The edge effect explained

The important thing when designing permaculture systems is to get the edges right. It is only on the edges, in natural systems, that you get accumulated surplus of material, not in the broad area.

We ourselves are traditionally edge dwellers. All life around the edges are more productive. Where two ecosystems meet, you will find there is a greater number of plant, insect and animal species and microbes. If we are to design a world of absolute abundance we need to design a world abundant in long convoluted edges between our ecosystems.
The edge (also known as the ecotone) between forests and grasslands is where the wind slows down and airborne nutrients slowly deposit and accumulate.

Here, you will find specialized species that live on the edge as well as numerous visitors from both forest and grassland ecosystems that are in constant interaction with the edge and thus increase the concentration of biodiversity.

Think about the edge between the river and the sea. These are the most productive ecosystems on earth, where saltwater creatures mingle with their freshwater counterparts and where nutrient rich river silt are deposited as the rushing water of the streams collide with the eb and flow of the sea

These types of multi-faceted edge systems are what we should strive to emulate in our permaculture designs.
– GEOFF LAWTON