Minimum trees for sustenance

I have a small orchard and I like to think about: will our 17 edible trees produce enough calories to survive on when they are mature?

This is a tough question. It depends on your climate and nutrients of the fruit. Like, we can't survive on oranges alone. Gotta get some fat and protein in the diet too.

If you wanted the smallest footprint to provide your own diet perpetually, what would you plant? How many acres would it require?

I did some back-of-the-envelope math/googling.

2000 cal/day --> average human needs 7.3e5 calories/year
A Hass avocado tree can produce up to 500 fruits/yr --> 227 calories/fruit --> 1.1e5 calories/yr. This means 7 very large, healthy Hass avocado trees might be enough to survive on.
An apple tree can produce up to 800 apples/yr --> 95 cal/apple --> 7.6e4 cal/yr --> An average person could meet their caloric requirement with 10 very large/healthy apple trees.

Those are smaller numbers than I expected. I think it could be done on a quarter acre for sure.

<<< If you wanted the smallest footprint to provide your own diet perpetually, what would you plant? How many acres would it require? >>>

That all depends upon your location and the resources available to you, of course. And by the use of "you", do you mean me personally or people in general? Lots of questions come to my mind, because soil, sun, water, soil, climate, etc all play significant parts. And the skill and experience of the grower also plays a major role.

I have already demonstrated that I personally can provide for 100% of hubby and my food needs via growing our own and using our excess to trade or sell to provide us with items we could not grow ourselves. In that I am located in a location that it very good for food production, plus can grow food year around, we have a garden plus orchard area of 3 acres plus additional space for chickens, sheep, and pigs. I could surely accomplish the goal with less garden space, but some disaster could result in starvation…….in the past we have had extreme storms that wiped out the garden, a neighbor’s loose cattle eat or otherwise destroy the entire garden, and waves of insect pests and fungal disease wipe out vast sections of the garden. Rather than growing just the minimum needed, I prefer to grow in abundance. The abundance assures that I won’t go hungry should a disaster strike and that there is plenty to provide me with feed for the livestock and cash for my other expenses.

What would I grow? Everything that we like to eat, plus items that sell well and for good cash at the farmers market. Snow peas are one of my big money producers, so I grow them in abundance.

Looking at the topic description……trees for sustenance…… let me consider. How many trees do we have? Well, first if all, I would hate to have to live on only the food our trees provide. It would be a horrible diet, to be sure. But let me inventory our trees.

Avocado….we have perhaps 10 producing trees right now, 99% of the avos go to feed the pigs. We eat one a week, at most, and sell a dozen at the market each week. Avocados are seasonal here.
Citrus…I think we have a dozen or so assorted citrus trees. We use perhaps a dozen pieces of citrus a week for ourselves. The rest either gets sold or fed to the livestock. Some of the trees are seasonal, some are not.
Papaya…I keep a few growing to provide food for the pigs. The fruits are poor quality when grown at my elevation, so we do not eat them. But they help make good pork. ‘
Cinnamon, allspice, clove, sweet bay, kaffer lime … one each. Gives us all that we need.
Macadamia…7 trees. We could use just 4 to meet our needs.
Guava…dozens. They grow wild. The sheep and pigs eat the fruit.
Jabotacoba … one. Provides for our needs.
Mulberry… 2. Gives us enough fruit for our desire.
Banana… not a tree technically. We maintain dozens of clumps. This gives us plenty for our own use, plus plenty to sell. Plus plenty of trunks for feeding the pigs and running the imu (underground oven).

Many food trees will not produce at our elevation and climate zone. I am glad that I do not have to rely upon trees as my primary food source. One tree that I would love to be able to grow is breadfruit, but alas it won’t produce on my farm.

I think my answer for central Texas would be something like 5 avocado trees then 3 of:

Hazelnut, pecan, apple, nectarine, calamander.

It sounds like you have good variety Su Ba and I think that would be important.

