Agroecology: The Ecology of Sustainable Food Systems by Stephen R. Gleissman

NOTE: Due to availability I read the second edition of this book. A third edition is now available, but you can still find the second edition at a much more reasonable price. Many of the specific criticisms of this book may have been overcome in the more recent edition. In addition, it's likely that work has taken place to examine many of the subjects about which relatively little was known when the second edition of this book was written. As noted in the header post, there is much new information in the new edition.

I give this book 8.5 out of 10 acorns.

I've been giving a lot of thought recently to how I want to approach a more sustainable way of living, and of how I can live more lightly on the land. I've learned much from Permaculture, but equally have seen a number of criticisms, some of which I think are more valid than others, and have also encountered those practicing what they call Permaculture with a greater or lesser level if indifference towards care for the Earth and care for each other, to the point where my degree of alienation led me to wonder whether I wanted to remain under the Permaculture banner at all.

I stayed, but at one point it was a tough decision.

I'm aware there are other strands of thought that have overlap with Permaculture, such as organic farming, which is often less unsustainable than alternatives, and can at least avoid the worst exigencies of the agro-pesticide industry; Biodynamic farming incorporates some principles I endorse, along with many things that make no sense to me whatever; and agroecology which, at its best, incorporates sustainable agriculture with sustainable societies, borrowing heavily and openly from social sciences and the science of ecology. The science of agroecology is defined as “the application of ecological concepts and principles to the design and management of sustainable food systems.”

My own suspicions of science run deep, and it's a channel regularly gouged deeper by scandals over (sometimes deliberately) poor experimental design, selective publication and biased results and interpretation from science linked to industries as disparate as oil, pharmaceuticals, nutrition, genetic modification and cattle ranching, among others. That does not mean I'm willing to ignore what good science can teach us.

It's no good saying that you work with natural processes if you lack a comprehensive understanding of what those processes are.

One of the strengths of agroecology is that it increasingly incorporates socially sustainable activities into its activities, including the notion of human ecology. This is a subject more often honoured in the breach than the observance in Permaculture, in spite of the emphasis given to it even by Mollison, and I think this is something those of us interested in or practising Permaculture might benefit from thinking more about. This is the focus of the last section of this volume.

This book is widely regarded as the standard on agroecology. It is not a simple book: it's a first-year university level text, and as such is an introduction, but one that is not a casual read. It's a textbook, not something to be found in a corner of the gardening section, and it's priced accordingly.

Agroecology is informed by many of the same principles that inform much of permaculture. An emphasis on systems thinking would be familiar to both the agroecologist (or the farmer applying its principles) and the permaculturalist. The former might not talk about function stacking, but she'd know it when she saw it. There is a certain amount of overlap with important Permaculture texts, from Mollison through to Jacke and Toensmeier's Edible Forest Gardens. Agroecology's great strength, at least to my mind, is that it's informed as much by good science as it is by good practice emerging, as it did, from a realisation that the study of ecology was in a position to inform that good practice. This is, at its best, applied ecology, with roots in agronomy and, increasingly, social justice. It emerged in the tropics, mostly among poor communities, not a bunch of rich gringos growing stuff as a hobby. Reading a list of the author's main influences it's interesting to note how many of them do not have white male names.

I may not be a rich gringo by European standards, but I'm getting by on more than a couple of quid a day. When the agroecologist talks about sustainability he means it; when one talks about simplicity this is the cultural default, not a lifestyle choice. In this sense, the application of agroecology to richer countries is much more of a threat to the status quo than something that can be dismissed as a rich person's fad.

I like that.

It is a textbook, as I mentioned, but it's designed to take the student from a point of the level of scientific knowledge of a person leaving formal education at the age of around 18 to give a functional grasp of ecological and agronomic concepts and methods. It's expressly designed to teach principles that can be applied anywhere. In scientific terms it is a primer, pitched at the first-year university student and, as such, refers the reader heavily elsewhere.

Much of the first part of this book will not be new to anyone with more than a passing knowledge of permaculture. The specific criticisms of mainstream agricultural practices could have been written by many people frequenting these forums. The role of agroecology seems entirely compatible with the principles of permaculture:

Ecological methods and principles form the foundation of agroecology. They are essential for determining (1) if a particular agricultural practice, input, or management decision is sustainable, and (2) the ecological basis for the functioning of the chosen management strategy over the long term.

