Such a tiny portion of total biomass (and therefore nutrients) is tied up in large fauna that even a very dramatic megafaunal extinction event probably does not make much of a ripple in global nutrient cycling. Locally it may be more important, as in the wildebeest example, or as in the annual salmon migration in North America. As for the late Quaternary megafaunal extinctions, I am not personally convinced by the near-total lack of evidence for the cause being an impact - too many exceptions and no clear evidence of an impact. But either way, the ecological impact was probably greater through loss of apex herbivores and predators than through nutrient cycling of the corpses (see  Campbell et al., 1994, Bison extirpation may have caused aspen expansion in western Canada Ecography, 360-362.)

Such a tiny portion of total biomass (and therefore nutrients) is tied up in large fauna that even a very dramatic megafaunal extinction event probably does not make much of a ripple in global nutrient cycling. Locally it may be more important, as in the wildebeest example, or as in the annual salmon migration in North America. As for the late Quaternary megafaunal extinctions, I am not personally convinced by the near-total lack of evidence for the cause being an impact - too many exceptions and no clear evidence of an impact. But either way, the ecological impact was probably greater through loss of apex herbivores and predators than through nutrient cycling of the corpses (see  Campbell et al., 1994, Bison extirpation may have caused aspen expansion in western Canada Ecography, 360-362.)

Thanks, Ian.  A bolide strike to the Laurentide ice sheet would not provide the preferred crater evidence with shatter cones and shocked quartz. The ice sheet would absorb a lot of energy;  a meltwater pulse would have occurred (and did).  However, there is a layer in the Netherlands & Belgium ( the Usselo horizon) which contains abundant fused quartz, charcoal and some melt glass. There is also a global platinum signal ( Petaev et Al. 2010). And now sedimentary Pt evidence (Moore et al 2017).  If an impact occurred during the late glacial, not only would there be nutrients from carcasses but a large pulse of Ca .. wood Ash from massive wildfires is mostly CaCO3.   If we add the biomass of forests it may become more significant .  Thanks for the reference. I will take a look...I am sure the megafauna had a dramatic impact on vegetation.

http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0587.1994.tb00113.x/abstract  Link to your paper

On a global to regional scale, the amount of macro-nutrients stored in the fauna seems minute compared with the amounts in the phytomass and soil, as Ian has argued already. 

Frequent and/or large scale taiga and savanna fires may redistribute the macro-nutrients N and C from the terrestrial biosphere first into the atmosphere and P and Ca from the biosphere initially into the pedosphere (soil). In principle, these redistributed macro-nutrients may be taken up in substantial amount by the biosphere were and when these are the local/regional limiting nutrient for plant growth or by physical/chemical processes in the marine hydrosphere.

Perhaps, Hein, the macronutrients seems minute to you.   Consider this http://rarehistoricalphotos.com/bison-skulls-pile-used-fertilizer-1870/

How vast were the herds of bison before Columbus?

Also, the passenger pigeons were so plentiful at one point (est. 3 billion), historically, that there are accounts of their flyover causing a darkening of the sky for days...They broke limbs off trees from the weight of flocks roosting in trees.  Their dung would certainly have affected at least the local nutrients

"The migratory flights of the passenger pigeon were spectacular. The birds flew at an estimated speed of about sixty miles an hour. Observers reported the sky was darkened by huge flocks that passed overhead. These flights often continued from morning until night and lasted for several days."

https://www.si.edu/encyclopedia_si/nmnh/passpig.htm

https://www.scientificamerican.com/article/3-billion-to-zero-what-happened-to-the-passenger-pigeon/

Additionally, the ivory islands north of mainland Siberia have been mined for the mammoth tusks there.   Over 100,000 animals remains were deposited there.

Re: wildfires, you have left out the massive wildfires that occur in the boreal forests.  As far as catastrophic wildfires,  the Peshtigo Fire (Wisconsin) of 1871 reduced that town to a bed of ashes. It happened the same time as the great Chicago Fire, and is thought to have been exacerbated by the logging debris in the area, drought, and a smoldering peat fire to the north, which eyewitnesses said erupted in an explosion before the fire.  One of the best sources for this is the eyewitness account by Father Peter Pernin

http://content.wisconsinhistory.org/cdm/compoundobject/collection/wmh/id/46445/show/46360/rec/1

These are just examples to think about when extrapolating to a larger scale extinction or wildfire.

Hi

Article An Update on the Global Stressors and Constraints Affecting ...

Thanks, Fatima!!!

You're welcome Dear Joanne