LECTURE NOTE WEEK 1 SEM2

CHAPTER 2

2.1 ECOSYSTEM CONCEPT

LEARNING OUTCOMES:

Define ecosystem
Describe lake ecosystem based on:

i. Light penetration (photic and aphotic)
ii. Distance from shore (littoral, limnetic)
Describe terrestrial ecosystem of tropical
rainforest stratification (emergent, canopy,
understory, shrub, ground layer/forest floor)

ECOSYSTEM

• Definition:

Ecosystem is the interacting system that
encompasses a community and its non-living

physical environment.

ECOSYSTEM

1) An ecosystem is the community of organism in area
and the physical factors which those organism interact.

2) Emphasizes energy flow and chemical cycling between
organisms and the environment.

3) Ecosystem is made up of:
i) Biotic (living) components consist of
producers, consumers and decomposers/ detritivores.

ii) Abiotic (Nonliving) components or physical
environment.

4) An ecosystem is an open system because it is unable to
sustain itself

• Open system : A system in which energy and nutrient are
exchanged between environment.

ECOSYSTEM

• Ecosystem requires energy input from sun and
nutrient inputs from environment

• Energy flow through an ecosystem in one way
direction.

• Eventually, much of this energy returns to the
environment as heat.Energy cannot be
recycled.

• Nutrients (e.g: P,S,N,H2O) are recycle.

• The efficiency of energy flow & nutrient cycle
stabilize the ecosystem

LAKE ECOSYSTEM

LAKE ECOSYSTEM

▪ Many aquatic biomes are physically or chemically
stratified (layered) vertically or horizontally as illustrated for
a lake.

▪ Can be classified based on :

i. Light penetration
✓ Photic zone
✓ Aphotic zone/profundal
zone

i. Distance from shore
✓ Littoral zone
✓ Limnetic zone

LAKE ECOSYSTEM

(BASED ON LIGHT PENETRATION)

▪ Based on light penetration , lake ecosystem is divided into
two zones.
✓ Photic zone
✓ Aphotic zone/profundal zone

LAKE ECOSYSTEM

(BASED ON LIGHT PENETRATION)

✓ Zone of surface waters
penetrated by sunlight

✓ light penetration sufficient for
photosynthesis

✓ Inhabit by plankton (E.g
phytoplankton, zooplankton
)many fish species and frogs.

LAKE ECOSYSTEM

(BASED ON LIGHT PENETRATION)

✓ Open water below the level of light penetration
✓ Where there are insufficient light for photosynthesis
✓ Situated beneath the photic zone
✓ Inhabit by heterotrophs feeds on dead organism
✓E.g organism: bacteria

LAKE ECOSYSTEM

(BASED ON LIGHT PENETRATION)

**✓ Plants and algae do not live in this zone.

✓ Food drifts into aphotic zone from the littoral and limnetic zones.
✓ Bacteria decompose dead plants and animals that reach the aphotic

zone, thus liberating minerals.
✓ Minerals not effectively recycled as no photosynthetic organisms to absorb

and incorporate them into food web→ mineral rich & anaerobic

LAKE ECOSYSTEM

(BASED ON

✓ Based on distance from shore are divided into 2 zone :
1. Littoral zone
2. Limnetic zone

LAKE ECOSYSTEM

(BASED ON

✓ Shallow, well lit water close to the shore where aquatic plants are dominant
✓ E.g of plant : floating plants (water lilies, duckweed), emergent

plants, submerged plants
role: producing oxygen and providing food and shelter
✓ E.g of animal : insect larvae, crayfish, crustaceans, frogs, turtles and many
fishes (such as carp, perch and bass).

cattail duckweed water lily

LAKE ECOSYSTEM

(BASED ON

✓ Well lit open surface water, further from shore
✓ Habitat of phytoplankton, zooplankton, microscopic animal and
fishes
✓ Role of phytoplankton: serves as the base of lake’s

food chain and producing oxygen
✓ Due to its depth, less vegetation grows here.

