Transcript Unit 2 Lesson 3 * Changes in Ecosystems Lesson 4 * Human Activity

Unit 2
Lesson 4 – Changes in
Ecosystems
1
Nothing Stays The Same
• Ecosystems and organisms are constantly
changing and responding to daily, seasonal, and
long-term changes in the environment.
– Eutrophication – is the process in which organic matter
(life) and nutrients slowly build up in a body of water.
• The growth and decay of organisms in the pond can fill it
with organic material, which becomes soil. Meadow plants
then grow in the soil.
• A pond turning into a meadow!
• SLOW change!
2
Nothing Stays The Same
• Ecosystems may change suddenly due to natural
events.
• Examples include: Strong winds, storms, forest fires,
volcanic eruptions.
• However, recovery brings new changes to an
ecosystem.
3
Ecological Succession
• Succession – is the slow development or
replacement of a community by another community
over time.
• 2 types of ecological succession
– 1. Primary succession – An area with no life and no soil.
• Usually formed from a volcanic eruption or retreating glaciers.
• The first organisms to live in an uninhabited area are called pioneer
species.
– Lichens and moss – grow on rock breaking the rock down into soil.
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Wind carries seeds over.
Small plants and grass grow.
Insects and small animals show.
Plants grow larger.
Forest forms.
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Primary Succession
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VIDEO
Ecological Succession
- 2. Secondary Succession – An
ecosystem already exists and is
damaged by a natural disaster.
- The soil is already there.
- Wind carries seeds.
- Small plants will regrow.
- Insects and small animals show.
- Plants grow larger.
- Forest forms again.
Only
Difference!!!!
This occurs after a
disturbance and
soil is already
there!!!!
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Secondary Succession
SONG
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Mature Ecosystem
• 2 signs of a mature ecosystem
– 1. Climax species – an established and stable
species in an ecosystem.
• Like big trees
– 2. Biodiversity – the number and variety of
species present in an area.
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Unit 2
Lesson 5 – Human
Activity
9
Growing Pains
• Humans negatively affect ecosystems!
• 1. Pollution – caused by any material or condition
that harms the environment.
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The burning of fossil fuels.
Pesticides.
Garbage.
Toxic chemicals.
• 2. Using up natural resources.
– Cutting down trees to make paper
– Using fresh water faster than it can be
replenished
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Growing Pains
• 3. Destroying Habitats
– Urbanization – human population growth in and
around cities is increasing.
• Destroying of natural habitats for building.
• If a habitat is damaged or destroyed, biodiversity is lost.
• More humans = a greater need for natural resources.
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Growing Pains
• Human impact on oceans!
– Pollution
• Point-source pollution – pollution coming from one source
(Ex: oil spill)
• Non-point source pollution – pollution coming from many
sources (Ex: fertilizers and pesticides running off into the
oceans)
• Raw sewage and trash (Ex: plastic bags and packaging)
– Fishing and Overfishing
• Due to a greater demand in seafood, many fish species
cannot reproduce fast enough to replace itself (overfishing)
– Coastal Development
• Building homes and businesses
• Damaging coral reefs
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Growing Pains
• Human impact on Freshwater ecosystems!
– Animal wastes, fertilizer and pesticides from farms
contain nutrients that can enter ponds, lakes and rivers as
runoff.
• An increase in the amount of nutrients causes eutrophication, which
disrupts the life.
– Constructing a dam - Dams block the flow of river water,
leading to less water downstream.
– Water quality is affected by air pollution.
• Acid rain from burning of fossil fuels.
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Save It!
• Ways to protect Ecosystems.
• 1. Stewardship – the careful and responsible
management of a resource.
• 2. Maintaining biodiversity – protecting habitats and
animals.
• 3. Conserving natural resources – protecting and
using natural resources wisely.
– Reduce – what you buy and use
– Reuse – what you already have
– Recycle – recovering materials from waste
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