The author goes on:

an agroecological approach helps us explore the theoretical basis for developing models that can facilitate the design, testing, and evaluation of sustainable agroecosystems.

That's what I'm looking for!

An agroecosystem is a site or integrated region of agricultural production — a farm, for example — understood as an ecosystem.

In principle at least that would theoretically include even a mainstream farm, but this seems to be the kind of approach emphasised by authors like Dave Jacke, Eric Toensmeier, Martin Crawford or even Bill Mollison, although the former make more of an attempt to place it on a scientific footing, and is close to my ambitions. Gliessman is by far the most intellectually rigorous. In short, this is an approach compatible with, even overlapping considerably with, Permaculture. It's not the same approach, and I think it's important to retain some important distinctions, as with those relating to Permaculture and say, Biodynamic approaches, forest gardening, and mob grazing (which I consider to be no more than an attempt to greenwash even more unsustainable forms of cattle ranching, although Gliessman does talk about it in favourable terms).

Section II, which talks about plants and the environmental factors that affect them, is very mixed. Some if it could be considered very much remedial from the perspective of anyone who has done much reading on ecology in general and on plants in particular.

That said, it's still well worth reading in that it comprehensively lays out the factors you need to consider when designing an agroecosytem, much more thoroughly than do, say Mollison or even Jacke and Toensmeier. Descriptions of solutions found to issues such as fluctuating temperatures, rainfall, wind and so on may well inspire your own practices. It's full of good ideas that many writers on permaculture typically fail to consider.

I certainly learned valuable things in particular about water and how it behaves in soils, for example. This led me to think about methods I could use to store and use water in retention ponds in a Mediterranean climate in order to extend cropping seasons and support plants during the dry season, combining a network of ponds with shelter belts, windbreaks and careful species selection (probably with high transpiration efficiencies), perhaps with a suitable breeding programme. The problem would be balancing evaporation with transpiration rates, which would depend on several factors. The ponds could also be used to grow crops such as water spinach (Ipomoea aquatica), water lotus (Nelumbo nucifera) and arrowhead (Sagittaria spp) as they dry out during the course of the dry season, before being cleared of nutrient-rich sediment prior to the wet season, thus also breaking the life cycle of mosquitoes. I'm not sure it would work, but I suspect it might bear experimentation. Other readers, facing inundation events as a result of climate disruption, may find the discussion of wetland adaptation (Chapter 9) extremely useful. Similarly, I'm also aware that the natural ecosystem in many Mediterranean areas is adapted to fire (Chapter 10), and this may bear further consideration: could, for example, an area designed for occasional surface burning be used as a firebreak to slow and weaken a fire that might damage crops that are not adapted to fire?

Many readers will be familiar with the work of H. T. Odum through the work of Bill Mollison (for example through his introduction to energy flows) but, judging by questions I've seen asked on this site, Chapter 11 (Biotic Factors in the agroecosystem) may provide some readers with an extremely valuable introduction to the relationships between organisms in these ecosystems and between organisms and the ecosystems themselves.

It's important to remember, however, that these factors interact to create an environmental complex (Chapter 12). It is because of these complex webs of interactions that research into agroecosystems is so difficult. Changing one variable may have unforeseen effects elsewhere in the system:

agroecological management, in contrast, begins with the farm system as a whole and designs interventions according to how they will impact the whole system, not just crop yield. Interventions may be intended to modify single factors, but the potential impact on other factors is always considered as well.

Having addressed the main individual factors in an ecosystem, it starts to get both more complicated and more interesting. We move on to

“the study of how groups of organisms interact in the cropping environment. This whole-system perspective stresses the need for understanding the emergent qualities of populations, communities, and ecosystems, and how these qualities are put to use in designing and managing sustainable agroecosystems.”

Chapter 13 (The Population Ecology of Agroecosystems) includes what I found to be an interesting discussion on r- and K-selection theory. To perhaps oversimplify, r-selected species produce large amounts of seed on the basis that some of it will grow. Most of our crop plants are r-selected species. K-selected species produce smaller amounts of seed but show some degree of care for whether it survives, perhaps wrapping it in a fleshy coat for dispersal. It is thought that r-selected species were particularly open to domestication because of their ability to colonise disturbed habitats. For those of us interested in the domestication of new foods, or the selective breeding of existing ones, this is probably a point to be borne in mind.

