The following is an article written for the Yass Tribune by Kate Wilson, President of the Yass Landcare Group.

Yass Landcare Group members and friends participated in a hands-on field day on the property of Mike and Denise McKenzie on Sunday 22 September. It was a great opportunity to see the work that has recently been carried out on their property – the second part of a two phase project to counteract gully erosion.

Workshop participants gather at an engineered structure which reinstates floodplain connectivity

Workshop participants gather at an engineered structure which reinstates floodplain connectivity.

The field day was led by project manager, Cam Wilson – a man with a mission to restore landscapes. Cam learned what he knows about landscape and water from working for two years with Peter Andrews, author of Back from the Brink, and Peter Marshall, who brings a scientific understanding of hydrology with effective practices.

Cam demonstrated how leaky weirs of various constructions can hold back the water in the landscape, rehydrating the surrounding land and allowing the water to slowly filter through the landscape. In big rain events, flood water is slowed and held suspended in such leaky weirs. This reduces erosion and prevents sediment from being carried down into the river.

Cam showed willing participants how to build fascines – bundles of logs tied together and placed in the gully. This technique is especially useful at the head wall of erosion and if carefully constructed, can stop erosion creeping back up through a paddock.

Logs being strapped together to create fascine bundles

Logs being strapped together to create fascine bundles.

A series of fascines tied together to create a solid grade control structure, slowing flows, capturing litter & sediment and providing improved conditions for biological rehabilitation

A series of fascines tied together to create a solid grade control structure, slowing flows, capturing litter & sediment and providing improved conditions for biological rehabilitation.

A log step under construction, with geotextile fabric lining the gully headwall

A log step under construction, with geotextile fabric lining the gully headwall.

The completed log step provides an armoured drop at the head of the gully, buying time for the long term solution of dense vegetation above to establish

The completed log step provides an armoured drop at the head of the gully, buying time for the long term solution of dense vegetation to establish above.

Some Landcare members also planted poplars under Cam’s direction, by simply digging a hole with a crowbar and plunging a cutting into the ground. The cuttings were taken from male trees which do not produce seed.  Although they are not a native tree, they will grow up quickly and can be coppiced many times over, producing large quantities of material for use in leaky weirs. If lopped during a drought, the leaf is equivalent to Lucerne in feed value and the bark high in micronutrients.

Yunan poplar established as pole cuttings under the guidance of Peter Marshall during a 2011 field day.

Yunan poplar established as pole cuttings under the guidance of Peter Marshall during a 2011 field day.

Perfect timing for the establishment of poplar cuttings, taking advantage of the moisture levels which are enhanced by the engineered structures

Perfect timing for the establishment of poplar cuttings, taking advantage of the moisture levels which are enhanced by the engineered structures.

A staggered planting of poplar cuttings will in time create a filtering net, while regular coppicing will provide materials for the construction of regular leaky weirs along the gully floor

A staggered planting of poplar cuttings will in time create a biological filtering net, while regular coppicing will provide materials for the construction of regular leaky weirs along the gully floor. The canopies will also provide shade to the North facing gully walls, the improved microclimate allowing ground cover to establish.

Cam has also overseen the construction – or rather the resurrection – of a chain of ponds on the property. He has converted a wide valley floor, overrun with river tussock, into a series of ponds with the help of an excavator. He is planting native trees and shrubs, along with grasses, rushes and sedges to create a diverse wetland for biodiversity. The sound (and sight) of frogs was delightful. Mike and Denise hope the wetland will attract numerous bird species too.

Newly constructed chain of ponds at Nanima Gold

Newly constructed chain of ponds at Nanima Gold.

Observing the new chain of ponds from up close

Observing the new chain of ponds from up close.

The Gorgeous Gullies Project was funded through Landcare Australia by Leighton Holdings.

To learn more about Cam Wilson’s work, check out his website at www.earthintegral.com

If your Landcare group is interested in conducting a workshop on low cost erosion control strategies please contact Cam to discuss possibilities.

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.

Images © Cam Wilson, Earth Integral, 2013

The following paddock layout offers a useful way of integrating trees into a grazing enterprise on sloping country. The aim of this approach is to minimise the impacts on production during the establishment phase, while offering significant benefits to both landscape and livestock once stock are reintroduced.

PADDOCK LAYOUT

Although shown here as a grid for illustration purposes, in a best case scenario the pattern is applied on a keyline cultivation layout, which offers extra water distribution benefits to the establishing trees. This particular example represents one of six paddocks, roughly equal in size on a small farm. A similar pattern can be adapted to a range of landscapes and different sized properties.

paddock layout

In short, the design incorporates a belt of trees which are planted across the top of the paddock, with water across the base. As seen in the image above, the paddock is divided into smaller cells by utilising temporary electric fencing, the width and quantity based on the desired number of grazing divisions on the property.

