Trees NOT to put on a slope?

Hello folks, here I am with yet another slope question:

OK, so I have this slope that varies from rolling hill to precipice (well, almost). Some parts you can walk/climb down, some parts not so much. My plan, one that I have slowly started implementing, is to make most of this slope (except for the currently dangerously steep part) into a food forest. I've cleared large chunks of it, so that I can actually walk there (it was an impenetrable jungle) and sown erosion control plants. I've also realised, from planting a few apple trees, that it is very rocky. I initially feared that I was landslide-exposed bedrock, but there's soil in there, it's just rocks of varying sizes sometimes lying very tightly packed. Digging with a spade is impossible, but it's light work with a terracing pick.

So, that's what I'm working with. Now, I have a long shopping list of trees and shrubs (to start with).

Is there anything I shouldn't plant on a slope like this? I've stayed away from dwarf trees, and for practical reasons I think I'll plant the nuts and chestnuts on the northern border where the land is flat and I don't need elaborate netting to keep my harvest from rolling into the river. But, is there anything that will root poorly in a slope and be an erosion risk?

Here's the plan right now for the curious. The gradient part is the slope, and dark grey parts are just planned... all the circles with numbers in them are the major trees that are currently in the ground and will stay there. 1 = Holly ; 2 = Ash ; 3 = Oak ; 4 = Hawthorn ; 5 = Crabapple ; 6 = Apple (Ontario, Ingrid Marie, Calville Étoilée); 7 = Cherry (Lapins). The brown part is a tractor road and the blue part is the river, obviously. ETA: The top part of the I-section is the part you can't walk down. The rest is OK, although it can occasionally be difficult i

The best advice would be to plan from seed or at the very least form 1yr old seedling, that way they will have a better root system.
The next would be to over sow and then to thin some out as they get taller. I would also plant some grapes running on the ground to protect the soil. So plant alot and then cull as the year goes by.

Emma, your image is not coming up.

Hi Ken. The server is temporarily unavailable, hence the picture is not loading. This happens once in a while, but it usually comes back online in a couple of minutes.

There it is!

For safety, I'd not want to plant heavy round fruit. Pumpkins and squashes, particularly in the steeper areas. Although you mentioned a concern of fruit rolling into the river, there is the concern of a heavy fruit rolling into a person, or a small hard fruit/nut underfoot upsetting an already precarious balance.
Are spring floods a hazard? It would be simply awful to lose early berries.
Where I live vines will grow to smother a fence or climb trees. This can be nice for privacy, but the thorns are a curse! In those steep areas that are difficult to traverse, I'd think people would grab a vine for better balance. Avoiding thorns might be in your interest. Raspberries are not as sweet when you are sliding downhill and its the only thing to grab. Hawthorns are asking for trouble. I'm in zone 8b and I have a lime in the front. Thorns on that are 3" long.
There is also a plant around here called a Barracuda Bush. The leaves are stiff and end up in a needle sharp point. If the slope is steep, there may be plants which could poke you in the eye.
If grabbing at trees for balance, consider avoiding a species which breaks easily. There are pines down here that won't bear the weight of a child without breaking. I have a stand of bamboo that will snap off at ground level if bent over with any effort.

Back in Maine (zone 5) there is the ostrich fern. The young, undeveloped leaves are a delicacy. I'm looking at the J area down by the river. Looks like a perfect spot.

remember when you plant on a slope make sure that you have placement where you will actually be able to harvest what you plant..otherwise it should not be a problem..if there isn't enough water soaking into the root zone you might want to put in a swale or bury some wood or something to hold water at the tree root zones..i had to do that with some sweet cherries that weren't getting enough moisture on the slope that they were on

My only comment would be that I would plant taprooted trees when possible... If chestnut will grow there so won't hickory. Personally I wouldn't be concerned about planting ANY kinds of trees there other than I'd want them to be firmly anchored and I'd want to make sure that there is always adequate sunlight penetration so that grasses can grow to hold the slope together. A closed canopy of shallow-rooted pine nuts would be at risk of slipping all at once.
With a few brushy wattles placed across the slope you can catch debris and eventually it will become a flat area. This is how we made paths on our mountain up in Alaska... the only flat land we had...

If your fruits and nuts roll away, perhaps that's a good thing! Spread the love!

Thanks you very much for your input, Ken. Spring floods are a hazard on the floodplain, a few metres' width around the river, but not in the slope itself. We're talking an elevation of probably around 15 metres (50ft) from river to house, and I won't be planting on the flood plain until I've had more time to observe it. I'm very curious about these edible ferns you mentioned. Although there are ferns quite literally everywhere (you know it's winter in Brittany when all of the country roads are suddenly 3 metres wider because the ferns on both sides have died back) that appears to be a species that is not native to us. I'll definitely have a deeper look into it.

Hi Brenda, and thank you for the advice. Yes, my shopping list is full of trees that do not grow so tall they need to be harvested with a ladder, and I'm definitely working around the "where can I walk" (and "where can I make a path, the day I'm less stable on my feet") principle. Thank you for the wood tip. If it turns out to hold water poorly during the drier months, I'll definitely do that.

Thanks, Mark! That wattle idea is quite inspiring. The reason I'm a bit worried about some trees perhaps being less suited is because we have a large ash tree lying across part of the slope that has apparently slid and been pulled out by the roots. I have no idea how long it's been there, but I'm guessing the tree got too heavy (it's significantly larger than anything else on the slope) combined with terrible slope management (the previous owner hasn't walked the slope for at least 10 years, maybe never during their 20 years here - it's been used as a place to toss old building material, oil cans, beer bottles etc. where they are hidden by the very invasive brambles).