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Home , Abiotic component, Ecological pyramid, Ecology, Ecosystem ecology

UNIT 2: AND

•Concept of ecology and , and of ecosystem; flow in an ecosystem; chains, food webs; Basic concept of and ecology; . •Characteristic features of the following: a) Forest ecosystem b) Grassland ecosystem c) ecosystem d) Aquatic ecosystems (, streams, lakes, , rivers, , )

ECOLOGY: Ecology (from the Greek “oikos” meaning "house" or "dwelling", and “logos” meaning "to study") is the study of the interactions of with each other and their environment. The hierarchy define each of the following. ~~ population ~ community ~ ecosystem ~

AUTECOLOGY & SYNECOLOGY: Autecology & Synecology are two main branches of ecology. Autecology is the study of individual or individual species. It is also known as . Synecology is the study of group of organisms of different species which are associated together as a unit in form of a community.

Levels of Ecological Study ORGANISMAL ECOLOGY - the study of individual organisms' behavior, , morphology, etc. in response to environmental challenges.

POPULATION ECOLOGY - the study of factors that affect and change the size and genetic composition of of organisms.

COMMUNITY ECOLOGY - the study of how community structure and are changed by interactions among living organisms

ECOSYSTEM ECOLOGY - the study of entire ecosystems, including the responses and changes in the community in response to the abiotic components of the ecosystem. This is concerned with such large-scale topics as energy and cycling.

LANDSCAPE ECOLOGY – study of the exchanges of energy, materials, organisms and other products of between ecosystems.

GLOBAL ECOLOGY - the study of the effects of regional change in energy and exchange on the function and distribution of organisms across the biosphere.

ECOSYSTEM: An ecosystem is a large community of living organisms (, and microbes) in a particular area. The living and physical components are linked together through nutrient cycles and energy flows. Ecosystems are of any size, but usually they are in particular places.

STRUCTURE OF AN ECOSYSTEM: An ecosystem consists of 2 components: 1. Abiotic components - The non living factors or the physical environment prevailing in an ecosystem form the abiotic components. They have a strong influence on the structure, distribution, behaviour and inter-relationship of organisms. Abiotic favtors are light, , , , topography, etc. Abiotic components are mainly of two types: Climatic Factors: Which include , temperature, light, , humidity etc. Edaphic Factors: Which include , pH, topography etc.

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2. Biotic Components: The living organisms including plants, animals and micro-organisms ( and Fungi) that are present in an ecosystem form the biotic components.

On the basis of their role in the ecosystem the biotic components can be classified into three main groups: Producers Consumers or Reducers.

Producers: The green plants have chlorophyll with the help of which they trap and change it into chemical energy of using simple inorganic compounds namely water and dioxide. This process is known as . As the green plants manufacture their own food they are known as (i.e. auto = self, trophos = feeder) The chemical energy stored by the producers is utilised partly by the producers for their own growth and survival and the remaining is stored in the parts for their future use.

Consumers: The animals lack chlorophyll and are unable to synthesise their own food. Therefore, they depend on the producers for their food. They are known as (i.e. heteros = other, trophos = feeder) The consumers are of four types, namely:

Primary Consumers or First Order Consumers or : These are the animals which feed on plants or the producers. They are called herbivores. Examples are rabbit, deer, goat, cattle etc.

Secondary Consumers or Second Order Consumers or Primary : The animals which feed on the herbivores are called the primary carnivores. Examples are cats, foxes, snakes etc.

Tertiary Consumers or Third Order Consumers:These are the large carnivores which feed on the secondary consumers. Example are Wolves.

Quaternary Consumers or Fourth Order Consumers or :These are the largest carnivores which feed on the tertiary consumers and are not eaten up by any other . Examples are lions and tigers.

Decomposers or Reducers: Bacteria and fungi belong to this category. They breakdown the dead organic materials of producers (plants) and consumers (animals) for their food and release to the environment the simple inorganic and organic substances produced as by-products of their .

