Wednesday, July 11, 2018

All downhill

In a landscape, meandering with gullies, it's easy to believe the forces of water can be somewhat destructive. And they can be! True to the natural sequences, Peter Andrews, outlines in his book, "Back from the Brink", however, I see other forces of nature at work too.

Within this eroding gully, forged by water, plants are playing their integral part. Over the years, tree roots from the formidable eucalyptus trees, have been uncovered by soil erosion. They cling to the soil in a last-ditch effort, to turn the tide in their favour again.

Right now, you can see the detritus (leaves) which have fallen to the ground. In winter we don't normally get a lot of rain, so the trees shed their leaves. For many months, they accumulate on the gully floor, waiting for the next storm season to arrive, in summer.

When the rain arrives in earnest, to collect water in the gully again, all that tree detritus will get caught in the tree roots as the water escapes. It slows the water, and filters nutrients, every time it rains.

The floods in 2011 (no doubt) brought down those rocks, wedged against the tree root. Which also acts as a natural barrier to catch tree detritus - but allows water to permeate through, with less soil erosion.

All those natural sequences, led to one essential repairing mechanism in the landscape. Silt accumulation. Those exposed tree roots, are now halting erosion - creating a series of steps on the upper landscape instead. Which is one way to reverse deep gullies, getting deeper, the faster water travels downhill.

I actually took note of this relationship between the tree roots and water flow, when I went scouting for rocks, recently. We're building our drystone retaining wall, and need more backfill.

Seeing how valuable these rocks have been, in repairing the gully, however, I wasn't about to remove them! It goes to show, even in a degraded landscape, such as ours', nature is diligently forging a repair schedule. Ergo, trees are absolutely essential on a sloped landscape!

What natural sequences, have you discovered happening in your backyard?


  1. Excellent post, Chris. I love the way you write more about what you notice around your property than about how you grow food. There are enough food-growing blogs around! I have exposed tree roots too and they function to collect detritus which eventually becomes soil. Branches and trunks falling across a slope do the same thing, but never if they fall with the slope. I've started deliberately laying branches across slopes to let leaves collect. These become rich areas for soil's no surprise that the resident blackbirds always dig there and around any edges where leaves collect, even the wire guards I put around plants. I've noticed that when a seedling grows on its own (provided the rabbits leave it alone!) it gradually collects leaves around its base in a self-mulching process. Traditional gardeners have a tendency to ignore these natural processes and strive to work against them in order to satisfy their aesthetic needs, which is a great pity. Nature is a great teacher as you show here.

    1. I can imagine exactly what you're describing, Bev. We get brush turkeys doing the same thing, as your Blackbirds. They certainly know where to find all the sweet spots! Anywhere water and detritus collects. :)

      Good observation with the wire guards. An example of an artificial intervention, providing the obstacle for nature to concentrate around. It's certainly there, where we take the time to notice. I was amazed it took me so many years to notice what that part of the gully was doing, lol. But then, there's a lot of ground to cover!

      I'm glad I have a natural aspect to our landscape, I can continue observing. It's taught me a lot, and reinforces what works. I can understand why natural processes get forgotten, if people don't have access to them. I'm glad for permaculture in that regard. In that it's a learning style which teaches observation, no matter where you live.

      Thanks for sharing your observations.

  2. A terrific post Chris. For people who aren't aware of the excellent logic of Peter Andrews, this may spark their curiosity. I see in my travels around our area, land owners and Councils chopping down trees and shrubs in creek beds, cleaning up everything to make it look clean, neat and tidy, but to the detriment of the landscape. It's these small observations that you photographed so well, that are what is so very important to us all to prevent erosion and to support a natural system. Leaky dams are the word around here on our place, to slow down the water (if it ever comes) and spread the moisture out further, allowing pasture grass to grow along a broader area. It's a no brainer.

    1. I agree Sally, Peter Andrews was somewhat of a landscape genius, in how natural sequences worked in Australia. He has all the knowhow on eliminating soil erosion, using nothing but what's already present in the landscape. I love that aspect, because it demonstrates we have a naturally regenerative landscape, seeking stability, rather than the extremes it's renown for.

      I hope the rain comes to you region soon, to fill your leaky dam. As I hope the rain returns to us, as well! :)

  3. On a lesser scale here, on our suburban block, the trees along the fenceline drop their leaves in Winter, we rake up those that fall on our rocky boundary 'path' (to add to compost) but others fall into the creeper that has stabilised a small slope and gradually decompose adding organic matter to that soil. More leaves fall and are 'caught' in the long strappy leaves of plants I've put in to define edge of a large garden bed and stop soil washing in to a stretch of that rocky path. They gradually decompose too and feed those plants/soil as they do so. If I raked them all up, because they can look untidy, I'd lose the goodness of those leaves that eventually break down. Meg:)

    1. That's a good observation Meg, and reminds me of an older home we rented in suburbia, before moving here. Where you get large trees in suburbia, they drop a lot of leaf detritus and end up in all sorts of places. Mostly, the understory plants catch them. Free fertiliser! You've made life easier for yourself, and your garden, by cleaning up the necessary areas (ie: a walkway) and letting nature deal with the rest. Love those big trees in suburbia!


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