Felling your way to a healthier forest: Guest post

886581_556288874393114_1316733164_o

All around Milkwood are patches of dry-sclerophyll eucalypt forest. Variously called ‘goat country’ or other less attractive names, this type of forest is in a stagnant phase due to poor land use over the last 150 years.

Can you rehabilitate it into useful, productive land? Sure you can! While also generating plenty of useful material for posts, poles, firewood, mushroom substrate, charcoal, mulch &/or land repair and erosion control…. 

This is our first ever guest post, by our good friend Cam Wilson. Cam works extensively with watershed restoration and silviculture projects throughout Australia, as well as being one of the Milkwood crew of educators…

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

moribund forest

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. 

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).

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, with the marked habitat trees amongst those retained of course.

Logs felled and lopped to a suitable size for whatever your use (i.e. erosion-control fascine-building material, firewood, mushroom cultivation etc)

The felled logs are lopped to a suitable size for whatever your intended use (i.e. poles, posts, erosion-control material, firewood, mushroom cultivation etc depending on quality)

In this case, the majority of the poles were carted down to a gully which is having erosion control works carried out under a Landcare sponsored project. (These will be turned into fascines, a topic for another post.)

Following the removal of any logs over 80-100mm, for erosion control structures, firewood, mushroom inoculation etc) the remaining brush can be thrown five metres either side, creating contours which snake around the landscape (stand downhill hold your arms out straight and use your thumbs as a rough way to mark out contours)

Following the removal of any logs over 80-100mm, the remaining brush can be thrown five metres either side, creating 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)

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

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 has 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.

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

hydrophobic1

Forest Litter following 80mm of rain

hydrophobic3

A 50mm layer of predominantly decomposed organic matter just below the litter.

hydrophobic4

This organic layer is basically bone dry following 80mm of rain

hydrophobic5

Meanwhile, the clay beneath is saturated

Therefore, in these conditions the seeds of under storey 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.

Article and Images © Cam Wilson, Earth Integral, 2013 – http://www.facebook.com/EarthIntegral

>> More posts about Forest Gardening and Silviculture here…

886581_556288874393114_1316733164_o

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

13 Comments

  1. Eli
    Posted April 2, 2013 at 7:47 pm | Permalink | Reply

    “Fencing to exclude grazing animals has long been regarded as critical for the regeneration of native understorey plants.”
    That 21 to 14.5 species comparison could well just have been a race to the bottom.
    And I think Allan Savory would have something to say about the miracles of exclusion fencing…

    • Posted April 3, 2013 at 7:59 am | Permalink | Reply

      Fair call Eli about Savory’s take.

      I’m not saying that long term exclusion fencing is the answer, however, based on the 10 year trials, exclusion in the early stages did have the greatest impact on under storey establishment. It’s chalk and cheese if you walk the site.

      The difficulty in these situations is it’s hard to convince roos, wallabies, deer, wombats, hares, wild pigs, goats and rabbits to stick to your rotational grazing plan. Take the top predator out of a system (the hunting and fire of aboriginals and then commercial farmers of the past), split up the land and replace them hobby farmers and the system can get quite out of balance that’s for sure.

      • Eli
        Posted April 4, 2013 at 5:32 am | Permalink

        Absolutely. I was thinking about penning in the pigs quite narrowly, feeding them and have them plough it deeply just before the rainy season. If you want results, getting the seed bank into the ground with some manure and hay and then have rain infiltration might work.

  2. David T
    Posted April 2, 2013 at 8:05 pm | Permalink | Reply

    Do you know if some of these fallen/felled gum trees are able to used in a hugelkultur raised garden bed? Does anyone in Oz do the HK beds as per Sepp Holzers Permaculture? I am reading this book right now.

    If I understand this post… Ummm. Some of the trees are being felled to allow for light in the canopy and also other species to grow, making the forest more plant species diverse?

    The issue after selective felling is that there a fungi that blocks other plants growing? (Perhaps this is why the Aboriginal people burned small areas of forest to kill of the protective tree “guard dogs”?)

    As it was in the beginning, it is almost a monoculture and therefore open to attack from die back, parasite and basically it grew itself into a stagnated system… :| is that right?

