May be of interest?

The perennial part of my garden does take very little maintenance and produces a vast amount: apples, pears, red/black currants, gooseberries...
How do you replace the food value of all the annuals: peas, beans, courgettes...grains wheat/oats ... potatoes?

One tree that would provide plenty of calories and store well would be hazel nuts but how do you keep squirrels at bay?

Can you be self sufficient with a perennial garden or, like hunter gatherers would you need to eat plenty of meat/fish as well?

The article is about low-maintenance gardening - not self-sufficiency. How many gardeners here grow wheat/oats? 

Steven Barstow's Blog https://www.edimentals.com/blog/ is full of plants that you never thought were edible and for ways in keeping them growing overwinter. His enormous salads  are incredible.