These simple substances are reused by the producers resulting in a cyclic exchange of materials between the biotic community and the abiotic environment of the ecosystem. The decomposers are known as Saprotrophs (i.e., sapros = rotten, trophos = feeder)

Ecosystem

Abiotic components Biotic components

Climatic Factors Edaphic Factors Producers Consumers Decomposers (Autotrophs) (Heterotrophs) (Saprotrophs) Rain Soil Primary Light pH Secondary Wind Minerals Tertiary Temperature Topography Quaternary

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FUNCTIONS OF AN ECOSYSTEM: In the ecosystem, biotic components and other materials like N, C, H2O Circulated within and outside of the .

The energy is transferred from one tropic level to the other in the form of a chain called as .

The important source of energy is the sun.

Some factors which are responsible for high . for example high temperature and rainfall accelerate and of dead organic matter.

Climatic changes is the functioning of ecosystem

Effects of local and regional shifts of energy, materials and populations on ecosystems and economic of rational use of ecosystem.

Production, consumption and decomposition are important functions of ecosystem.

Production: "Conservancy of solar energy into " Every year about 100 billion tones of organic matter is produced on the by "Photosynthetic organisms".

Photosynthesis by Green plants The plants capture the solar energy and converted into through the process of photosynthesis Chlorophyll 6 CO2 + 12 H2O C6H12O6 + 6O2 + 6H2 O

The Presence of chlorophyll in the plants absorbs sun light, CO2 and water to prepare carbohydrate and liberate .

Composition (Consumption): It is the process of transfer of material and transformation of energy from one tropic level to another through the process of eating and being eaten.

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Decomposition: It is a process in which complex compounds are broken into simpler compounds. The simple compounds can be utilizes for plants growth. This process is done by bacteria and fungi. In ecosystem dead bodies are decomposes by bacterial action.

ENERGY FLOW IN AN ECOSYSTEM An ecosystem comprises biotic and abiotic components which interact extensively with each other. Based on their ecological roles, the biotic components of an ecosystem can be classified as:

Producer: they are the green plants which absorb solar energy to synthesize complex organic compounds from simple inorganic substances by photosynthesis, they act as the ultimate food source to all the heterotrophs. The other producers are green and blue green algae, they are mainly found in aquatic , such as freshwater and marine water, they are the most important producers in earth (as 70% of the earth surface is covered with water).

Consumer: they are heterotrophs which ingest other organisms or organic , they are mainly animals primary : they are the herbivores which feed on plants e. g. snail, insect larva and secondary consumer : they are the carnivores which feed on primary consumers e. g. water beetles, tigers, etc. tertiary consumer : they are large carnivores which feed on the secondary and primary consumers as well as producers, e. g. man consumer : they are ( detritus feeder / ) which feed on detritus that refer to the particulate organic matter involved in the decomposition of dead organisms, e. g. earthworm and crab etc.

Decomposer: they are mainly bacteria, fungi and some flagellates, by means of their saprophytic activities; they decompose the eliminated products of animals and the dead bodies of the organisms into simple compounds, these compounds are absorbed as nutrients by the green plants again they enable the nutrients to be used continuously in a cyclic form in the ecosystem. They are most abundant in the soil or water bottom where the dead bodies of plant and animals accumulate when the temperature conditions are favourable, decomposition occurs rapidly

Energy and essential materials are therefore transferred from producers to consumers through the feeding processes. Eventually, decomposers break down the organic matter and release inorganic materials back to the environment. These inorganic materials are used by the producers as nutrients again.

Food chain: the transfer of from producers through a series of organisms with repeated eating and being eaten Ecosystem Producer Primary Secondary Tertiary consumer consumer consumer freshwater pond green algae mosquito larva fish rocky pond weeds molluscs sea birds

Grassland grass grasshopper lizard snake Woodland green plants caterpillars sparrow hawk

Food web: In general, the food chains in an ecosystem are not isolated, but are interconnected with one another; i. e. an may feed on several species of plants, and/ or be consumed by many consumers and so on, such a number of interconnected food chains is known as .

