Chapter 3 Ecosystems: What Are They and How Do They Work? Ecology is a study of connections in...
-
Upload
juliet-stone -
Category
Documents
-
view
215 -
download
1
Transcript of Chapter 3 Ecosystems: What Are They and How Do They Work? Ecology is a study of connections in...
Chapter 3 Ecosystems: What Are
They and How Do They Work?
Ecology is a study of connections in nature. How organisms interact with one
another and with their nonliving environment.
ENERGY FLOW IN ECOSYSTEMS
Food chains and webs show how eaters, the eaten, and the decomposed are connected to one another in an ecosystem.
Figure 3-17Figure 3-17
Food Webs Trophic levels are
interconnected within a more complicated food web.
Food webs show us the complex interactions between many food chains.
Figure 3-18Figure 3-18
Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs
In accordance with the 2nd law of thermodynamics, there is a decrease in the amount of energy available to each succeeding organism in a food chain or web.
Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs
Ecological efficiency: percentage of useable energy transferred as biomass from one trophic level to the next.
Figure 3-19Figure 3-19
Producers: Basic Source of All Food
Most producers capture sunlight to produce carbohydrates by photosynthesis:
Chemosynthesis:
Some organisms such as deep ocean bacteria draw energy from hydrothermal vents and produce carbohydrates from hydrogen sulfide (H2S) gas .
Productivity of Producers: The Rate Is Crucial
Gross primary production (GPP) Rate at which an
ecosystem’s producers convert solar energy into chemical energy as biomass.
Figure 3-20Figure 3-20
Net Primary Production (NPP) NPP = GPP – R
Rate at which producers use photosynthesis to store energy minus the rate at which they use some of this energy through respiration (R).
Figure 3-21Figure 3-21
Photosynthesis: A Closer Look
Chlorophyll molecules in the chloroplasts of plant cells absorb solar energy.
This initiates a complex series of chemical reactions in which carbon dioxide and water are converted to sugars and oxygen.
Figure 3-AFigure 3-A
Consumers: Eating and Recycling to Survive
Consumers (heterotrophs) get their food by eating or breaking down all or parts of other organisms or their remains. Herbivores
Primary consumers that eat producers Carnivores
Primary consumers eat primary consumers Third and higher level consumers: carnivores that eat
carnivores. Omnivores
Feed on both plant and animals.
Populations, Communities, and Ecosystems
Members of a species interact in groups called populations.
Populations of different species living and interacting in an area form a community.
A community interacting with its physical environment of matter and energy is an ecosystem.
Factors That Limit Population Growth
Availability of matter and energy resources can limit the number of organisms in a population.
Figure 3-11Figure 3-11
Factors That Limit Population Growth
The physical conditions of the environment can limit the distribution of a species.
ECOSYSTEM COMPONENTS Life exists on land systems called biomes and in
freshwater and ocean aquatic life zones.
Figure 3-9Figure 3-9
Nonliving and Living Components of Ecosystems Ecosystems consist of nonliving (abiotic) and
living (biotic) components.
Figure 3-10Figure 3-10
Core Case Study: Have You Thanked the Insects Today?
Many plant species depend on insects for pollination. Insect can control other pest insects by eating them …if all insects disappeared, humanity probably could not last more than
a few months [E.O. Wilson, Biodiversity expert]. Insect’s role in nature is part of the larger biological community in
which they live.
Figure 3-1Figure 3-1
THE EARTH’S LIFE SUPPORT SYSTEMS
The biosphere consists of several physical layers that contain: Air Water Soil Minerals Life
Figure 3-6Figure 3-6
Fig. 3-6, p. 54
Lithosphere (crust, top of upper mantle)
RockSoil
Vegetation and animals
Atmosphere
Continental Crust
LithosphereUpper mantle
AsthenosphereLower mantle
Mantle
Core
Biosphere
Crust
Crust (soil and rock)
Biosphere (living and dead
organisms)
Hydrosphere (water)
Atmosphere (air)
What Sustains Life on Earth?
Solar energy, the cycling of matter, and gravity sustain the earth’s life.
Figure 3-7Figure 3-7
What Happens to Solar Energy Reaching the Earth?
Solar energy flowing through the biosphere warms the atmosphere, evaporates and recycles water, generates winds and supports plant growth.
Figure 3-8Figure 3-8
Two Secrets of Survival: Energy Flow and Matter Recycle
An ecosystem survives by a combination of energy flow and matter recycling.
Figure 3-14Figure 3-14
BIODIVERSITY
Figure 3-15Figure 3-15
Why Should We Care About Biodiversity?
Biodiversity provides us with: Natural Resources (food water, wood, energy, and
medicines) Natural Services (air and water purification, soil
fertility, waste disposal, pest control) Aesthetic pleasure
Biodiversity Loss and Species Extinction: Remember HIPPO
H for habitat destruction and degradation I for invasive species P for pollution P for human population growth O for overexploitation