Your biggest forest garden lessons?

Hello fellow Permies!

In the spirit of crowd sourcing wisdom, gathered from our collective mistakes, I pose to you the following question: What is, or what are your biggest forest garden mistakes lessons that made you wiser?

I'll start!

1. Planting fruit trees untprotected on a former pasture on a vacation home property and being away lots.
This is how my permaculture practice begun. Living in suburban Netherlands, vacations on the French countryside. Bouncing with excitement I planted five fruit trees, blessed them with my joy and went away.
The deer were grateful. The gophers found lovely nesting sites. The elements tested the rusticity of those trees.

Sepp Holzer has a recipe for protective goo one can smear on tree trunks to deter deer. I made my own version (sinde I didn't have the determination to make bone-goo) out of tar, sand, cow poop and ashes. It worked really well.

The gophers. We tried solar-sonar thingies that "would deter gophers". I believe they threw a technoparty. We tried sticks in the ground with empty plastic bottles rattling in the wind. Better, but ugly. What worked? Human urine. The older and masculiner the donor, the better. It's a win-win really; the trees get nitrogen, gophers get deterred and masculine individuals somehow enjoy peeing in the wild. Great!

Thus remain the elements. The only cure herein is for the (over) Enthusiastic Gardener to pace themselves and to educate themselves. There are loads of different varieties of fruit trees and nut trees, and the local nurseries will probably have the best varieties for your area; sun, wind, rain, elevation, soil.

2. Fast forward eleven years (!) and I had moved to a new place with an old orchard (reasons.).
I decided to get sheep to mow the grass, since there was a serious risk of vipers and ticks lurking in the tall grass and we had more pressing things to do than mowing.
After an intense selfeducation period online (thank you for the advice here!) I decided to go for Ouessant sheep. They were small, so light on the soil, and 'rustic'. I love rusticity.
What I failed to notice, was that they also are a somewhat primitive race. So they love browsing. On the edges of the hedge and on ...tree bark.
After all the juicy tall grass had been mowed, the sheep peacefully shifted to peeling off bark from the fruit trees. It took me a while (1,5 days to be exact) to notice what was going on in my otherwise so peaceful orchard.
In the big hurry to fix the problem I wrapped wire fencing around the trees. I now remember again the deer deterring goo - the reason to write this post - which I'll apply as soon as we've made a system to keep the ram at bay whenever I want to work in the orchard. Never a dull moment, huh?

So, what are your forest garden lessons? I'd love to read about them!