1. Ecosystem
BFT 1023
Chapter-11
BY
Dr. Md. Shafiqur Rahman
UMK
2. This Chapter will cover
• Definition of Ecosystem
• Types of Ecosystem
• Terrestrial Ecosystem
• Aquatic Ecosystem
• Importance of each Ecosystem
3. Ecosystem:
An ecosystem is a biological environment
consisting of all the organisms living in a
particular area, as well as all the
nonliving (abiotic), physical components
of the environment with which the
organisms interact, such as
air, soil, water and sunlight.
4. Types of Ecosystem:
• Natural
– Terrestrial ecosystem
– Aquatic ecosystem
– Lentic, the ecosystem of a lake, pond or swamp.
– Lotic, the ecosystem of a river, stream or spring.
• Artificial
- ecosystems created by humans.
5. • Terrestrial ecosystems
Terrestrial ecosystems are found everywhere
apart from water bodies. They are broadly
classified into:
There are seven major types.
Location usually dependent on the latitude of
the area, and amount of precipitation
6. The Forest Ecosystem
• These are the ecosystems where abundance
of flora (plants) is seen and they have a large
number of organisms living in relatively small
areas. Therefore, the density of life in forest
ecosystems is very high. Any small change in
the ecosystem can affect the whole balance
and collapse the ecosystem.
7. Tropical evergreen forest:
Tropical forests which receive an average
rainfall of 80 to 400 inches in a year.
These forests are marked by dense
vegetation comprising of tall trees with
different levels. Each level gives shelter
to different kinds of animals.
10. Tropical Rain Forest
Types:
• Tropical Rain Forest Precipitation -
250cm/year
• Little temp. variation/abundant moisture
• Contains more species than other biomes.
12. • The Grassland Ecosystem
• Grasslands are found in both temperate and
tropical regions of the world but the ecosystems
are slightly varying. This area mainly comprises
of grasses with very little amount of shrubs and
trees. Main vegetation is grasses, legumes and
plants belonging to composite family. Many
grazing animals, herbivores and insectivores are
found in grasslands. Two main types of
grasslands ecosystems are:
13. Savanna: These tropical grasslands are
seasonally dry with few individual trees.
They support large number of grazers
and predators.
15. Prairies: This is temperate grassland. It is
completely devoid of trees and large
shrubs. Prairies can be categorized as
tall grass, mixed grass and short grass
prairie.
16. • The Mountain Ecosystem
Mountain lands provide a scattered but diverse array
of habitats in which a large range of plants and
animals are found. At higher altitudes harsh
environmental conditions generally prevail, and only
treeless alpine vegetation is found. The animals living
here have thick fur coats fro prevention from cold and
hibernate in winter months. Lower slopes commonly
are covered by coniferous forests.
17. The Desert Ecosystem
Desert ecosystems are found in regions receiving an annual
rainfall of less than 25cm. They occupy around 17 percent
of all land on the planet. Due to very high
temperature, intense sunlight and low water
availability, flora and fauna are very poorly developed and
scarce. Vegetation is mainly bushes, shrubs, few grasses
and rarely trees. Leaves and stems of these plants are
modified to conserve water. The best known desert plants
are the succulents like spiny leaved cacti. Animal life
includes insects, reptiles, birds, camels all of whom are
adapted to the xeric (desert) conditions.
18. 3. Deserts
• Precipitation 20cm/year
• Dry, sparce vegetation; scattered grasses
• Parts of Africa, Asia, Australia, North
America
21. Tropical deciduous forest:
Dense bushes and shrubs rule here along
with broad levels of trees. This type of
forests is found in many parts of the
world and large variety of flora and
fauna are found here.
26. Tundra
Enriches Earth just south of ice-covered
polar seas in Northern Hemisphere.
Covers 20% of earth’s land surface.
Trees are not found in the tundra because
growing season is too short.
29. Aquatic Ecosystems
An aquatic ecosystem is an ecosystem
located in a body of water. It comprises
aquatic fauna, flora and the properties
of water too. There are two types of
aquatic ecosystems, Marine and
freshwater.
30. The Marine Ecosystem
Marine ecosystems are the largest ecosystems
with coverage of nearly 71% of the Earth's
surface and containing 97% of the planet's
water. The water in Marine ecosystems has
salts and minerals dissolved in them in high
amounts. Different divisions of marine
ecosystems are:
31. • Oceanic: The relatively shallow part of the
ocean that lies over the continental shelf.
• Profundal: Bottom or deep water.
• Benthic Bottom substrates.
• Inter-tidal: The area between high and low
tides.
33. Ocean Ecosystems:
• Very large amount of Earth is covered by
ocean (~75%)
• 40% of all photosynthesis occurs in oceans.
• 3 types of oceanic ecosystems
• Shallow ocean waters
• Deep ocean water
• Deep ocean surface.
34. Deep ocean surface.
–Photosynthetic plankton is base of
food chain.
–Only occurs in Deep ocean surface &
Shallow ocean ecosystems
–No photosynthesis can occur in deep
ocean because light cannot penetrate
deeply into water.
35. The Freshwater Ecosystem
In contrast to the Marine
ecosystem, freshwater ecosystems only cover
0.8% of the Earth's surface and contain
0.009% of its total water. There are three
basic types of freshwater ecosystems:
36. Freshwater Ecosystem
Lentic: Still or slow-moving water like
pools, ponds, and lakes.
Lotic: Fast-moving water like streams and
rivers.
Wetlands: Places where the soil is
saturated or inundated for at least some
time.
37. Freshwater Ecosystem
These ecosystems are home to
amphibians, reptiles and almost 41% of
world’s fish species. Faster moving
turbulent water typically contains
greater concentrations of dissolved
oxygen, which supports greater
biodiversity than the slow moving water
of pools.
