Elisa Chelsea Ellie Trophic Cascades Herbivores can limit plant populations but In most places plants are abundant and herbivores dont limit plant growth Sowhy is the world green HSS hypothesis ID: 234752
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Trophic CASCADES
Elisa, Chelsea, EllieSlide2
Trophic Cascades
Herbivores can limit plant populations, but…In most places, plants are abundant and herbivores don’t limit plant growth
So…why is the world green?Slide3
HSS hypothesis
for why the world is green (Hairston, Smith, & Slobodkin, 1960)Slide4
Why is the earth green?
According to the HSS hypothesis the Earth is green because there are carnivores…
Carnivores keep the herbivore population in check which allows producers to keep producingSlide5
Carnivores
Herbivores
ProducersSlide6
Carnivores
Herbivores
Producers
No predators
Limited only by foodSlide7
Carnivores
Herbivores
Producers
No predators
Limited only by food
Limited by predationSlide8
Carnivores
Herbivores
Producers
No predators
Limited only by food
Limited by predationSlide9
Carnivores
Herbivores
Producers
No predators
Limited only by food
Limited by predation
Limited by competition and resourcesSlide10
Trophic cascade
– influence of producers or consumers on species that are two or more trophic levels away
Top-down Control – influence of predators on the relative abundance of lower trophic levelsBottom-up Control – influence of producers on the relative abundance of higher trophic levelsSlide11
Conditions for
Trophic Cascades
1. Consumers can control biomass of preySlide12
Conditions for Trophic Cascades
If
Cpredator > Pprey Prey controlled by predator
If Cpredator < Pprey Prey not be
controlled by predatorP = productionC = consumption
Bioenergetic budgetG=growth (~ production)C=consumptionR=respiration
F=fecesE=excretaSlide13
Conditions for Trophic Cascades
2. Simple and well-known food webSlide14
From Brooks and Dodson 1965
alewife
Conditions for Trophic Cascades
3. Size-selective predationSlide15
What is biodiversity?
Biodiversity is the variability among living organisms from all sources, including terrestrial, marine, and other aquatic
ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species, and of ecosystems.Slide16
Why is it important?
Biodiversity affects key ecosystem
processes in terrestrial ecosystems such as biomass production, nutrient and water cycling, and soil formation and retention—all of which govern and ensure supporting servicesSlide17
THE END!!!
Elisa, Chelsea, Ellie
Bye