abiotic Biotic Ecosystem structure © 2022, Aakash BYJU'S. All rights reserved 3 Ecosystem functions 4 Productivity Decomposition Nutrient cycling 5 Food chain Grazing food chain Energy flow Detritus food chain Food Web 6 7 © 2022, Aakash BYJU'S. All rights reserved 10% law Ecological pyramids 8 Pyramid of numbers Pyramid of biomass Pyramid of energy 9 Ecological successions Primary succession Nutrient cycle 10 Secondary succession 11 Ecosystem services Carbon cycle Phosphorus cycle Summary © 2022, Aakash BYJU'S. All rights reserved Ecosystem  Ecosystem is the functional unit of nature.  The term was coined by A.G. Tansley.  It is self-sustainable.  Organisms interact and use available resources, such as food, space, light, heat, water, air and shelter to survive.  Each population of organisms and the individuals within it interact in limited specific ways wherein they can derive benefit from other organisms.  Interactions between different organisms are numerous and are described according to their positive (beneficial), negative or neutral effect on each other.  The interactions between living things and their nonliving counterparts in the environment make up a total ecosystem.  Entire biosphere (global ecosystem) = sum of all local ecosystems. © 2022, Aakash BYJU'S. All rights reserved Types of Ecosystem  There are 2 types of ecosystem based on location: Terrestrial Land ecosystem Aquatic Water ecosystem © 2022, Aakash BYJU'S. All rights reserved Types of Ecosystem Natural ecosystem Man-made/Anthropogenic ecosystem Develops in nature without human interference Created and maintained by human beings Terrestrial Forest Aquatic Pond Desert Grassland © 2022, Aakash BYJU'S. All rights reserved Ocean Aquarium Crop fields Garden Did You Know!  Agriculture or agroecosystem is the first and largest man-made ecosystem.  It was formed for fulfilling the needs of the increasing human population. Agricultural crop fields © 2022, Aakash BYJU'S. All rights reserved Components of Ecosystem  Ecosystem is made up of biotic and abiotic components. Biotic components All living organisms © 2022, Aakash BYJU'S. All rights reserved Ecosystem Abiotic components Physical environment of living organisms Components of Ecosystem Temperature Water Abiotic factors Light Soil © 2022, Aakash BYJU'S. All rights reserved Components of Ecosystem Biotic factors Producers Consumers Secondary consumer/ Second order consumer Primary consumer/ First order consumer    Feeds directly on producers Also called herbivores Ex - grasshopper, cow, tadpoles, molluscs Decomposers    Feed on herbivores Also called primary carnivores Ex - spiders, lizards, hydra, frog Tertiary consumer/ Third order consumer    Top carnivore  Not eaten by any other organism Note:  Can exist at any level  E.g. - tiger, lion, panthers, peacock © 2022, Aakash BYJU'S. All rights reserved Feed on secondary consumers Also called secondary carnivores Ex - snake, large fishes Components of Ecosystem Producers Decomposers  Green photosynthetic plants  Saprophytic microorganisms  Also called autotrophs/transducers/con verters  Also called reducers as they are capable of decomposing dead organisms  Producers in terrestrial ecosystem - herbaceous, woody plants  Functions -  Producers in aquatic ecosystem - phytoplankton, algae, submerged plants Complex organic substrates Simple organic substrates © 2022, Aakash BYJU'S. All rights reserved o Brings about cyclic exchange of minerals between biotic and abiotic elements o Naturally replenishes soil with minerals Inorganic compounds Process of decomposition Components of Ecosystem The interaction of biotic and abiotic components results in physical structure that is characteristic for each type of ecosystem. Abiotic factors Biotic factors Physical structure © 2022, Aakash BYJU'S. All rights reserved Structure of Ecosystem Species composition Physical structure of ecosystem Stratification  Physical structure of ecosystem includes species composition and stratification. © 2022, Aakash BYJU'S. All rights reserved Structure of Ecosystem Stratification Species composition   Identification and listing of plants and animals in an ecosystem. Based on geography and climate – it differs from one ecosystem to another.  Vertical distribution of species at different levels  E.g. - Following subdivision are present in a forest o Top layer - Trees o Second layer - Shrubs o Bottom layer - Grasses and herbs Coral reef © 2022, Aakash BYJU'S. All rights reserved Grassland Function of Ecosystem Components Productivity - Synthesis of organic matter by producers Decomposition - Degradation of dead organic matter Nutrient cycling - Cycling minerals and nutrients Energy flow – Sequential process of movement of energy through the ecosystem © 2022, Aakash BYJU'S. All rights reserved Function of Ecosystem Components Productivity (Rate of biomass production) Primary productivity  Rate at which biomass is produced by producers during photosynthesis per unit area over a time period  Expressed in terms of weight as (gm/m2)/yr  Expressed in terms of energy as (kcal/m2)/yr © 2022, Aakash BYJU'S. All rights reserved Secondary productivity  Rate of formation of new organic matter by consumers Productivity Primary productivity is divided into: Gross primary productivity (GPP) Net primary productivity (NPP)  It is rate of production of organic matter during photosynthesis.  