ecosystems at the heart of global change (terrestrial lecture 1)

Question 1

How is carbon dioxide exchanged between the atmosphere and biosphere?

Answer 1

• photosynthesis transfers co2 from atmosphere into biosphere
• plant (autotrophic)/soil (heterotrophic) respiration and disturbance release terrestrial co2 into atmosphere

Question 2

Define:

• gross primary productivity
• net primary productivity
• net ecosystem productivity
• net biome productivity

Answer 2

GPP: rate at which photosynthesis occurs

NPP: GPP - plant respiration (autotrophic)

NEP: NPP - soil respiration (heterotrophic)

NBP: NEP - C lost due to disturbance

Question 3

What are ecosystem structure/function?

Answer 3

ECOSYSTEM STRUCTURE

• what lives there & their traits
• biodiversity, biomass, leaf area, adaptations etc

ECOSYSTEM FUNCTION

• the processes that operate & how they are controlled
• carbon exchange w/ atmosphere, hydrological cycle and energy exchange, biotic interactions

Question 4

What is the ecosystem concept?

• what are they
• what controls ecosystem structure/function
• what do ecosystems control

Answer 4

• ecosystems are units comprising communities of organisms and their environment
• abiotic and biotic factors important in controlling ecosystem structures and function
• ecosystems control fluxes of carbon, nutrients, water and energy between the land, atmosphere and oceans

Question 5

What are the components and direction of Earth’s surface energy balance?

Answer 5

Solar radiation brings energy to the earth
Some of this energy is reflected (albedo)

Outgoing longwave radiation (OLR) is infrared radiation emitted from earth to space

Some is lost from the earth surface as sensible heat

Evapotranspiration transfers energy from biosphere to atmosphere (has a cooling effect)