This has two important implications. One is that unwanted “weed” species also tend to be r-selected, resulting in competition. The second is that the r-species that we want to domesticate, especially in the early stages, are most likely to be dispersive, and become a potential environmental problem off the site. The process of domestication has typically bred out those traits that assist dispersal in many existing crop plants, but the same cannot be said of others in the early stages of domestication. This strongly suggests care needs to be taken while engaging in the domestication process, especially of plants from outside our own respective bioregions.

A number of our domesticated plants have no known living wild relatives. Was it the process of domestication that drove them to extinction?

The other side to this coin is that perennial cropping systems might benefit from the cultivation of K-selected plants, thus avoiding the conditions preferred by r-selected “weed” species. Better yet, the traits of the two might be combined. There is a whole chapter on genetic variation and how to preserve it.

This book is particularly strong on the emergent properties of agroecosystems – the results of which should, at least in theory, help us to achieve the overyielding that is the objective of effective permaculture (which you are shown how to calculate). This is where all that groundwork of understanding the individual properties discussed above becomes useful. In many ways, Gliessman is much superior in general terms to even Jacke and Toensmeier: these authors are good at explaining how principles apply to forest gardens/temperate homegardens, but Gliessman gives a better overview of what those principles are. He also exhibits much better structure than Mollison's work. Gliessman wants you to understand communities – in detail. Once you understand those it makes it much easier to understand how to design high-yielding perennial polycultures. For example, it's clear that there is important work to be done in exploring the limits of the principle of competitive exclusion (the principle, somewhat oversimplified, where two or more organisms or species cannot occupy the same niche). The understanding that organisms and species are often selected as much or more for coexistence than competition has implications not only for our agroecosystems but perhaps also for social systems.

I'm giving a lot of thought to the implications of this principle for the introduction of plant species from other ecozones, as well as what the mechanisms for coexistence are, and how to artificially select for them.

There are points where I think that some issues could have been better thought through. Gliessman presents a strong case for the inclusion of nonhuman animals in agroecological systems, and argues strongly for a return to more mutualistic relationships. That said, one case study is based on Allan Savory's work, which has since been shown to have its own weaknesses. In addition, and I've said this before: it's true that livestock can be fed on “agricultural wastes”, but these “wastes” can be used as livestock feed, mushroom substrate, biofuels or mulch among other things. There is a tradeoff between these uses that Gliessman, at least in this edition, fails to examine.

He's not the only one, but I had come to expect better intellectual rigour from Gliessman that I might not from some other authors. The use of nonhuman animals for other purposes (such as work) presents ethical questions outside the scope of this book or this review. It is, however, clear that the continued involvement of nonhuman animals in agriculture is likely to be minimal and highly context dependent: even pasture-raised livestock is not necessarily always appropriate, and the factors involved are highly complex, and this author seems more aware of this than most. While I concur that there is no reason why humans should be the only animals in these ecosystems, the same principle applies to animals as it does to plants: the species and its niche must be considered in each case. Gleissman's example of the Serengeti is not necessarily a legitimate comparison with an agroecosystem: the former is undoubtedly highly diverse, but its human carrying capacity is much poorer.

It's no good introducing, say, chickens if they are going to scratch up all your seedlings or create a moonscape. The grower may wish to consider allowing or encouraging colonisation by smaller native species as more suitable than the deliberate introduction of larger browsers and grazers. Direct comparison with aboriginal ecosystems may be very difficult, or even simply a false comparison, in the absence of the original predators, or even when comparing the behaviour of modern domesticated species with that of the extirpated or extinct herbivorous megafauna. Animals (including but not limited to) humans are key to energy flow in ecosystems: the question is what animals in what circumstances and in what densities. This is a complicated subject that cannot be reduced to “cows good” (or even, necessarily, “cows bad”). The grower may wish to take the place of certain identified larger herbivores. The introduction of, say, beaver might be great from an ecosystem perspective, but it would be hell on your fruit trees, while the artificial construction of dams coupled with managed coppicing might achieve better-controlled results. It's also worth considering the differences between the value of nonhuman animals in nutrient cycling as distinct from nutrient concentration and removal. Trophic inefficiency may require the review of even many indigenous crop-livestock systems. Livestock may inhibit afforestation, and may be the cause of erosion rather than inhibiting it, while soil compaction may decrease water infiltration.

