Contentious Perspectives on Weeds

Adam Grubb holds up some shepherd’s purse on an edible weeds walk
Photo: Phuong Le

The permaculture movement has long been criticised for its approach to environmental weeds. Debates also rage within the movement itself, and perspectives vary widely. Some like David Holmgren are quite outspoken in their defense of certain declared weeds for their landscape repairing properties. It was brave then of the Weeds Society of Victoria to invite Holmgren and others with equally provocative and interesting views to present at their 45th annual meeting and seminar series entitled Contentious Perspectives on Weeds, which took place last month. I was lucky enough to attend, so I’ll give you a blow by blow run down and offer a few thoughts on reconciling the most extreme views.

Firstly however, I should say that for me, the most memorable part of doing my Permaculture Design Certificate was seeing the Spring Creek Community Forest in Hepburn Springs, managed by David Holmgren, Su Dennett, their goats and their neighbours. It is a long stretch of degraded but beautiful gully filled with a mix of native and exotic species, peppered with useful species like black walnut, apples, cherry plums, cricket bat willows, californian redwoods, next to grey box and other natives on the dryer slopes. The once fertile creek flats were stripped back to bedrock gullies and denuded piles of mullock heaps during the gold rush. It was subsequently colonised by blackberries, which became a fire risk for the houses adjacent. Without funding, and using the processes of observation, succession and selective planting, David and his neighbours seem to have created a fire-retardant, productive commons, one that is rebuilding the fertility in the denuded gully. That non-indigenous species were welcome to help achieve this goal seemed shocking to me, but somewhat liberating too, when I understood the processes of succession of which they were a part.

For the last six years I’ve been learning about and teaching people about edible and medicinal weeds (The Age carried this story about it a few years ago). Edible Weeds Walks have proven probably our most popular short course at Very Edible Gardens. On the walks I always, cautiously, talk about ecological perspectives on weeds as often valuable pioneers of disturbed soils, and it’s a topic which meets with much interest and surprisingly little resistance given how deep anti-weed thought runs though our culture. So with that as an introduction to what has formed my perspectives coming into the conference, here’s a report from it.

Around 50 people made their way to the city fringe location of the DPI offices in Attwood, Victoria where a broad ranging and passionate collection of presenters gave perspectives on weeds from the realms of psychology, culture, permaculture, beekeeping, biofuels, edibility, art, ecology, and even military strategy.

John Dwyer who has recently completed a PhD thesis, Weeds in Victorian Landscapes, presented a paper on Weed psychology and the War on Weeds. He quoted Professor William Stearn in the 1956 Journal of the Royal Horticultural Society:

Taken as a whole, weeds are not so much a botanical as a human psychological category within the plant kingdom, for a weed is simply a plant which in a particular place at a particular time arouses human dislike…

Dwyer questioned why “fear and loathing” have become widespread in our approach to weeds. One thread of investigation was tracing the heritage of the weed concept to our desire for control and cleanliness, and notions of dirty pollutants in contrast to virtuous crop or native plant cleanliness. The concept of pollutants are deep human concepts which exist in all studied cultures. Dwyer suggested that emotive language reflects and compounds fear and anxiety towards weeds. While he acknowledged many actual cases where this is justified especially in agriculture, he said the language makes it difficult to see scientific, unbiased views on the ecological roles and impacts of exotic species. Terms like ‘noxious’, ‘feral’, ‘alien’, and ‘invader’ are examples. Facilitator Brendan Roughead in part-jest asked how our perspective might change if we referred to exotic weeds as “new Australians.”

Diego holds up some salsify
Photo: Adam Grubb

Dr Paul Downey from the University of Canberra presented next on The plant invasion processes, and understanding the impacts of plant invasions. It was an impressive distillation of what seemed an uncountable number of his own published papers and field work. He questioned: if this is a war on weeds, where are the achievable goals, where are the strategies, and where is the information gathering and feedback needed to proceed successfully? Often he said the unstated goal is complete eradication of a species, when this is not even remotely possible. He said, “We need to achieve something as a result of the killing. Not just killing per se.” He presented on some of his own work with Bitou Bush, and offered ways to both judge the impact on biodiversity a weed has, decide strategically on areas to focus on, choose achievable goals, and report on the outcomes in a standardised, statistical way. He also mentioned what was for me one of the most memorable parts of the conference, the Von Manstein Matrix, but you’ll need to Google that!

