The zoning in Permaculture is as well a way to design a framework where will be integrated Technical and Biological Closed loops.
More we go to zone 5 more we find biological independent closed loops, more we move to Zone 0 more the loops are either domesticated or integrated to technical loops.
It is per definition easy to see that Zone 5 biological mechanisms are independent from any human impact. Let’s see how the integration works when getting closer to Zone 0. If you grow vegetables in Zone 0 you’ll use compost which is maybe originated both from mulch or green vegetation harvested in Zone3 produced by biological loops. The manure can come from a chicken coop part biological part technical, maybe you’ll shred the green vegetation using a shredder (technical) then use simple tools to form the piles, use “technical” methodology (Berkeley composting) to make your compost, etc… The vegetables after processing produce scraps which are recycled in a worm farm (Technical and Biological) and the worm casting will feed newly planted tree seedlings in Zone 3 to speed up the growth of the wind break you realized was missing.
This is just an example and if we take into account the multitude of closed loops we will integrate in the farm operations we assume that the zoning can help in this integration by facilitating the most permanent or structural hybrid Biological/Technical Closed Loops processes.
With this in mind you could design your zones not only in term of simplistic logistic consisting in counting the annual frequency of presence in an area but by defining the annual presence in an area when operating (or piloting) a specific hybrid closed loop. Resources areas within zones are then bound by the most frequent hybrid processes. And path logistic is then designed to facilitate these processes.
For example egg production can include the following steps of the technical process; chicken care, egg harvesting, chicken food complement, located in the limit of zone 1 and zone 2 and let the biological steps of the process (mainly chicken going errand); controlling insects, controlling weeds, scratching the soil, etc, located in zones 3 and 4.
Another example is the presence of predators coming from Zone 5 and impacting the actors (as preys) of a specific process. You decide to use a non permeable interface to these predators between zone 5 and the areas where the process take place. This may change the localization of Zone 5 to use natural existing edges.
When your Permaculture farm mature, together with a more precise involvement on specific processes you want to focus on, you may use this “process orientated” methodology to redesign your zones and optimize the predominant hybrid closed loops.
In this schema a hybrid process is represented inside the zones. Next step would be to modify the zoning to better adapt to this process.