The term ecosystem was coined by A.G. Tansley in 1935.
An ecosystem is an interaction between a biotic community and
its abiotic environment.
• The term weather and climate both refer to atmospheric
conditions- temperature, humidity, precipitation, wind
direction and wind velocity- but they refer to different
• Weather- ―It is the short-term state of atmospheric
conditions at a particular place and time‖.
• Climate – “Refers to average atmospheric condition,
and the extent of their variation, at a particular place
over a longer time.‖
Climate is the state factor that most strongly governs the global
pattern of ecosystem structure and processes.
• Climate gives rise to predictable types of ecosystems.
• Climate is a key mechanism by which ecosystems interact with
the total Earth System.
World biomes are controlled by climate. The climate of a region will
determine what plants will grow there, and what animals will inhabit it. All
three components, climate, plants and animals together form a biome.
Three major climate groups.
Three major climate groups show the dominance of special combinations
of air-mass source regions.
Group I : Low-latitude Climates - i Tropical Moist Climates
ii Wet-Dry Tropical Climates
iii Dry Tropical Climates
Group II : Mid-latitude Climates - i Dry Mid Latitude Climates
ii Mediterranean Climates
iii Moist Continental Climates
Group III : High-latitude Climates - i Boreal Forest Climates
ii Tundra Climates
iii Highland Climates
1.Tropical Moist Climates (RAINFOREST)
• Average temperature: 18 °C
• Annual Precipitation: 262 cm. (103 in.)
• Latitude Range: 10° S to 25 ° N
• Global Position: Amazon Basin; Congo
Basin of equatorial Africa; East Indies,
from Sumatra to New Guinea.
Group I : Low-latitude Climates - These climates are controlled by
equatorial a tropical air masses.
2.Wet-Dry Tropical Climates (SAVANNA)
• Temperature Range: 16 °C
• Annual Precipitation: 0.25 cm.
• Latitude Range: 15 ° to 25 ° N and S
• Global Range: India, Indochina, West Africa ,
southern Africa, South America and
the north coast of Australia
3.Dry Tropical Climate (DESERT BIOME)
• Temperature Range: 16° C
• Annual Precipitation: 0.25 cm.
• Range: 15° - 25° N and S.
• Global Range: southwestern United States
and northern Mexico Argentina; north Africa;
south Africa; central part of Australia.
Group II : Mid-latitude Climates- Climates in this zone are affected by
two different air-masses. The tropical air-masses are moving towards
the poles and the polar air-masses are moving towards the equator.
These two air masses are in constant conflict. Either air mass may
dominate the area, but neither has exclusive control.
1.Dry Mid latitude Climates (STEPPE)
• Temperature Range: 24° C (43° F).
• Annual Precipitation: less than 10 cm in the
driest regions to 50 cm in the moister steppes.
• Latitude Range: 35° - 55° N.
• Global Range: Western North America ,
Eurasian interior, from steppes of eastern Europe
to the Gobi Desert and North China.
• Temperature Range: 7 °C (12 °F)
• Annual Precipitation: 42 cm (17 in).
• Latitude Range: 30° - 50° N and S
• Global Position: central and southern California; coastal bordering the
Mediterranean Sea; Cape Town region of South Africa.
3.Moist Continental Climate
(DECIDIOUS FOREST BIOME)
• Temperature Range: 31 °C (56 ° F)
• Average Annual Precipitation: 81 cm
• Latitude Range: 30° - 55° N and S
(Europe: 45° - 60° N).
• Global Position: eastern parts of the United States and southern
Canada; northern China; Korea; Japan; central and eastern Europe.
Group III : High-latitude climates - Polar and arctic air masses
dominate these regions. Canada and Siberia are two air-mass sources
which fall into this group. A southern hemisphere counterpart to these
continental centers does not exist. Air masses of arctic origin meet
polar continental air masses along the 60th and 70th parallels.
1.Boreal forest Climate (TAIGA BIOME)
• Temperature Range: 41 °C, lows; -25 °C, highs; 16 °C
• Average Annual Precipitation: 31 cm (12 in).
• Latitude Range: 50° - 70° N and S.
