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UNIT 4: BIOSPHERE, BIOMES AND
ECOSYSTEMS
Refer to Chapter 52 – Campbell and Reece, 2010, learning guide
notes and slides
ECOLOGY:The study of the interaction between
organisms and with the environment to ensure survival and reproduction
IMPORTANT TERMINOLOGY•Biosphere: Zone of air, land and water at the surface of the Earth in which living organisms are found.
•Community: A group of organisms of different species living in a specific area at a specific time and interacting with one another.
•Biome: One of the biosphere’s major communities, characterized in particular by certain climatic conditions and particular types of plants and animals.
IMPORTANT TERMINOLOGY•Biotic organisms:
Living organisms, including animals, plants, fungi, bacteria, viruses ect.
•Abiotic components:
Non-living things in the environment e.g. light, gasses (air), water, soil, temperature.
•Ecosystem: A biological community together with the abiotic environment, characterized by the flow of energy and the cycling of inorganic nutrients.
•Biodiversity: Total number of species found in an area.
BIOSPHERE:The biosphere is the entire part of the earth that can maintain life.
It includes the :Atmosphere,
Lithosphere and Hydrosphere.
ATMOSPHERE:
The lower part above the soil.Makes up a layer of gases, airborne particles
and water vapour that surrounds the earth. The most important gasses are:
nitrogen (78%), oxygen (21%) and
carbon dioxide (0.03%)
LITHOSPHERE:Includes the land masses made up of soil and rock.
The lithosphere is important for the following reasons:
It provides the substrate for habitat for plants and
animals.It is a source of minerals essential for growth and
maintenance.It provides air and water to roots of plants and soil
animals.It plays an important role in biogeochemical cycles.
LITHOSPHERE:
HYDROSPHERE:oRefers to the part on earth that consist of water
e.g. rivers, dams, oceans, lakes, ponds, streams.oWater covers ¾ of the earth’s surface.
The hydrosphere is important for the following reasons:
oIt provides water which is most important consti-
tuent of all living organismsoIt provides the rainfall that supports terrestrial
ecosystems.oOcean currents have enormous influence on
climatic conditions in all parts of the world.
HYDROSPHERE:
BIOMES:A specific area in the biosphere,
characterized by a specific climate and occupied by specific animals and plants
It is divided into 2 types of major biomes:
♥Terrestrial biomes♥Aquatic biomes
: Terrestrial biomes
•Tundra•Grasslands (savannas)•Deserts•Forests(coniferous-and deciduous- and tropical rain forests)•Shrub lands
: Tundra biome
Is the coldest of all the biomes. Tundra, means treeless plain. It is noted for its frost-molded landscapes, extremely low temperatures, little precipitation, poor nutrients, and short growing seasons
:Is a tropical grassland with some clumps of trees.
Has wet and dry season. Average Annual Rainfall- 59 mmAverage Temperatures in the Dry Season- 93º FAverage Temperatures in the Wet Season- 61º FPLANTS Wild grasses, generally tall and several clumps of trees. These trees can be palm, pine, and acacia. ANIMALS Animals, mainly herbivores, are generally large in size. Animals include elephants, giraffes, zebras, gazelles, and wildebeeste. Carnivores, such as the lions, leopards, and hyenas, balance out the ecosystem.
Grasslands (savannas)
: Grasslands (savannas)
:A desert is a dry area where less than 50 mm of rain falls each year.
About one fifth of the Earth's surface is desert.
Deserts can be hot or cold.
Short grasses can be found in nearly all deserts. Desert plants include sagebrush, creosote bushes and cacti.
Deserts are home to many reptiles, insects, birds, and small mammals.
Deserts
:Deserts
:Coniferous forestDeciduous forest
Tropical rain forest
Forests are characterized by the greatest diversity of species.Temperature is on average 20-25° C
Forests
:
Forests
:Characterized by shrubs, grasses, herbs
and geophytes.Herbivorous, rodents, birds and insects
are found in this biome.Wide open spaces provide favorite
nesting and hunting perches for crows,
common ravens, and raptors.
Rodents, like the vole, survive by taking advantage of the natural cover comprised of the vegetation.
