Paul MorganTerracing: the gardener’s response to gravity and gradient, then and now

Terraces, terraces everywhere on the Cinque Terre’s vertiginous slopes. (And believe me for yours truly they are sickeningly vertiginous.) Sick, but impressive, as lines of terracing snake along the contours around the hills dropping away into an azure sea. The terraces allow crops of grapevines, vegetables, olive and fruit trees to be grown on slopes that would otherwise be far too steep for cultivation. The stone walls that comprise the terraces date back to the BC when Roman soldiers were rewarded with land to farm as a pension for their service to the conquering generals who happened to make Rome great as they built their political careers on conquests.

Ancient stone terracing along the Cinque Terre

Ancient stone terracing along the Cinque Terre

Just why the soldiers would go to the trouble of covering these massive hills with stone walls when there was equally good agricultural land waiting to be conquered and cultivated on easy flatlands remains a mystery to me. But build the walls they did, and generations of peasants have been adding to them for over two thousand years since.

Stone path through the olive trees, Cinque Terre

Stone path through the olive trees, Cinque Terre

Young rainforest canopy of the revegetation project in the gully, Bronte

Young rainforest canopy of the revegetation project in the gully, Bronte

Clambering up and down these steep hills overlooking the Mediterranean, I am deeply inspired by what has been achieved here. These stone retaining walls sit on slopes as steep as the Bronte Gully where I have been labouring for two decades with other Bushcare volunteers turning tip into rainforest. Our plan is to establish a bit of wild nature on what was once the council tip in a crowded bit of Sydney. While much of the harbor city has retained a high proportion of bush, in the bit where I live, they paved Paradise, literally. At the bottom of the gully there’s a concrete drain, where once a lively little stream splashed and sparkled over sandstone rocks and pools. Bush now accounts for a tiny fraction of 1% of our suburb’s land area.

View south east down Bronte Gully. In left foreground is recently terraced and planted ground. Beyond this 7 year old planted regrowth. Running diagonally from lower right is 15 year old rainforest with coral trees (exotic weeds) with red flowers and no leaves. These coral trees covered most of the steep slop when our revegetation program began.

View south east down Bronte Gully. In left foreground is recently terraced and planted ground. Beyond this 7 year old planted regrowth. Running diagonally from lower right is 15 year old rainforest with coral trees (exotic weeds) with red flowers and no leaves. These coral trees covered most of the steep slop when our revegetation program began.

Really, we need to manage our cityscapes far better if we are to live in them sustainably. We can no longer afford to follow the Roman town-planning model of relentless bricks and mortar relieved only by grand marble monuments to the alpha-male ego. We need to bring wild nature back into the city, and the best way to do this is to lend nature a hand by cultivating a natural ecosystem until it becomes self-sustaining. As with any form of gardening, this involves nurturing plants we want and eradicating those we don’t. We have to remove coral trees planted on the dump as revegetation but which have spread widely through the gully. This is a greedy, woody weed, that blocks out light and sucks moisture from the soil, severely retarding the rainforest species’ growth.

Looking down a recently terraced slope of over 60 degrees. Note the amount of building rubble

Looking down a recently terraced slope of over 60 degrees. Note the amount of building rubble

The height of those slopes at home may be miniscule compared with these Italian hills, but the steepness of terrain is just the same, as is the challenge of cultivation – how to level and stabilise the steep ground, prop it against gravity’s relentless embrace, so that we can cultivate our chosen plants.

Looking up the steep slope retained by its mini terraces

Looking up the steep slope retained by its mini terraces

Here, the crops are grapevines, olives and vegetables for human consumption. At home we are cultivating rainforest trees that will replace habitat lost to a barbaric model of waste disposal. And one day those plants will take over the job of stabilising the slope themselves. But until the roots get a good hold on the steep slopes, the plants are vulnerable to gravity. Each time we come through clearing the weeds that compete with the young trees for water, nutrients and space, our every step creates a little avalanche pushing soil down hill.

Erosion gully created by surface runoff on steep ground at Bronte after heavy rain washed out mulch and soil. Note wooden terracing remains intact. Otherwise damage would have been much worse.

Erosion gully created by surface runoff on steep ground at Bronte after heavy rain washed out mulch and soil. Note wooden terracing remains intact. Otherwise damage would have been much worse.

Furthermore when it rains heavily, as it is want to do in Sydney, the damage is much worse as precious soil is washed away. Our local council decided to carry out a bit of their own landscaping above the gully last year, effectively turning a large area of paving and grassed parkland into catchment draining into our land rehabilitation site. No sooner had they finished than a cloudburst cut a canyon through our most recently rehabilitated slope, washing out new plants and dumping half a ton of soil and mulch at the bottom of the slope. In amongst that lot was a mass of weed seed deposited into an area of established rainforest that had been free of weeds for eight years. Thanks guys!