It is the organic matter available for consumption by the heterotrophs.  Plants use some of the GPP in respiration (R).  GPP – R = NPP © 2022, Aakash BYJU'S. All rights reserved  R = Respiratory loss Productivity Factors affecting primary productivity Photosynthetic capacity of producers Soil moisture Temperature Solar radiation available Availability of nutrients Reasons for low primary productivity of deep marine habitats  Low light which decreases further with depth  Limited nutrients - Most limiting nutrient of the marine ecosystem is nitrogen © 2022, Aakash BYJU'S. All rights reserved Productivity Some important terms  Community productivity = It is the rate of net synthesis and build up of organic matter by a community per unit time and area  Ecological efficiency = Energy converted into biomass at trophic level Energy present in biomass at lower trophic level  Photosynthetic efficiency = Gross primary productivity X 100 Incident total solar radiation  Net production efficiency = Net primary productivity Gross primary productivity © 2022, Aakash BYJU'S. All rights reserved X 100 X 100 Did You Know? Total biosphere productivity is approximately 170 tons Terrestrial Aquatic Productivity is 115 billion tons Productivity is 55 billion tons © 2022, Aakash BYJU'S. All rights reserved Decomposition  The process of breaking down complex organic matter into simpler compounds like nutrients, minerals, carbon dioxide and water is known as decomposition.  The complex materials are the dead plant remains such as leaves, bark, flowers and dead remains of animals, including faecal matter.  The complex materials constitute detritus, which is the raw material for decomposition. © 2022, Aakash BYJU'S. All rights reserved Decomposition - Fragmentation  Decomposition occurs in a stepwise manner starting from fragmentation.  The detritivores like earthworms, small insects etc., feed on the detritus (dry leaves) and break them down into smaller particles. This process is known as fragmentation. Detritus Earthworm Fragmentation © 2022, Aakash BYJU'S. All rights reserved Decomposition - Leaching  Water soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts. This process is called leaching. Detritus Fragmentation Leaching © 2022, Aakash BYJU'S. All rights reserved Decomposition - Catabolism Fungal, bacterial enzymes act on the detritus to degrade it into simple inorganic substances. This is catabolism. Detritus Fragmentation Leaching Catabolism © 2022, Aakash BYJU'S. All rights reserved These three processes occur simultaneously. Decomposition - Humification  During decomposition, accumulation of dark amorphous substance (as a thin layer) is called humification. The dark substance formed is called humus. Nutrient rich Colloidal in nature Catabolism Humus Humification Highly resistant to microbial action Extremely slow rate of decomposition © 2022, Aakash BYJU'S. All rights reserved Decomposition - Mineralisation  Humus is further degraded by action of microbes.  It releases inorganic substances from humus. Hence, this process is known as mineralisation. Catabolism Humification Mineralisation Mg H2O © 2022, Aakash BYJU'S. All rights reserved N H2O Cu Fe Ca Decomposition A tree grows in the soil Some are eaten by insects and other animals. Nutrients and energy enter food web. Fragmentation A green leaf falls to the ground Leaves partially consumed by decomposers such as fungi and bacteria. They begin to lose form and become litter Further, decomposition by earthworms, bacteria, soil, mites, fungi, etc. © 2022, Aakash BYJU'S. All rights reserved Detritus Some nutrients leach into soil by chemical action Leaching Catabolism Humification Organic rich soil Mineralisation Decomposition Nutrient immobilisation  Phenomenon in which inorganic nutrients in the soil are taken up by microbes in soil and converted into organic form by incorporation of nutrients in living microbes  Immobilised nutrients become available again for solubilisation after the death of microorganisms  Immobilisation protects nutrients from being washed out and lost from ecosystem © 2022, Aakash BYJU'S. All rights reserved What Affects Decomposition? 