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Monthly Archives: April 2013

This post is a pictorial example of how to apply P.A. Yeomans’ Keyline-patterning for deep ripping, direct drilling or tree planting. It is meant to hopefully help clarify the subject a little for those who’d like to apply keyline patterning to their landscape in some respect, as I’ve seen and heard a number of incorrect applications and explanations floating around the internet. Nice to have a few clearer digital images too.

For a rundown on other aspects of Keyline design, a good starting point is to check out Abe Collins and Darren Doherty’s article, Keyline Mark IV, or visit Ken Yeomans site, http://www.keyline.com.au, where you can purchase Yeoman’s book, ‘Water for Every Farm’.

Finding the Keypoint and Keyline

If you would like to take advantage of the water distribution benefits offered by keyline pattern cultivation, identifying the keypoint and keyline are critical.

(Click on the first image to see a larger slideshow)

Application of Keyline patterning for:

Cultivation (i.e. Deep ripping, Pasture Cropping)

If you’ve decided to rip a paddock to help ease 100 years of compaction (having properly assessed the suitability of the landscape for this practice), or you’re direct drilling for a Pasture Crop, it doesn’t take a great deal more effort to do so on a keyline pattern. Here’s how I go about it.

Tree Mounds

Utilising keyline patterning for setting out tree rows can be very advantageous for any situation where equidistant rows are favourable, particularly where machinery is utilised in management of the inter-row.  There are two well known proponents of this method: The first is Darren Doherty, (many would have seen the image iconic image taken of the Tree Crop paddock on George Howson’s agroforestry property, Dalpura Farm), Mark Sheppard is another.

Here’s an example of how to set out a 4 lane tree belt using keyline patterning.

The same sort of approach can be taken for larger plantations, but there has to end up being some stub rows, or else the runs can get ridiculously steep and be erosion hazards in their own right.

Before you do any sort of hillside cultivation or earthworks which encourage more water to soak into a hillside, make sure you check the local environmental conditions carefully, particularly the presence of dispersive or slaking soils, saline seepage or the occurrence of slips in the local region. Entire hillsides of topsoil have been lost by ripping in the wrong place.

Disclaimer: Where water flow is concerned there are substantial risks involved. While the information and images we publish are formulated in good faith, with the intention of raising awareness of landscape rehydration processes, the contents do not take into account all the social, environmental and regulatory factors which need to be considered before putting that information into practice.  Accordingly, no person should rely on anything contained within as a substitute for specific professional advice.

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Article and Images © Cam Wilson, Earth Integral, 2013

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Weeping Willow

“I believe that the presence of willows along streams in agricultural zones can be shown to be almost universally preferable to cleared streams in those zones. I would also suggest that even relatively low-disturbance eucalypt-Acacia dominated riparian vegetation may not have compelling benefits over willows under many circumstances.” (Wilson, 2007)

It would be fair to presume the comment above had been made by Peter Andrews, Natural Sequence Farming originator and outspoken champion for the much maligned willow. In fact, this statement came from Dr Michael Wilson, a stream ecologist who supervised numerous PhD and Masters research projects in Ballarat, Victoria, during the early 2000s, comparing streams flanked by willows; 100 year old, multi-strata, native regrowth, and cleared land with introduced pasture.

The full paper which is linked to at the bottom of this article goes into more detail, but here’s a summary from Wilson (2007) to give you the gist:

– On average, willow-lined streams had a higher retention of sediment (187t more/km) and organic matter (30t more/km) than the native forest.

– “Willow-mediated aggradation in these channels is converting them from incised channels to in-fill channels that are more characteristic of pre-European conditions”.

Litterfall of willow and native-reveg reaches had a similar annual distribution pattern due to the not-so-well-known summer dominant leaf drop habit of many Eucalypts.

– The annual weight of leaves, twigs, bark and flowers was very similar at the willow and native sites.

– With similar annual litterfall amount and distribution, coupled with dense shade patterns in the seasons of maximum productivity, the overall metabolism (and resulting biological oxygen demand) was also very similar.

