topic 2 ecosystems
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Topic 2 Ecosystems. Objectives. To define concepts and terms associated with ecosystems To give an overview of how an ecosystem works and the roles of energy and carbon To look at pyramids of number and of biomass To look at population interactions. Ecology. - PowerPoint PPT PresentationTRANSCRIPT
Topic 2 Ecosystems
Objectives To define concepts and terms associated
with ecosystems To give an overview of how an
ecosystem works and the roles of energy and carbon
To look at pyramids of number and of biomass
To look at population interactions
Ecology Ecology is “the scientific study of the
abundance and distribution of organisms and the interactions that determine distribution and abundance.”
Begon and Townsend 2006
What does this really mean – try to give concrete examples.
Ecosystems What do you understand by an
ecosystem?
Can you name ecosystems?
Definition An ecosystem describes a distinct
ecological unit that consists of both the living and non-living elements within it. An ecosystem can be permanent, such as tundra or desert, or it can be seasonal, such as a wetland formed from spring rains.
Abiotic/Biotic factors
Light Soil type Underlying geology Temperature Humidity Oxygen concentration Soil acidity Exposure
Predation Competition Symbiosis Disease Grazing
Abiotic factors Biotic factors
Ecosystems
What makes up our ecosystem Plants present Animals present Animals moving in and out Bacteria and fungi present Energy coming in Energy leaving Physical factors that define the habitat: heat,
rainfall, soil type, bedrock, pH, exposure to wind, waves, flooding, morphology, light and shade.
Influence of man’s activities
Food webs Show the interrelationship of organisms
within an ecosystem as predator, prey, consumer and competitor.
Trophic levels Producer Primary consumer (herbivores) Secondary consumers Tertiary consumers Top predators Detritivores or decomposers Omnivores – may occupy several trophic levels. What is the original source of energy? Give examples of each level of a food chain
Food chain What does this actually show in terms of
energy? What happens to energy at each stage?
Photosynthesis 1. Fixes energy 2. Fixes Carbon 3. Produces Oxygen 4. Carbon/energy moves up the food
chain Some energy is fixed within the
ecosystem autochthonous Some is fixed outside and imported
allochthonous Some is exported
Energy transfer How is energy passed on used? Where is energy lost?
Understanding this, explain why farmers often choose to keep farm animals inside.
Energy inputs and outputs in grassland
Inputs to the ecosystem Outputs from the ecosystem
Sunlight Migrating animals
Carbon (in a lake)
Allochthonous Autochthonous
Pyramids of number and biomass
Pyramid of number Pyramid of biomass
Pyramids of number & biomass
Oak tree 1 Herbivorous insects 500 000
Predatory insects 25 000
Small insect eating birds 100
Hawk 1
Oak tree 50 000 kg
Herbivorous insects 500 kg
Predatory insects 50 kg
Small birds 1 kg Hawk 100g
Data Numerical Data Biomass
Plot these data to produce two pyramids for the same ecosystem
What did you observe
Key terms
Species Bronzy inca
One of some 340 hummingbird species known in the Americas
Groups of similar organisms with similar features capable genetically and geographically of interbreeding.
There may be many similar but distinct species in a family
Term Definition
Population Population Mexico has
hawksbill turtles populations in Baja California and Yucatan
These are separate but may mix with other populations of the same species.
A group of individuals of the same species living in the same area.
A population may be completely or partially isolated from others, or there may be extensive mixing
Habitat Habitat This Mexican
scorpion is one of over a hundred species found in the country. Its habitat is caves – how can you tell?
This is the physical place in an environment where an animal lives. Its address
Niche Turkey vulture This is a carrion eating
species. It eats freshly dead, not putrefying meat
It cannot cut into larger animals so must wait for the king vulture to do so
It does not kill live animals like the black vulture
This is the role it occupies in the ecosystem. It is like its job.
Community The plant and
animal species present on the ‘estepa’ surrounding the school form a typical community
Interacting populations of species within an area
The organisms making up an ecosystem