Energy Flow through ecosystems

Photosynthesis equation

6CO2 + 12H2O --> C6H12O6 + 6O2 + 6H2O

A meat-based diet requires

7-times more land than a plant based diet

Miami Model

89% of variation in NPP on a global scale can be explained by precipitation and temperature alone

About how much energy is lost in each trophic level?

90%

secondary production

Amount of chemical energy in consumers' food that is converted to new biomass.

Conservation of Energy

Energy cannot be created or destroyed

Net Secondary Productivity (NSP)

Energy converted to consumer biomass (assimilated energy left after respiration)

Net Primary Productivity (NPP)

Energy converted to producer biomass what is left after respiration

assimilated energy

Energy that consumer digests and absorbs (consumed-pooped energy) AKA gross secondary production

CHange in producer biomass

Estimate NPP by harvesting plants to determine mass of growth over period of time.

biomass pyramids often inverted in ____________ systems?

aquatic, because primary producers may be eaten as quickly as they grow

assimilation efficiency

assimilation/consumption

Energy is lost

at each level

Detritivores and decomposers

break down wastes and dead organisms Important for nutrient cycling

Some energy is not

consumed (creating a green world)

consumption efficiency equation

consumed energy/net production energy of the next lower trophic level

ecological efficiency equation

(Net Production energy of a trophic level)/Net production energy of the next lower trophic level 5-20%, 10% is a rule of thumb

Units of Energy

1 kcal=1000 cal 1 joule= 0.239

Why is photosynthesis not efficient?

1% of the solar energy striking the producers is captured by photosynthesis +(GPP), 60% is lost during respiration, 40% of GPP supports the growth and reproduction of producers (NPP). 99% of solar energy reflected by plants, because the sunlight is largely in a wavelength form that plants cannot absorb

estimating primary production

1. Change in producer biomass 2. CO2 exchange 3. Remote-sensing

Remote Sensing to estimate NPP

1. MEasure absorption of blue and red light and reflection of green light from satelite images 2. Calculate indices indicating vegetation biomass

Using that donut example, if 108 donuts, or 40,000 kcal is used in primary prodction, how much is the consumption energy?

10,000 kcal, or 27 donuts

How much donuts are used by primary consumers?

1970 kcal used in growth and reproduction by primary consumers; 5 donuts

gross vs net primary production

60% of the 1% absorbed is respired; 40% of the 1% absorbed is used for growth; this is the net primary productivity

What is the approximate ecological efficiency of the primary consumers in our example? Given Numbers: Photosynthetic efficiency = 0.01 100,000 Net primary production efficiency = 0.4 40,000 Consumption efficiency = 0.25 10,000 Assimilation efficiency = 0.48 4,800 Net production efficiency = 0.41 2,000 Is the Answer: A. 5% B. 10% C. 15% D. 20%

A 5% Net Production Efficiency =2000 Net Primary Production efficiency = 40,000 2000/40000 = 0.05 or 5%

Great Oxygenation event

A time about 2.5 billion years ago, when a significant amount of oxygen appeared in the atmosphere caused by photosynthetic cyanobacteria, causing an extinction of most Earth's species at the time

Assuming ecological efficiencies for herbivores = 20% and for carnivores = 5% Chimpanzees can eat both plant and animal material. Given a finite amount of energy (NPP of 100 Kcal for example), how many times more chimps could be supported on an herbivorous diet than on a carnivorous diet? A. 4 times greater B. 10 times greater C. 20 times greater D. the same E. actually, lower

C. 20 Herbivores: 100 kcal * 0.20 = 20 kcal for herbivores Carnivores: 100 kcal * 0.2* 0.05 1 kcal So in this example, herbivores have 20x more energy available to them

GPP equation

GPP = NPP + R

NPE is lower for ___________ than ________________

Homeothermic and mobile animals; poikilothermic and sedentary ones

trophic pyramid

Illustrate distribution of energy or biomass among trophic groups in an ecosystem. Number of trophic levels is limited: Energy runs out Aquatic has 5 levels, terrestrail has 3/4

Co2 Uptake experiments

Light vs Dark bottle.

Primary consumers have _____________ assimilation efficiencies than secondary consumers

Lower, since plant matter is less digestible Leads to assimilation efficiency of 0.48, of 4800 kcal or 13 donuts

In light bottle

Measure net CO2 upttake, since you can measure: CO2 used in photosynthesis - co2 released by respiration

NPP equation

NPP = GPP - R

NSP equation

NSP = GSP - R (Food Eaten-Energy in faeces) - respiration

NPE equation

Net Production Energy/Assimilated Energy

Ecological efficiency (food chain efficiency)

Net Production from one trophic level compared to the next lower level Incorporates consumption, assimilation, net production efficiencies

net production efficiency (NPE)

Of Food Assimilated, some is used for growth and reproduction, rest is lost through respiration

Some energy is not assimilated

Pooped Out

Some energy is used for

Respiraton, not growth or reproduction

Why is it that high precipitation does not mean increased NPP?

Too much water, leads to fungal growth

Gross Primary Productivity (GPP)

Total Energy acquired via photosynthesis (or chemosynthesis)

Respiration

Uses oxygen to release chemical energy to drive cellular processes

How much energy is recycled back through decomposers?

Very Small Amount, bout the same as the Seattle Seahawk's Playoff Chances (written 11/30/2021, when they have a 1% chance of making the playoffs)

In dark Bottle

You can measure CO2 released by respiration

Brown Food Web

detritus based food web

Food Chains Descrive

energy transfer

In decomposers, energy is released as

heat

Possible underestimations of NPP due to

herbivory, below-ground biomass, mutualstic exchanges

Energy transfer efficiency (in donuts)

if 10,000,000 kcal of light comes in (27,030 donuts) comes in, photosynthesis uses only 100,000 kcal (270 donuts), and the NPP is 40,000 (108 donuts)

Changes in spectral reflectances over time give

information on seasonal and annual variation

energy in each trophic level

is less than the one below B

Productivity varies with

latitude and across biomes Warmer areas may see more Net primary Productivity, and when you have a moderate amount of rainfall, you see a high amount of net primary productivity

Most energy enters the biosphere via

photosynthesis. Exception is chemosynthesis near deep ocean vents

Energy flows from

producers through successive trophic levels

primary productivity

rate at which energy is captured and converted into chemical bonds by photosynthesis of chemosynthesis

Energy is the

the ability to do work

Net Primary production is

the amount that can be passed up the food chain

The Higher an individual eats on the food chain

the more energy that is needed to support its diet

Amount of energy lost depends on

transfer efficienct