Gully gouged out of hill by surface runoff. This ground was previously covered by 30cm of mulch. Note the building rubble exposed by washout

Gully gouged out of hill by surface runoff. This ground was previously covered by 30cm of mulch. Note the building rubble exposed by washout

The sandy soil here is precious because there is so little of it. Mostly the ground is building rubble: bricks, chunks of concrete and sandstone from houses demolished to make way for a shopping mall 40 years ago, in the good old days when a developer could just dump his rubbish in the nearest convenient bit of bush. Our site is effectively a landslide of building rubble covered in weeds.

Looking across the slope to the weed-fields of lantana, cestrum, Madeira vine beyond. These dense weeds must be removed before terracing, planting and mulching can be done

Looking across the slope to the weed-fields of lantana, cestrum, Madeira vine beyond. These dense weeds must be removed before terracing, planting and mulching can be done

The only effective way to prevent the further land sliding down this slippery slope, as the Roman legionnaires realised is to terrace, little walls damming the downward flow – lots of them all the way up the slope. This way, soil, mulch and water accumulate in the pockets behind the walls, and we gardeners can tend the plants on level ground without adding to the problem, and heavy rain soaks into the ground instead of racing downhill washing all before it.

Dry stone wall in the gully

Dry stone wall in the gully

What I find so inspirational here in Italy’s Cinque Terre is the rock walls. Just as at our site at Bronte, the ground is mostly rock (well brick, concrete and rock at Bronte). We have been using treated pine poles to build our little terraces at home. But these are toxic and costly, and we have very limited financial resources. But if I can use the abundance of bricks and stone in the ground to build dry-stone walls, we not only get our retaining walls for nothing, but we also clear the ground of the excess of brick and stone. I have done this in a few places in the past, but have been put off because it is so time consuming. I guess I just need to change perspective. Just as here in the Cinque Terre, the walls (and the resulting rainforest) are going to be around for a long, long time.

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Paul Morgan

About Paul Morgan

Paul Morgan is a gardener who left the horticulture industry to become a clinical counsellor and psychotherapist. He remains an enthusiastic amateur gardener and bush regeneration volunteer, and now combines these interests writing about the why of gardening, the psychology, cultural meanings and science behind gardening and the human relationship with Nature.

4 thoughts on “Terracing: the gardener’s response to gravity and gradient, then and now

  1. Eugene on said:

    or you could leave it and just let nature be. You are creating just another artificial construct after all. Maybe what’s there is not the kind of nature you prefer, but it’s nature none the less. Read Tim Low “Feral Future” and see the benefits conferred on various species by lantana for instance.

  2. Thanks for your comment Eugene.
    You seem to be very clear about what Nature is. Unfortunately it’s not that simple for me. I can find no clear black and white distinction between what is natural, and what is artificial, only ambiguous shades of grey. It is a question that has been argued over by philosophers for millennia without resolution. And now that we have officially entered the Anthropocene geological age (where geological evidence of human impact on the earth system is manifest) there is no pure Nature untainted by human hand any more. As Tim Low points out in Feral Future and the New Nature, there are winners and loser species in the Australian environment that has emerged from 2 centuries of European land management, just as there were winners and losers (extinctions) from Aboriginal colonisation of the continent (see The Future Eaters by the other Tim). What was here when Europeans invaded, took over, colonised, whatever you want to call it was not natural. It was a managed landscape, managed by Aboriginal people (through periods of massive climate change), to maximise food production for human consumption. Thats what we humans do. We alter our environment to increase our chances of survival. That’s our nature, which we have arrived at through natural selection. To do nothing and just let Nature be would not be natural as far as I am concerned. But then again, it’s in my nature to see things ambiguously like that.

  3. Eugene on said:

    I see we are on the same page Paul. No argument from me about the fact that most of what we see (saw) on this island was an indigenous cultural artifact. Since we’ve arrived and sacked the original gardeners without bothering to ask them how they did it, we just have to stumble along wondering about the best way to manage the place. A very tricksy, conflicting endeavour it is proving to be.
    The only point I would raise with you, albeit being entirely ignorant of where and what you are trying to achieve, is that nature – being vast and in a constant state of flux especially in these new climatic climes, appreciates being left alone sometimes. Ecosystems, however new, need time to adjust and this happens in a myriad of bewildering ways and it’s often a conceit of the conservationist/ecowarrior/landcare group that they know how best to” improve” a situation. I share a view that is held by many permaculturalists that when it comes to the broader landscape (after safety has been taken into account) it is best to adopt a position of minimal interference.

    I suspect we share a similar reading list. Emma Marris in her book “The Rambunctious Garden” makes many salient points about this approach of minimal intrusion in these volatile times, but I admit that every acre demands a different approach. Rewilding is a tricky business indeed.

  4. Victor Dave on said:

    I admire your efforts. Reclaiming is hard work indeed. Best of luck. One day post the end results!

    I am reclaiming an unused area and every spade you turn over introduces WEEDS. Noxious, non-native weeds. What was a dry area for five years has recently become standing water. But, garden, I must.

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