– Root mats of willows were found to provide beneficial habitat to native fish in the absence of large woody debris.

– There was a disproportionately large association between pool-riffle sequences and willows, formed by the root mats of the willows.

“Pool-riffle sequences are extremely valuable habitat and for that reason alone it is worthwhile (maintaining willows). But it becomes even more valuable when it can contribute to ideas focused on restoring the whole of the floodplain complex in agricultural landscapes.”

“In all the streams we have studied, clearing willows will mobilise sediment, nutrients and organic matter, will make heterotrophic streams more autotrophic, will threaten habitat values for invertebrates and fish and will threaten pool-riffle sequences. Native vegetation planted where willows are cleared will take many decades if not hundreds of years to mature, for the canopy to close over and for significant limb fall to occur.”

View the full article:

Click here to view the full article, Willows: Weeds of Retention 

Wilson, M., 2007. Willows: Weeds of Retention. Proceedings of the 1st Natural Sequence Farming Workshop. ‘Natural Sequence Farming: Defining the Science and the Practice’, Hazell, Peter and Norris, Duane, Bungendore, NSW,  2007. http://www.nsfarming.com/workshop/

Regrowth dry-sclerophyll forest like you see below is a common sight across the Southern Tablelands. It would be fair to estimate this growth at 10-15 years old, but in actual fact, the trees in this image at Mulloon Creek Natural Farms (MCNF) were all dated by an ANU researcher at 80 to 100. This forest is stagnant and moribund.

It’s a common story: hillsides were ringbarked, grazed and burnt repeatedly by early pastoralists of the region, until it no longer paid to do so (i.e., the decent soil was gone). With an even race for the light, the young Eucalypts take off (in this case the epicormic regrowth from the last ringbarking effort), but when the canopies of the closely spaced trees touch, they basically hit pause, limited by competition for nutrients, moisture and light.

moribund forest

Unless you’ve got the right species and are after coppiced poles, this result isn’t good from a number of perspectives, whether it’s sawlog production (insufficient size), habitat (lack of hollows and minimal niches), or soil conservation (exclusion of grass and shrub groundcover) to name a few.

Research carried out by students of ANU Professor John Field showed the effects of various treatments (thinning, exclusion, disturbance & fertiliser) on the health of the forest (stand basal area, and diversity of species). See the abstract of their findings at the bottom of this post.

These studies have informed the guidelines for carrying out Private Native Forestry (PNF). This legislation provides a sensible set of guidelines to forest management which allows a good balance between production and ecology.

Even low quality timber from a forest like this can be put to some good uses (I’m particularly interested in erosion control uses, but poles, posts, firewood, mushroom cultivation, mulch, & charcoal are a few obvious other uses) while at the same time, the health of the forest as a whole can be improved, providing environmental benefits to the landscape below and potentially the surrounding climate.

The PNF regulations allow this work to be carried out without the risk of massive fines, and a PNF Property Vegetation Plan can be easily obtained (find out more here). The following are a series of images taken at Nanima Gold, the property of Mike and Denise McKenzie where we’re carrying out some gully repair work.

Pre-felling, trees are marked as either existing habitat or recruitment trees under the Private Native Forestry guidelines. Trees are thinned to a given basal area depending on the forest type.

Pre-felling, trees are marked as either existing habitat or recruitment trees under the Private Native Forestry guidelines. Trees are thinned to a given basal area depending on the forest type.

The felled logs are lopped to a suitable size for whatever your intended use. In this case, the majority of the poles were carted down to a gully where we are building fascines as part of a Landcare sponsored erosion control project at Nanima Gold. (The fascines are a topic for another post.)

contour brush

Following the removal of any logs over 80-100mm, the remaining brush can be thrown five metres either side, creating 10m wide contours which snake around the landscape (as a quick way to mark rough contours along a slope: stand downhill, hold your arms out straight, stick your thumbs up and you’d be surprised how accurately you can find your next mark).

The brush contours become more important the barer the understorey, such as in this older project I built for The Mulloon Institute.

