7 - Foodwebs (2) Flashcards
1
Q
Why is the world green? (Hairston et al 1960)
A
Green plant biomass accumulates
because herbivores are kept in check by predators (top down control)
2
Q
Why is the world green? (Hairston et al 1960)
A
The world is prickly and tastes bad –
plants defend themselves and herbivores compete for limited resources (bottom up control)
3
Q
Bottom up
A
- plant chemical defense
- nutritional limitations
4
Q
Top-down
A
- predator control of herbivore numbers
5
Q
Why are oceans blue?
A
1)Most water is too deep for photosynthesis
2)Large plants can only survive in restricted condition
3)Seawater is too nutrient poor to maintain dense phytoplankton populations
(Bottom-up control)
6
Q
A
