I designed my food forest this way without knowing it. I started off with mostly annuals and mulch while starting to plant the perennials. Then as time went on I've been planting more perennials to fill the open niches. As the niches get filled there is less room for annuals but more fertility in the soil so I can still maintain a similar yeild by planting more densely. As the canopy closes I will transition more to what the video describes as the abundance phase where I won't have enough light for the annuals but the perennials will be in full production and all the niches will be filled. If say I'm about half way there after 5-6 years. Starting to get larger and larger berry crops and have been able to propagate the perennial vegetables like rhubarb and horse radish. Starting to get real fruit sets on the peach and apple trees. I basically took the Mark Shepard approach of observing what grows wild and like a weed in your area and find varieties and plants that are the same for the food forest.