FENCING DIVISIONS

The temporary fence is run straight up and down the slope. Although perceived as an erosion risk by many at first, due to stock tracking up and down the slope, the short presence of animals and significant pasture rest & recovery offered by a time-controlled grazing approach means that this problem is largely avoided. On the contrary, significant benefits are offered by taking such an approach as outlined further down.

There are many options for electric fencing. The following end assembly of David Marsh’s is a simple  and cheap option for permanent electric fencing and KiwiTech fencing is the most elegant version of temporary fencing I’ve come across, allowing rapid assembly and disassembly while on a quad bike.

equ end assembly

Simple and cheap end assembly for permanent electric fencing. Design & Image: David Marsh

Kiwitech catalogue

WATER PLACEMENT

Dick Richardson has practiced Holistic Management grazing for almost as long as anyone and was one of the people credited in the original Holistic Management Handbook when they were detailing the how to’s. Dick, who comes from South Africa, now manages Hanamino, the Carbon Cocky award winning property of Charlie Arnott near Boorowa.

A few years ago, he told me that he was going to the effort of moving troughs from the top of the paddocks to the bottom. His reasoning was that although he understood the thought process behind why someone would put the water at the top of a paddock (to get nutrient in the form of dung transported to the highest point), it goes against the animal’s instincts. If you watch the cattle when they enter a new paddock, the highest point is often the last place they will look for water, meaning they are wasting effort and getting stressed, all of which affects production. Placing water where they expect to find it can pay dividends.

There are many options for portable water, but once again you can’t go too far past the consummate professional David Marsh.

water infrastructure

Left: Trough on skids, towed easily behind the 4 wheeler. Right: Quick couplings for emptying trough and connecting main line. Large diameter feed-pipe allows a smaller volume trough to be utilised resulting in less wastage and an easier time when shifting. Images: David Marsh

NUTRIENT CYCLING

Through the Millennia, there has been a common behavioural pattern in the wild herd: the open meadow offers sustenance and hydration, while the wooded hills offer a sheltered camp with a wide view, important for the ever hunted.

cattle under trees

By mimicking natural patterns, there are often advantages to be gained. Animal impact and pasture recovery offered by an Holistic Management grazing approach is a classic example. The age old pattern mentioned above, of drinking and feeding on the low ground and camping on the high ground is another which can be harnessed.

Gravity is one of entropy’s playing partners. The flowing path of water is the means by which the land is slowly eroded into the ocean. Life systems do their best to slow this process, and in the case of the herbivore, it sets gravity’s goal back a step or two.

Laden with a gut-full of food and water, the ruminant tramps up the hill seeking the afternoon shade. Arising after its rest, a parcel and a squirt of goodness are deposited on the ground, ensuring the ongoing health of the landscape below.

Although it’s on a smaller scale, the grazing strips running up and down the slope, with water at the base and woodland at the top, allow this timeless and fertility-renewing pattern to take place once again.

nutrient cycling

Single cell movement

Left: Stock feeding in the open paddock in the morning. Right: Lounging in the shade in the afternoon, transporting nutrients uphill.

A reconnection of valley floor to hilltop is one of the processes which both Paul Newell and Peter Andrews consider important, and has been implemented for that reason by Soils For Life Case Study participant Martin Royds.

PLANTING DENSITY & LAYOUT

The chosen tree planting density is another aim to mimic successful natural processes, in this case the grassy woodlands which existed in abundance at the time of Euro settlement. By many early explorers’ accounts, both pasture and soil were in excellent condition at the time.

Planting pattern2

Planting Pattern: (Click for a larger view)

Inspirational tree-planting grazier John Weatherstone of Lyndfield Park, has an entire paddock of Gleditsia triacanthos (Honey Locust) planted in this exact spacing (trees @ 7m, rows @ 14m).

HL & cattle 2

From a production perspective, this layout enables the trees to be separated from stock using a (semi) permanent electric fence, while the inter row can be cropped for the period of time that stock are excluded, making productive use of that land. When applied to sloping country, a keyline layout provides equidistant rows while also offering water harvesting benefits.

25 years after planting that paddock, John says, “It’s the best pasture on the property. Even if they didn’t produce any pods (the Honey Locust), if I could have every paddock planted out like that I would.”

HL & cattle 1

This statement is a result of John observing that highly palatable C3 grasses can benefit greatly from the dappled shade provided by the Gleditsia, staying greener for longer into the summer. Studies in the Southern Tablelands have shown that native pasture can also increase production when provided with shade.