39. • Economic Benefits
• The mangroves supply forestry products
(firewood, charcoal, timber, honey
• etc.) and fishery products (fish, prawn, crab, mollusk etc.). Due to high
• calorific values, mangrove twigs are used for making charcoal and
firewood.
• One ton of mangrove firewood is equivalent to 5 tons of Indian coal, and it
• burns producing high heat without generating smoke. The mangrove wood
• with high content of tannin is used as timber for its durability. The
• pneumatophores are used to make bottle stoppers and floats. Nypa leaves
are
• used to thatch roofs, mats and baskets. Shells of mangrove molluscs are
used
• to manufacture lime.
40. Importance of Ecosystems
Mangroves attract honey bees and facilitate
apiculture activities in some areas. For
instance, the Sundarbans provide employment
to 2000 people engaged in extracting 111 tons of
honey annually and this accounts for about 90%
of honey production among the mangroves of
India (Krishnamurthy, l990). In Bangladesh, an
estimated 185 tons of honey and 44.4 tons of
wax are harvested each year in the western part
of the mangrove forest (Siddiqi, l997).
41. The Importance of Ecosystems.
Ecosystems are communities of living things and
the environmental features that support them.
Ecosystems are essential to human
life, providing us with innumerable and
invaluable services.These Ecosystem services are
the goods and services derived from natural
and managed ecosystems upon which human
welfare depends, and include everything from
clean air and water to food and fuel.
42. The Importance of Ecosystems.
Ecosystems are communities
of living things and the Ecosystems are
essential to humanlife, providing us with
innumerable and invaluable services.These
Ecosystem services are the goods and
services derived from natural and managed
ecosystems upon which human welfare
depends, and include everything from
clean air and water to food and fuel.
44. Mountain Ecosystem
Half of the world's population depends on
mountain water
An estimated one-tenth of the human
population derive their life-support directly
from mountains. Yet, mountains are important
not only for their inhabitants, but for millions of
people living in lowlands. At the global
scale, mountains' greatest value may be as
sources of all the world's major rivers, and many
smaller ones (Mountain Agenda, 1998).
45. Mountain Ecosystem
Mountain water is also a source of
hydroelectric power, most of which is used
on the plains below. Historically, water
wheels have provided energy in mountain
regions, mainly for grinding grain. In rural
Nepal there are an estimated 25 000 water
wheels and over 900 micro-hydropower
turbines - a more recent technology - that
provide a critical source of energy
46. Threats to the ecosystem
There are generally considered to be nine
major threats to the stability of ecosystems
on Earth. Climate change and loss of
biodiversity are often the most
publicised, although there are seven other
factors that may be equally threatening.
47. Threats to Ecosystems
The spread of agriculture and other human
activities into natural habitats poses a
large threat to ecosystems. Similarly, the
disruption of fresh water systems through
damming and diversion by humans can
lead to vast habitats becoming dry and
barren(empty).
48. Threats to Ecosystems
Chemical pollution can have devastating effects of
the health of ecosystems (as well as humans)
and the release of aerosols into the atmosphere
(through activities such as burning fossil fuels)
damages ecosystems in numerous ways. The
release of aerosols (among other things) can
also lead to the depletion of the ozone layer
which threatens to allow harmful solar radiation
to cause damage to organisms and ecosystems.
49. Threats to Ecosystems
Another potential threat to global
ecosystems that is the acidification of
the oceans due to increased carbon
dioxide in the atmosphere, which can
have serious knock-on effects on
important aspects of ocean chemistry.
50. Threats to Ecosystems
1. Loss of crop & grazing land
2. Depletion of world's tropical forests
3. Extinction of species
4. Rapid population growth
5. Shortage of fresh water resources
6. Overfishing, habitat destruction, &
pollution in the marine environment
51. Threats to Ecosystems
7. Threats to human health
8. Climate change
9. Acid rain
10. Pressures on energy resources
52. Main threats to ecosystems from
human activities
Population and consumption growth.
Infrastructure development (dams, urban
growth, highways).
Land conversion (deforestation, agriculture, urban
growth).
Overharvesting and overexploitation
(overfishing, wasteful irrigation).
Release of pollutants (human waste, agricultural and
industrial chemicals).
Introduction of exotic species (replacing and
overwhelming indigenous species).
53. River pollution
• Every day, 2 million tons of human waste are
disposed of in water courses.
• 40% of water bodies assessed in 1998 in the
United States were not deemed fit for World
distribution of hydropower recreational use due
to nutrient, metal and agricultural pollution.
• 5 out of 55 rivers in Europe are considered
pristine, and only the upper sections of the 14
largest rivers retain 'good ecological status'.
• In Asia, all rivers running through cities are
badly polluted.
54. Impacts of waterways diversion and
fragmentation
• 60% of the world's 227 largest rivers are
severely fragmented by dams, diversions and
canals, leading to the degradation of
ecosystems.
• In 1998, the Aral Sea had lost 75% of its total
volume. Its demise was caused primarily by
the diversion of the inflowing Amu Darya and
Syr Darya rivers.
55. Wetlands loss
• 50% of the world's wetlands have been lost
since 1900.
• More than 80% of the wetlands along the
Danube River have been destroyed since the
start of the 20th century.
• The Mesopotamian Marshlands in the Tigris
and Euphrates river basins were devastated
by damming and river channelisation.
56. Biodiversity loss
• Between 34 and 80 fish species have become
extinct since the late 19th century, 6 since
1970.
• At a global level, around 24% of mammals
and 12% of birds are classified as threatened.
• In the United States, 120 of 822 freshwater
fish species are considered
threatened, representing 15% of total fish
species.
