My last post dealt with the permaculture edible forest garden, and it received some commentary on a couple of Facebook groups and permaculture forums. A lot of the responses were, predictably, from permaculture advocates who took umbrage at my having deigned to critique their philosophy at all, but there was one very valid criticism concerning yields: while I had compared weights of different crops per acre, a more useful approach would be to compare calorific yield. Doing this for the crops I listed gives a result looking something like this:
Crop tonnes/ha Cal/100g m cal/ha
potatoes 40 70 27
wheat 8 333 26.6
hazelnuts 3.5-4 646 25.8
Sweet chestnuts 4.75 200 9.5
As you can see, hazelnuts do perform extremely well on this score, having a very high calorific value, but as explained in the article, in a forest garden, the trees would be at wider spacing and the yield per hectare would be lower as a result.
As was pointed out to me by one commentator, apples score very high, comparable to wheat and potatoes and coming in behind only US corn (maize). Can apples substitute for those foods as a staple crop? For a food to be classified a staple it requires not just calories but high levels of macronutrients including proteins and oils; so I do not think we would thrive on a diet of mainly apples, although the person who pointed this out to me was adamant that we could and indeed should, precisely because they are a tree crop. An original argument for sure, and not one I have heard before in any of the forest gardening literature. Once again, though, the yields cited are from conventional apple orchards, not forest gardens.
Most of the other critiques were based on misunderstanding the article (aka not reading it properly!). The whole issue of yields was questioned- why am I comparing yields from tree crop monocultures- we know that forest gardens produce far more than they would, even though there is no data! This is of course the whole point: unless anyone has any better ideas, the use of tree crops as a proxy makes perfect sense, as they will almost certainly be producing the staple crops with the highest yields (and the most calories)- but they will not be achieving such yields in forest gardens, and indeed one of the best known forest gardeners, Martin Crawford, grows his nuts in a separate orchard, with nothing but mown grass beneath the trees.
Not everyone on the permaculture forum took the same defensive line- one commentator asked “So who ever said it was a good idea to grow vegetables under trees anyway?” implying my whole article was a straw man, apparently missing that I had carefully quoted directly from the principle authors in Britain and America who advocate this kind of system. Again, the question of yields is important since these authors- Jacke, Whitefield, Hart, and the UK Permaculture Magazine, really do position forest gardening- including growing vegetables under the trees in a multi-storey system- as a sustainable and viable alternative to modern industrial agriculture.
Another recent permaculture author who makes similar claims- not specifically for forest gardens but for general systems based on perennial woody agriculture- is Mark Shepard. There is an interesting review of his book here, coming to similar conclusions to myself, and further commentary here on the issues of perennials vs. annual crops.
Another commentator seemed indignant that I was not only critiquing Hart’s invocation of a new “Age of Gaia” but also, apparently, that I completely discredit ecology aswell. They did not say exactly where I do this, but I guess it might be in the section on systems and complexity, where I cite to Gleason’s 1926 paper The Individualistic Concept of the Plant Association. Far from dismissing ecology as a science, I am here quoting one of the most fascinating chapters in the history of this young science, the famous Clements-Gleason debate. The earlier view- originally from Tansley who coined the word “ecosystem”- saw nature as best represented on the community level, with more or less fixed boundaries around ecosystems and communities of plants and animals who had co-evolved over long periods of time. This was promoted by Clements and became the dominant paradigm, but later gave way to Gleason’s view of nature more as a continuum, in constant flux, with no fixed boundaries around communities.
I suggested by the response above, the permaculture community has not moved on with the new paradigm. It is certainly this old conception of nature being in a state of balance on which the whole philosophy of permaculture rests- which is precisely why forest gardens, based as they are on the adage of “copy nature”, are still considered so important. Hart explicitly takes this further almost into the realms of religion with his Gaia quote, but so do many others in the permaculture community- as indeed I did once myself. Even Clements probably never saw natural systems in this way. Forest gardens are however largely entirely novel systems, resembling nature only in structure and function and relying on previously untried assemblies, mixing wild, “native”, exotic and domesticated species together, so it is questionable to what degree they could be said to be “mimicing nature” in any case.
The Clements-Gleason debate is still ongoing, and demands an essay in its own right- perhaps I shall return to it as some point.
Finally, some conspiracy theories were spun around my essay, with comments along the lines that my real intention was to make a hatchet job on permaculture in an attempt to justify modern industrial farming. I have no hidden intentions, but simply wanted to explore the origins of the forest gardening idea and consider theoretical reasons why it is unlikely to meet the claims being made for it from within the permaculture community. Certainly, if it really held the promise being made for it, everyone would be doing it, but as I point out at the outset, despite some 30 years of promotion, the concept has failed in any way to capture the interest of more than a handful of farmers. The undeniable fact that there are costs and externalities for industrial agriculture does not mean that forest gardens- or even agroforestry- are necessarily a viable alternative solution.
More interestingly from a sociological point of view is the question as to why they are still so popular (within the permaculture fraternity) as an idea, with so much being claimed for them, when for the most part what are actually planted as forest gardens here are little more than orchards with a few herbs and soft fruit bushes, with even the most enthusiastic advocates getting most of their produce from more conventional annual vegetable beds. It is relatively easy to create wildlife gardens, or low-intensity food gardens that are also great habitat, and require few inputs, but for the time being at least it seems that the low-input high-output garden remains an appealing but unattainable dream.