SB4bSB4bExplain the flow of matter and Explain the flow of matter and energy through ecosystems byenergy through ecosystems by

•Arranging components of a food Arranging components of a food chain according to energy flowchain according to energy flow

•Comparing the quantity of energy Comparing the quantity of energy in the steps of an energy pyramidin the steps of an energy pyramid

•Explaining the need for cycling of Explaining the need for cycling of major nutrients (C, O, H, N, P)major nutrients (C, O, H, N, P)

Ecosystems

Chapter 13.2 Page 402

An ecosystem An ecosystem includes both includes both

BioticBiotic andand AbioticAbiotic factors.factors.

Characteristics of Life:Characteristics of Life:

BIOTIC BIOTIC FACTORSFACTORS

What is Life?What is Life?

1)1) Made up of CellsMade up of Cells• Smallest unit of life• Unicellular – Single-celled organism• Multicellular – Many-celled organism

2)2) ReproductionReproduction• Replacing yourself so the species doesn’t die out• Sexual – two cells from different parents unite• Asexual – a single parent

Life Continued…Life Continued…

1)1) Obtain and use energyObtain and use energy• Chemical reactions used to power an organism’s

body• Gives energy for growth, reproduction, etc.• Three methods for obtaining energy:

• Photosynthesis• Breaking down dead things• Eating

• All energy comes from the sun.

More about life…More about life…

1)1) HomeostasisHomeostasis• Keeping internal conditions “normal”• For example, body temperature and shivering

2)2) Based on a universal genetic Based on a universal genetic codecode

• All organisms are based on a genetic code, usually Deoxyribonucleic Acid (DNA)

• Controls how you pass on your traits

And more about life …And more about life …

1)1) EvolutionEvolution• Organisms Change over time• Organism adapts, survives, reproduces, and passes

on traits that allowed it to adapt.• If an organism can’t adapt, it dies off (Natural

Selection)

2)2) Respond to the EnvironmentRespond to the Environment• Organisms and species depend upon and

interconnect with one another• React to changes around the organism

And finally…And finally…

1)1) Grow and DevelopGrow and Develop• Organisms change over their lifetime; have a

distinct life cycle

BioticBioticBiotic factors are Biotic factors are living things, such living things, such as plants, animals, as plants, animals, fungi, and bacteria.fungi, and bacteria.

BioticBiotic

Each organism plays a Each organism plays a particular role in the particular role in the ecosystem. For example, ecosystem. For example, earthworms play a key earthworms play a key role in enriching the soil.role in enriching the soil.

AbioticAbioticFactors are nonliving things such Factors are nonliving things such as moisture, temperature, wind, as moisture, temperature, wind, sunlight, and soil. The balance sunlight, and soil. The balance of these factors determines of these factors determines which living things can survive in which living things can survive in a particular environment.a particular environment.

For example:For example:

Coral reefs near salt Coral reefs near salt marshes have more marshes have more fish than reefs fish than reefs farther out at sea.farther out at sea.

Why?Why? Mangrove trees in Mangrove trees in the marshes provide food the marshes provide food and shelter for newly and shelter for newly hatched fish.hatched fish. Abiotic factors that affect the growth of trees include low levels of oxygen & changing levels of salinity due to daily tidal changes.

What are abiotic factors?

•Temperature•Sunlight•Humidity•Water•Soil type•Minerals

Moisture.Moisture.

Copyright © 2010 Ryan P. Murphy

Temperature.Temperature.

Copyright © 2010 Ryan P. Murphy

Wind.Wind.

Light.Light.

Soil.Soil.

Nutrients.Nutrients.

Changing one Changing one factor in an factor in an ecosystem can ecosystem can affect many affect many other factors.other factors.

An ecosystem is An ecosystem is a complex web of a complex web of

connected connected bioticbiotic and and abiotic abiotic

factors.factors.

You may not think of You may not think of yourself as part of the yourself as part of the ecosystem, but humans, ecosystem, but humans, like other species, rely on like other species, rely on the environment for the environment for survival. All species are survival. All species are affected by changes to affected by changes to bioticbiotic and and abioticabiotic factors factors in an ecosystem.in an ecosystem.

BiodiversityBiodiversity

Biodiversity is the Biodiversity is the assortment, or assortment, or

variety, of living variety, of living things in an things in an ecosystem.ecosystem.

Species Diversity

An area with a high An area with a high level of biodiversity, level of biodiversity, such as a rain forest, such as a rain forest, has a large has a large assortment of assortment of different species different species living near one living near one another.another.

The amount of biodiversitybiodiversity found in an area depends on many factors, including moisture and temperature.

Biodiversity Varies

Naturally

There is a trend towards more species in warmer, wetter areas and fewer in colder and drier areas.

Numbers of bird species occupying areas of North America.

BiodiversityThere are many measures of biodiversity.

Considering species diversity, more diverse communities tend to be more productive.

Remember, however, that this is one set of communities.

Biodiversity

Why Worry About the Relationship Between Biodiversity and Community

Stability?

Because this understanding is essential for knowing how many species and of what types can be lost before a community collapses.

Science (2005) 309:90

We really don’t have a satisfying answer to this fundamental question.

There are Biodiversity “Hotspots”

Less than 1% of Earth’s surface supports 20% of known plant species and probably a greater portion of animal species.

Biodiversity hotspots for tropical rain forest and chaparral ecosystems.

Biodiversity hotspots are significant for conservation plans.

How rapid is the current rate of extinction? The number’s hard to pin down, but generally accepted estimates put it at 10-100 times the rate before extensive human–induced environmental modifications. For example, in the U.S. ~ 225 vascular plant species have become extinct in the past 50 years and about 650 of the remaining 20,000 species are threatened.

Biodiversity is Being Lost Rapidly Through Extinction

Dire News

Not all agree that we’re seeing a mass extinction, but it’s clear species loss has accelerated sharply above background.

What are the Causes of Accelerated Extinction?What are the Causes of Accelerated Extinction?

Habitat loss

Pollution

Introduction of exotic species & diseases

Overharvesting

Effect of rabbit Effect of rabbit introduction to Australiaintroduction to Australia

Climate change

Keystone Species

A keystone species is a species that has an unusually large effect on its ecosystem.

An example of a keystone species is the beaver. By felling trees to construct dams, beavers change free-flowing stream havitats into ponds, wetlands, and meadows. This modification leads to a cascade of changes within their ecosystem.

Refer to Figure 13.6 Page 404

Beavers as Keystone Species

Keystone species form & maintain a complex web of life. Whatever happens to that species affects all the other species connected to it.

Pop Quiz

Define the following:

1. Biotic & give example

2. Abiotic & give example

3. Biodiversity

4. Keystone species & give example

HAVE A GREAT DAY!