Download Community Ecology - Jedi`s Biology Web Page

Community Ecology
Chapter 8
•
•
•
•
•
•
•
Community Ecology
A biological community consists of interacting species, usually living within a defined
area. A community lies between the spatial scales of a population and a biome.
Community Ecology is the study of how a given ecosystem functions.
Matter is conserved
Matter = all material in the universe that has mass and occupies space
• The law of conservation of matter: matter can be transformed from one type of
substance into others
• But it cannot be destroyed or created
Because the amount of matter stays constant
• It is recycled in nutrient cycles and ecosystems
• We cannot simply wish pollution and waste away
Energy fundamentals
Energy = the capacity to change the position, physical composition, or temperature of
matter
• Involved in physical, chemical, biological processes
Potential energy = energy of position
• Nuclear, mechanical energy
Kinetic energy = energy of motion
• Thermal, light, sound, electrical, subatomic particles
Energy is conserved but changes in quality
•
•
First law of thermodynamics = energy can change forms, but cannot be created or
destroyed
Second law of thermodynamics = energy changes from a more-ordered to a less-ordered
state
• Entropy = an increasing state of disorder
Second Law of Thermodynamics
•
The Flow of Energy Through Ecosystems
Producers, Consumers, and Decomposers
The Path of Energy Flow
•
Food Chains
• Trophic levels: Feeding levels in a food chain
•
Food Webs –
Trophic Pyramid
The Path of Energy Flow
•
Ecological Pyramids
•
Ecological Pyramids
•
The Path of Energy Flow
Example: Thermodynamics in Action
The Path of Energy Flow
The Path of Energy Flow
•
Desert Biomass Pyramid
•
The Path of Energy Flow
Temperate Forest Biomass Pyramid
•
•
•
•
Levels of biological diversity (biodiversity)
Humans are reducing Earth’s diversity of life
Biodiversity = variety of life at all levels of organization
• Species diversity
• Genetic diversity
• Population and community diversity
Species diversity
Species diversity = the number or variety of species in a particular region
• Richness = the number of species
• Evenness (relative abundance) = the similarity in numbers between species
Speciation adds to species richness
• Extinction reduces species richness
Some Species Have Major Influences on Community Composition
•
Keystone species influence ecological communities more than would be expected from
their abundance.
Keystone species
•
•
Types of Ecological/Species Interactions
Focus: nature and consequences of interactions among species in a community.
5 Species interactions:
• competition
• predation/parasitism
• commensalism
•
•
mutualism
(amensalism)
Competition: Seeking and Using Scarce Resources
•
Organisms using the same limited resources are competitors.
• intraspecific (within sp.)
• interspecific (between/among spp.)
Ecological Succession