• Global Position: central and western Alaska;
Canada, from the Yukon Territory to Labrador;
Eurasia, from northern Europe across all of
Siberia to the Pacific Ocean.
2.Tundra Climate (TUNDRA BIOME)
• Temperature Range: -22 °C to 6 °C (-10 °F to 41 °F).
• Average Annual Precipitation: 20 cm (8 in).
• Latitude Range: 60° - 75° N.
• Global Position: arctic zone of North America;
Hudson Bay region; Greenland coast; northern
Siberia bordering the Arctic Ocean.
3.Highland Climate (ALPINE BIOME)
• Temperature Range: -18 °C to 10 °C (-2 °F to 50°F)
• Average Annual Precipitation: 23 cm (9 in.)
• Latitude Range: found all over the world
• Global Position: Rocky Mountain Range in
North America, the Andean mountain range in
South America, the Alps in Europe, Mt. Kilimanjaro
in Africa, the Himalayans in Tibet, Mt. Fuji in Japan.
Ecosystem is an open system.
It is broad and flexible.
The function of an ecosystem is related to energy
flow and material cycling through and within the
Some of the major natural ecosystems are forests,
grasslands, deserts, mountains, seas, rivers, lakes,
The functioning of an ecosystem comprises the following three aspects:
There are two essential components of an ecosystem. They are:
1.Abiotic factors and 2.Biotic factors
The ultimate source
of energy for life on
earth is SUN!!!
Energy flows in only one
direction from producers
to tertiary consumers
Consumers: Organisms that obtains energy by feeding on other
There are 3-Types of consumers:
3.Scavengers and decomposers.
Producers: Organisms that use the energy from the sun to produce
their own food.
Ex : Plants, algae and some bacteria.
1. Herbivores: Heterotrophs
that consume plants only. (First
Ex : cows , deer, rabbits..
2. Carnivores: Heterotrophs that
consume other animals. (Second
Ex : Humans , cats…
3.(i) Scavengers: Organisms
that feed on dead organisms.
(ii) Decomposers: Break down
wastes and dead organisms and
return the raw materials to the
Ex : Bacteria and fungus.
Food chain - a model that shows how
matter and energy moves through an
ecosystem. Energy moves from
producer to consumer to decomposer.
Food web: many overlapping food chains forms Food web
Productivity of an ecosystem means the amount of organic matter
produced or accumulated by plants or producers per unit of time and area.
Types Of Productivity:
1. Primary Productivity
2. Secondary Productivity
3. Net Productivity.
Primary productivity - the amount of organic matter made in a
given time by green plants in an ecosystem.
Primary productivity is of two types:
Gross primary production – total organic matter used up in
respiration during a particular period.
Net primary production – the amount of organic matter
produced or stored in plant tissues in excess of that used up by
the plants during respiration.
Secondary productivity – the capacity of energy storage at
the consumer level or 2nd trophic level.
Net productivity - the rate of storage of organic matter not
used by the consumer level or 2nd trophic level.
The natural flow of water through various components of
environment resulting in the global circulation is called water cycle.
Steps in Hydrological Cycle:
Evaporation: Surface water is heated by sun and evaporates to become
water vapour, water vapour floats in the air.
Condensation: As water vapour rises into the air it gradually cools and
condenses and become minute droplet of water.
Clouds: Tiny droplets of water together forms clouds.
Precipitation: The fall of water on earth surface in any form of water it
may be in the form of dew, drizzle, rain is known as precipitation.
Runoff: Precipitated rain water accumulates and flows on the surface
and sub- surface towards rivers, streams, and underground stores and
ultimately reaches to sea.
Percolation: The process of stored water flowing under earth, merge to
the ground water source is called percolation and infiltration.
Transpiration: The water which directly evaporates from leaves of
plants is called Transpiration.
Completion of Cycle: All the water bodies continues its journey towards
the natural slope and meet the sea where the cycle starts again
• The earth's water supply stays the same but humans can alter the
cycle. As population increases, and living standards rise this can
increase the demand for water.
• Humans impact the water cycle by polluting the water in rivers,
streams, reservoirs etc.
• We are polluting it with harmful chemicals and disgusting
substances by dumping waste into the ocean.