1. Climatic condition: Temperature, moisture Rate of decomposition is slower in cold and dry conditions. © 2022, Aakash BYJU'S. All rights reserved Rate of decomposition is faster in warm and moist conditions. What Affects Decomposition? 2. Aerobic and anaerobic conditions Rate of decomposition is faster in presence of oxygen. Rate of decomposition is slower in absence of oxygen. © 2022, Aakash BYJU'S. All rights reserved What Affects Decomposition? 3. Chemical composition of detritus O OH HO O HO NH HO O O NH O Chitin © 2022, Aakash BYJU'S. All rights reserved If chitin, lignin, tannins and cellulose are present in the detritus, the rate of decomposition is slow. H O OH n If water-soluble substances like sugars, nitrogenous compounds etc., are present in the detritus, the rate of decomposition is quicker. Nutrient Cycling Movement of nutrient elements through various components of an ecosystem is also known as nutrient/ biogeochemical cycle. Nutrient cycles are of two types Biogeochemical cycle Living organism Rocks, air and water © 2022, Aakash BYJU'S. All rights reserved Chemical processes Gaseous cycle Sedimentary cycle Have reservoir in the atmosphere E.g.- Carbon, oxygen and nitrogen cycles Have reservoir in the earth’s crust E.g.- Phosphorous and sulphur cycles Nutrient Cycling The function of the reservoir is to meet the deficit which occurs due to imbalance in the rate of influx and efflux of nutrients. Reservoir Efflux Factors affecting nutrient release Influx Soil © 2022, Aakash BYJU'S. All rights reserved Moisture pH Temperature Energy Flow  It is a sequential process of the movement of energy through a series of organisms in an ecosystem.  Sun is the only source of energy common to all ecosystems on Earth, except for deep sea hydrothermal vents. Incident solar radiation (100%) Photosynthetically active radiation (PAR) (Less than 50%) Energy loss (45-49%) Captured in photosynthesis (GPP) (1-5%) Respiratory loss (0.2-1%) NPP (0.8-4%) © 2022, Aakash BYJU'S. All rights reserved Absorbed by gases/water vapours; reflected by clouds; scattered by dust particles (More than 50 %) Sun-Source of Energy  50 per cent of all the sun’s radiation is Photosynthetically Active Radiation (PAR) 2-10% of PAR PAR Only 2-10% of PAR is captured by plants and photosynthetic bacteria © 2022, Aakash BYJU'S. All rights reserved Energy Flow  Energy from plants is transferred to other organisms.  Energy flow in an ecosystem is always unidirectional.  Herbs, shrubs and woody plants act as producers. o Green plants of the ecosystem are producers. o Examples: © 2022, Aakash BYJU'S. All rights reserved ▪ Forest ecosystem: Trees ▪ Aquatic Ecosystem: Phytoplanktons Energy Flow  All other organisms depend on plants (directly or indirectly) for their food needs.  Hence, they are called consumers and heterotrophs. o Herbivores are primary consumers. ▪ Animals that feed on producers ▪ Example: Terrestrial system: Insects, birds, deer etc. Aquatic system: molluscs, clams etc. o Primary carnivores are secondary consumers. ▪ Animals that feed on herbivores (indirectly feed on plants). ▪ Example: Fox feeding on deer. o Secondary carnivores are tertiary consumers. ▪ Animals that feed on primary carnivores (indirectly depend on plants). ▪ Example: Tiger feeding on fox. © 2022, Aakash BYJU'S. All rights reserved Food Chain  Chronological (organisms arranged order) series of organisms each depending on other for food.  Each level in a food chain where transfer of energy takes place is called trophic level.  Organisms of a trophic level depend on the organisms at the lower trophic level for their energy demands. Types of food chain Grazing food chain/ Predator food chain © 2022, Aakash BYJU'S. All rights reserved Detritus food chain/ Saprophytic food chain Parasitic food chain/ Auxiliary food chain Food Chain – Trophic levels 4th trophic level Top carnivores (Tertiary consumers) 3rd trophic level Carnivores (Secondary consumers) 2nd trophic level Herbivores (Primary consumers) 1st trophic level Producers © 2022, Aakash BYJU'S. All rights reserved Food Chain – Trophic levels 1st trophic level Fresh weight  Total biomass (mass of organic matter) of producers in a unit area = standing crop of producers © 2022, Aakash BYJU'S. All rights reserved Dry weight Biomass expressed in fresh or dry weight  Fresh weight is weight recorded immediately after the organism dies or part of an organism is harvested.  Dry weight is the weight of the organism or part of the organism after it has been dried. Food Chain – Trophic levels Standing crop of 4th trophic level  Standing crop refers to amount of living matter present in different trophic levels at a given time  Expressed in numbers or biomass of organisms per unit area Standing crop of 3rd trophic level Standing crop of trophic level 2nd Standing crop of 1st trophic level © 2022, Aakash BYJU'S. All rights reserved Grazing Food Chain Primary consumer Secondary consumer Deer Tertiary consumer Producer © 2022, Aakash BYJU'S. All rights reserved As an organism consumes another organism, the energy produced by producers is passed on to next organism.  