I looked at your photo and I am assuming that the area of concern is behind the dry streambed, since I cannot see the trunk of the willow. There are a couple issues to consider. If you add soil, you run the risk of smothering the roots of the tree. Even a few inches of soil spread on top of the root system of a tree can smother them, preventing air exchange from taking place in the original root zone. The fibrous roots that are currently near, or just below, the surface would be buried and you risk a slow decline or death to the tree. The same concern would be with adding a retaining wall and building up the bed. The other concern with the retaining wall is that to build it properly requires digging a footer for a compacted stone base. Digging that trench, roughly 4-6" deep, will cut off another large part of the root system as it extends from the tree. Without the footer, the wall will most likely shift and settle unevenly in the years ahead. The other concern with raising the area is that there is a wooden fence. If you raise the dirt level along the fence, ,it will cause premature rotting of the fence pickets. If you have a better pic of the area, I might be able to give you some other ideas of what to do. Try taking a pic while standing in the yard, so I can see under the tree.

?efore investing on any fixes, I would first want to know why the tiles keep breaking. I'm not a tiler, but for me that would be a big red flag that something about the installation is going awry.

Short run of counter on the window wall, with only two small uppers on either side of the range's upper cab with it's over-the-range vent fan, as the kitchen window cuts short the space. From the right, there will be: 15" drawer base with 15" upper, then the 30 range and cab over, then an 18" upper. (That one will not line up with the 27" drawer cab below which goes partly under the window, meeting up with the small 24" sink cab. The last on the left of the sink base will be an 18" DW.) There will be no upper to the left of the window, as it is narrow, and abutting this run will be an old hoosier. Because the cabs will be Shaker QS oak, I planned the flanking uppers up to the low under-8' ceiling to both be lighted glass. Now I am wondering if having both with glass will look off as the symmetry is already off and it may look like they were supposed to be matched but didn't quite make it. Should I make only the 18" have glass, and the 15" solid to look different and deliberate? Also, electrician has wired for undercab lighting only for where the 18" will be, not the 15". Will this look odd? (The base cabs have been waiting to be delivered, uppers have to be reordered as the stove was moved. The now unusable 3 uppers will be used elsewhere.)

While it is still shocky...I would re-pot that tree into a larger pot...or get it in the ground. Yes, young avo trees are very subject to sunburn. Consider shadecloth while small. Make sure you keep them well-watered...avos love water (not mucky however).