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UNIT 2

THE ECOSYSTEM


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2.1 BIOTIC, ABIOTIC FACTORS,

AND TROPHIC LEVELS


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BIOTIC FACTORS

Biotic factors are the living components that

shape an ecosystem; any organism that affects

another organism.

Biotic components are:

Animals

Plants

Bacteria

Fungi


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ABIOTIC FACTORS

Abiotic factors are the non-living components

of an ecosystem, affecting the life of

organisms.

Abiotic factors can be harmful to the

ecosystem.

Abiotic components are:

Temperature, light, water, soil, rocks, and human

influence.


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WATER

Water is one of natures

most important things is

life. Essential to life, an

organisms survival

depends an water.Water is

necessary for digestion andabsorption of food; helps

maintain proper muscle

tone-, supplies oxygen and

nutrients to the cells; rids

the body of water; andserves as a natural air

conditioning system.


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SUNLIGHT

The sun provides light

and warmth and it is

the energy source for

almost all ecosystems

on Earth. Sunlightpowers

photosynthesis by

plants, the main

producer in most

terrestrial ecosystems.


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TEMPERATURE

Most life exists within a

fairly narrow range of

temperatures, from about

0 C to about 50 C. Few

organisms can maintain an

active metabolism below 0C for long, and most

organisms enzymes are

denatured (they lose their

shape and stop working)

above 50 C. However,extraordinary adaptations

enable certain species to

live at extreme

temperatures.


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SOIL

Soil is the product of abiotic

forces (such as ice, rain, and

wind) and the actions of living

things (such as

microorganisms, plants, and

earthworms) on the rocks andminerals of Earths crust. The

structure and chemical

makeup of soil and rock in an

area affect the types of plants

that grow there. In aquatic

environments as well, the

characteristics of underlying

sand and rock affect the type

of plants and algae that can

grow. This in turn affect the

other organisms found there.


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OXYGEN

Oxygen is an

important component

of life. Most living

things consume

oxygen in differentforms and quantities.

Most of the oxygen

that is used in

respiration is to obtain

chemical energy from

the fats and

carbohydrates in our

food.


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WIND

Many plants use the

help of the wind to

disperse seeds over

long distances.

Organisms disperse tofind new habitats rich

in needed resources.

Strong winds can be

very destructive.


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TROPHIC LEVELS

There are trophic levels within an ecosystem;

these are the feeding positions that biotic

components occupy on the food chain.

The word trophic derives from the Greek

trophe referring to food or feeding.

A food chain represents a succession of

organisms that eat another organism and are,

in turn, eaten themselves.


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TROPHIC LEVELS

Trophic levels in a food chain are:

Trophic level 1 primary producers

Trophic level 2 herbivores or primary consumers

Trophic level 3 predators, carnivores wh

ich

eatherbivores or secondary consumers

Trophic level 4 carnivores which eat othercarnivores or tertiary consumers

Trophic level 5 - apex predators whichhave no

predators, at the top of the food chain

The path along the chain forms a one-way flow alongwhich energy travels in the form of food.


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TROPHIC LEVELS

1. Producers - (autotrophs) are typically plants oralgae. Plants and algae do not usually eat otherorganisms, but pull nutrients from the soil or the

water and manufacture their own food usingphotosynthesis. In this way, it is energy from thesun that usually powers the base of the foodchain.

An exception occurs in deep-sea hydrothermalecosystems, where there is no sunlight. Here primaryproducers manufacture food through a process calledchemosynthesis.


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TROPHIC LEVELS

2. Consumers - (heterotrophs) cannot

manufacture their own food, and need to

consume other organisms. They are usually

animals. Animal that eat primary producers,

such as plants, are called herbivores. Animals

which eat other animals are called carnivores,

and animals which eat both plant and otheranimals are called omnivores.


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TROPHIC LEVELS

3.Decomposers (detritivores) break down dead

plant and animal material and wastes and

release it again as energy and nutrients into

the ecosystem for recycling. Decomposers,

such as bacteria and fungi (mushrooms), feed

on waste and dead matter, converting it into

inorganic chemicals that can be recycled asmineral nutrients for plants to use again.


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TROPHIC LEVELS

In real world ecosystems, there is more than

one food chain for most organism, since most

organisms eat more than one kind of food or

are eaten by more than one type of predator.

A diagram which sets out the intricate

network of intersecting and overlapping food

chains for an ecosystem is called its food web.


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FIRSTTROPHIC

LEVEL

The plants in this

image, and the algae

and phytoplankton in

the lake, are primary

producers. They takenutrients from the soil

or the water, and

manufacture their

own food by

photosynthesis, using

energy from the sun.


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SECOND

TROPHIC LEVEL

Rabbits eat

plants at the first

tropic level, so

they are primary

consumers.


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THIRDTROPHIC

LEVEL

Foxes eat rabbits

at the second

trophic level, so

they are

secondary

consumers.


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FOURTHTROPHIC

LEVEL

Golden eagles

eat foxes at the

third trophic

level, so they are

tertiary

consumers.


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DECOMPOSERS

The fungi or theearthworms

feed on deadmatter,

converting itback to nutrients

that primaryproducers can

use.


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Desert


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Taiga forest


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Temperate forest

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