Energy is gained from photosynthesis.  Such a food chain is known as grazing food chain. Fox Grazing Food Chain (GFC) Plants  Tiger Grazing Food Chain Grazing food chain (GFC) examples:  In aquatic ecosystem, GFC is major conduit of energy flow. Primary consumer Secondary consumer Rodent Clams Snake Tertiary consumer Producer Grains © 2022, Aakash BYJU'S. All rights reserved Hawk Secondary consumer Primary consumer Fish Tertiary consumer Producer Phytoplankton Shark Detritus Food Chain Bacteria and fungi Decomposers  Food chain where energy is obtained from dead organic matter  Begins with dead organic matter, followed by decomposers, detritivores and then their predators  In terrestrial ecosystems, a much larger fraction of energy flows through DFC than through GFC. Detritivores Earthworm Detritus food chain (DFC) Dead organic matter Sparrow Predators © 2022, Aakash BYJU'S. All rights reserved Detritus Food Chain 1st trophic level 2nd trophic level Heat Heat 20,000 kJ Heat 3rd trophic level 2,000 kJ Heat 4th trophic level Heat 200 kJ 5th trophic level Heat 20 kJ Heat Heat 6th trophic level Heat 2 kJ Heat 0.2 kJ Heat  Energy is lost in DFC as well.  Example: o Plants die without being consumed by animals. o Their biomass is not passed onto next consumer. o Decomposition of waste/dead matter leads to loss of energy in the form of heat. Decomposers © 2022, Aakash BYJU'S. All rights reserved Detritus Food Chain Decomposers  Decomposers are heterotrophic.  They are also known as saprotrophs (sapro = to decompose).  They meet their energy and nutrient requirements by degrading dead organic matter.  When an organism dies, decomposers secrete digestive enzymes that breakdown dead and waste materials into simple, inorganic materials.  They are subsequently absorbed by the decomposers. © 2022, Aakash BYJU'S. All rights reserved Bacteria Fungi Earthworm Detritus Food Chain Decomposers Earthworm (Detritivore) The earthworm, which is a detritivore, feeds on such bacteria, fungi and further decomposes detritus. © 2022, Aakash BYJU'S. All rights reserved Earthworms are eaten by small birds such as sparrows. Food Web  An animal may be eaten by different animals and thus, different food chains get interconnected, and one animal may be a link in more than one food chain.  Bear, fish, deer, fungi etc., are such organisms that lead to interconnection of food chains. Bear Hawk Fox Fish Rodent Deer Fruits © 2022, Aakash BYJU'S. All rights reserved Clams Fungi Earthworm Snake Sparrow Food Web Food web is a network of food chain interconnected to each other.  Food web is more real than food chain. o E.g. - Jackals are both carnivores and scavengers o E.g. - Sparrow is a primary consumer when it eats seeds but secondary consumers when it eats insects and worms  Food Web is essential for the stability of an ecosystem.  Provides opportunity for the endangered prey to recover its number. © 2022, Aakash BYJU'S. All rights reserved 10% Law  At every stage of organism's lifecycle, energy is lost to environment.  Example: o Excretion o Respiration Heat Heat Energy flow in ecosystem follows 1st law of thermodynamics It states that energy can neither be created nor destroyed, only altered in form. Energy is always conserved. © 2022, Aakash BYJU'S. All rights reserved 10% Law  Energy flow in the ecosystem follows the 2nd law of thermodynamics. o  It states that whenever energy is converted from one form to another, there is a tendency toward disorder (entropy) in the system or some of the energy is lost to environment. Thus, energy is lost to environment when it moves from one trophic level to other. © 2022, Aakash BYJU'S. All rights reserved 10% Law 20,000 kJ 1st trophic level 2,000 kJ 2nd trophic level 200 kJ 2 kj 20 kJ 0.2 kJ 3rd trophic level 4th trophic level 5th trophic level 6th trophic level 10% Law  10 percent of the energy is transferred to each trophic level from the lower trophic level  Proposed by Lindeman in 1942  Consequently, an ecosystem can support only a limited number of trophic level (3-5) © 2022, Aakash BYJU'S. All rights reserved Ecological Pyramids  It is the graphical representation of ecological parameters at the successive trophic levels of a food chain. Number of individuals Biomass Energy © 2022, Aakash BYJU'S. All rights reserved Ecological Pyramids  To constructs the ecological pyramids, all organisms at that trophic level should be included.  Trophic level represent functional levels.  