Chapter 19, then, is worth reading, but it's probably the chapter most in need of careful critical analysis before application to any individual system. Low-intensity livestock integration may be appropriate under certain circumstances, but the specifics may need to be considered very carefully. While I concur with Gliessman that intensive livestock production has to go, the realities mean that replacing this with range-fed or waste-fed livestock at the same levels of consumption cannot conceivably work: the view that “it's okay if it's range-fed” is at best grossly oversimplistic.

The final section covers the transition to sustainability: having placed ecology into agronomy, final chapters discuss subjects closely allied to some of Mollison's interests – putting culture back into agriculture. In many ways this is a more sophisticated analysis than is typically found in permaculture, but is entirely consistent with my interpretation of Mollison's vision. A box discusses the relationship between permaculture and agroecology, which Gliessman treats as a positive one.

By this point the reader will probably not be surprised to learn that there is considerable overlap between the ideals embodied in agroecology and those found in permaculture. Crucially, this book examines a specific protocol for the transition process. One of this book's strengths is that, while most permaculture texts assume a start on a moonscape (and some practices such as chicken tractoring actually encourage it), this book assumes that there is an existing system to be converted. It also emphasises a point that seems to bear repeating: an agroecosystem is not a “natural” ecosystem: a temperature homegarden is not “natural woodland” any more than mob-grazed pasture is prairie. This book provides tools to examine the degree of sustainability in the system: a system requiring unsustainable inputs is not sustainable, whether that's straw mulch or supplementary feed. Respective carrying capacities may have to be compared. Natural ecosystems are important reference points, not equivalents. The determination of this requires careful research.

At the same time, we need to be aware that the use of cheap migrant labour, whether underpaid East Europeans or free WWOOFers, may mask as long-term sustainability problem. While permaculture tends to assume improved social conditions, there are valuable pointers here about means to go about ensuring what we believe about it is supported by the experience of those involved, and thus predicting whether or not the system can continue indefinitely, as well as how we as a society might go about implementing such broad-scale changes.

Perhaps the most useful section of all the chapters in the book is the recommended reading list and list of internet resources. Buying all of it would quickly lead to bankruptcy, but I expect to give my librarians something to do. The intellectual exercises in each chapter will encourage you to think about a range of important design questions.

In general I think that many permaculturalists would benefit from learning lessons from agroecology and its more empirical approach. I found the intellectual rigour and clear structure refreshing. One of those lessons is the approach itself. We have learned from practices found in the works of a limited number of authors to the exclusion of work that might more effectively meet the same objectives. This book is aimed at the educated audience, and may not suit the more practical mindset, but one of agroecology's strong points is that it has been able to develop links with centralised institutions designed to share best practice between scientists and farmers and to learn from the farmers themselves in a reflexive process. Precisely how useful this book will be to any individual will depend largely on the scale at which they are working. It's aimed at those working with farmers, which implies field scale and up, so it would probably come into its own around half a hectare or one acre, but the suburban gardener or someone working on an urban project would probably get things out of it. Designers, whether for their own habitat or professionals, will probably find the intellectual exercises at the end of each chapter extremely useful for developing their own thinking. Readers will find it complements many existing writers on related subjects (many mentioned above). It's certainly worth reading in conjunction with these authors.

All that said, it has emphasised to me just how much needs to be changed in our societies and the way in which we as societies buy and consume food if permaculture and broader agroecosytem approaches are to be accepted as any more than a niche fad, a message that also come across in Eric Toensmeier's Carbon Farming Solution. I expressly encourage readers to develop partnerships with relevant academic institutions, preferably locally in order to benefit from intellectual expertise, and to develop the skills required to assist most effectively in conducting useful studies.

In spite of minor weaknesses, I strongly and unreservedly recommend this book to any permaculturalist who has a mindset that is in any way compatible with an empirical approach. I strongly commend it to others as well. I learned a great deal from it, and think anyone concerned with the development of sustainable food systems might benefit from it.

Thank you for the review and all the useful links.