PHYTOPLANKTON
ZOOPLANKTON

LAKE ECOSYSTEM

▪ In between photic and aphotic region ,
✓ photosynthesis rate = respiration rate → compensation point
✓ NPP (net primary productivity) = 0
✓ NPP: net gain of organic material in photosynthesis

NPP = GPP – Plant respiration

Compensation point

TERRESTRIAL ECOSYSTEM:
TROPICAL RAINFOREST

TERRESTRIAL ECOSYSTEM:
TROPICAL RAINFOREST

✓ The richest and most diverse biome (structure & species
diversity)

✓ Located at tropical region

✓ Receive large amount of rain throughout the year

✓ High humidity

✓ Exists near the equator in South and Central America,
Africa and Southeast Asia *

TERRESTRIAL ECOSYSTEM:
TROPICAL RAINFOREST

✓ Layers of the Rainforest composed of 5 layers:
✓ Emergent layer
✓ Canopy layer
✓ Understory layer
✓ Shrub layer
✓ Ground layer / Forest floor

✓ Each layer has a unique set of environmental conditions and
organisms adapted to them

Solomon 11th edition pg.1224

TERRESTRIAL ECOSYSTEM:
TROPICAL RAINFOREST

Strata Example of tree Example of animal
Emergent layer Eagle
Jati, Cengal, Meranti, Tualang
Canopy layer tree Sloth, Gibbon
Snake, owl
(Koompassia excelsa)
Nephelium sp. Caterpillar, butterfly
Ant
Understory layer Rattan

Shrub layer Hibiscus sp.
Moss
Ground layer/
Forest floor

TERRESTRIAL ECOSYSTEM:
TROPICAL RAINFOREST

EMERGENT LAYER

CANOPY LAYER

UNDERSTOREY LAYER
SHRUB LAYER
GROUND LAYER

TERRESTRIAL ECOSYSTEM:
TROPICAL RAINFOREST

EMERGENT LAYER

❑ The topmost story consists of the crowns
of the oldest, tallest trees.
❑ *Reaches a height : over 150 feets (45 m)
❑ exposed to direct sunlight

❑ Usually supported by buttress roots to
brace against the high winds

❑ Most trees are broad-leaved,
hardwood evergreens

Large trunk

Buttress root supports the tallest trees

TERRESTRIAL ECOSYSTEM:
TROPICAL RAINFOREST

EMERGENT LAYER

❑ Leaves often have thick, waxy layers to hold water
❑ Take advantage by the greater air movement above
canopy by developing winged seed/fruits that dispersed by
wind to other part of the forest

❑ Sunlight is plentiful

❑ Animal: eagles, monkeys, butterflies,
insect-eating bats

TERRESTRIAL ECOSYSTEM:
TROPICAL RAINFOREST

CANOPY LAYER

❑ *Reaches a height of 100-115 feets
(30-35m)

❑ Most canopy trees have smooth, oval
leaves that come to point

❑ They shed rain quickly, discouraging
the growth of lichens and mosses

TERRESTRIAL ECOSYSTEM:
TROPICAL RAINFOREST

CANOPY LAYER

❑ Epiphytes, include orchids and bromeliads
grow well in the canopy at the trunks or
branches of the tree
❑ In locations where they can access more
sunlight that filters through the canopy

❑ Animals: hummingbird,
woodpecker, iguana, tree frog,
sloths, toucan

TERRESTRIAL ECOSYSTEM:
TROPICAL RAINFOREST

UNDERSTORY LAYER

❑ *Reaches a height of 20m
❑This layer gets little sunlight
❑ Limited light: unique ways to
survive, such as the solar-
collecting dark green leaves
soft-stalked species of families such as

ginger family and acanthus

TERRESTRIAL ECOSYSTEM:
TROPICAL RAINFOREST

UNDERSTORY LAYER

❑ Plants here have difficult time with pollination because
lack of air movement, most rely on insects

❑ Some produce strong smelling flowers, others produce
flowers and fruits on their trunks

❑ Animals: snakes, frogs,
jaguars, lots of insect

TERRESTRIAL ECOSYSTEM:
TROPICAL RAINFOREST

SHRUB

❑ Almost no plants grow, few flowering plant that live
here tolerate deep shade

❑ *Shrub : less than 3% of light
: reaches height 8m

❑ Example of tree: Hibiscus sp.

❑ Example of animal: Caterpillar, butterfly

TERRESTRIAL ECOSYSTEM:
TROPICAL RAINFOREST

GROUND LAYER

❑ *Ground layer : less than 1% of light
❑ The ground is usually dark and damp//

high humidity//little light penetration

❑ and covered with little of rapidly decomposing plants
and animals that break down into usable nutrients

❑Vegetation at ground layer is generally not dense
except near stream banks or where a fallen tree has
opened the canopy.

Lack of vegetation on forest floor
due to lack of sunlight

TERRESTRIAL ECOSYSTEM:
TROPICAL RAINFOREST

GROUND LAYER

❑ Animals: insects, cockcroaches, beetles,
centipedes, scorpions, earthworm along with
fungi

Question: What is meant by tropical
rainforest?
Answer: Forest that is located at the
tropical region and received large amount
of rain throughout the year.