Ecosystem Ecology
Ecosystem Ecology
I. Introduction
- Ecosystem: an assemblage of organisms, together with their
chemical and physical environments
Ecosystem Ecology
I. Introduction
II. Energy Flow
Ecosystem Ecology
I. Introduction
II. Energy Flow
A. Productivity
1. Gross Primary Productivity
Total photosynthetic productivity:
CO2 + H20 -----> Glucose + O2
Ecosystem Ecology
I. Introduction
II. Energy Flow
A. Productivity
1. Gross Primary Productivity
Total photosynthetic productivity:
CO2 + H20 -----> Glucose + O2
Metabolism
Growth
Reproduction
Ecosystem Ecology
I. Introduction
II. Energy Flow
A. Productivity
1. Gross Primary Productivity
Total photosynthetic productivity:
CO2 + H20 -----> Glucose + O2
Ecosystem Ecology
I. Introduction
II. Energy Flow
A. Productivity
2. Net Primary Productivity:
- energy stored in biomass
RESPIRATION
------
Metabolism
Growth
NPP
Reproduction
GPP
Ecosystem Ecology
I. Introduction
II. Energy Flow
A. Productivity
2. Net Primary Productivity:
- energy stored in biomass
- measurements
Ecosystem Ecology
I. Introduction
II. Energy Flow
A. Productivity
2. Net Primary Productivity:
- energy stored in biomass
- measurements
- factors affecting NPP
Ecosystem Ecology
I. Introduction
II. Energy Flow
A. Productivity
2. Net Primary Productivity:
- energy stored in biomass
- measurements
- factors affecting NPP
- light
Ecosystem Ecology
I. Introduction
II. Energy Flow
A. Productivity
2. Net Primary Productivity:
- energy stored in biomass
- measurements
- factors affecting NPP
- light
- water
Ecosystem Ecology
I. Introduction
II. Energy Flow
A. Productivity
2. Net Primary Productivity:
- energy stored in biomass
- measurements
- factors affecting NPP
- light
- water
- temp
Ecosystem Ecology
I. Introduction
II. Energy Flow
A. Productivity
2. Net Primary Productivity:
- energy stored in biomass
- measurements
- factors affecting NPP
- light
- water
- temp
- nutrients
2. Net Primary Productivity:
- factors affecting NPP
- Nutrients: Nutrient Use Efficiency =
grams of dry mass produced/gram of nutrient absorbed
Lower NUE for a nutrient means it is more limiting (need more to produce the
same biomass).
2. Net Primary Productivity:
- energy stored in biomass
- measurements
- factors affecting NPP
- light
- water
- temp
- nutrients
- Global Patterns
2. Net Primary Productivity:
- energy stored in biomass
- measurements
- factors affecting NPP
- light
- water
- temp
- nutrients
- Global Patterns
Ecosystem Ecology
I. Introduction
II. Energy Flow
A. Productivity
3. Net Secondary Productivity
- assimilations efficiencies – A/I
seed eaters: 60-80%
browsers: 30-40%
detritivores: 15%
Ecosystem Ecology
I. Introduction
II. Energy Flow
A. Productivity
3. Net Secondary Productivity
- assimilations efficiencies – A/I
seed eaters: 60-80%
browsers: 30-40%
detritivores: 15%
herbivores: 60-70%
carnivores: 80-90%
Low AE? Must eat more to get energy needed.
Horse – ‘hindgut ruminant’ – less
efficient, high throughput
Cattle – ‘foregut ruminant’ – more
efficient, can eat less.
Ecosystem Ecology
I. Introduction
N:P :: 50:1
II. Energy Flow
A. Productivity
3. Net Secondary Productivity
- affected by nutrient ratios,
growth rates, and most
limiting variable. May need to
eat a lot to get enough of the
limiting variable.
N:P :: 15:1
Fast growing; need higher ratio of
Phosphorus for DNA synthesis.
Ecosystem Ecology
I. Introduction
II. Energy Flow
A. Productivity
3. Net Secondary Productivity
- Net Production Efficiency = P/A
NSP
What might this
depend on???
