I have been looking into permaculture recently and it seems to be a very interesting concept for a person interested in producing their own food in a sustainable manner. I do however have some issue with the permaculture principle of increasing edges within your system. My understanding is that edges in nature are highly diverse and productive and therefore if you introduce edges into say your veggie patch you potentially have more microclimates and potential to have more species, meaning more food in your garden.
However, I come from a ecological background where edges in disturbed environments are the bad. They are the areas where weeds occur, water evaporates, winds increase, pests are present, etc, etc. As such, I fear the introduction of significant amounts of edges into a garden will in fact create issues for your garden and may in fact bring weedy species into your space, taking over other spaces that could be utilised for specialised species, increase evaporation and winds. I am also concerned about the weedy species that might become successful in your garden, may also become successful in adjacent areas, be that your neighbour's garden or a pristine environment.
People I have listened to about the principle of permaculture edges indicate that edges are a natural system. My thoughts on this matter are not quite the same as what I perceive to be a black and white representation of the natural environment. Edges are in fact quite rare, transition spaces are in fact more common resultant from gradual changes in soils, geology, climate, species and so on. I would appreciate if anyone could either further explain or clarify this principle in permaculture. Until such time I am hesitant to adopt this principle in my garden with any vigour.