Transcript Community Ecology

Ecosystem
All biotic + abiotic features of an area.
Biotic: living organisms
Abiotic: non-living features
Through ecosystems, we study energy flow and
nutrient/chemical cycling.
Ecosystem Production
• Primary production: amount of light
energy converted to chemical energy.
• Trophic efficiency: amount of
production transferred from one level to
the next.
Energy is lost through respiration and waste
Food Webs are short
• Constrained by inefficient transfer of energy
between trophic levels (~10%/level).
Predict: Areas with greater productivity
should have…
• Shorter webs are more stable.
Predict: More variable environments should
have…
How are trophic levels regulated?
(meaning, why isn’t the whole earth covered in rabbits?)
Top-down regulation?
Bottom-up regulation?
(Can you describe how each of these might work?)
Community
Group of actually or potentially
interacting species living in the same
place.
How do communities form?
• Assemblage of species based on similar abiotic
needs?
Prediction:
• Interdependent species clustering together?
Prediction(s):
Measuring Biodiversity
Species diversity measures the
number of species (richness) and
number of individuals/species (abundance)
in a community.
Hot topic:
What’s the link between biodiversity,
productivity, and stability?
• invasion
• disease
Detritus: non-living organic material
(e.g. dead organisms, feces, molts, etc)
Detritivores:
• linked to all levels of trophic structure
• good measure of ecosystem activity (e.g.
energy flow, chemical recycling)
Difference between Detritivores and
Decomposers?
Carbon, Phosphorus, Nitrogen and energy
are all cycled through ecosystems
in similar pathways.