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Evolutionary history of tropical forests

Evolutionary history of tropical forests. Geologic eras: a revision. Permian 225 million years ago. Triassic 200 million years ago. Jurassic 135 million years ago. Cretaceous 65 million years ago. The Earth: always changing. Present day.

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Evolutionary history of tropical forests

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  1. Evolutionary history of tropical forests

  2. Geologic eras: a revision...

  3. Permian 225 million years ago Triassic 200 million years ago Jurassic 135 million years ago Cretaceous 65 million years ago The Earth: always changing Present day

  4. Rainforest distribution under various climate regimes RAINFORESTFROST LIMITS

  5. Leaf morphology tells us about past temperature

  6. Angiosperm revolution: 90 million years ago mil. yrs

  7. Late Cretaceous: origin of many rainforest plant taxa

  8. Paleocene: first closed canopy rainforests, in three tropical belts

  9. Oligocene: after Eocene cooling, rainforests only around the equator

  10. Paleocene/Eocene thermal maximum: “super greenhouse” distribution of rainforests, resulting in many important dispersal events The sudden warming probably triggered by massive CO2 discharge from ocean see vents, or deep-ocean gas hydrates?

  11. Miocene: “greenhouse” distribution of rainforests in a single wide belt

  12. Last glacial maximum 16-20,000 yr ago: rainforests fragmented

  13. Latitudinal extent of tropical rainforest climates is highly variable

  14. The oldest rainforests: New Caledonia, Madagascar, East Australia New Caledonia managed to stay in tropical climatic zone for the past 70 mil years

  15. Changes in distribution patterns: Nypa fructicans, one of the oldest contemporary palm species known from fossil records (70 mil years old) Fossil Nypa roots

  16. Land bridge between the Americas: 3 million years ago

  17. Our unstable times: geologically fast changes in temperature and see level

  18. Closed forest retreat during last glacial maximum This and following vegetation maps: Jonathan Adams,University of Adelaide

  19. Vegetation change between last glacial maximum and present

  20. Vegetation change between last glacial maximum and present 22-16 ya - glacial maximum

  21. Vegetation change between last glacial maximum and present

  22. Glacial maximum: SE islands connected with the continent Old rivers

  23. Changes in altitudinal zonation from the last glacial maximum

  24. Colombian Andes Changes in the upper forest limit during late Quarternary East Africa New Guinea

  25. Continental altitudinal profiles: high elevations in Africa lead to smaller lowland rainforest areas during glacial maximum During the last glacial maximum, only 15% of land area in Africa was in the lowland rainforest zone, compared to 35% in S. America and 40% in Asia AND tropical forests in Africa are now the least diverse... The curve shows % of land area below a particular elevation in km

  26. Variable proportion of forests and grasslands in S. America during past 10,000 years [based on pollen analysis] grasses and sedges ByrsonimaCuratella

  27. Forest area change in past 20,000 yr in Africa pollen from lake sediments

  28. Do species boundaries correspond to glacial forest refugia?

  29. Reconstructed species richness maxima [Pleistocene glacial refugia] for butterflies, lizards and birds only partially overlap

  30. Conclusions: The present distribution of tropical forests is very recent and most species evolved in different places than those they are facing now. Current decrease in rainforest area has a recent precedent - during past glacial maximum, only 18,000 years ago. The present-day rainforest ecosystems are therefore not venerable finely-tuned systems, but rather hastily assembled makeshift contraptions. This last point is well explained in: Daniel H. Janzen (1985) On ecological fitting. Oikos 45: 308.

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