Trophic level: organisms in a food chain occupy different trophic levels, which indicate their place in the through the community; organisms whose food is obtained from plants by the same number of steps in the food chain belong to the same

Producers- first trophic level Primary consumers - second trophic level

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Secondary consumers- third trophic level Tertiary consumers - fourth trophic level

Energy flow in the ecosystem Productivity: Refers to the amount of energy or living materials fixed in a population, or a trophic level, or an entire ecosystem in a given Gross primary productivity: rate of dry matter production by photosynthesis in an ecosystem, it does not represent the actual amount of food potentially available to heterotrophs because some of the organic are used to meet plant respiration and .

Net primary productivity: it is the which is incorporated into a during a specific time intervals, minus the part respired Secondary productivity: it is the rate of incorporation of biomass at the consumer levels during a specific time interval. Production is the difference in biomass within a certain time interval.

Energy flow: As solar passes through the biosphere, large parts are used to perform other functions; only small parts can be used in photosynthesis.

Energy Dissipation Percent / % Reflected 30 Direct conversion to heat 46 Evaporation, precipitation (drives hydrological cycle) 23 Wind, waves and currents 0.2 Photosynthesis 0. 8 Total 100

Pyramid of energy: at each transfer of energy from one trophic level to the next higher, there is always a loss of energy from the system: energy transformation is never 100% efficient and the living organisms in each trophic level required certain amount of energy for maintaining basal metabolic rate, for growth and and movement, it overcomes the difficulty encountered in pyramids of number and biomass, i. e. inverted pyramid never occurred here it shows the total amount of energy utilized by the organisms in different trophic level in a square metre, over a given period of time, i .e. it shows the amount of new tissues of organisms produced in a unit time (productivity).

BASIC CONCEPT OF POPULATION AND COMMUNITY ECOLOGY: Levels of Individual Population – same species, same time, same area

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Community – all the different populations in an area Ecosystem – all the different plus the abiotic factors in an area Biosphere – all areas on Earth where exists

Basic population characteristics = total number of individuals (N) = number of individuals per unit of area n Helps us understand if the species is rare or abundant Population distribution = how individuals are spaced relative to others in the population Random – no pattern of location ( in a forest) n Uniform – fairly even spacing (nesting birds) Clumped – individuals gather around each other (schooling fish) n Population sex ratio = the ratio of males to females Usually 50:50 Population increase is related to the number of females Population age structure = the number of individuals in each age category

Factors that influence population size Density-dependent factors Influence an individual’s odds of survival in a manner that depends on the size of the population Example: available food These factors are also called limiting The population limit in an ecosystem is its Density-independent factors Have the same effect on an individual’s odds of survival regardless of the size of the population Example: a Carrying capacity – this is overshoot followed by die-off Community Interactions… - the use of one species as a by another Four categories: True predators – kill and eat their prey Herbivores – consume plants as prey; typically only eat some of the plant; rarely kill the plant Parasites – live on or in a organism; rarely causes the death of their host Pathogen – disease-causing parasite & – lay eggs inside another organism

Mutualism – two species interacting in a way that increases the survivability of both Plants and the insects that pollinate them nAcacia trees and – one species benefits from an association with another but the other is not helped nor harmed Birds nesting in trees

Keystone Species: The species on which the ecosystem stability depends – removing it leads to instability: Food supply species (figs) Predator-mediated – the predator keeps the numbers of the superior competitor in check. Without the predator, the competitor over-populates the ecosystem (sea stars) Ecosystem engineers – create habitat for other species ()

CHANGES IN COMMUNITIES OVER TIME (ECOLOGICAL SUCCESSION) Ecological succession – predictable replacement of one group of species by another, Two types: 1. Primary succession – occurs only on surfaces without any soil (new volcanic area; abandoned parking lot) 2. Secondary succession – occurs in disturbed areas that have not lost their soil – the original vegetation has been removed as in a forest or even abandoned farmland