Couple the pasture benefits with the fact that the trees offer shade and shelter to stock, thereby reducing stress and increasing production potential, as well as the multiple benefits offered by Gledisia (see below) and you can start to understand John’s glowing endorsement.

SPECIES

In this example, Gleditsia triacanthos inermis (Thornless honey locust) makes up 3/4 of the stand, while appropriate indigenous woodland species the rest.

The honey locust can provide multiple livestock and landscape benefits. Examples from the Lyndfield Park Story include:

  • Serve as a fire retardant
  • Deep rooted and are drought tolerant
  • Produce nutritious pods for stock fodder (up to 100km per mature tree per season. These pods have a nutritive value equal to oats grain or quality pasture and are produced with no extra costs once the trees are established)
  • Produce foliage which is also palatable to stock
  • Reduce the amount of water reaching the water table (thereby helping fight dry land salinity)
  • Provides dappled shade (see background) which maintains lush pasture longer into the summer
  • Suited to the open conditions of a woodland setting and allows pasture growth right up to the trunk
  • Late to leaf out and early to drop, maximising winter sun to C3 grasses beneath
  • Recycle nutrients (which had leached below the root zone of pasture plants, these are recycled back onto the soil surface through the foliage and pods)
  • Slow the increase in soil acidity
  • Produce timber (a dense hardwood with a number of uses)
  • Produce excellent honey
  • Enhance the view (it’s an attractive tree that is green in summer, turning gold in autumn)
  • Cycle deep nutrients which are returned to the surface as leaf litter

A word of warning on Gleditsia triacanthos: Honey Locust are a listed noxious weed in Queensland and in a climate that is more favourable than the Southern Tablelands, there is significant woody weed potential. If planted from seed, they will usually develop sharp 25mm thorns which can go through tyres. To avoid this situation, and ensure that each tree produces a significant quantity of nutritious pods, trees should be budded with material from a heavy bearing thornless variety (see below). 1 in 10 should be a male tree to ensure good pod set.

Budding Gleditsia

Budding seedlings using material from heavy bearing thornless varieties is essential to avoid tyre puncturing thorns in the paddock.

By including a portion of appropriate indigenous woodland species, this offers long term benefits to native biodiversity, with the associated benefits to production. (To avoid further pollution of successful genetics, aim to source seed from the local winners of the region.)

If you’re interested in design assistance for your property, feel free to get in touch

Disclaimer: While the information and images we publish are formulated in good faith, 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.

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

Article and Images © Cam Wilson, Earth Integral, 2013

John Ives

The work of John and Robyn Ives on ‘Talaheni’, showcased yesterday at the ‘Soils For Life’ field day, was a huge vote for the benefits offered by decisions based on time spent monitoring.

A self confessed eccentric with a background in ag science, John has applied his scientific methodology to getting to the bottom of some of the most pressing problems on his property.

Clever management of soil, water, plants & animals based on his findings have resulted in:

  • the virtual elimination of dryland salinity in one of the most susceptible areas in Australia
  • an increase in soil organic carbon (SOC) from below 1% to around 4% (that’s higher than some high profile regenerative farmers in far better soils)
  • some of the best wool on the planet (based on wins in international competitions).

Read more about the Ives’ efforts in:

Talaheni Case Study by Soils For Life

Salinity Management in a variable landscape, CRC on Plant-based Management of Dryland Salinity, Salt Magazine.

Dam Salinity: A report card on our risk and progress, John Ive, Agribusiness Chain V10, p 42

Can drought really help your revegetation effort?, John Ive, Agribusiness Chain 2007.

Talehani reveg before & after

Whenever I’ve heard Paul Newell’s name mentioned, there has been nothing but respect from those present.

A lifetime in agricultural research and as a wheat and sheep farmer in various locations has lead Paul to be well qualified to develop ‘Landsmanship’, a practice, discipline and philosophy based on an ‘applied ecological’ approach to agriculture.

Paul’s land management approach has been described as NSF (Natural Sequence Farming, a term which he coined) without bulldozers, with biological elements skilfully utilised in time and space to reinstate landscape function to essential soil, water, vegetation and biodiversity processes, within a productive agricultural environment.

Below is a link to a paper on the Natural Sequence Farming website, written by Paul, along with esteemed ecologist, Professor David Goldney.

“Natural ecology should become the highest discipline in a farmer‘s mind. Much like the disciplines of medicine facilitate healing of the body of people we love, similarly, understanding ecology can help facilitate the health and well being of the body of land and water systems we love as our living habitat landscapes, since each farmer, so we are told, wants to leave his or her land in better condition than when he/she inherited or purchased it.”

A presentation of the practice, discipline and philosophy of Landsmanship, by Paul Newell and Professor David Goldney

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.

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

Article and Images © Cam Wilson, Earth Integral, 2013

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