One organism can occupy more than one trophic level simultaneously. Sparrow as secondary consumer when it eats insect Sparrow as primary consumer when it eats seed, fruit, etc © 2022, Aakash BYJU'S. All rights reserved Ecological Pyramids 01 Pyramid of numbers Pyramid of biomass Pyramid of energy © 2022, Aakash BYJU'S. All rights reserved 02 03 Ecological Pyramids Pyramid of numbers Upright Trophic levels Number of individuals Tertiary consumers (TC) 3 Secondary consumers (SC) 354,000 Primary consumers (PC) 708,000 Producers (P) 5,842,000 Pyramid of number in grassland ecosystem  The number of top carnivores is too small to support any other trophic level and they do not act as prey for any other organism. © 2022, Aakash BYJU'S. All rights reserved Ecological Pyramids Pyramid of numbers  Trophic levels Upright o If the number of insects feeding on a big tree are counted, then inverted pyramid is obtained. Large birds (TC) Small birds (SC) Insects (PC) One big tree (P) Pyramid of number on a big tree ecosystem © 2022, Aakash BYJU'S. All rights reserved There are exceptions to this generalization: Inverted o The number of small birds depending on the insects are less and the number of larger birds eating the smaller birds are few, then upright pyramid is obtained. Ecological Pyramids Pyramid of biomass Upright Trophic levels Dry weight (Kg m-2) Tertiary consumers (TC) 1.5 Secondary consumers (SC) 11 Primary consumers (PC) 37 Producers (P) 809 Pyramid of biomass in forest ecosystem  Pyramid of biomass in terrestrial ecosystems is usually upright. © 2022, Aakash BYJU'S. All rights reserved Ecological Pyramids Pyramid of biomass  Trophic levels Inverted Large fishes (TC) Small fishes (SC) Zooplankton (PC) Phytoplankton (P) Pyramid of biomass in aquatic ecosystem However, a different shape of the pyramid of biomass can be seen in aquatic habitats o The pyramid of biomass in sea is generally inverted because the biomass of fishes far exceeds that of phytoplankton. o The producers are very small and have limited biomass, they also reproduce and die quickly. o So, there is less biomass of producers at any given time compared to consumers. © 2022, Aakash BYJU'S. All rights reserved Ecological Pyramids Pyramid of energy  Pyramid of energy is always upright, it can never be inverted, because when energy flows from a particular trophic level to the next trophic level some energy is always lost as heat at each step.  Primary producers convert only 1% of the energy in the sunlight available to them into NPP.  Each bar in the energy pyramid indicates the amount of energy present at each trophic level in a given time or annually per unit area. © 2022, Aakash BYJU'S. All rights reserved Ecological Pyramids Pyramid of energy Always Upright Trophic levels Energy (J) Tertiary consumers (TC) 10 Secondary consumers (SC) 100 Primary consumers (PC) 1000 Producers (P) 10,000 Pyramid of energy in any ecosystem © 2022, Aakash BYJU'S. All rights reserved Limitations of Ecological Pyramids 1 2 3 Does not account for same species belonging to more than one trophic level Does not accommodate food web; assumes simple food chain No place in ecological pyramids for saprophytes © 2022, Aakash BYJU'S. All rights reserved Ecological Succession  It is the gradual and fairly predictable changes in the species composition of a given area.  This change is orderly and sequential.  Succession and evolution are ideally parallel processes. Based on area of origin Primary succession It occurs in an area which has been bare from the beginning. © 2022, Aakash BYJU'S. All rights reserved Secondary succession It occurs in an area where natural biotic communities have been destroyed. Primary Succession Succession starts in an area where there are few or no living organisms (barren area).  Newly exposed sea floor  Newly cooled lava sediments  Newly created pond or reservoir  Bare rock Pioneer species is the first biotic community which develops in a bare area. E.g. - Lichens on rocks, phytoplankton and zooplanktons in a new pond. Bare area with only rocks © 2022, Aakash BYJU'S. All rights reserved Grasses and small plants begin to appear Bigger plants begin to appear Primary Succession Sere Seral stage/Community  It is the entire sequence of communities that successively change in an area. E.g. bryophytes, herbs, shrubs, on a bare rock.  They are the individual transitional communities.  Following things occur during different seral stages: o Diversification of species o Increase in number of species o Increase in total biomass Bigger plants begin to appear © 2022, Aakash BYJU'S. All rights reserved Trees begin to appear Climax Community It is the last community that forms as a result of ecological succession which is relatively stable and is in near equilibrium with the environment. E.g. : Forests © 2022, Aakash BYJU'S. All rights reserved Secondary Succession Secondary succession is recolonization of habitats (of plants and animals) after major disturbances like: © 2022, Aakash BYJU'S. All rights reserved Abandoned farmland Flooded land Deforested land Forest fire Secondary Succession  After disturbances, all the vegetation is lost, only soil is left.  