David Trood aks Weedy Gardener did a couple of videos where he tried to eat his weight from his garden to see if it could sustain him. It was a really interesting experiment and gave a real life look into living from your own produce (and how hard that can be). In the end, it was a local tree to his region, the bunya tree/ monkey puzzle tree/ Araucaria bidwillii that saved his bacon. This tree was of such cultural significance to the Aboriginal people of that area that the fruit's ripening signals some of the largest gatherings of indigenous people from all over the region. It's a fascinating story!

I grew up in a region where pecan trees had a lot of economic and cultural significance. While we didn't subsist on them by any means, it is interesting how a tree and its produce can contribute to the culture and survival of a people and place.

I know you asked about trees, but I thought I'd mention Mathew Trotter's Annual Staple Crop Calculator that is available here.

And here's a long thread discussion about the plants he chose.

Joylynn, I plan to go check out his list. But one of the mistakes I see gardeners do over and over is to grow things that they don’t eat.  It’s fine to grow a row of beans, but if no one in the family wants to eat them, then I’ve seen those beans fail to get picked, end up in the trash pile. At least in my area, those beans could be picked and donated to our local food Hub. But I’m not sure other areas have food Hubs like we do here. Our own food Hub in Naalehu makes free meals for residents and participates in food giveaways, such as the Kau Kau For Keikis program.

I suggest my students keep track of what they eat for a month, then look to see what of those foods they could grow for themselves.  Thus no two gardeners would be growing exactly the same crops taken from somebody’s list. They could add more exotic veggies, such as baby beets or snow peas, when they are ready for them.

As a side story, we have a retired agronomist here who is having an enjoyable retirement growing food on a half acre. He gives it all away to neighbors and our food Hub. So his case is different. He grows what he finds is interesting to learn about. He tries crops that are challenging, figuring out how to get beyond the difficulties. Right now he is collecting the various banana varieties we have here. And trying his hand at trellised crops.

Su Ba touches on this, but I'm going to be blunt about it:

Depending on your climate, you either need foods that produce all year, or a mixture of foods that produce at different times of the year.

Or as Su does, you need foods you can feed to a pig/goat/duck that you can then eat when your trees aren't producing.

Preserving food can be a huge amount of work and often uses a lot of energy, although I'm guessing Central Texas would be great for a solar food dryer. But you then need to like that food dried.

Su Ba wrote:
Papaya…I keep a few growing to provide food for the pigs. The fruits are poor quality when grown at my elevation, so we do not eat them. But they help make good pork. ‘

Totally off topic here, but they're good WITH (and without) pork too-- where I live is just a bit too cold for them, but we keep a few trees to cook the fruit as a vegetable, like a pipinola/chayote. My Japanese family makes them stir fried with garlic and miso... if your farmers market caters to this sort of client you may have some demand, I know I can barely keep my aunties and mother in law away when they know my tree has green fruit....

I also would not be a happy survivor, we have a lot of fruit trees that would be happier just a smidge warmer. Avocados are good, but they're seasonal. Bananas will yield here but take for freaking ever and grow reaaaaaaally slowly.
As mentioned above, you need either stuff that yields all year round, or you need things that store well. Not sure where you're at but I'd personally be thinking pecans (or some other nuts).

My opinion:
Keep planting trees, as many as you can. Some of them will be destroyed by pests, will not survive climatic/soil conditions, become stunted or will not give enough fruits.
When you build the tree canopy then you will have natural shade for half-shade loving fruiting bushes, vegetables.
I already have 80 fruit/nut trees and plan on planting 40 more with grapes in between.
Because most of the trees I have will be harvestable in late summer/late fall, now when I shop for trees I'm focusing on early harvest cultivars. Of course this also has its limits due to late frosts that could damage the bloom that came too early.
Also, the trees are the easiest way for me to make my land produce edible output. Vegetables do not like my climate with high diurnal temperature changes, winter grains are also tricky.