Hi Mikaela!
I'd like to welcome you to high desert
gardening. I love it! I find it easier than the New England I grew up with. Mostly sunny days, and you control the
water, which is at the ground level. So it's very controlled conditions, which makes a lot of things easy.
No slugs, which I'm phobic about. Mulch does great: I collect it from rampant
Lepidium latifolium stands along the river before they form flowers or seeds every year, or in winter for more ornamental white mulch; and as my trees grow I also use prunings for mulch. I've never had damping off of seeds, although the dry air means I have to water seedlings and transplants daily till they get their
roots down deep.
Oddly, it turns out powdery mildew is perfectly happy in very dry weather, and destroys many of my plants at the end of the season, despite no rain at all and very low humidity in the air, haha. Well, it usually comes at the end after the harvest so it doesn't matter too much.
For your tree question I'd recommend you post that as a post on its own in a tree forum in Permies, and include your picture. People who are all about trees (even if not interested in spending time welcoming newcomers today) will see it.