Saturday, September 1, 2012

Plant guilds in Vanuatu

"There is an enormous difference in the way we make a design in permaculture and the way an agriculturist would make it.  Really what we are up to is trying to let things function in a natural way."

  - Bill Mollison, Wilton, NH (USA) PDC 1981 -


Companion planting, or planting two or more plants who help each other, with each other, is one tool we can use to increase the resilience of our cropping systems. 

For example, planting dill and alliums (onion family) between mounds of potatoes can help attract beneficial insects to the umbrelliferous flowers of the dill, while the allium roots exude antibacterial & antifungal compounds which can protect potato tubers from fungal infection, and give us total yield of three crops from the same space.

Photo: Fruit & nut trees occupy the understory of this coconut plantation on Malekula Island, while swamp taro & cattle occupy the ground level.

In permaculture design we refer to this as 'guilding'.  We can use it to mimic the diversity found in natural systems and assemble our planting guilds by selecting plants occupying different niches; for example, selecting deep rooted plants to row next to shallow rooted plants, or identifying understory trees which can be planted under our canopy.

We can take this a step further by designing for maximum functional diversity; in other words, seeking to connect elements in our system so that the needs (or 'inputs') of one element are met by the products or behaviors ('outputs') of another element in our system. 


Photo: Needs / Products / Functions = Functional Analysis.

By using the 'Functional Analysis' tool to map the needs, products & characteristics of our species palette, we can begin to make these connections to create gropings of plants which are mutually beneficial when grown together.  For example, we can grow vines up a taller crop, select an edible ground cover to ramble in an understory, and intercrop nitrogen-fixing species to provide for our soil fertility needs.


Photo: A guild is a family of plants who work together. At the Department of Agriculture's demonstration plot on Efate, Piper nigrum (back pepper) grows up nitrogen-fixing 'Erythrina varigata' (Indian Coral Tree).

Students were tasked with designing their own localized guilds using these patterns, starting with grouping plant species they are already familiar with in the different niches they occupy, and then looking to re-assemble them by looking for functional relationships between the plants:

Photo: Amsen Wille from the Vanuatu Department of Agriculture presents his group's plant guild designs.

Photo: 1) Banana, cacao & Island cabbage (Abelmoschus manihot) grow in the understory of a coconut plantation, with Sweet potato (known locally as 'Kumala') as a ground cover.  Glyricidia provides fertility to the system, banana & Island cabbage provide a shorter term crop while cacao is maturing, and sweet potato lends productivity  at ground level while serving as a living mulch to protect topsoils.

2) 'Whitewood' (Endospermum medullosum), a locally prized timber crop, creates a closed canopy which few plants can tolerate.  Swamp taro (Alocasia macrorrhiza) can fill this niche and turn it into a productive space - this guild was expanded further as an alley crop between Glyricidia to provide fertility to the system.

3) Citrus is placed with nitrogen-fixing Pigeon pea (Cajanus cajun) as a nurse crop to protect & feed it in its early stages (and yield an edible crop), while pawpaw (papaya), Island Cabbage, and Chinese cabbage (known locally as 'Whitebone') give additional yields in space & time.


Bill Mollison said, "If you do something right, it will do a lot more right itself," and we experienced this phenomenon with this practical exercise.

Students were asked first to group plants according to niche, and then to create guilds by looking for functional relationships between these plants - and in doing so they also managed to stack crops in space, stack yields in time, and increase diversity & fertility.


"Our job is to put things in the right place and then let them rip."

  - Bill Mollison, Wilton, NH (USA) PDC 1981 -


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