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Lecture 13

ISCI 1001 Lecture Notes - Lecture 13: Ecological Pyramid, Food Chain, Rodent

3 pages60 viewsFall 2015

Interdisciplinary Science
Course Code
ISCI 1001
John Buschek

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Thursday, October 15th, 2015
ISCI 1001 – Lecture 13 Note
Communities (Ecological):
-Energy flow through a community
oPasses through trophic hierarchy
Trophic levels (feeding)
Producers (autotrophs), consumers (1°, 2°, 3°), decomposers, detritivores
Trophic pyramid: *diagram in lecture slide*
-From bottom to top: Producers, 1° consumer, 2° consumer, 3° consumer
-Note: bars can represent Energy, biomass, numbers
Food chain:
-Real communities – food webs are a better picture
-Grass (prod.) -> Grasshopper (1° cons.) -> rodent (2° cons.) -> hawk (3° cons)
-General rule: lose about 90% of biomass, numbers, etc. at each upward step in pyramid
Do some organism have more “important” niches?:
-Maybe; “keystone” species
-Pisaster ochraceus (sea star (star fish))
NW US Coastline:
-Took small area
oThey removed all sea stars (top predator) for 6 yrs
-Beforehand there were 15 species
oAfter 6 yrs -> 8 species
Community Response to Disturbance:
-1° succession -> start from no life
-2° succession -> start from some disturbed community
oForest -> farmland -> taken out of farming
New Picture: *diagrams in lecture slide*
-Multiple equilibria
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