2.3 Flows of Energy and Matter

What links ecosystems together?

Energy and matter flows

What drives the energy flows?

The sun, through solar radiation, made of visible and invisible wavelengths

How much solar radiation is intercepted an what by?

60% is intercepted by atmospheric gases and dust particles

How much energy is reflected back into space?

35%

How much energy is available to plants on Earth’s surface?

1-4%

How much energy is available to be passed from one trophic level to another?

Approx. 10%

This is why food chains are short since they run out of energy to pass between trophic levels

Ecological efficiency formula?

(energy used for growth/ energy supplied) x 100

What is productivity?

The conversion of energy into biomass over a given period of time. It is the rate of growth or biomass increase in plants and animals.

(measured per unit area per unit time)

Define the key terms: gross, net, primary and biomass

**GROSS:** total amount of something made as a result of an activity

NET: amount left after deductions are made… it is what you have left

**PRIMARY:** related to plants (secondary relates to animals)

**BIOMASS:** living mass of an organism or, sometimes, dry mass

What is net productivity (NP)?

Gain in energy or biomass that remains after deductions due to respiration

= some energy is used up in staying alive (breathing) instead of growing

What is primary productivity? (PP)

Gains by autotrophs (green plants) in energy or biomass through the light energy converted into chemical energy by photosynthesis

What is gross primary productivity? (GPP)

Total gain in energy or biomass by green plants. It is the energy fixed or converted from light to chemical energy by green plants.

What is net primary productivity? (NPP)

Total gain in energy or biomass by green plants after allowing for losses to respiration.

NPP = GPP - R

What is gross secondary productivity?

Total energy/ biomass taken up by consumers and is calculated by subtracting the mass of fecal loss from the mass of food eaten

GSP = food eaten - fecal loss

What is net secondary productivity? (NSP)

The total gain in energy/ biomass by consumers after allowing for losses to respiration.

NSP = GSP - R

Describe flows of energy

**How much:** Infinite

**When:** once

**Outputs:** all organisms give out energy all the time through respiration

**Quality:** degrades from higher to lower quality energy so entropy increases

**Storages:** temporarily stored as chemical energy

Describe flows of matter

**How much:** finite

**When:** cycles and cycles repeatedly

**Outputs:** all organisms release waste nutrients, carbon dioxide and water

**Quality:** may change form but doesn’t degrade

**Storages:** stored long and short term in chemical forms

How does energy flow?

In one direction, starting as insolation and leaving as heat through respiration of decomposers

What is the maximum sustainable yield?

The largest amount that can be taken from a species over an indefinite period of time

It is equal to half of a species’ carrying capacity