Shrub lands
:Shrub lands
:Wetlands
Marshes
Swamps
Bogs
Lakes
Oceans
Ocean currents
Intertidal zones
Aquatic biomesWetland
Marshes
SwampsBogs
Intertidal zone
Oceans and Ocean currents
BIOMES OF SOUTH AFRICA:
Biomes of South Africa:
•Succulent Karoo •Savannas •Fynbos •Grasslands •Forests •Nama-Karoo •Marine and Coastal Ecosystems •Wetlands
:ABIOTIC AND BIOTIC
FACTORS
The two main components which influence an organism in
its natural habitat, are the abiotic (non-living) and biotic
(living) components.
ABIOTIC FACTORS:
Abiotic components include the following: Temperature,
water,
soil,
light,
physiographic factors.
TEMPERATURE:Cold blooded organisms?
Warm blooded organisms?
Day plants and animals?
Nocturnal animals and plants?
Adaptations of plants to temperature changes
1. Seed germination: most seeds will germinate only after exposure to a period of low temperature.
2. Deciduous trees: shed their leaves in autumn to limit their metabolic processes, like photosynthesis and growth.
3. Annuals: Survive cold seasons as seeds
4. Geophytes: are perennial plants with their resting buds below ground level, e.g. bulbs, rhizomes, corms and tubers.
Adaptations of animals to temperature changes:
1. Exothermic animals (coldblooded animals) cannot maintain their own body temperature, -hibernate (winter sleep) during the cold months, or they can lie on a rock in the sun to warm their bodies and barrow in the sand to cool down.
2. Endothermic animals (warm blood animals) maintain a constant body temperature and aren’t influenced by the fluctuations of the environmental temperature. But some of these animals hibernate during the cold winter months because food is scares.
Adaptations of animals to temperature changes:
1. Body covering: Thick fur, feathers and layers of body fat help mammals and birds to keep them warm.
2. Migration of birds: some birds fly to warmer parts of the world during the cold months, it is a seasonal movement.
3. Aestivation: During the hot dry summer months snail aestivate (summer sleep)
WATER: Main component of living cells and is
essential for all living organisms. 65% of the human body and 90% of plant
bodies consist of water.
Adaptations of plants to meet their water requirements
XEROPHYTES
HYDROPHYTES
MESOPHYTES
LIGHT:Plants need light for photosynthesis – to
produce food.
Food provide energy for animals.
Adaptations of plants to light intensity:Sun plants: these plants can tolerate a lot of light intensities.Shade tolerant plants: grow in shade, big leaves to absorb as much light possible e.g. ferns.Phototropism: The growth movement is the tropic responses of shoots and roots of plants to the stimulus of light. Shoots are positive phototropic and roots are negative phototropic.Floral initiation: Some flowers open in high light intensity and some close in high light intensity, this is due to their type of pollinators.
Adaptations of animals to light intensity:
Many animals need light to find food, hiding places, nesting sites and mating partners, and to escape their enemies.Day, night and twilight animals: Diurnal animals are active during the day, Nocturnal animals are active during the night. Crepuscular animals are active mainly during twilight.Pigmentation: Pigments (dark skin) absorb the ultraviolet light of the sun to prevent the deeper laying tissue from damaging.
Adaptations of animals to light intensity:Migration: Birds and some mammals move to different places during the autumn months when the daylight hours decrease.
Reproductive behaviour: The longer days of spring cause the reproductive organs of many animals to start growing, this gives rise to their breeding season.
Soil / edaphic factor
SOIL:Soil is the habitat of most plants which are of importance to produce food.Soil have different pH.Most plant species prefer a neutral pH of 7.Acid soils are usually infertile because the acidity makes the mineral salts very soluble.Humus forms part of the topsoil, a dark coloured soil that consist of the remains of dead organic matter.Humus is the fertile part of the soil.
SOIL:Three types of soil are found: Loam, clay and sand.Loam is the most fertile.The type of soil can be identified according to: particle size, stickiness, air content and water-retaining ability.Soil contains the water and minerals needed by plants to grow in. Many animals have a habitat in the soil.
Physiographic factor
ASPECT:Position of an
area with relation to the sun
SLOPE:
ALTITUDE: height above sea level
•can affect the rate of water run-off.
