Download xCh23 Ecology GW

What is ecology?

The study of how organisms adapt to
The environment
Other organisms
Ecology – basic concepts
Energy flow
Trophic (feeding) relationships
Global climate change
Energy flow in ecosystems
We use the energy that plants
capture from the sun
Photosynthesis
(plants, algae)
Cellular respiration
(all organisms)
Producers:
The beginning of the food chain

Plants



The leaf is the primary site of
photosynthesis
Solar-powered
chemical factories
Produce food for
themselves and other
organisms
Capture solar energy
and use it to build
carbohydrates from
CO2 and water
Basic Photosynthesis

Photosynthesis feeds
nearly all life on earth




Plants take light energy and
CO2 and convert them into
sugars
Generate oxygen
Without plants we would
have no food to eat or
oxygen to breath
Animals exhale CO2 that
plants need for
photosynthesis
Food Chains
Energy passes from 1 trophic level to another




Step 1: Producers
Producers
Plants and algae
capture solar energy and produce
food
Primary consumers

Herbivores

Secondary consumers

Decomposers


Carnivores & omnivores
break down dead organisms,
return nutrients to the soil
The food chain continues

Last step in the food chain
Fungi decomposing
a dead log
Consumers



Herbivores
Carnivores
Omnivores

eat plants & animals


Decomposers get energy from the dead material
left by all trophic levels.
They break down organic substances, making them
available to other organisms

Trophic structure of a community
Increase nutrients in the soil
Where do humans fit in the
food chain?
Checkpoint



You are eating a pizza. At which
trophic level(s) are you feeding?
Flour (in the crust) and tomato sauce
Primary consumer
Cheese and meat
Energy loss in ecosystems
In a food chain,
only about 10%
of the energy at
one trophic level
is available to
the next
Secondary consumer
What limits the length of food
chains?


Most of the energy
captured by plants is
lost
Only about 10% of
the calories an
herbivore eats are
stored as body mass

An idealized energy pyramid
Inefficient conversion of energy

Producing animals for
food is less efficient than
directly eating the grains

Only 10% is of the energy
in the grain eaten by cattle
is converted to meat
available to the next
link in the food chain.
Where does the energy go?
Food energy available to humans

Eating plants instead of animals reduces
our impact on the environment
Global warming
Global Climate Change
The Greenhouse effect
Global warming
What is the evidence for
global warming?



What is global warming?
How is it affecting living
organisms?
What can we do about it?
The whole earth is warming
2000-2005 compared to 1950-1980
The largest temperature increases are in dark red
Why is the earth warming up?

Greenhouse
gases in
atmosphere
Solar energy
passes through

Radiant
heat is
trapped
“Greenhouse gases”
(CO2, methane, water
vapor) trap heat in the
atmosphere.
Burning fossil fuels
releases huge amounts
of CO2 into the
atmosphere
Atmospheric concentration of CO2

Global warming is
associated with
increased CO2 in
the atmosphere
The Greenhouse Effect

Global warming 101 Natl Geo 3:04
http://www.youtube.com/watch?v=oJAbATJCugs
The industrial revolution
How CO2 enters and leaves
the atmosphere
The Carbon cycle
Who are the “bad guys”?


The US accounts
for 18% of all
greenhouse
emissions –
ranking it second
in the world
China emits 19%
of the global total
What is the major source of CO2
released by human activities?
Burning carbon-containing fossil fuels
Likely effects of global warming



Increasing drought
Decreasing crop
productivity
Melting of ice in glaciers
and the polar ice caps,
causing sea level to rise
If sea level rises by 15 feet, large
areas of Florida will disappear
How is global warming altering
the oceans?
If sea level rises 15 feet

Flooding

Water quality – coastal sewage release



13 of 20 largest cities in world are at sea level, as are hospitals and watertreatment plants
Many cities around the world have sewer systems that overflow into water
supplies during heavy rainstorms
Increase in water-borne diseases
Excess CO2 has made the oceans
more acidic
The effects of ocean acidification
How urgent is climate change?
No emission cuts
A doomsday scenario for coral reefs?
Science 318:1230, 2007
Ecological footprint of people in
different countries
Ecological footprint


A way to understand our
consumption of energy and
resources
The ecological footprint
= amount of land required
to provide the raw
materials an individual
consumes

Acres
food, fuel, water, housing
and waste disposal
The ecological footprint of a person in the US
is 10X greater than someone in India
Families in India and the US
display their possessions
Resource consumption


We in the industrialized
countries, with 20% of
world population, use
86% of the world’s
resources
The other 80% of the
world’s population must
share the remaining 14%
of the resources
We need to reduce our
resource consumption

If all humans lived at our standard of living, 6
planet earths would be needed.
How can we do it?


Phase-out coal
Increase energy efficiency


Use renewable energy



Needed: Stronger emission standards and a carbon tax
Solar, wind, geothermal
Improve the electrical grid
More R&D


R E DUC E CO2
EM I SSI O N S
Renewable Energy Sources

Top candidates
Solar power
Wind power
 Nuclear power



Next generation of nuclear reactors (reduced waste)
Carbon capture and sequestration
YOU can make a difference

What can we do about
global warming?
Conserve energy:
 Walk, bike, use public transit,
or carpool
 Make sure your tires are fully

inflated and your car tuned up
 Lower your water heater and
home thermostats

Safety issues
Waste disposal
The Greatest Threat
“There is no doubt in my
mind that climate change is
the greatest threat facing the
biosphere today.”
 Only run your dishwasher with





full loads
Reduce your shower length and
temperature
Turn off lights when leaving a room
Use recycled paper
Reuse or recycle as much as you can
Global Warning DiCaprio 4:44

http://www.youtube.com/watch?v=C3
pujlkSTqo&NR=1