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Causes of Landscape Pattern

Causes of Landscape Pattern. Temporal variation in abiotic factors: Milankovitch Cycles. Changes in the earth’s orbital parameters Leads to changes in inputs of solar radiation by about 3.5% Causes Ice ages

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Causes of Landscape Pattern

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  1. Causes of Landscape Pattern

  2. Temporal variation in abiotic factors: Milankovitch Cycles • Changes in the earth’s orbital parameters • Leads to changes in inputs of solar radiation by about 3.5% • Causes Ice ages • About a 5oC change in mean global temperatures between glacial and interglacial conditions

  3. About a 5oC change in mean global temperatures between glacial and interglacial conditions • For the current Interglacial period, peak warming, about 1-2oC warmer than present, occurred about 9000-4000 years ago (not shown in figure above) • The “Little Ice Age” was about 1oC cooler than current temperatures • Anthropogenically driven climate change (“super interglacial”) due to the burning of fossil fuels is predicted to result in a warming of about 2-4oC over the next century.

  4. PNW Vegetation Response: Glacial to Interglacial Brubaker 1991

  5. PNW Fire Frequency/Size Response: Little Ice Age to Present Wallin et al. 1996

  6. Decadal variations in climate: The Sahel zone in Africa End of colonial rule for most countries in this region Variation in the position of the 200 mm/yr rainfall boundary over the period from 19870-1990. Dark line is mean position. Rainfall departures from the long-term mean for the Sahel Zone of Africa

  7. Decadal variations in climate: El Nino/Southern Oscillation

  8. Decadal variations in climate: El Nino/Southern Oscillation Tend to be great snow years in the PNW!

  9. Decadal variations in climate: El Nino/Southern Oscillation

  10. Temperate Forest • Majority lie between 40o and 50o. • Rainfall averages 650 – 3,000 mm. • Fertile soils • Long growing seasons dominated by deciduous plants. • Short growing seasons dominated by conifers. • Biomass production can be very high. • Many major human population centers.

  11. Fig. 3 from Waring and Franklin 1979

  12. Spatial patterns: Landform constraints on moisture and nutrients From Swanson et al. 1988

  13. Spatial patterns: Landform constraints on disturbance From Swanson et al. 1988

  14. Spatial patterns: Dispersal constraints

  15. Spatial patterns: Potential range changes under 2 x CO2

  16. Biotic Disturbance Agents • Beaver • Bison • Bugs • Humans

  17. Historic Changes in Forest Cover

  18. Forest Cover Change in Wisconsin

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