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Pioneer species – plants that are able to colonize new areas at the early stages of succession. They grow rapidly and need lots of – the later stages of succession. Generally considered to be the ‘typical’ type of community for that The Major Points: The species living in a particular place gradually change over time as does the physical and chemical environment within that area. Succession takes place because through the processes of living, growing and reproducing, organisms interact with and affect the environment within an area, gradually changing it. Each species is adapted to thrive and compete best against other species under a very specific set of environmental conditions. If these conditions change, then the existing species will be outcompeted by a different set of species which are better adapted to the new conditions. The most often quoted examples of succession deal with plant succession. It is worth remembering that as plant community’s change, so will the associated micro-organism, and animal species. Succession involves the whole community, not just the plants. Change in the plant species present in an area is one of the driving forces behind changes in animal species. This is because each plant species will have associated animal species which feed on it. The presence of these herbivore species will then dictate which particular carnivores are present. The structure or 'architecture' of the plant communities will also influence the animal species which can live in the microhabitats provided by the plants. Changes in plant species also alter the fungal species present because many fungi are associated with particular plants. Succession is directional. Different stages in a particular habitat succession can usually be accurately predicted. These stages, characterised by the presence of different communities, are known as 'seres'. Communities change gradually from one sere to another. The seres are not totally distinct from each other and one will tend to merge gradually into another, finally ending up with a 'climax' community. Succession will not go any further than the climax community. This is the final stage. This does not however, imply that there will be no further change. When large organisms in the climax community, such as trees, die and fall down, then new openings are created in which secondary succession will occur. Many thousands of different species might be involved in the community changes taking place over the course of a succession. For example, in the succession from freshwater to climax woodland. The actual species involved in a succession in a particular area are controlled by such factors as the and history of the area, the , microclimate, , and other environmental factors. For example, the species involved in a succession from open freshwater to climax woodland in Central , would be quite different to those which have been quoted in these pages as occurring in Britain. However, the processes involved would be the same. Succession occurs on many different timescales, ranging from a few days to hundreds of years. It may take hundreds of years for a climax woodland to develop, while the succession of invertebrates and fungi within a single cow pat (cow dung), may be over within as little as 3 months. By this time, the dung has been transformed into humus and nutrients and has been recycled back into the soil. The holes clearly visible in the cow pat (right) have been made by the animals which have colonized it.

4 Stages of Ecological Succession When talking about the types of ecological succession it is important to remember that the “types” occur within the stages, but they may not necessarily be unique to that stage. What determines the stage that an ecosystem is in is dependent on its energy balance – which is discussed in the next section. There are four main types of ecological succession: Pioneer – pioneer types are the new life forms that enter into a primary succession and begin to take hold. This can be anything from a seed to a bacterium to an insect or to an animal wandering into a new area and bedding down to make it their home. The pioneer has no connection to the environment, but it does find enough present in the new ecosystem to begin to establish its life.

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Establishing – the establishing type can be hard to pinpoint because it crosses into the pioneer and sustaining. Establishing is the process in which life forms identify elements in an ecosystem that can sustain their basic needs – such as food, water and safe habitat. Sustaining – Sustaining type means that life in the ecosystem has begun to enter into a pattern that allows for a cycle of life to continue. This means that birth and death are occurring, and there is little migration outside of the ecosystem – this is most common in the climax succession. Producing – the producing type occurs during the secondary succession. This is when life forms are breeding and growing, but there is migration because what is produced is also not capable of being supported within the ecosystem. There are also more areas of overgrowth or due to seed levels. Pioneer species are the ones that thrive the new habitat at the beginning of ecological succession. Pioneer species are ‘r-selected’ species that are fast growing and well-dispersed. Early succession is therefore dominated by so called ‘r-selected’ species. As succession continues, more species enter the community and begin to alter the environment. These are called ‘k-selected’ species. They are more competitive and fight for resource and . The species that are better suited for the modified habitat then begin to succeed the other species. These are superseded by newer set of species. This goes on till the stage of climax or equilibrium is achieved. When succession reaches a climax, where community is dominated by stable and small number of prominent species and no other species can be admitted, that is called the state of equilibrium or the climax community.

