We know very little directly about Pleistocene megafauna behaviour other than their body size. But by looking at contemporary megafauna when can strong correlations between body size and day range, gut residence time, population densities.
They developed a model to examine lateral diffusion by megafauna, with phosphorus as an example mineral. The lateral diffusivity is a power law scaling function of body mass.
They model the nutrient diffusion from the floodplains of the Amazon to the wider Amazon basin. Argue that nutrient diffusion now is still not in equilibrium after the megafaunal extinctions. Doughty Wolf and Malhi (2013) Nature Geoscience.
Next look at sodium, which plants try their best to get rid off but animals are desperate for. Many continental interiors far from the sea are sodium limited, because sea salt aerosol input is important. They now apply the same model for sodium diffusion. The model suggests that 15,000 years ago the megafauna diffused sodium inland and also reduced concentrations in plants near the coast.
How to test these predictions? Look at transects of sodium in Ghana and Gabon
Did the extinctions affect tree diversity. Apply the same diffusion model to seed dispersal and see how tree ranges differ. This is work in progress.
Did the Pleistocene extinctions affect land cover reflectivity (albedo) and climate? Albedo can be more important than carbon as a tree effect. Animals can be affected by climate, but can also affect climate. Doughty Wolf and Field (2010), Geophysical Research Letters
Jim Estes: there is a whole parallel literature developing in the marine literature, with deep diving megafauna playing a key role in nutrient dispersal in the oceans.
They developed a model to examine lateral diffusion by megafauna, with phosphorus as an example mineral. The lateral diffusivity is a power law scaling function of body mass.
They model the nutrient diffusion from the floodplains of the Amazon to the wider Amazon basin. Argue that nutrient diffusion now is still not in equilibrium after the megafaunal extinctions. Doughty Wolf and Malhi (2013) Nature Geoscience.
Next look at sodium, which plants try their best to get rid off but animals are desperate for. Many continental interiors far from the sea are sodium limited, because sea salt aerosol input is important. They now apply the same model for sodium diffusion. The model suggests that 15,000 years ago the megafauna diffused sodium inland and also reduced concentrations in plants near the coast.
How to test these predictions? Look at transects of sodium in Ghana and Gabon
Did the extinctions affect tree diversity. Apply the same diffusion model to seed dispersal and see how tree ranges differ. This is work in progress.
Did the Pleistocene extinctions affect land cover reflectivity (albedo) and climate? Albedo can be more important than carbon as a tree effect. Animals can be affected by climate, but can also affect climate. Doughty Wolf and Field (2010), Geophysical Research Letters
Jim Estes: there is a whole parallel literature developing in the marine literature, with deep diving megafauna playing a key role in nutrient dispersal in the oceans.