Primary Productivity

Jason BroshearKatherine EchementZach MoningLeo Sack

Photosynthesis

Photosynthesis

Respiration

Carbon Cycle

Sink Amount in Billions of Metric Tons

Atmosphere 578-766

Soil organic matter 1500 to 1600

Ocean 38,000 to 40,000

Marine sediments and sedimentary rocks 66,000,000 to 100,000,000

Terrestrial plants 540 to 610

Fossil fuel deposits 4000

Greenhouse Effect

Primary Productivity

Phytoplankton

Phytoplankton

• Single-celled plants• Photosynthesis• Lots of them – about

half of plant biomass on the planet

Phytoplankton – nutrient influence

Biological Pump

Phytoplankton Distribution

• Where is the most phytoplankton productivity?

Arctic and Southern Oceans• In high latitudes,

most nutrients rarely used up

• Limiting factor: dissolved iron

• “Fertilize” these regions with iron, more productivity

• Solution to global climate change??

Problems with Iron Fertilization• Zooplankton grazing

also a limiting factor• Much added iron

“lost” – affects on other ecosystems?

• Limited effect on CO2 – most recycled in water, not sinking

• Not economically feasible solution

Boreal Forest: Background• The northern boreal ecoregion accounts for about one third of this

planet's total forest area.• Is considered one of the largest carbon sinks.• Most dominant tree species are conifers which are well-adapted to

the harsh climate, and thin, acidic soils. • There are innumerable water bodies: bogs, fens, marshes, shallow

lakes, rivers and wetlands, mixed in among the forest and holding a vast amount of water.

• Fire is a crucial disturbance factor in the boreal ecoregion because it facilitates the destruction of old, diseased trees along with the pests that are associated with those trees.

• Some trees such as aspen and jackpine actually require fires to stimulate their reproductive cycles. Furthermore, the nutrient-rich ash left behind helps fuel plant growth.

Grasslands: Background

• Tropical grasslands (Savannas) and temperate

• Savannas have wet and dry seasons - heavy rain and seasonal fires

• Grasses are dominant, trees and large shrubs mostly absent

• Large and small mammals, reptiles, birds, etc.

Grasslands

Net Primary Productivity of Different Biomes

0

5

10

15

20

25

desertsemidesert

tundralake/stream

temperate grassland

boreal forestagriculture

temperate foresttemperate woodland

tropical savannatropical forest

wetland

Ecosystem

Area (10^12 m^2)

0

200

400

600

800

1000

1200

desertsemidesert

tundralake/stream

temperate grassland

boreal forestagriculture

temperate foresttemperate woodland

tropical savannatropical forest

wetland

Ecosystem

NPP (gC/m^2/yr)

Nitrogen Cycle

Phosphorus Cycle