Tags
design, ecology, erosion, farm, history, kangaroos, livestock, permaculture, planning, revegetation, soil, southwestern Fleurieu, trees, water, waterways
Recently we’ve been obsessing a bit about the history of our landscape (here, here, and even here, for example). It comes as the consequence of the last few years of reading and thinking about how Australia’s landscape and water systems have changed over time, but we hope it’s not purely an intellectual exercise. Understanding how our landscape was 200 years ago acts as a good guide for planning its future potential and limitations. By attempting to unravel the threads of actions and consequences that have reshaped these hills and valleys over the last couple of centuries, we can also not just address symptoms (such as treating an erosive headcut with a Zuni Bowl), but can also have a go at working on the causes of dysfunction in our soil, water and ecosystems. A lofty goal, but as Wes Jackson quips, “if your life’s work can be accomplished in your lifetime, you’re not thinking big enough!”
This spaghetti-and-meatballs flowchart is our first go at representing what might have happened in our neighbourhood over the last 180-odd years, compiled from reading, observations, historical records and discussions. It provides us with a list of things to do as we attempt to address elements of this (for example, in this year’s tree planting, we’re inoculating our seedlings with beneficial fungi to restore mycorrhizal networks). We expect this chart to be tweaked, adjusted and rewritten over time as we discover new ideas or revise our assumptions. Perhaps a next step might be to construct a sequel that shows how we might attempt to improve some of this stuff.
Are there connections, consequences or other things we’ve missed, overstated or got plain wrong? We’d love to hear your thoughts and ideas.
Yarnauwi Farm 
Nice! How about fire in the landscape? Frequency, intensity, timing – what is the fire history, recent and extended, and what might be a suitable regime for the future with a shift in vegetation cover and a view to human survival?
Hey Sharn, that’s a great suggestion. My understanding is that before colonisation the landscape was managed through Aboriginal burning practices to create a mosaic of different plant associations and densities. However, post-colonisation, I haven’t found evidence of fire in the immediate area – certainly there have been plenty of fires in the highland pine plantations, and few between Delamere and Second Valley, so it could be 150 or more years since the immediate area has been burnt. That in itself would say something about how the dynamic of the landscape has changed in terms of fire-dependant species no longer germinating, soil nutrient loads and various other fire effects. Hmm, much to consider – thanks!
DEWNR’s fire management maps are helpful for looking at fire history, looks pretty small and scattered down that way, some larger fires in the 80’s – http://www.environment.sa.gov.au/firemanagement/Fire_Management_Maps
Thanks for that Sharn, another useful mapping tool! It suggests that there haven’t been any fires of note in our neighbourhood in recent times. I came across a reference in a ForestrySA Management Plan to bushfires that apparently burnt most of the Fleurieu in 1934, but contemporary newspaper accounts also suggest that that didn’t reach our property (there are references to the then property owner back-burning and preventing the fire reaching Anacotilla). Hmm. I guess we assume it hasn’t been burnt for 80 years at least!
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I reckon the flow chart captures most of the processes that have caused changes in the landscape although the fire question is an interesting one…
Within 15min walking distance around our place we can see the whole spectrum, one valley that has virgin open forest has a good mix of large and small trees with shruby understory, healthy creek with no erosion and wet land plants. Other area that are open fields have only large trees with limited patches of scrub. The worst is the land over the other fence owned by MINDA that is currently WAY overstocked with cattle, lots of weed species (olives, blackberries, broom ect), virtually no scrub and a few big trees and a heavily eroded waterway.
I was thinking about your place, and how you might deal with those few parts around the waterway that are really severely eroded with steep slopes of solid raw exposed clay, which mostly devoid of anything growing and poor soil health with few nutrients.
Knowing nothing about this stuff, maybe a slightly more drastic intervention is required to help things along abit? A plan could go something like:
Get the tractor in there to flatten off the slopes abit by moving some dirt around to reduce the speed of the water run off allow half a chance for some moisture retention.
Stake some bales of hay across the bottom of the slopes to help retain the water and stop further sediment from being washed away.
Mixed up the moved clay with some gypsum and a few loads of mulch and old hay and spread that across the slopes – as hay has lot of sugary grass it’s loaded up with bugs that could help kick start the soil bacteria to break down the mulch and improve the soil health.
Plant some appropriate shrubs and trees to help retain the new top soil as it forms.
I hope Annkia is going well and the family is finding a new equilibrium…
Thanks for your thoughts Andrew, all good to consider. We’ve started implementing some approaches such as one rock dams, Zuni bowls and so on to start gathering sediment and raising the floor of the gully, and since excluding stock we are beginning to see a fuzz of native grasses return to many of the slopes. It appears that much of the erosion has actually settled, so were reluctant to conduct earthworks that might reawaken the beast! Our focus then, as you point out, is to start building organic matter to support more life. A precursor to this is to establish some kind of canopy over the gullies through trees along their edges, because in summer, especially, it’s effectively an arid microclimate. We have found some miraculous local species are actually thriving in the most hostile bare clay bank faces – Rock wattle (Acacia rupicola), is an inspiration in this context, thriving on the south facing banks where they can avoid the harshest of the summer heat. You’ve got lots of interesting ideas there, and we’ll certainly ponder them further!
Interesting reading! The word ” grazing” (livestock, kangaroos) doesn’t even come close to describing the impost of introduced species such as rabbits which can also chew things off below ground level!
How true Sue, and feral animals aren’t something we’ve fully accounted for in this chart either. Thankfully, our rabbit numbers are pretty low, probably because our fox numbers are pretty substantial! That said, some of the erosion could be the consequence of historic warren cave-ins, and I know that rabbit numbers were a big issue in the region in the early 20th century, with one of the former property owners being fined for not controlling them. Another valuable line of inquiry for us to explore!