Permaculture co-originator David Holmgren presented on the topic Weeds or wild nature? A permaculture perspective. It was the broadest and most difficult to summarise presentation, which took the major influences on his development of permaculture and perspectives on weeds: limits to growth and the topic of global oil peak, indigenous perspectives on nature, 19th century economic botany, Howard Odum’s ecological systems thinking, and his own work studying native ecosystems of Central Victoria (published in Trees on the Treeless Plains). He emphasised that weeds are adapted to disturbance, and “almost all ‘weed invasions’ occur in a context of human disturbance to a greater or lesser degree.” He referred to weeds performing the role of ecological pioneers, stabilising soil and water resources, and providing habitat while other longer lived species become established. He said, in the context of human disturbance and climate change, “many exotic species have greater potential to better stabilise soil and water resources than locally indigenous species.” Holmgren showed the results of some of his own work in Spring Creek, as mentioned above. Holmgren referenced recent scientific papers on “novel ecosystems” and “conciliation biology” (eg. 1, 2, 3, 4), which echo his own view that new ecosystems composed of mixed indigenous and exotic species are of value and interest. He believes they can serve as models for sustainable perennial agriculture since novel ecosystems are easier to understand than long co-evolved ecosystems, where more details in plant/fungi/animal/microbe interactions are specialised and obscure.

David Severino, Chairperson, Victorian Apiarists’ Association Melbourne, presented next on The place of weeds in the honey industry. He listed capeweed, clover and many other weedy species as essential to his personal beekeeping business and to the industry in general. Bees are required for pollinating a large percentage of the global food supply, and without weeds providing a varied diet and emergency food supply when crops fail to flower, he believes the industry could not do this effectively. By the way of one example, the industry would have lost thousands of colonies in the almond crops this year, were it not for weeds. Blackberry, Patterson’s Curse and Blanket Weed honeys are also highly sort after by consumers for their flavour.

Graeme Allison of the DPI presented Bruce Shelley’s paper based on their joint research on Some issues associated with the introduction of weedy species as biofuel crops. Echoing David Holmgren, he said that the end of cheap energy is coming, and that energy security is a rapidly emerging issue. In order to produce large amounts of biomass for first and second generation (which includes the use of woody plants) biofuels, his project needed to look at fast growing, easy to propagate, locally adapted species: ie. plants with the potential to naturalise. He presented their research into the likely ranges of 30 plants with biofuel potential. The research looked at both current and projected climatic conditions in 2050, as part of their risk assessment. He suggested that some declared weedy species such as Arundo donax (Giant Reed) can be grown with minimal risk in many areas.

Sydney-based artist, Diego Bonetto presented on Nettle, dock, dandelion and wild fennel: environmental weeds or environmental belonging. Diego’s website highlights edible and cultural uses of weeds. His presentation covered the connection people from different cultures in Australia can have with weeds, which in many cases are the same plants as found their countries of origin. Diego talked about people from both Australian rural and international heritages using weedy species as food plants, and of different ways of interacting with nature from the Anglo-Celtic traditions. He noted that some of this activity is actually illegal, where transporting of declared noxious weed material as food is involved, and went so far as to question if any plant should be illegal.

Geoff Carr of Ecology Australia and the Invasive Species Council finished the conference with a presentation entitled Conflicts in weed management: under what circumstances should we tolerate ‘beneficial’ invasive plant species? He earlier characterised David Holmgren’s presentation as “human-centric and old testament.” He called for better quantification of weed control outcomes and better monitoring. He echoed Paul Downey’s message that intelligent strategy was often missing in weed management, describing some of the War on Weeds infantry as something of a “Dad’s Army”. Whereas Downey had earlier questioned the concept of “sleeper weeds” – a War on Weeds parallel to terrorist sleeper cells – Geoff inferred they are certainly real, and “it’s the people that should be noticing them who are asleep.” While he mentioned some cases of wildlife being dependent on naturalised weeds, he said we must take a “guilty until proven innocent” approach to weeds and apply the precautionary principle. He said the impact of weeds in Australia has been catastrophic environmentally and economically. Carr said he would continue fighting this destruction even if “there is only one square metre left”.

