tree for sloped yard
I am a new homeowner and new to this forum and new to gardening too. I would very much appreciate some insights into planting trees / flowers on sloped backyard.
I have attached a picture of our sloped backyard. This is held together by a retaining wall - stone facade with wood behind it. The structure was probably built in 1996. I would estimate the incline to be about 15 - 20 degrees.
We would like to plant a tree in the middle (towards the upper right of the photo and within the larger bed).
What trees would be suitable for such a slope? We stay in the San Francisco Bay Area (zone 9B).
Our gardener suggested planting a tree with wide roots but not heavy branching. He suggested Chinese Elm. I understand that these trees have mostly surface roots. Is this OK, or are there better trees / options?