Behold, the tree trunk.

 Being a good caregiver to trees is so important. They offer us shade, clean the air and give us the sound of breeze. It takes so many years to grow a decent size tree, replacing one can take a very long time. Above, in my 'simple' drawing I have illustrated a few points about the tree. The space between the trunk and where the edge of the canopy is called the 'dripline.' This is where the rain drips off the tree (where did they come up with that?) In many cases the root zone will be twice that distance from the trunk. Realizing how far out the roots can go, might stop us from inadvertently destroying them with digging or frequent driving over the root zone area. This diagram would represent a mature tree.

 Why do roots come out of the ground? These are the lateral roots and they will grow towards the best conditions. In compacted soil, that may be cruising along the surface. Should these be buried up? No, just leave them. Could you? Yes, but do not bury more than a couple of inches or you could suffocate the roots.Eventually, they will likely move up in the soil again. Some types of trees and older trees are more likely to have exposed roots.

 A cut away of a real tree. Why did they do that anyway, poor thing! Good example of where the roots located.

 Where oh where am I to go to find adequate water and nutrients. I could almost cry for some of these poor trees. Let me see, sidewalk on one side, asphalt on the other. Obviously this tree is trying it's best by bringing so many roots to the surface. A tree in this situation would appreciate some extra water now and then.

 This poor tree above likely had a good portion of it's root system trimmed off to install this brick wall. The tree obviously looks older than the brick. The root system also 'anchors' the tree in place, remove half of it's anchors......watch out below. This tree will likely be the first on the block to blow over in a storm. Another problem is, they have removed 1/2 it's vascular system. That's like taking out 1/2 of our blood veins and expecting us to be okay. (to put it bluntly)

Another tree trunk no no. NEVER bury up tree trunks with a raised bed like this. The trunk, all the way down to the buttress, needs to be exposed to air. The buttress, is where the tree flares out at the bottom. Over time the trunk can rot at the crown due to the contact with wet soil. Although I don't sell trees, I love them. I have been trained as a "Woodland Advisor", a program instructed by the MN DNR and the U of M.
Watering trees: Often we plant them and walk away. Trees should be watered deeply every 7-10 days the first year, unless rain is adequate. Adequate is 1-2" per week. Trees that have been planted for 2, 3 or even 4 years still can use extra water if not enough rain. We are really in a drought right now, at least by St. Peter. If this continues, I would recommend watering all the trees you have in your yard asap in the spring. My favorite yard trees? Autumn Blaze Maple (Acer freemanii) and the Heritage River Birch (Betula nigra).