Small plants like grasses slowly start growing here.  Later, bigger plants like shrubs appear.  With time, trees appear to reach the climax community. o Example : Forest Grasses and small plants begin to appear © 2022, Aakash BYJU'S. All rights reserved Bigger plants begin to appear Climax community Ecosystem characteristics that Change During Succession Change in diversity of species - Some species colonise an area and their populations become more numerous, whereas populations of other species decline and even disappear Little diversity to high degree of diversity - Increase in the number of species Total biomass increases Increase in humus content of soil Aquatic or dry conditions to mesic conditions - Both hydrarch and xerarch successions lead to medium water conditions (mesic), neither too dry (xeric) nor too wet (hydric) Vegetational changes - This in turn affect food and shelter for various types of animals. Thus, as succession proceeds, the number and types of animals and decomposers also change © 2022, Aakash BYJU'S. All rights reserved Xerarch Succession Stage I - Lichen stage  Lichen are symbiotic association of (algae) photobionts and mycobionts (fungi).  They are pioneer species.  They can tolerate desiccation, excessive heat and cold temperatures.  They secrete acids to dissolve rock to form soil. This process is called weathering. Bare rocks without water Stage II - Moss stage  Mosses help in further weathering as their rhizoids can penetrate deeper.  This leads to accumulation of more soil and organic matter which can retain more moisture. © 2022, Aakash BYJU'S. All rights reserved Growth of moss on rocks Xerarch Succession Stage III - Grass stage  The roots of grasses penetrate the rocks and contribute to weathering.   They provide shade to small animals. Accumulates soil and moisture helps in germination of seeds of annual grasses and herbs Growth of grass and shrubs Stage IV - Shrub stage  The roots of shrubs penetrate the rocks and contribute to weathering.  They provide shade for larger animals. Stage V – Forest/Climax stage  Trees begin to grow.  The land can turn into coniferous, deciduous or temperate forest. © 2022, Aakash BYJU'S. All rights reserved Forest Hydrarch Succession Stage I - Plankton stage  Phytoplanktons and zooplanktons are the pioneer species.  The death of these organisms provide organic matter. Stage II - Submerged plant stage  Submerged plants are rooted in the bottom mud layer.  The death of these organisms provide organic matter.  Water becomes shallower. Growth of phytoplanktons Submerged plants © 2022, Aakash BYJU'S. All rights reserved Hydrarch Succession Stage III - Submerged free-floating plant stage  Free floating plants provide minerals and organic matter.  The water becomes shallower on the periphery. Stage IV – Reed-swamp stage  Amphibious plants start to grow.  They transpire large amounts of water.  They produce organic matter.  Their tangled roots accumulate silt. Submerged free-floating plants Amphibious plants © 2022, Aakash BYJU'S. All rights reserved Hydrarch Succession Stage V – Marsh-meadow stage Reed-swamp stage is invaded by marshy plants. Pond becomes shallower due to deposition until it gets transformed into terrestrial habitat. Stage VI - Scrub stage  Shrubs can tolerate sunlight and water-logged conditions.  They transpire large amounts of water.  They add organic matters to bottom layer. Shrubs Stage VI - Forest stage  This is the climax stage.  Trees begin to grow.  The land can turn into coniferous, deciduous or temperate forest. © 2022, Aakash BYJU'S. All rights reserved Forest Nutrients  Organisms need a constant supply of nutrients to grow, reproduce and regulate various body functions.  Numerous different nutrients are needed to sustain life.  However, the most essential ones are carbon, hydrogen, oxygen, phosphorus and sulphur- in short also known as "CHNOPS“.  Along with them there are other nutrients needed like calcium, potassium, sodium, etc. Nutrients required to Grow H 1 1.008 Hydrogen S 16 32.06 Sulfur P 16.00 Oxygen 15 30.97 Phosphorus © 2022, Aakash BYJU'S. All rights reserved O 8 N 15 14.01 Nitrogen C 6 12.01 Casrbon Standing State The amount of nutrients such as carbon, nitrogen, phosphorous, calcium, etc., present in the soil at any given time, is referred to as standing state.  The amount of nutrients vary in different kinds of ecosystem.  The amount of nutrients vary on a seasonal basis. Pond Ocean © 2022, Aakash BYJU'S. All rights reserved Desert Grassland Forest Gaseous Cycles Carbon cycle  Carbon is important element found in all the living beings.  