NPP
Ecosystem Ecology
0.5%
Birds
I. Introduction
II. Energy Flow
A. Productivity
0.7%
Shrews
3. Net Secondary Productivity
- net production efficiency = P/A
6-10%
Most
Mammals
Up to 75% for sedentary
poikilotherms
Ecosystem Ecology
I. Introduction
II. Energy Flow
A.
Productivity
B.
Trophic Pyramids
Ecosystem Ecology
I. Introduction
II. Energy Flow
A.
Productivity
B.
Trophic Pyramids
- ecological efficiency: NSP/NPP (5-20%)
Loss due to 2nd Law
NPP of Secondary Carnivores
NPP of Primary Carnivores
NPP of HERBIVORES
NPP of Producers (PLANTS)
a. trophic "pyramids"
This is why large carnivores are RARE,
and why they have large RANGES
Loss due to 2nd Law
NPP of Secondary Carnivores
NPP of Primary Carnivores
NPP of HERBIVORES
NPP of Producers (PLANTS)
Ecosystem Ecology
I. Introduction
II. Energy Flow
A.
Productivity
B.
Trophic Pyramids
C.
Detrital Foodchains
Predators
Herbivores
Ecosystem Ecology
I. Introduction
II. Energy Flow
A.
Productivity
B.
Trophic Pyramids
C.
Detrital Foodchains
Detritivores
NPP
Herbivores
Temperate forest: 1.5% - 2.5%
Old-field Habitat: 12%
Plankton: 60-99%
Ecosystem Ecology
I. Introduction
II. Energy Flow
A.
Productivity
B.
Trophic Pyramids
C.
Detrital Foodchains
D.
‘Biomass Accumulation Ratios’
If we know the mean ‘standing crop’ of biomass from year to
year, and we know the net productivity, we can calculate how
long, on average the biomass persists:
BAR (per year) = (biomass/m2) / (np of biomass / m2 / yr)
Ecosystem Ecology
I. Introduction
II. Energy Flow
A.
Productivity
B.
Trophic Pyramids
C.
Detrital Foodchains
D.
‘Biomass Accumulation Ratios’
If we know the mean ‘standing crop’ of biomass from year to year, and we know
the net productivity, we can calculate how long, on average the biomass
persists:
BAR (per year) = (biomass/m2) / (np of biomass / m2 / yr)
Forests: ~ 20 years
Phytoplantkon: ~20 days
Tropical leaf litter: 3 months
Temperate leaf litter: 2-20 years
Ecosystem Ecology
I. Introduction
II. Energy Flow
A.
Productivity
B.
Trophic Pyramids
C.
Detrital Foodchains
D.
BAR
E.
Human Concerns
E. Human Concerns
E. Human Concerns
E. Human Concerns
E. Human Concerns
500% increase in 50 years, with population increase of 250%
E. Human Concerns
A doubling of meat production per capita
E. Human Concerns
25% of catch by weight discarded
E. Human Concerns
E. Human Concerns
6-10 lbs of feed for 1 lb increase in cattle weight
2-5 lbs of fish meal for 1 lb increase in farmed fish weight
E. Human Concerns
Edible kilocalories produced from
kilocalories of energy required for
cultivation are:
18.1% for chicken,
6.7% for grass-fed beef,
5.7% for farmed salmon
0.9% for shrimp.
123% for potatoes
250% for corn
415% for soy
input calories converted to calories able
to be utilized by humans
So, for every 100 calories of energy we put in to raise
chickens, we get 18 calories of energy produced in chicken
meat. 100 cal into soy, 415 calories out.
E. Human Concerns
Food production, per capita
(400 kg per year is healthy minimum)
SO HOW DID WE
DO IT?
E. Human Concerns
EXTENSIFICATION – MORE AREA
E. Human Concerns
EXTENSIFICATION – MORE AREA
E. Human Concerns
The best land has already been used;
further expansion in marginal areas is
costly and requires more
supplementation
E. Human Concerns
47% of historical
forested land has
been cut
E. Human Concerns
INTENSIFICATION
E. Human Concerns
E. Human Concerns
The best land has already been used; further expansion in
marginal areas is costly and requires more supplementation
E. Human Concerns
Global NPP (dry mass) = 224 billion tons. 59% is terrestrial, and of this,
humans 35-40% is controlled by humans, either eaten directly or fed to
animals we will consume