Ecosystems
Biotic & Abiotic
factors
What do you know?
On your tables there
are two picture
Do both meet the
description of an
ecosystem?
You must be able to:
• Define an ecosystem.
• Identify examples of an ecosystem.
• Examine biotic an abiotic factors in an ecosystem.
• Analyze the constant reaction and interdependance
between biotic and abiotic factors.
Biotic Factors/ Living factors
Biotic components
Producers:
• Plants are
auototrophs
Primary
consumers:
• Heterotrophic
organisms
• Dependent on
plants
Decomposers:
• Lives on dead organic matter
• Put nutrients back into the soil.
Secondary consumers
• Heterotrophic
• Dependent on
primary consumers
• Carnivores
Abiotic factors/ Non-living factors
ABIOTIC FACTORS
Climatic factors:
• Light
• Temperature
• Water
• Atmospheric
gases
• Wind
Edaphic factors
(refers to ground)
• Soil type
• Groundwater
• pH of the soil
Physiographic factors
• Aspect (slope
direction)
• Slope
• Altitude above sea
level
SOIL
Main soil types:
• Sandy soil
• Loamy soil
• Clay ground
Soil’s water holding
capacity
• Clay soil = lots of water
• Sandy soil = Little water
• Loamy soil = Moderate water
Soil-pH
• Acidity/ alkalinity (the pH) of the
soil affects plant growth.
• Most plants grow better in soil
that is slightly acidic (low pH).
Soil’s air content
THE MORE AIR = THE MORE
OXYGEN FOR THE PLANTS
• Sandy soil – Large
air spaces
• Clay soil – Small
air spaces
• Loam soil – Moderate
amount of air
Water & the water cycle
Importance of
wetlands
• Important ecosystems.
• Habitat & source of
water for different
types of plants and
animals.
• Acts as filtration of
polluted water.
• They act like giant
sponges in dry years.
Importance of
wetlands to people
• Provide water.
• Plant crops and catch
fish in the lakes.
• Reeds to build.
• St Lucia = tourist guides
= job opportunity.
Light
Photosynthesis:
• Plants get energy through
photosynthesis.
• Produces oxygen for respiration.
• Photo Period: Light accelerates
photosynthesis.
• Prefer different amounts of light.
E.g., Chrysanthemums = 10
hours of light needed to
bloom & Namaqua daisies only
open in bright sunlight.
Animals and light
• Diurnal animals (DAY).
• Nocturnal animals (NIGHT).
Light and seasonal change:
• Seasons – Change in the luminous
intensity of light.
Temperatuur
Night and day temperatures
• Effect on behaviour.
• E.g., Reptiles
• Plants’ flowers.
• Activity of desert organisms.
• E.g., Cacti
Temperature and seasonal change
• Temperature is related to light.
• Summer = temperature higher, daylight hours more.
• Winter = temperature lower, daylight hours less.
1) Migration
• Seasonal movement due to climatic
conditions.
• E.g., Swallows
• Amount of food and water.
• E.g., Butterflies
2) Hibernation/Wintersleep
Decrease in body processes
• Only active on warmest parts.
• True hibernation – inactive.
• E.g., Bushveld-saddle-nosed bat – heart
rate 4 beats per min.
Movement and behaviour
Temperatuur
Effects of temperature on animals
3) Estivation/Summersleep
• Decrease in body activity and
processes
• Warm and dry – the animals take
shelter – prevent water loss.
• E.g., Bullfrogs buried in mud.
• Air sack to provide oxygen for
respiration.
Temperatuur
Effect of temperature on plants
• Cold winter – dormant seeds or bulbs.
• Peaches and plums – low temperatures
– seeds germinate.
• Some plants need high temperatures –
to germinate.
• E.g., tomatoes – need high
temperatures for germination.
• E.g., Peas and beans – grow best at
low temperatures.
Atmospheric gases
and wind
• The atmosphere is a blanket
of gases that surrounds the
earth.
The three most important gases
in the atmosphere:
• Nitrogen 78%
• Oxygen 21%
• Carbon Dioxide 0,03%
[Other gases (methane etc)
0,07%]
Atmospheric gases
and wind
Wind
• Rol in pollination and seed
dispersal.
• Rol in distribution of certain
insects.
• Wind has an effect on
transpiration.
• Plants lose more water when it is
windy.
• Wind also accelerates evaporation
from rivers, lakes and the sea.
Physiographic factors
Factors relating to the physical characteristics
of the land.
1) Height
• Altitude above sea level.
• Temperatures are lower, less oxygen, more sunlight.
• 2) Slope
• Steep or flat.
• Steepness: How fast water flows away.
• 3) View
• North view: More sunlight and warmer, low moisture, succculent
plants.
• Southern view: Less sunlight, high humidity, ferns.
Assessment
5 min
1. Assess the biotic and abiotic factors that influence you in the
classroom. Name two factors for each.
(4)
2. Which soil type has the best water holding capacity?
(1)
3. Is the above soil type also the best for plant growth?
(1)
4. How are nocturnal animalsʹ eyes adapted to see in dim light?
(2)
5. How do high and low temperatures affect animalsʹ body processes?(2)
Total: 10
Summary
• Essential
relationships between
life and the
environment.
• Remember, our role is
as custodians of the
earth.
Any questions?