    • Posted April 3, 2013 at 8:10 am | Permalink | Reply

      Hi David

      In degraded regrowth forest like this, you may just stubble upon a dead old tree which was never cleared, with an amazing diameter of 1m or so. Given reduced competition for nutrients and moisture this is the potential: quite a contrast to the spindly sticks in the photos above.

      In this case, the regular burning disturbance by Aboriginals and then Pastoralists was removed, providing ideal conditions for Eucalyptus rossii to densely establish. With too much competition for moisture, nutrients and light they hit pause, that’s why it stagnated.

  3. Posted April 2, 2013 at 8:40 pm | Permalink | Reply

    “Fencing to exclude grazing animals has long been regarded as critical for the regeneration of native understorey plants.”
    Does this mean total exclusion or as mentioned in the article “the short term integration of pigs” may be beneficial. What about crash grazing cattle in these situations as fire management practice or using cattle for the same idea as pigs, periodic disturbance and manuring. Are the pigs intended to be a one off “treatment” or on a regular cycle?
    Thanks.

  4. fraseroldmillroad
    Posted April 2, 2013 at 8:42 pm | Permalink | Reply

    By the way, this is really good stuff.

  5. Posted April 3, 2013 at 8:23 am | Permalink | Reply

    Hi Fraser.

    In the trials, fire disturbance also had an impact on seedling under storey establishment. A trial of the pig idea is supported by John Field, the ANU senior lecturer who oversaw the PhD and Masters research in the forest, as an alternative disturbance to the burning carried out in the experiments.

    I personally don’t think that this poor landscape will be able to carry pigs on a long term basis and are rather a short term tool. However, Boxgum grazing are doing so successfully on gentler slopes, in better soils and in more open woodland.

    There are certainly examples of decent pasture beneath this forest type when trees are much wider spaced. Annual burning was utilised by the aboriginals to keep the system in that condition (read the Biggest Estate on Earth), and the same can be done with cattle if that is the long term management object.

  6. Posted April 3, 2013 at 9:48 am | Permalink | Reply

    Ah, something I can relate to! We have a spotted gum monoculture growing on our slopes, along with ironbarks (narrow leafed and swamp). Naturally the spotted gums are superior in number over the ironbarks, but I’m guessing with time the ironbarks will eventually dominate, as they’re longer living and less brittle in extreme weather. We get black cockatoos fly through, so plan keeping the ironbarks.

    We fell saplings for fire management around the house and lay them in the various gullies we have to catch run off. In these areas around the gullies, we find the understory plants are establishing better.

    I agree this is not the kind of country to keep livestock long term. Their needs are better served lower down the slopes, where all the minerals are collected. For this reason we cannot realistically look at keeping livestock beyond chickens. Even goats would struggle in the kind of monoculture we have here. It’s not impossible, just not sensible while in the transition process of restoring forest diversity.

    It’s good to read thoughts on our more inhospitable areas, as a means to capturing a tangible yield – even if it’s just collecting soil microbes. As this really seems to be the deal changer for transforming landscapes from hydrophobic to hydroponic.

  7. Posted April 4, 2013 at 11:21 am | Permalink | Reply

    It must be very satisfying.

  8. Posted April 9, 2013 at 11:07 am | Permalink | Reply

    Thanks for this sharing of information as we are about to move to a farm with four + varieties of eucalypts, acacia and scrubby undergrowth yet to be identified but typical dry schlerophyl. I’ve found some interesting fruiting fungi and excited about doing a ful blown flora, fauna and fungi audit!
    Delighted to hear of the Private Native Forestry…..as some areas seriously need to managed as per Bill Gammage’s The Greatest Estate on Earth – an excellent read and helped re-shape my thinking!

  9. Posted April 10, 2013 at 9:22 am | Permalink | Reply

    I was going to thin down an area on our property today, and this article convinced me it was definitely a good idea :) Need some erosion barriers etc. Cheers :)

  10. Chris
    Posted May 12, 2013 at 10:46 pm | Permalink | Reply

    Be careful big brother is watching ie in the form of your local council & CMA. Enforcers of the native veg act and the threatened species act. Make sure you check the zoning of your land in the LEP and what RAMAS are allowed.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Follow

Get every new post delivered to your Inbox.

Join 11,356 other followers