Wayne, I am not a scientist but have a strong interest in landscape level preservation and management. What troubles me is the degree to which effects of grazing and fire are similar, or at least over lapping in many cases. This would seem to muddy the water regarding an answer to the question you posed. A number of studies (see J. Gill et al) point to grazing as being more of a vegetation influence than fire during the pleistocene, at least in many parts of the world. All paleo-ecologists seem to agree that fire frequency shoots up in many areas with die off of mega fauna and arrival of humans.
I suspect a bit of bias in most management approaches. We also go through swings of favoring various approaches, from fire suppression and grazing suppression to embracing and encouraging these same forces. In Europe, Vera and his followers are bringing back big grazers from Spain to the Caususes. See the Rewilding Europe website for some great pictures. Almost no use of fire there, as far as I can tell. They do not even use the term oak savanna, they call it oak "wood pasture". Because of a long cultural history of deer and cattle "parks" such grazing is an accepted aspect of management in Europe. This spring I was surprised to see that even Greenwich Park in London has a small herd of red deer. In Africa, most people seem to accept a combo of grazing and fire. In North America, I see great negative bias towards grazing and a positive bias towards fire. Maybe this goes back to Curtis and notions that burning by Native Americans is "natural". The old shifting baseline rears its head. Accepting that we can never really go back, it is still useful to have a better sense of trade offs between these two factors. How many systems that we now consider "fire dependent" were also "mega fauna adapted" ? Thinking of pine barrens, jack pine, scrub and shinnery oak, long leaf pine, sequoia, etc. Has anyone even looked at whether some of those serotinous cones might also have been rendered fertile by trampling or the molars of species like mammoths, mastodons, flat-headed peccaries or even the short-legged species of musk ox? It is a challenge to consider the landscape level vegetation response to the combo of missing herbivores in North America. African scientists such as Owen-Smith look at North America and say our grazers had a key stone role. I am interested in evidence based studies. So much speculation and assumption. Any thoughts on this are welcome. David Burg President, WildMetro
