Biogeography Round 2

Biosphere Influential

Vladimir Vernadsky 1926

Tropical Forest

• mean annual temp in coldest months >18C

• difference of <5C from coldest to warmest month

• common where every month has precipitation of >100mm, with only short dry period

Boreal Forest

• 500-1500mm/year

• 5-15C during vegetation season

Savannah

• 400-1500mm per annum

• 18-25C mean annual temp

Desert

• generally less than 250mm per year

• 20-25C mean annual temp

Temperate Deciduous Forest

• 500-2500 mm per year

• 10-15C mean annual temp

Tundra and Polar Desert

• 50-2000mm/year

• only just above 0C during growing period

Ecosystem People to Remember

• Alexander von Humboldt, 1769-1859

  • one of the first thinkers on ecology

  • realised the physiological constraints on organisms

• David Keeling, high precision measurements of CO2, 1958-present

  • ‘smoking gun’ of humanity’s impact

• Arthur Tansley, 1935, ecosystem concept (including exchanges as well as organisms)

Atmosphere and Ecosystem Carbon Stocks

• atmosphere >800 GtC

• terrestrial ecosystems 2300 GtC

VCF Amazon Deforestation

• soil-vegetation-atmosphere transfer model (SVAT)

• increase in surface temperatures by up to as much as 2.5C

• decrease in total precipitation by up to 800mm

• increase in deep soil temperature by up to 3.5C

• decrease in evapotranspiration by up to 400mm

CO2 Sources and Sinks

• Sources

  • 90% from industrial activity, 9.7 GtC/year

  • 10% from land use change, 1.1. GtC/year

• Sinks

  • 48% in atmosphere, 5.2 GtC/year

  • 29% in forests/plants, 3.2 GtC/year

  • 26% in oceans, 2.9 GtC/year

Pleistocene Sea Levels

230m+ total amplitude

Climate and Biogeographic Models

1. Equilibrium climate and biogeographic vegetation models (IPCC 1995: VEMAP group)

2. Specified climate and dynamic vegetation (IPCC 2001)

3. Fully coupled dynamic climate and vegetation models (IPCC 2001)

4. DGVMs that include NBP(net bioproductivity) estimate (e.g. fire frequency) and land use change