MULTIPLE CHOICE QUESTIONS

1. Most stable ecosystem is (a) Forest (b) Desert (c) (d) Mountain

2. Zone consisting air, water and soil is known as (a) Hydrosphere (b) (c) Lithosphere (d) Biosphere

3. Word oikos means ______and logos means ______(a) Houses and study of (b) Study and houses (c) Only houses (d) Study of people

4. Earthworms and bacteria are called (a) Producers (b) Consumers (c) Decomposers (e) None of these

5. The that is always upright (a) Pyramid of energy (b) Pyramid of biomass (c) Pyramid of number (d) None of these

6. Important abiotic factors in ecosystems include which of the following? (a) temperature (b) water (c) wind (d) both (a) and (b)

7. All of the following statements about ecology are correct except: (a) Ecology is the study of the interactions between biotic and abiotic aspects of the environment (b) Ecology is a discipline that is independent from & evolutionary history (c) Ecologists may study populations and communities of organisms. (d) Ecology spans increasingly comprehensive levels of organization, from individuals to ecosystems

8. Which of the following are important biotic factors that can affect the structure and organization of biological communities? (a) nutrient availability, soil pH, light intensity (b) predation, competition, disease (c) all

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(d) all of the above

9. Scientific study of the interactions of organisms with the physical environment is called (a) Ecosystem (b) Ecology (c) Environment (d) Trophic structure

10. The three major living components of an ecosystem are (a) Producers, consumers & Decomposers (b) Autotrophs, Producers & Decomposers (c) Heterotrophs, consumers & reducer (d) Detritivores, consumers & Decomposers

11. The green plants are also called (a) Producers (b) Consumers (c) Reducers (d) Detritivores

12. Example of omnivores is (a) Lion (b) Hawk (c) (d) Snake

13. The most important organisms of an ecosystem are (a) Herbivores (b) Producers (c) Carnivores (d) Protozon

14. Consumers are also called (a) Photo-autotrophs (b) Saprotrophs (c) Heterotrophs (d) Reducers

15. Sequence of eating and being eaten in a ecosystem is called (a) Food web (b) Natural cycle (c) Ecological Pyramid (d) Food chain

16. Detritus food chain starts from (a) Green plants (b) Grass (c) Dead organic matter (d)

17. Nutrients are recycled in ecosystem by (a) (b) Energy flow (c) Producers (d) Consumers

18. The flow of energy is (a) One way (b) Cyclic (c) Linear and one way (d) None of these

19. Food chain always starts with (a) Respiration (b) Photosynthesis (c) fixation (b) Transpiration

20. The ecological pyramid always starts with the following at the base (a) (b) Producer (c) Consumer (d) None of these

21. Ecology deals with the study of: (a) Living beings (b) Living and non living components (c) Reciprocal relationship between living and non living components (d) Environment

22. Autecology deals with (a) Ecology of species (b) Ecology of many species (c) Ecology of community (d) All the above

23. Synecology deals with (a) Ecology of many species (b) Ecology of many populations (c) Ecology of community (d)None of the above

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24. The pyramid of energy in any ecosystem is (a) Always upright (b) May be upright or invented (c) None of the above (d) Always inverted

25. Energy flow in ecosystem is (a) Unidirectional (b) Bidirectional (c) Multidirectional (d) None of the above

26. An ecosystem must have continuous external source of (a) Minerals (b) energy (c) food (d) All of the above

27. The source of energy in an ecosystem is (a) ATP (b) Sunlight (c) D.N.A (d) R.N.A

28. Trophic levels are formed by (a) Only plants (b) Only animals (c) Only carnivorous (d) Organisms linked in food chain

29. Biotic potential is counteracted by (a) Competition with other organisms (b) Producer is the largest (c) Limitation of food supply (d) None of the above

30. The of occurrence of additional species found in the or transitional zone between adjoining ecosystems is known as (a) Edge effect (b) Root effect (c) Raman effect (d) Coolidge effect