• These reasons can create an imbalance and change the quality and
quantity of the water.
Human Impacts On Hydrological Cycle
Biological and geochemical processes move nutrients between organic
and inorganic parts of the ecosystem
Chemical elements are available to ecosystems only in limited amounts.
Life on Earth depends on the recycling of essential chemical elements.
Nutrient circuits involve both biotic and abiotic components of
ecosystems and are called Biogeochemical cycles.
There are two general categories of biogeochemical cycles:
Gaseous forms of carbon, oxygen, sulfur, and nitrogen occur in the
atmosphere, and cycles of these elements are global.
Sedimentary forms: Elements that are less mobile in the environment,
such as phosphorus, potassium, calcium, and trace elements generally
cycle on a more localized scale in the short term.
The concentration of carbon in living matter (18%) is almost 100
times greater than its concentration in the earth (0.19%). So living
things extract carbon from their nonliving environment. For life to
continue, this carbon must be recycled.
Carbon exists in the nonliving environment as:
carbon dioxide (CO2) in the atmosphere and dissolved in water
carbonate rocks (limestone and coral = CaCO3)
deposits of coal, petroleum, and natural gas derived from
dead organic matter, e.g., humus in the soil
Carbon enters the biotic world through the action of autotrophs:
• primarily photoautotrophs, like plants and algae, that use the
energy of light to convert carbon dioxide to organic matter.
• and to a small extent, chemoautotrophs — bacteria and archea
that do the same but use the energy derived from an oxidation of
molecules in their substrate.
Carbon returns to the atmosphere and water:
• by respiration (as CO2)
• decay (producing CO2 if oxygen is present, methane (CH4) if it is not.
Since the Industrial Revolution approximately 150 years ago,
human activities such as the burning of fossil fuels and deforestation
have begun to have an effect on the carbon cycle and the rise of
carbon dioxide in the atmosphere. Human activities affect the carbon
cycle through emissions of carbon dioxide (sources) and removal of
carbon dioxide (sinks).
When oil or coal is burned, carbon is released into the
atmosphere at a faster rate than it is removed. As a result, the
concentration of carbon dioxide in the atmosphere increases.
Deforestation is the permanent removal of trees from forests.
This large-scale removal of trees from forests by people results in
increased levels of carbon dioxide in the atmosphere which causes
Green House Effect.
Human Impacts On Carbon Cycle
All life requires nitrogen-compounds, e.g., proteins and nucleic acids.
Air, which is 79% nitrogen gas (N2), is the major reservoir of nitrogen.
The nitrogen molecule (N2) is quite inert . Organisms cannot use
nitrogen in this form.
Plants must secure their nitrogen in "fixed" form, i.e., incorporated in
compounds such as:
nitrate ions (NO3
The Nitrogen cycle involves four major processes:
1. Nitrogen Fixation: To break nitrogen molecule(N2) apart so that its
atoms can combine with other atoms requires the input of substantial
amounts of energy. Three processes are responsible for most of the
nitrogen fixation in the biosphere:
atmospheric fixation by lightning
biological fixation by certain microbes.
2. Ammonification: When a plant or animal dies, or an animal expels
waste, the initial form of nitrogen is organic. Bacteria like proteus,
streptomyces etc., or fungi in some cases convert the organic nitrogen
within the remains back into ammonium (NH4
+) and the process is called
ammonification or mineralization
4. Denitrification: The three processes above remove nitrogen from
the atmosphere and pass it through ecosystems. Denitrification
reduces nitrates to nitrogen gas, thus replenishing the atmosphere. .
This process is performed by bacterial species such as pseudomonas
and Clostridium in anaerobic conditions.They use the nitrate as an
electron acceptor in the place of oxygen during respiration. These
facultatively anaerobic bacteria can also live in aerobic conditions.
3. Nitrification: Ammonia can be taken up directly by plants usually
through their roots. Most of the ammonia produced by decay is
converted into nitrates. This is accomplished in two steps:
Bacteria of the genus Nitrosomonas oxidize NH3 to nitrites (NO2
Bacteria of the genus Nitrobacter oxidize the nitrites (NO2
It is important for the ammonia to be converted to nitrates because
accumulated nitrites are toxic to plant life.
