My first Stirling Engine book...

A few weeks ago I ordered my first Stirling Engine book. Got it from powells.com and was ordered via amazon.com.

It was "An Introduction to Stirling Engines", by James R Senft,
ISBN 0-9652455-0-0
1993 (Sixth Printing 2004)

It looks to be a good book. But I do note there is no Table of Contents or Index. It has good review both on the net & by word of mouth.

Lots of basic diagrams, cut-aways, pictures and historical stuff.

After I've read it, I'll decide what to get next.

Next, I've been thinking about another Senft book, "An Introduction to Low Temperature Differential Stirling Engines", ISBN 0-9652455-1-9. The other I'ld like to get is "The Regenerator and the Stirling Engine", by Allan J. Organ, ISBN 1860580106, but I want to build something that works from a Plan first. The Organ book is for serious designers!


Gnoll110

technorati:
stirling+engine solar+energy james+r+senft allan+j+organ

'The Harmonious Wheatsmith'

I found this reference Thursday night, 'The Harmonious Wheatsmith' by Mark Moodie (ISBN 0-9517890-0-7). It's about a method of no-till farming developed by Marc Bonfils, a French ecologist/grain farmer.

Yesterday I found this abstract

Author: Mark Moodie
The only text on the Bonfils/Fukuoka no-till methods of cereal cultivation. A delightfully idiosyncratic booklet with quirky illustrations.
Book's abstract at permaculture.org.uk

This morning I found this

An e-book of 'The Harmonious Wheatsmith'

then this

Authors website with e-book versions of his works (Buy via payloadz.com/paypals.com)

Here is Marc Bonfils, the developers enter on wikipedia,

I also remembered that CSIRO was doing Clover/Lucerne research in the early 1990s. They were using Lucernes summer growth to produce a mulch layer for winter growing veggies and Clovers winter growth to produce a mulch layer for summer growing veggies.

I saw a backyard Clever Clover patch in suburban Canberra in the early 1990's. It was during an 'open garden' organized by Permaculture ACT (now defunct). An Ex-Pacters out there?

While googling I found these interesting looking links.

Australian Journal of Soil Research
Long-term effects of crop rotation, stubble management and tillage on soil phosphorus dynamics
E. K. Bünemann, D. P. Heenan, P. Marschner and A. M. McNeill

Australian Journal of Agricultural Research
The effect of boron supply on the growth and seed production of subterranean clover (Trifolium subterraneum L.)
BS Dear and J Lipsett

Australian Journal of Experimental Agriculture
Survey of the productivity, composition and estimated inputs of fixed nitrogen by pastures in central-western New South Wales
A. M. Bowman, W. Smith, M. B. Peoples and J. Brockwell

Grains Research and Development Corporation (GRDC)
Research Update for Growers - Southern Region - September 2004
Putting the system together - Testing the value of lucerne with GRAZPLAN decision support tools
Libby Salmon, CSIRO Plant Industry

Then I hit pay dirt.

product info from the Diggers Club website and

info from a Canberra Organic Growers Society member. and

Organic Weed Management Survey results, Uni of New England research project

All the initial 'Clever Clover' stuff I found was from this decade. Then I found an early reference.

And guess where it was...

...in a article written by David Holmgren in 1991
Development of the Permaculture Concept.
There is a reference to Clever Clover in the Natural Farming section (page 4-5)

Attempts to apply his [Fukuoka] methods have not necessarily been successful because any sustainable system is context and site specific. However, farmers inspired by Fukuoka or working independently have developed similar methods to produce organic and biodynamic grain. The techniques of growing grains and legumes together, over sowing of crops with no intervening cultivation or use of herbicide, and appropriate use of flooding and animals for weed control are now accepted in agriculture as at least possible. Recent research work by C.S.I.R.O. on vegetable growing using living mulches and green manure crops (including Clever Clover) without cultivation reflect as least the conceptual influence of Fukuoka's work.

Perhaps the most universal aspects of Fukuoka's work, the learning from nature, remains the most difficult for people to adopt and without that no amount of technical information on permaculture will lead to sustainable systems.

then back to the 2000's where I found a similar observation to David Holmgren's about the value of observing nature.

In a Science Show discussion panel, with the subject of the 'Serendipity in Science', Clever Clover and its originator Richard Stursacre are used to illustrate observation and serendipity.

