Design notes…
Nature: wild and weedy
WEEDS. Most people don’t notice them. Most people detest them. Fewer people eat them. Fewer still understand why they occur where they do. Fewer again understand their role in ecological succession. Nature, however, plants with them.
Take these photos. Almost every plant you see is a ‘weed’. Some have earned the status of ‘invasive weed’, the worst-possible category in the restoration ecologists’ and bushland regenerators’ catalogue of evil plants.
Strategy: outcompete, overrun, occupy
The photos show a fine botanical collection of weeds.
There’s bitou bush, Chrysanthemoides monilifera. It’s a dense shrub growing to maybe three metres in height. Its glossy leaves are well adapted to retaining moisture in hot weather.
Bitou bush was imported to stabilise sandmining sites such as that here at what is now Randwick Environment Park. It succeeded in doing that. Bitou bush liked Australia as much as its South African homeland, so it decided to stay and multiply its population. Bitou bush did this so well it took over large patches of semi-wild land, outcompeting other species including native plants by shading them out and occupying their growing space. It was a classic overrun and occupy strategy.
Doing this comes naturally to bitou bush, however doing its own thing greatly annoys restoration ecologists and their bush regenerator fellow travellers. Deploying edged weapons and targeted chemical attacks they attempt to wind back the occupied territory in a probably-doomed attempt cleanse the land of the species.
Not far from where this patch of wild nature thrives, a homeowner has planted a neatly trimmed hedge of bitou bush around his fenceline. Seems someone has found a use for the plant.
Strategy: occupy, deter
It’s the stiff, spiky branches that make it so uncomfortable for the cats trying to sneakingly penetrate it to get at the small birds that seek refuge in this large thorny shrub. Now, its value as small bird habitat is recognised by bush regenerators who hold back on their eagerness to eradicate the shrub.
Lantana, Lantana camara, is a bushy, spreading shrub to four or more metres in height whose centre of origin is Central and South America. Look closer and you might see its flower clusters spanning the pink, yellow and reddish range of the colour spectrum. Lantana’s branches are stiff and brittle.
Reframing for preferred meaning
This is an invasive weed according to bushland regenerators. That’s a term favoured in the militarist jargon of the industry.
There is emotive appeal in the way the term positions some plants as aggressors in our ecosystems, predisposing people to favour their removal. Calling a plant an invasive weed is what in communications we call ‘reframing’. It creates a preferred meaning around the plant and subtley gets people to think about it in the desired way, as a botanical enemy.
Strategy: infiltrate, occupy
Olive tree? Well, kind of. The tall tree we see in one of the photos rising above the shrub layer of bitou bush and lantana, the tree with the olive green leaves, is just that — olive. African olive, Olea europaea ssp cuspidata.
Growing up to ten metres in height and breadth, the African olive is not the delicious European olive we like in our salads, pizzas and pastas. The African olive bears no edible fruit. It does, though, like to form colonies of the same species in what is a slow motion infiltrate and occupy strategy. It is the successful deployment of this strategy that leads to it being called a weed as it takes over territory once the home of Australian native vegetation.
I first made the acquaintance of this species when I was a landcare educator at Calmsley Hill City Farm on Sydney’s south west urban fringe. There, it thrived in the clay soil and was the dominant species on the eastern slope of the ridge that separated the Georges River catchment from the Nepean catchment. There was a government funded scheme to remove it at the time, and like any scheme to remove vegetation from steep slopes, soils had to be stabilised against erosion by replacing the weedy species with native tree species.
Why here?
So, why have these so-called weedy species, the bane of so many bush regenerators, found a home here?
We know the answer to that question. Were we to look below the viewing platform people stand on, where these photos were made, we would find a stormwater drain. It diverts runoff from the surrounding urban area into the ephemeral wetland hidden behind the barrier of weedy vegetation. It brings with it all the stuff that these self-regenerating wild and weedy plants regard as nutrients. As would any intelligent species, they have set up home close to their food supply.
The weed assembly here in Randwick Environment Park demonstrates a few principles of permaculture design we might copy in our food gardens.
One of the principles is called relative location. In the home food garden it usually refers to placing the annual vegetable garden close to the house, or elements of design close to where they will be used. The annual vegetable garden is visited frequently for both maintenance and harvesting. Placing it close to the dwelling makes visiting it convenient.
Here in our weed assembly nature has used the same principle by creating the conditions for the species to grow in close relative location to their nutrient source coming out of the drain.
We can also interpret this as another permaculture design principle: harvesting energy and resources where they occur.
There’s another design principle known to permaculture practitioners which we see here: stacking.
In stacking, plants are arranged in vertical layers according to their need for light. In permaculture design of the home or community garden, the purpose is to make the most productive use of vertical space by arranging useful species as a ground layer of smaller plants, a medium layer of large shrubs and small trees, and a canopy layer of taller trees. Much like we find in the bush, really. Take a look next time you are out. How many vertical layers can you see?
There are only two layers in our weed assembly. Lantana and bitou bush compete for ground-level space and form a dense shrub layer. African olive grows above as a canopy layer.
In our weed assembly it isn’t permaculture designers adopting nature’s structural principles. It is nature itself, using those detested weeds.
So, there we have it, wild nature at work. The ecologically recombinant ecologies of the Anthropocene. Welcome to the new nature.
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