Many human activities have a significant impact on the nitrogen cycle.
Burning fossil fuels, application of nitrogen-based fertilizers, and other
activities can dramatically increase the amount of biologically available
nitrogen in an ecosystem.
In terrestrial ecosystems, the addition of nitrogen can lead to nutrient
imbalance in trees, changes in forest health, and declines in biodiversity.
In agricultural systems, fertilizers are used extensively to increase
plant production, but unused nitrogen, usually in the form of nitrate, can
leach out of the soil, enter streams and rivers, and ultimately make its
way into our drinking water.
Additionally, increases in nitrogen in aquatic systems can lead to
increased acidification in freshwater ecosystems.
Human Impacts On Nitrogen Cycle
Sulfur is the 10th most abundant element in the environment, with atomic
number 16. It is a bright yellow crystalline solid in its normal state, with most
of it stored underground in rocks and minerals and in ocean floor deposits.
Sulfur is used for fertilizers, gunpowder, matches, and in insecticides and
fungicides. It is a part of vitamins, proteins and hormones.
Steps of Sulfur Cycle :
The cycle begins with the weathering of rocks, which releases stored
Sulfur comes into contact with the air, converting it to sulfate (SO4).
Sulfate is taken up by plants and microorganisms and is changed to
Sulfur moves up the food chain.
When organisms die, some of the sulfur is released back to sulfate
and enter microorganisms.
Natural sources emit sulfur into the air.
Sulfur eventually settles back to the Earth or comes through
rainfall, with some also going to the ocean.
Sulfur is also drained to rivers and lakes, eventually to the oceans.
Some of the sulfur from oceans go back to the atmosphere
through the sea spray .
Remaining sulfur go to ocean floor and form ferrous sulfide, which
is responsible for the black color of most marine sediments.
Effects of Sulfur Cycle on Nature
Sulfur is one of the processes that allow natural weathering and other
natural processes .
Sulfur Cycle does not allow acid rains because it regulates the amount
of sulfur present in the atmosphere, hydrosphere, and lithosphere .
Sulfuric acid forms sulfuric acid smog when it mixes with water vapor.
Effects of Human Progress on the Sulfur Cycle
Human activities since the start of the Industrial Revolution contributed
to most of the sulfur that enters the atmosphere. One-third of all sulfur
that reaches the atmosphere comes from human activities.
Emissions from human activities react to produce sulfate salts that
create acid rain .
Sulfur dioxide aerosols absorb ultraviolet rays, which cools areas and
offsets global warming caused by greenhouse effect.
Phosphorus enters environment from rocks or deposits.
Apatite is the phosphate rock where phosphate is available.
Weathering and erosion releases phosphate ions that are soluble in water.
Phosphate then acts as fertilizers or nutrients for land plants.
When animals and plants die, phosphates will return to the soils or oceans.
Again during decay,
Phosphorus cycles through plants and animals much faster than it does
through rocks and sediments.. A lot of phosphate goes into the water from
erosion and leaching Water plants use this phosphate as nutrients.
Phosphorus and phosphorus-based compounds are usually solids.
Phosphorus normally occurs in nature as part of a phosphate ion (PO4).
Phosphorus is an essential nutrient for plants and animals in the form of
Phosphate is a component of nucleotides, it forms nucleic acids.
Human Impacts On Phosphorus Cycle
Humans effect the phosphorus cycle by moving phosphorus around
and it becomes runoff. When it is in run-off in can end up in large
stores of water and the phosphorous can cause eutrophication to
occur and this can kill animals and plants in the water.
In many areas, excess phosphates from large amounts of fertilizer
used in agriculture are a problem. Phosphates are also a common
ingredient in pesticides. Other major sources of phosphates in
aquatic ecosystems include outflow from sewage treatment
facilities and runoff of animal waste from livestock feedlots.
Phosphate pollution of lakes and rivers results in heavy growth of
algae and cyanobacteria, making the water murky. Microbes
consume a great deal of oxygen as they decompose the extra
biomass, a process that depletes the water of dissolved oxygen.
These changes lead to reduced species diversity.