31. The complex network of interconnected food chains is called (a) Trophic level (b) Food web (c) Ecological pyramid (d) Ecology chain

32. The area to which a species is biologically adapted to live is known as (a) Niche (b) Habitat (c) Succession (d) Community

33. The largest lake situated in is in Orissa. Which is the lake? (a) Chilka lake (b) Vembanad lake (c) Woolar lake (d) Dal lake

34. The animal which consumes decaying organic matter is (a) (b) (c) Herbivore (d) Producers

35. A set of organisms that resemble one another in appearance and behaviour is called a (a) Exons (b) Prions (c) Species (d) guilds

36. An ecosystem gradually merges with an adjoining one through a transitional zone is called the (a) (b) (c) ecotone (d) shore effect

37. The conversion of to is known as (a) ammonification (b) nitrification (c) denitrification (d) all of these

38. The presence of which is necessary for photosynthesis (a) Chloroform (b) Chlorophyll (c) (d) Polymer

39. The Primary Consumers are also called as (a) Herbivores (b) Carnivores (c) (d) None of these

40. The forests which occur in law rain fall area is (a) Evergreen forests (b) deciduous forests (c) Coniferous forest (d) all the above

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41. Plants adapted to open, sunny are (a) Sciophytes b) Heliophytes c) Mesophytes d) Epiphytes

42. Study of inter-relationship between organisms and their environment is (a Ecology b) Ecosystem c) Phytogeography d)

43. Temperate forests occur in India in a) Indo-gangetic plains b) Himalayas c) Eastern India d) Southern peninsula

44. Which one is ’s cleaner? a) Consumers b) Producers c) Decomposers and Scavengers d) Symbionts

45. In India, tropical evergreen forests occur in a) Himachal Pradesh b) Madhya Pradesh c) Assam d) Tamil Nadu

46. The relationship between nitrogen fixing bacteria and leguminous plants is an example for a) b) Predation c) d) Commensalism

47. Forests grow in high rain fall areas are a) ever green forests b) temperate forests c) d)

48. A Hawk that eats a frog is a a) Producer b) Primary Consumer c) Secondary Consumer d) Tertiary

49. An example of lotic system a) Pond b) River c) Lake d) Reservoir

50. Complex interlinked food chains are called a) Food Web b) Food net work c) Trophiclevels d) Food pyramid

51. Lotic ecosystem refers to a)Static water system b) Ecosystem of flowing water c) Ecosystem of estuaries d) Deep marine water system

52. Autotrophs are ______a) Consumers b) Herbivores c) Saprophytes d) Producers

53. Organisms which depened on Producers for are called a) Autotrophs b) Saprophytes c) Consumers d)

54. The source of atmospheric oxygen is a)itrogen cycle b) Green Plants c) Water d)

55. Plants which grow in shade are called a) Sciophytes b) Heliophytes c) Oxylophytes d) Epiphytes

56. The term ‘Ecology’ was coined by a) A.G.Tansley b) Earnst Haeckel c) d) Linnaeus

57. Nitrogen gas returns to the atmosphere by the action of a) Nitrogen fixing bacteria b) Denitrifying bacteria c) Nitrifying bacteria d) Nitrate

58. Photosynthesis is found in a) Producers b) Decomposers c ) Consumers d) Scavengers

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59. Phytoplankton are a) Producers of forest b) Producers of lakes c) Consumers of Ocean d) Omnivores

60. Gas released during photosynthesis is a) b) Nitrogen c) Oxygen d)

61. An example of an a) Plants b) Soil c) Animals d) Bacteria

62. The simplest natural can be seen in a a) River b) Lake c) Pond d) Water Tank

63. What is lotic habitat? a) Standing or still water habitat b) Marine habitat c) Running water habitat d) Stagnant water

64. What is lentic habitat ? a) Running water habitat b) Standing or still water habitat c) Marine habitat d) None

65. When number of food chains is interlocked this is called a) food link b) food chain c) food web d) pyramid

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