Flash runoff on this hillside has carried soil and organic material downhill

In that particularly degraded piece of forest, the bare path in the centre of this photo was caused by flash runoff, carrying soil and organic material downhill.

After one decent downpour, this brush contour has collected a significant amount of soil and organic debris

After one decent downpour, this brush contour collected a significant amount of soil and organic debris, acting like a hillside leaky weir.

When you create conditions in which worms are happy inside a dead forest like this, you know you're on a reasonable path

When you create conditions in which worms are happy inside a dead forest like this, you know there’s a reasonable chance you’re on the right track. I wish I could press fast forward and see what the result of these brush contours is in 50 years time.

More studies have shown the formation of hydrophobic (water repellant) soils under some Eucalypts. This is believed to be caused in part by mycorrhizal fungi, which help to direct moisture towards the roots of the associated Eucalypt, while creating unfavourable conditions for establishment of any competition.

The following pictures were taken after 80mm of rain, illustrating the extreme hydrophobicity in the Eucalyptus rossii forest at MCNF, pictured above (click on an image for a larger view).

Therefore, in these conditions the seeds of understorey grasses and shrubs either don’t have the moisture to trigger germination in the first place, or if they do germinate, they have to fight through 50mm of bone dry material to get any moisture. Hence, the relatively bare forest floor in the pictures above.

With this in mind, an extra layer of disturbance which may be useful in promoting under storey establishment is the short term integration of pigs, their rooting action helping to break up the fungal mats and reduce competition while grasses and ground covers establish (the pigs having moved on of course).

Disclaimer: To avoid hefty fines, ensure you follow relevant local legislation. No person should rely on anything contained within as a substitute for specific professional advice.

You can visit and ‘Like’ our Facebook page to hear about future posts.

Article and Images © Cam Wilson, Earth Integral, 2013

Private Native Forests, Southern Tablelands of NSW: Silvicultural Treatments Revisited

Simon Roberts, Chris Chartres, John Field & Chris McElhinny, 2006.

Forestry Program, SRES, ANU, ACT.

Abstract

Regrowth stands of dry sclerophyll forest extend from Central Victoria through the NSW Southern Tablelands to Southern Queensland (Field and Banks 1999). The ‘Mulloon Creek’ property, 15 km east of Bungendore in NSW is representative of this forest type. In the past, the property was extensively cleared (1890’s, 1920’s and 1950’s) and grazed (until the early 1980’s), and now supports a regrowth forest possessing a degraded structure compared to its predicted pre-European state.

In 1991, Field and Banks (and others) established a silvicultural experiment to investigate the effects of different treatments on this forest. Their preliminary findings (Field and Banks 1999) indicated treatments such as thinning and burning had little effect on overstorey or understorey growth, however fencing to exclude grazing by native and feral herbivores promoted the establishment and growth of understorey plants. The long term results, however, demonstrate that these silvicultural treatments are effective management techniques.

One-way analysis of each treatment on the overstorey (statistically in isolation of each other) reveals that thinning and burning both had significant effects on Relative Growth Rates (%BA Increment/Yr). The effect of thinning on the treatments had the most significant impact on tree growth. Over the twelve year period however, the burnt treatment had a significantly greater percentage annual basal area increment. Unlike thinning or burning, the effect on relative growth rate of exclusion fencing is not significantly different. Similarly to fencing, fertiliser had very little effect on relative growth rates of trees at the end of seven years since the application.

The understorey results were evaluated in a similar way. Only the fences treatment had a significantly higher mean richness of perennial species (21) compared to the unfenced treatment which had only 14.5 species. Fencing to exclude grazing animals has long been regarded as critical for the regeneration of native understorey plants.

Reference

Field, J.B., Banks, J.C.G., (1999). Effects of Silvicultural Treatments on Growth Rates of Trees and Diversity of Understorey in a Private Dry Sclerophyll Forest, Southern Tablelands, NSW. IFA conference “Practicing Forestry Today”, Hobart