Panel Transcript

David Salt: David Salt from ANU – just a bit of serendipity that I’m aware about, a friend of mine Richard Stursacre, he’s a young scientist at CSIRO Land and Water and he came up with this system called Clever Clover which was all about low till agriculture and he basically stumbled on this idea when he was trying to figure out how to help farmers basically till the soil without causing it any damage. And it was a system of sowing vegetables through sub-clover which would naturally die down and you basically didn’t have to cultivate it at all. He’s a really wise scientist but he says the secret of his success and it ties into so much of what you people have been saying, is that he gives himself a time of reflexion, he says that the most important part of his day, in fact the time when he does all his science is when he goes out into his field trials and he wanders through them and he doesn’t do anything but in his mind he moves the various components of the systems that he’s working on around in his head and he just asks himself questions – what if I do this, this way, or what if I do that this other way? And basically it’s that time in his experimental garden that first half hour he says that’s all the science, the rest of the day is just work, but it’s the reflexion where he actually does his science. So it would be great if you come up with a system basically where we all get half an hour in our garden each day where we just reflect upon what’s important in life.

Brad Collis: I’d very much like to follow on from that because I know Richard Stursacre and he’s developed something which I think is of far more profound importance than Clever Clover. He’s developed a little device that will tell you where the water is in the soil as it travels down through the soil, a Wetting Front Monitor it’s called. I believe that this could possibly go down in history as one of Australia’s greatest discoveries ever because three quarters of the world’s water is used to grow crops. With this device you can tell exactly how much water you need to put on the paddock and no more, you can then turn the tap off. You can make one of these devices with computer electronics and things like that and it can be expensive but you can also make it for 25 or 30 cents with a clay pot and a polystyrene rod.

This could actually fundamentally change the world from a water deficit world into a world with adequate water to do all the things we need to do. But Australia hasn’t shared this knowledge with the rest of the world. We’ve spent as far as I’m aware the last few years trying to commercialise this product with a small company and not really getting anywhere and yet this is knowledge that every country on earth desperately needs at the moment. How do we reduce the impact of the thirst of the irrigation industries that support our urban communities? This is a technology that will work on an African family farm or on a big Australian cotton spread. I think it’s a classic example, it’s very smart science, it’s good physics and good mathematics encased in some very humble and basic technology and it’s a classically Aussie solution to the problem. And I think that that’s what this country really you know is made of, clever science but very basic robust useable technology which is you know essentially one of our traditions. And I think you know Stursacre’s discover embodies what we have got to give to the world in the coming 50 years when water is going to be absolutely short, a third of the world’s countries without enough water, are severely water stress by 2030.

I wonder if a 'Wetting Front Monitor' is anything like the 4 foot steel rod an old farmer I know uses? ;)

I did some searches on Richard Stursacre, both on google & CSIRO, but it lead nowhere.

I do agree about the best thinking being done when your out in nature. I walk in the mornings, it's my best thinking time.


gnoll110

the+harmonious+wheatsmith mark+moodie marc+bonfils clover lucerne csiro clever+clover permaculture+act subterranean+clover trifolium+subterraneum medicago+sativa david+holmgren natural+farming permaculture masanobu+fukuoka richard+stursacre

Sustainability within a Generation:A new vision for Australia

David is currently speaking on the ABC, at the National Press Club in Canberra.

David Suzuki has been talking to the ACF about an Australia version of this Canadaian document.

We need to be creating submissions for each on the following area like:
Food
Transport
Energy
Air
Water
Waste
etc

Towards the goals of

GENERATING GENUINE WEALTH: Supplementing the narrow goal of economic growth with the objective of genuine wealth

IMPROVING EFFICIENCY: Increasing the efficiency of energy and resource use by a factor of four to 10 times

SHIFTING TO CLEAN ENERGY: Replacing fossil fuels with clean, low-impact renewable sources of energy

REDUCING WASTE AND POLLUTION: Moving from a linear "throw-away" economy to a cyclical "reduce, re-use, and recycle" economy

PROTECTING AND CONSERVING WATER: Recognizing and respecting the value of water in our laws, policies, and actions

PRODUCING HEALTHY FOOD: Ensuring Australian food is healthy, and produced in ways that do not compromise our land, water, or biodiversity

CONSERVING, PROTECTING AND RESTORING AUSTRALIAN NATURE: Taking effective steps to stop the decline of biodiversity and revive the health of ecosystems

BUILDING SUSTAINABLE CITIES: Avoiding urban sprawl in order to protect agricultural land and wild places, and improve our quality of life

PROMOTING GLOBAL SUSTAINABILITY: Increasing Australia’s contribution to sustainable development in poor countries


Gnoll110

Technorati:
permaculture global+warming peak+oil food transport energy air water waste

Of Weeds and Native Legumes

Today I found a negative comment about permies from an bush regenerator. It relates to farm/garden escapee plants.

