Plant very densely, to create an interconnected root system, cover the soil, accumulate organic matter and release hormones that promote even more growth. Then prune heavily, which sends signals for the plants to grow more, and generates more matter to cover the soil. It simulates herbivores eating and stepping on the plants. It's a disturbance that helps the forest grow faster.
RE: https://puntarella.party/@antanicus/117047000002131050
Another principle is creating strata to ensure each plant gets the amount of sunlight it needs. Plants that need more light create shade for plants that need less. When plants find themselves in the wrong stratum, they develop diseases.
This is the part that made me think of what farmers have been doing with solar panels.
Another principle is making the system self-sufficient in water, through plants that can accumulate and distribute it. This part I don't understand as much I think (not that I'm an expert in the other parts). I'll try to read a bit more about it. The presenter said that animals that can be seen as invasive in gardens, such as slugs, are sometimes only coming for the water, and not actually eating anything. It's important to observe and understand what is happening.
Of course, all of this requires a deep understanding of the species of plants, animals, fungi etc that grow in a given place, and how they interact. As well as careful planning accounting for the time, space and other resources available. Ernst Götsch says the main input humans bring to a syntropic forest is knowledge.