Carbon constitutes 49% dry weight of organisms.  Carbon cycle occurs through atmosphere, ocean and through living and dead organisms.  Atmosphere is the reservoir for gaseous nutrient cycle. Atmosphere (Reservoir) Living organisms Ocean © 2022, Aakash BYJU'S. All rights reserved Gaseous Cycles Carbon cycle  Carbon is present in atmosphere in the form of carbon dioxide.  Only 1% of the global carbon is found in the atmosphere.  71% of carbon is present in dissolved form in the ocean.  Some of the remaining carbon dioxide is captured by plants. © 2022, Aakash BYJU'S. All rights reserved Gaseous Cycles Carbon cycle  Carbon from atmosphere reaches plants in the form of carbon dioxide which is converted to glucose by photosynthesis.  Animals get the required carbon through plants. o Primary consumers like deer feed on plants to get the carbon. o Carnivores like tiger feed on deer.  When these animals and plants die, decomposers release carbon.  Decomposers act on decomposing and decaying matter, further contributing to the release of carbon dioxide.  Carbon is released back as Carbon dioxide majorly through respiratory activities of producers and consumers. © 2022, Aakash BYJU'S. All rights reserved CO2 in atmosphere Photosynthesis (terrestrial food chain) Burning of forest fuelwood and organic debris Detritus food chain Oil and Gas Limestone and Dolomite Coal Gaseous Cycles Carbon cycle  In addition to the above, burning of wood, forest fire and combustion of organic matter, fossil fuels, volcanic activity are other sources which release carbon dioxide into the atmosphere.  Carbon cycle’s part on land ends here. Carbon cycle occurs through oceans as well. CO2 in atmosphere Photosynthesis (terrestrial food chain) Burning wood and fossil fuels Burning of forest, fuel, wood and organic debris Volcanic activity Detritus food chain Oil and Gas Limestone and Dolomite © 2022, Aakash BYJU'S. All rights reserved Forest fires Coal Gaseous Cycles Carbon cycle  In oceans, carbon dioxide is captured by underwater plants, seaweeds and phytoplankton.  These producers are eaten by smaller fishes, which in turn are eaten by larger fishes.  Carbon is transferred from one organism to another when one feeds on the other.  Some of the carbon dioxide is released back into the atmosphere when these organisms respire. © 2022, Aakash BYJU'S. All rights reserved 71% of global carbon is found dissolved in oceans 71% of global carbon Gaseous Cycles Carbon cycle  Further, when these organisms die, decomposers present in the ocean decompose them.  Some of the carbon is released as carbon dioxide  Shells and skeleton of these organisms get deposited in the deep ocean to form calcareous sediments.  Thus, some amount of the fixed carbon is lost to sediments and removed from circulation. © 2022, Aakash BYJU'S. All rights reserved Gaseous Cycles Complete carbon cycle CO2 in atmosphere Photosynthesis (terrestrial food chain) Burning of forests, fuel, wood and organic debris Respiration and decomposition Plankton photosynthesis (aquatic food chains) Coal Detritus food chain CO2 in water Decay organism Calcareous sediments © 2021, BYJU'S. All rights reserved © 2022, Aakash BYJU'S. All rights reserved Organic sediments Oil and Gas Limestone and Dolomite Carbon Cycle  Carbon cycle maintains and balances total amount of global carbon.  However, human activities have significantly affected the carbon cycle.  Human activities have increased the rate of release of CO2, thereby causing increase in the global temperature.  CO2 Total amount of global carbon For example: o Rapid deforestation o Massive burning of fossil fuels for energy and transport. Increase in global temperature © 2022, Aakash BYJU'S. All rights reserved Carbon Cycle Primary production and respiration CO Biotic and abiotic components CO2 release CO2 absorption CO2 release due to human activities 2021, BYJU'S. AllBYJU'S. rights reserved © 2022, Aakash All rights reserved 2 CO 2 Fossil fuel combustion and industrial processes Ocean Changing land-use Phosphorus Cycle  Phosphorus is another biologically important element.  It is a major constituent of different biological membranes, ATP molecules, nucleic acids.  ATP Cell membrane Nucleic acids 30.97 Phosphorus They are also required in large quantities to make bones and teeth, as well as shells in certain animals. Bones and teeth © 2022, Aakash BYJU'S. All rights reserved P 15 Shells of certain animals Phosphorus Cycle Rocks are major natural reservoir of phosphorus. Minute amounts of phosphate is released into the soil solution when rocks undergo weathering.   