In some parts of North America, such as California, the climax ecosystem has frequent forest fires -- that is, relatively dry forest that in absence of human intervention would burn perhaps every couple of years. This creates a more open landscape, with large trees widely spaced and little deadwood or underbrush.
In other regions, such as the Carolinas, the climax ecosystem is for infrequent forest fires -- relatively moist forest that in absence of human intervention would burn perhaps on the order of once per century, during an unusually dry summer. This creates a forest with a lot of deadwood, moss, and so on, material that make fires very intense when they do happen.
Where is the boundary between the two? The references I have found so far, remark in general terms that western states tend to have frequent forest fires and eastern states infrequent forest fires; can it be narrowed down more precisely than that? Is there a map available showing the extent of each, or even a list of which states would fall primarily into each category? Or does reasonably correspond to something for which maps are readily available, such as Köppen climate classification?
In all cases, I'm interested in what the climates would produce in the absence of human intervention, i.e. the boundaries in temperature and rainfall conditions that would produce each kind of forest (or, in even drier conditions, no forest at all), not the changes in groundcover and fire frequency brought about by human activity.