Yes. It puts the root crown above the sog.

Olpea has an entire orchard planted in this manner. You have to avoid the wet feet and a berm is one way to accomplish that.

For most fruit trees, you have to prevent "wet feet" or soggy earth around the root system. Berms function much like a raised garden bed by raising the soil level and allowing the upper portion of the roots and the crown to be above the soggy ground.

For some species, like peaches, it is extremely helpful even when drainage is pretty good.

Thank you! So if berms are like raised beds, will they reduce the ability of my trees to make it through a cold winter? My sister noticed in her raised beds that she couldn't over winter her carrots.

How would you prevent soggy feet otherwise? My soil has high clay content but with lots of rocks, especially where we are doing our fruit trees. We're thinking a pear, an apple, a peach, and maybe an apricot.

My guess would be that type of soil is best suited for the pear and second best for the apple. I would put those two in your worst locations and save your best locations with the greatest drainage for the peach and apricot. If you go to most abandoned homesteads and look at their orchard you will typically still see a pear tree growing. When I bought my place many years ago a pear was still here from the original homesteaders. It was reported to be well over a hundred years old.

I believe that it is not freezing roots that usually kill fruit trees in extreme weather, it is the death of above ground cambium. In wet soils the roots grow close to the surface anyway and trees are more likely to die prematurely in any case- so having them in berms would likely improve their chances for survival in extreme weather. If you have any doubt, just use an airy mulch for insulation.

You are in a Z6 like myself and I've not experienced weather that extreme in the several decades I've lived here. A test winter in a Z5 can sometimes kill peach trees.