Ecosystem Ecology I. Introduction II. Energy Flow A. Productivity 3. Net Secondary Productivity - assimilations efficiencies – A/I carnivores: 80-90% (no cell walls to deal with)

Ecosystem Ecology I. Introduction II. Energy Flow A. Productivity 3. Net Secondary Productivity - assimilations efficiencies – A/I carnivores: 80-90% seed eaters: 60-80% herbivores grazers (leaf-eaters): 60-70% browsers (woody twigs and buds): 30-40%

Ecosystem Ecology I. Introduction II. Energy Flow A. Productivity 3. Net Secondary Productivity - assimilations efficiencies – A/I carnivores: 80-90% seed eaters: 60-80% herbivores grazers (leaf-eaters): 60-70% browsers (woody twigs and buds): 30-40% detritivores: 15%

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 II. Energy Flow A. Productivity N:P :: 50:1 Ecosystem Ecology I. Introduction II. Energy Flow A. Productivity Only get twice the N they need. 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; but then may get too much of other stuff. N:P :: 15:1 Get 6x the N they need BOTH EAT PHYTOPLANKTON (100:1 :: N:P) 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 I. Introduction II. Energy Flow A. Productivity 0.5% Birds Ecosystem Ecology 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 Productivity Trophic Pyramids

Ecosystem Ecology I. Introduction II. Energy Flow Productivity Trophic Pyramids - ecological efficiency: NSP/NPP (5-20%) NPP of Secondary Carnivores Loss due to 2nd Law 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 NPP of Secondary Carnivores Loss due to 2nd Law NPP of Primary Carnivores NPP of HERBIVORES NPP of Producers (PLANTS)

Ecosystem Ecology I. Introduction II. Energy Flow Productivity Trophic Pyramids Detrital Foodchains Predators Herbivores

Ecosystem Ecology I. Introduction II. Energy Flow Productivity Trophic Pyramids Detrital Foodchains NPP Detritivores Herbivores Temperate forest: 1.5% - 2.5% Old-field Habitat: 12% Open Ocean (Plankton): 60-99%

Ecosystem Ecology I. Introduction II. Energy Flow Productivity Trophic Pyramids Detrital Foodchains ‘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) / (npp of biomass / m2 / yr)

Ecosystem Ecology I. Introduction II. Energy Flow Productivity Trophic Pyramids Detrital Foodchains ‘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) / (npp of biomass / m2 / yr) Forests: ~ 20 years Tropical leaf litter: 3 months Phytoplantkon: ~20 days Temperate leaf litter: 2-20 years

Ecosystem Ecology I. Introduction II. Energy Flow Productivity Trophic Pyramids Detrital Foodchains BAR Human Concerns

E. Human Concerns

E. Human Concerns: NPP

E. Human Concerns: NPP

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

input calories converted to calories able to be utilized by humans 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 E. Human Concerns 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 converted 21% is ‘virgin forest’

E. Human Concerns INTENSIFICATION – yield=kg/m2 area

E. Human Concerns

E. Human Concerns The best land has already been used; further expansion in marginal areas is costly and requires more supplementation. Also, degraded soils require supplementation

E. Human Concerns Global NPP (dry mass) = 224 billion tons. 59% is terrestrial, and of this, 35-40% is controlled by humans, either eaten directly or fed to animals we will consume 1 species 10-30 million species