Lack of annual slash-and-burn in North America? In many areas of South America, Africa, India and Southeast Asia, "slash-and-burn" agriculture is employed whereby every year the stubble from the previous year is burned along with other live cuttings.

In North America, this does not seem to have ever happened. It is true that in New England (where I am from) the old-time farmers cut down all the trees and burned them to get pot ash, but this seems to have been a one time event. Once land was cleared of trees, it was not burned over and over again. Also, in many cases land was cleared without burning at all, the trees and stumps simply being hauled away.

Is there some difference in climate that results in tropical areas being subjected to repeated annual burnings whereas lands in North America are not? What causes the difference?
Slash and burn has been used in North America and still is at times.  I see regular field burning near me where fields are particularly rocky and tilling if impractical for the crops grown.  It also occurs when there is intrusions of some noxious weeds that are controllable through fire as effectively and much cheaper than chemical controls.

In general, I would consider slash and burn in disfavor because of it consumptive nature.  The practice does provide some otherwise missing nutrients, but it consumes large quantities of biomass while doing so.  More favored in many regions it to use that biomass to supplement the soil by tilling it in and allowing it to aerate the soil while slowly breaking down and augmenting the soil.  Between being fortunate enough to have good soil to begin with, or the ability to augment with either natural or chemical supplements, many North American farms do not need the quick fix burning can supply so opt for the slower, longer term solution of turning in the organic materials.