Maths as a tool to get insights into the past. He starts with a quote by Hairston, Smith & Slobodkin ("The World is Green”) indicating that herbivores must not matter in determining the effect of vegetation on climate. If it does not affect albedo or CO2 it does not matter.
Example of vegetation cover and convective clouds around the rabbit-proof fence in Australia. Their model suggests loss of megafauna in Eurasia caused warming as dark trees encroached into snow-covered grasslands.
Animals matter because they move and can transport nutrients and genes. This can be represented as a diffusivity in a random walk. How can we get numbers for the diffusivity?
Diffusion of animals is a function of body size. The diffusivity of materials is a function of how many animals there are, how much material there is in the biomass, how much they eat, how far they walk and their gut residence time.
They develop the model and evaluate it in Kruger National Park. He argues that it would be impossible to reconcile the nutrient budget of Kruger National Park without taking megafaunal nutrient diffusion into account.
Presents global picture of nutrient dispersal. Africa and South Asia are hotspots, everywhere else is cool and dark. How different this would have been without the megafaunal extinctions.
Andrew Balmford: IUCN maps are areas where they recently occupied. Where they actually exist is greatly reduced and restricted compared to IUCN maps
Some questions say that now we have to take feral exotics into account into modern—day maps they are performing functions that extinct megafauna once did.
The papers he mentions are available here
Doughty, C.E., Wolf A., and Malhi Y. (2013) The legacy of the Pleistocene megafauna extinctions on nutrient availability in Amazonia, Nature Geoscience,Advance Online Publication. Supplementary Information.
Wolf, A., Doughty, C.E., and Malhi, Y. (2013) Lateral Diffusion of Nutrients by Mammalian Herbivores in Terrestrial Ecosystems. PLoS ONE 8(8): e71352. doi:10.1371/journal.pone.0071352. Supplementary Information.
Example of vegetation cover and convective clouds around the rabbit-proof fence in Australia. Their model suggests loss of megafauna in Eurasia caused warming as dark trees encroached into snow-covered grasslands.
Animals matter because they move and can transport nutrients and genes. This can be represented as a diffusivity in a random walk. How can we get numbers for the diffusivity?
Diffusion of animals is a function of body size. The diffusivity of materials is a function of how many animals there are, how much material there is in the biomass, how much they eat, how far they walk and their gut residence time.
They develop the model and evaluate it in Kruger National Park. He argues that it would be impossible to reconcile the nutrient budget of Kruger National Park without taking megafaunal nutrient diffusion into account.
Presents global picture of nutrient dispersal. Africa and South Asia are hotspots, everywhere else is cool and dark. How different this would have been without the megafaunal extinctions.
Andrew Balmford: IUCN maps are areas where they recently occupied. Where they actually exist is greatly reduced and restricted compared to IUCN maps
Some questions say that now we have to take feral exotics into account into modern—day maps they are performing functions that extinct megafauna once did.
The papers he mentions are available here
Doughty, C.E., Wolf A., and Malhi Y. (2013) The legacy of the Pleistocene megafauna extinctions on nutrient availability in Amazonia, Nature Geoscience,Advance Online Publication. Supplementary Information.
Wolf, A., Doughty, C.E., and Malhi, Y. (2013) Lateral Diffusion of Nutrients by Mammalian Herbivores in Terrestrial Ecosystems. PLoS ONE 8(8): e71352. doi:10.1371/journal.pone.0071352. Supplementary Information.