POP₄ ³⁻ POP₄ ³⁻ POP₄ ³⁻ POP₄ ³⁻ POP₄ ³⁻ POP₄ ³⁻ POP₄ ³⁻ POP₄ ³⁻ POP₄³ ⁻ POP₄ ³⁻ POP₄ ³⁻ POP₄ ³⁻ POP₄ ³⁻ POP₄ ³⁻ POP₄ ³⁻ POP₄ ³⁻ POP₄ ³⁻ POP₄ ³⁻ POP₄ ³⁻ POP₄ ³⁻ PO₄³⁻ POP₄ ³⁻ POP₄ ³⁻ Phosphorus occurs as phosphate in rocks © 2022, Aakash BYJU'S. All rights reserved PO₄³⁻ PO₄³⁻ PO₄³⁻ Phosphorus Cycle  The released phosphate gets dissolved into the soil solution and also get leached into surface water. © 2022, Aakash BYJU'S. All rights reserved  The dissolved phosphate present in the soil is absorbed by the plants. Phosphorus Cycle  Herbivores and other animals obtain phosphorus by consuming plants. © 2022, Aakash BYJU'S. All rights reserved  After the animals die, they along with other waste products are decomposed by the phosphatesolubilising bacteria in the soil.  Phosphate-solubilising bacteria release phosphorous again into the soil. Phosphorus Cycle Consumers Weathering of rock minerals Producers PO₄³⁻ PO₄³⁻ PO₄³⁻ PO₄³⁻ PO₄³⁻ PO₄³⁻ PO₄³⁻ PO₄³⁻ PO₄³⁻ PO₄³⁻ Phosphorus in soil solution PO₄³⁻ PO₄³⁻ Runoff Phosphate solubilising bacteria act on detritus © 2022, Aakash BYJU'S. All rights reserved Phosphorus Cycle Consumers Phosphate solubilising bacteria act on detritus Decomposition Phosphorus in soil solution Weathering of rock minerals © 2022, Aakash BYJU'S. All rights reserved Producers Litter fall Uptake Runoff Ecosystem Services They are the products of ecosystem processes which are beneficial to humans. Ecosystem services © 2022, Aakash BYJU'S. All rights reserved Ecosystem Services Among the products of ecosystem processes, soil formation is the most beneficial ecosystem service to humans. 60 50 Percentage of service 40 30 20 10 0 Soil formation Climate regulation Habitat for wildlife Service © 2022, Aakash BYJU'S. All rights reserved Recreation Summary  Ecosystem - It is the functional unit of nature which is self - sustainable. Types of ecosystems (based on location) Terrestrial Aquatic Types of ecosystems (based on presence/absence of human interference) Natural © 2022, Aakash BYJU'S. All rights reserved Anthropogenic Summary Structure of ecosystem Temperature Producers Consumers Biotic factors Decomposers Abiotic factors Water Light Soil © 2022, Aakash BYJU'S. All rights reserved Summary Energy flow Productivity Functional aspects of ecosystem Decomposition Nutrient cycling © 2022, Aakash BYJU'S. All rights reserved Summary Detritus Decomposition © 2022, Aakash BYJU'S. All rights reserved Dead remains of plant and animal including faecal matter Fragmentation Detritivores break detritus into small particles Leaching Soluble inorganic nutrients go down into soil as salts Catabolism Degradation of detritus by fungal and bacterial enzymes Humification Accumulation of dark amorphous substance named humus Mineralisation Degradation of humus by action of microbes Summary Grazing food chain © 2022, Aakash BYJU'S. All rights reserved Detritus food chain Producer - Plant Dead organic matter Primary consumer - Deer Earthworm Secondary consumer - Fox Sparrow Tertiary consumer - Tiger Hawk Summary Ecological pyramid Pyramid of biomass Pyramid of numbers   In grassland ecosystem, it is upright. In a big tree ecosystem, it is upright and inverted. © 2022, Aakash BYJU'S. All rights reserved   In forest ecosystem, it is upright. In aquatic ecosystem, it is inverted. Pyramid of energy  It is always upright and can never be inverted. Summary Based on plant habitat Based on area of origin Xerarch succession Primary succession It occurs in an area which has been bare from the beginning Secondary succession It occurs in an area where natural biotic communities have been destroyed. © 2022, Aakash BYJU'S. All rights reserved Ecological succession It is the gradual and predictable change in the species composition of a given area. Ecological succession in dry areas.  Lichen stage  Moss stage  Grass stage  Scrub stage  Forest stage Hydrarch succession Ecological succession in wet areas.  Plankton stage  Submerged plant stage  Submerged free-floating plant stage  Reed swamp stage  Marsh meadow stage  Scrub stage  Forest stage Summary Primary v/s Secondary succession Primary succession Secondary succession Occurs in barren area Occurs where natural biotic communities have been destroyed Soil is absent and is formed during the course of succession Some soil and microbes are present Pioneer communities (initial species) are migrants Pioneer communities (initial species) are already present Many seral communities are formed Fewer seral communities are formed Takes 1000 years or more Takes 50-200 years or more © 2022, Aakash BYJU'S. All rights reserved Summary Carbon cycle Phosphorus cycle Gaseous type of cycle Sedimentary type of cycle Involves respiratory release into the atmosphere Doesn’t involve respiratory release into the atmosphere Atmospheric inputs of carbon are higher Atmospheric inputs of phosphorous are much lower Involves gaseous exchange between organism and environment Absorbed by plants from soil through roots and then passed on to consumers © 2022, Aakash BYJU'S. All rights reserved