Ecosystems and the Biosphere

Ecosystem

1Ecosystem

Ecosystem: A community of interdependent organisms and the interactions with the physical environment in which they live.ORAnecosystemis acommunity of living organisms (plants, animals and microbes) in conjunction with thenon-living components of their environment (things like air, water and mineral ,soil), interacting as a system.

2CONCEPTThe term ECOSYSTEM was introduced by A.G.Tansley in 1935 .The term ECOSYSTEM is made up of two words : ECO and SYSTEM .ECO means ecological sphere or region of space where living things can exist .System means interacting organisms living in a particular habitat ( living space)TYPES OF ECOSYSTEMEach ecosystem is a unique combination of a variety of organisms and physical conditions such as soil, climate etc. There are two types of ecosystems

STRUCTURE OF AN ECOSYSTEMCOMPOSITION OF BIOLOGICAL COMMUNITY (TROPHIC ORGANISATION)DISTRIBUTION OF NON-LIVING MATERIALS (NUTRIENTS ETC.)RANGE OF GRADIENT CONDITIONS LIKE LIGHT, TEMEPRATURE etc.What makes up an ecosystem? Biotic Factors (Living things)

Examples: include all living organisms.

7PLANTS (PRODUCERS)Plants: photosynthesis and absorb energy from the sun.Producers or Autotrophs (self-feeding).can store the most amount of energy.

8CONSUMERSAnimals: cannot get energy on our ownconsidered Consumers or Heterotrophs (different food) because eat the producers9ConsumersHerbivores (primary consumers): eat only plants matter Ex: deer, miceCarnivores (secondary): eat meat. Ex: Eagle, TigerOmnivores (secondary): eat both plants and animals.Ex: turtles, bears, humans

10SCAVENGERS AND DECOMPOSERS.

Fungi and scavengers: (vultures, hyenas)Decomposers: breakdown tissues into organic matter to be recycled!(mushrooms, bacteria, worms, microbes) 11What makes up an ecosystem? (cont.)

Abiotic Factors (non-living)

Examples include: type of soil, land, temperature, acidity, availability of nutrients, climate.

122 Essentials in an ecosystem: Energy and NutrientsSunlight is source of ENERGY

energy stored in plants as starch

Energy CANNOT be recycled=FLOWS

NUTRIENTS are recycled naturally by DECOMPOSERS

13FUNCTIONS OF AN ECOSYSTEMRATE OF ENERGY FLOWRATE OF NUTRIENT CYCLINGPRODUCTIVITY

15Nutrients and Biogeochemical cyclesAs you can see Energy flows continuously through each member of the ecosystem. Its recycled!!What about Nutrients?Next time:Nutrient Cycles

16Energy and Nutrients energy flows in one direction: from sun to producers to consumers

17Food Chain A single chain or series of steps showing who eats who.

Example: grass --deer-lion

Shows only a ONE WAY flow of energy18CHARACTERISTICS OF FOOD CHAIN There is unidirectional flow of energy from sun to producers and then to a series of consumers of various types. Thus, a food chain is always straight and proceeds in a progressing straight line. Usually 80 to 90 % of energy is lost as heat at each transfer. Usually there are 4 or 5 trophic levels. Shorter food chains provide greater available energy and vice - versa. Omnivores occupy more than one trophic level and, some organisms occupy different trophic positions in different food chains.

TYPES OF FOOD CHAIN There are mainly two types of food chains operating in nature. Grazing food chain (a) Terrestrial Food Chain (b) Aquatic Food Chain Detritus food chain.FOOD WEBFood web can be defined as, "a network of food chains which are interconnected at various trophic levels, so as to form a number of feeding connections amongst different organisms of a biotic community".Thus, instead of a simple linear food chain, there is a web like structure formed by these interlinked food chains. Such interconnected matrix of food chains is called 'food web'.

Food Web:

22How to read a food web

They show complex feeding relationships that result from interconnecting food chains.Food webs are different depending on where you are on the globe.Food webs are good indicators to the health of the Ecosystem.A food chain differs from a food web, because the complexnetwork of feeding relations are aggregated into trophic species and the chain only follows linearpathways

23Inputs and Outputs of Energy

24TROPHIC LEVELS IN FOOD CHAIN The producers, consumers, and decomposers all work together to give each other energy.It forms a systems of levels: Trophic levels (eating levels): Shows Energy flowAn animal at the top of the food chain would have to eat a lot more to get enough energy required for life.Energy is lost as things are consumed.25A trophic level is the position occupied by an organism in a food chain.Trophic levels can be analyzed on an energy pyramid.Producers are found at the base of the pyramid and compromise the first trophic level. Primary consumers make up the second trophic level.Secondary consumers make up the third trophic level.Finally tertiary consumers make up the top trophic level.Trophic Levels

27ECOLOGICAL PYRAMIDSAn ecological pyramid is a graphical representation of ecological parameters like number or biomass or accumulated energy at different trophic levels in a food chain of an ecosystemTerm coined by Charles Elton , also known as Eltonian Pyramids.

TYPES OF ECOLOGICAL PYRAMIDSPyramid of Number

Pyramid of Biomass

Pyramid of Energy

PYRAMID OF NUMBERPyramid of number shows the number of organisms at each trophic level per unit area of an ecosystem.

PYRAMID OF BIOMASSTheamountoflivingmatter inagivenhabitat expressedastheweightoforganisms perunitarea.

Biomass is preferred to the use of numbers of organisms because individual organisms can vary in size.

.

PYRAMID OF ENERGYPyramid of energy shows the amount of energy input to each trophic level in a given area of an ecosystem over an extended period.

COMPARISON OF PYRAMIDSNumber and biomass of organisms at any trophic level depends on the rate at which food is being produced.Energy flow provides a suitable index for comparative evaluation of all components of an ecosystem.THANK YOU!