BIOTIC COMPONENTS
OF AN ECOSYSTEMThe biotic component is that part of the total
environment created by living, interacting organisms. The living components of an ecosystem consist of
producers, consumers and decomposers.
Producers (plants)The sun which is the primary source of energy, gives energy to the plants to produce food through photosynthesis.Plants use the light, carbon dioxide, water and the green pigment chlorophyll in their leaves to produce sugars and oxygen.These plants that produce food through photosynthesis are called producers.They are autotrophic organisms because they can manufacture their own food.Plants are the most numerous of all the biotic components.
Producers (plants)Plants that are not found naturally in an area are called invader plants and could cause other endemic plants to die out, because the invader plants use a lot of water. Many plants have medicinal value.
Sutherlandia frutesence used to treat the symptoms of flu.
Aloe contain which is used as a laxative ingredient .
Consumers (Animals)Animals are consumers because they are, directly/indirectly dependent on the food produced by the producers (plants), they
consume this food.
Consumers therefore have a heterotrophic feeding method – they cannot make their own food and are dependent on the producers for
nutrition.
Different types of consumers are found:Primary consumers:
They feed directly on producers – called herbivores.
Different types of consumers are found: Secondary consumers:
They feed on the primary consumers – include carnivores (eat meat) and omnivores (eat meat
and plants).
Different types of consumers are found:
•Tertiary consumers: •They feed on primary and secondary consumers. They are also carnivores. Animals that feed on dead bodies of animals are called scavengers.
DecomposersDecomposers are micro-organisms that break down complex organic matter into simple inorganic matter.They obtain their energy for the decaying animals and plants.They are heterotrophic animals.We refer to them as saprophytic organisms.They include fungi and bacteria.
BIODEGRADABLE AND NON-BIODEGRADIBLE
Today we mainly use biodegradable substances in our everyday life; these are substances that can be broken down by these decomposers,
which replace the useful elements back into the soil for plants to grow.
Non-biodegradable substances e.g. plastic, glass ext. are harmful to the environment because it cannot be broken down into useful elements.
ENERGY FLOW Energy flow begins when producers absorb solar energy for the process of photosynthesis.Energy flows through an ecosystem via photosynthesis because as organic nutrients pass from one component of the ecosystem to another, such as when an herbivore eats a plant or a carnivore eats an herbivore, only a portion of the original amount of energy is transferred. Eventually the energy dissipates into the environment as heat.
ENERGY FLOW Only about 10% of the food energy taken in by an herbivore is passed on to carnivores.A large portion goes to detritus feeders (decomposers) via defecation, excretion and death, and a large portion is used for cellular respiration.
ENERGY FLOW
TROPHIC LEVELS:•A trophic level is a level of nourishment with in a food web.
•The trophic levels are: •producers (plants), •primary consumers (herbivores), •secondary consumers (carnivores +/ omnivores), •tertiary consumers (carnivores and scavengers) and •decomposers (fungi and bacteria)
FOOD CHAINSThe interaction of the autotrophic and heterotrophic components in which one organism consumes another, is called a food chain. In a food chain there is a continuous flow of energy from the sun, through the plants to the various animals. In a food chain there are always a producer and a consumer. All food chains begin with a green plant and may consist of three to five links.
EXAMPLES OF FOOD CHAINS:
FOOD WEB:Consists of various food chains that interact with one another, therefore, interacting of energy flow within an
ecosystem – it can be described as a diagram which shows trophic/feeding relationships)
FOOD PYRAMID
Number pyramid – Pyramid constructed to show the relationship between the different numbers of
each trophic level.
Energy pyramid – Pyramid constructed to show the amount of energy received by each trophic
level.
Biomass pyramid – Pyramid constructed to show the dry weight of each trophic level in an
ecosystem.
INVERTED FOOD PYRAMIDS
Have more herbivores than producers.
NUTRIENT CYCLESThe inorganic substances e.g. carbon, hydrogen, oxygen, nitrogen, phosphorus etc. within an ecosystem can be used over and over again. They are in limited supply. Therefore they have to be cycled and re-used.Different important nutrient cycles are:
1.Nitrogen cycle2.Carbon cycle3.Oxygen cycle 4.Water cycle
CARBON CYCLE