One core philosophical divide in the conference was most readily seen between David Holmgren on one hand, and Geoff Carr on the other. Carr is driven by conservation, Holmgren by creating sustainable human ecosystems. Carr puts the needs of native plants and animals first and foremost. Holmgren focuses first and foremost on limiting environmental impacts at home and in the local community through productive and sustainable use of landscape. Carr sees invaded, mixed ecosystems as catastrophes, a process which is happening constantly, even as we sleep. Holmgren is interested in what happens after invasion, in learning from these ecosystems and using the lessons to design novel ecosystems which provide for human needs.

They both have obviously worthy and hugely important goals. Since conservation says nothing about human needs, we are forced to look at it in a larger framework. If we can, as Holmgren claims (his family produce most of their own food from their own 2.5 acre property), produce for more of our needs in low input and zero pollution permaculture-styled systems, then our systems of production themselves would be biodiverse and provide ecosystem services. From the perspective of a conservation agenda, they lower our ecological footprint, freeing up agricultural land for use by wildlife and native plants. They also produce less CO2 and pollution. To me it seems that the view of permaculture as “human centric” might reflect a blind spot to how one’s own clothes, one’s food, one’s house, one’s transport is produced and fuelled. If it is not from a sustainable system, then it directly and indirectly contributes to destruction of habitat.

Holmgren’s goal of sustainable human ecosystem presupposes that humans are not inherently destructive to nature. The conservation agenda, in isolation, has the danger of suggesting the opposite. If humans – and invasive species – are inherently destructive, and inherently separate from nature, there is no hope for conservation short of human extinction and exotic species eradication. Since the former is politically unpalatable, the latter often unachievable, this would seem a defeatist agenda, resulting in tragic-heroic visions of saving the “last square metre” of untarnished native ecosystems.

That doesn’t really answer the question of whether invaded ecosystems represent an unmitigated ecological catastrophe or that they might have value as “novel ecosystems”. Does this merely come down to our perspectives – is it a psychological categorisation? Or can we select a set of indicators – such as soil loss, carbon capture, water quality, native and overall biodiversity, value to endangered species, perhaps value to beekeepers and sustainable human sustenance, and so on – and monitor these novel ecosystems with the rigour of Paul Downey’s work? That would seem to be a way forward.

In terms of practical strategies, Holmgren in his conference paper offers these important caveats:

In highlighting the positive aspects of naturalised and migrant plants to balance what I believe is an anti-ecological and damaging orthodoxy, I don’t want to give the impression that I believe no caution is required in introducing new species. In my teaching of permaculture I have always emphasised the distinction in power and potentially problematic introduction to new environments of animals (especially vertebrates including fish) compared with plants. Clearly top predators are the most problematic of all introductions…. I also distinguish between introduction in radically modified environments and relatively pristine environments….

In Trees On the Treeless Plains: A revegetation manual for the volcanic plains of central Victoria (1994) I used a hierarchy for species selection in broad acre farm revegetation and tree planting; Use a local indigenous species in preference to an Australian native species, in preference to an exotic species. However, the multifunction nature of species selection in permaculture, often means locally indigenous or even Australian native species will not do the job. For example, in many environments, shelterbelt designs may require deciduous species to avoid long winter shadows over crops. Additionally, a need for fire retardant and animal fodder species would lead to well proven exotics such as elms and oaks while no Australian species can match these criteria (in central Victoria).

It was certainly a highly engaging conference. So broad were the perspectives it felt like the first and certainly not the last words on the topics for the group. Much credit must go to the Weeds Society of Victoria for their bravery and particularly the organisers, who included Rodney Jones, Ros Shepherd and James O’Brien, and to Brendan Roughead of the DPI who did an excellent and difficult job as facilitator concluding and summarising the major points and themes of the day, and to all the thoughtful and knowledgeable presenters who put themselves into a potential firing line. Thanks must also go to the participants who were passionate yet respectful in their interactions on what are indeed contentious and equally important issues.

Proceedings will be published in Plants Protection Quarterly:

Video of David Holmgren talking about managing Spring Creek:


Adam Grubb is a Director and permaculture designer with Very Edible Gardens in Melbourne Australia. He’s currently working on an edible weeds booklet which will be available though the Very Edible Gardens website in a few months.