I posted a comment in defence of permies and why I think using the equivalent natives is an issue in the current legal environment.

I will also to expand on my ecoliving centre post here.

Here is Robyn Williamson original post.

We all know that seeds are the first link in the food chain and that nobody's getting anything to eat without them. We have a widely accepted definition of what permaculture is, but WHAT IS A WEED?

SEEDS, WEEDS AND PERMACULTURE

We all know that seeds are the first link in the food chain and that nobody's getting anything to eat without them. We have a widely accepted definition of what permaculture is, but WHAT IS A WEED? [For some answers to this I have relied heavily on "A Field Guide to Weeds in Australia" Rev. Ed. 1979 (Inkata Press P/L Melbourne) by Charles
Lamp and Frank Collett, who in turn have relied heavily on authors of various publications about the flora of Australia and the world.] The following is an attempt to shed light on the question and elaborate on the sound advice put forward by Russ:

On Wednesday, January 19, 2005, at 06:59 am, Russ Grayson wrote:

> Biologist Tim Low treated the Permaculture and weeds
> issue in a book published several years ago, probably
> influencing the perception of the link between weeds and
> Permaculture and taking it to people who otherwise
> would have remained ignorant of it. This, though, is what
> comes when you act in the public sphere, which is what
> Permaculture has done to a limited extent but which it
> will likely increasingly do as the accredited training
> takes it more mainstream. Permaculture organisations and
> teachers are going to have to repeatedly refute such
> assertions as those made by Low and clarify those
> made in the way that McMinn makes his. To ignore such
> allegations and to fail to publicly refute or discuss
> them does not make them go away. It merely confirms the
> criticism in the minds of readers. To adopt a policy of
> silence in today's media-saturated culture is to
> surrrender the argument to those making the allegations.

[Ignorance is the key word here]

> As always, critics should be asked for evidence - hard
> evidence, preferably, rather than circumstantial. To
> McMinn's credit, he had provided this.

As we have learned from permaculture there are no "answers" to problematic issues like "weeds", only solutions and/or useful suggestions. One way to answer a question however, is with another question, so we can begin by using words like what, where, when, who, why, how and finding out which plants are weeds.

WHAT IS A WEED?
Weeds are often defined as *plants out of place* or worse *a plant growing in the wrong place* such as an exotic in the Australian bush or grasses in a vegetable garden. To a wheat farmer, a weed could be anything growing in a wheat field that is not wheat. *A plant for which we have not yet found a use* is another description which is somewhat negative and certainly inaccurate in a permaculture sense
where every element in the design has at least 2, if not 3 or more functions. Every plant has its uses and functions even though humans may not be fully aware or choose to remain ignorant of them.

"Weeds" are most often the first plants to colonise disturbed ground, their roots bind the soil and protect it from erosion, their leaves shade and mulch the topsoil stabilising soil temperatures and preventing evaporation, they provide habitat for other organisms, their leaves transpire vapour which is part of the natural water cycle, their flowers produce nectar and pollen, etc., we can come up with a dozen or more functions for any plant before we consider what direct use they may be to humans. In practice, they are "indicators" of soil and climatic conditions and permaculturists observe them closely in order to "read" the landscape. They are also accumulators or "miners" of various minerals, e.g. chickweed accumulates copper.

WHICH PLANTS ARE WEEDS?
A Field Guide to Weeds in Australia has photos and details of around 300 species with weedy potential including both exotics and indigenous native plants. Here are some examples that may or may not surprise you:

Yarrow - Achillea millefolium
Bird rape - Brassica campestris (a parent of "Canola") a.k.a. "colza" or coleseed oil, an industrial grade lubricant used as a fuel in lamps and in the manufacture of rubber
Tagasaste - Chamaecytisus proliferus (is this now called Leucaena?)
Good King Henry - Chenopodium bonus-henricus
Chicory - Cichorium intybus
Afghan melon - Citrullus colocynthis
Paddy melon - Cucumis myriocarpus
Couch - Cynodon dactylon
Nut grass - Cyperus rotundus (a native - arguably the world's worst weed)
Wild rocket - Diplotaxis tenuifolia (the last time I bought so-called 'Baby Rocket' it was about $20 a kilo - that's for the leaves!)
Fennel - Foeniculum vulgare (a weed or a feed, depending on your taste buds)
Topped lavender - Lavandula stoechas
Nardoo - Marsilea drummondii
Lucerne/alfalfa - Medicago sativa
Evening primrose - Oenothera stricta
Kikuyu - Pennisetum clandestinum
Cane grass - Phragmites australis
Plantain/ribgrass - Plantago lanceolata
Broadleaf plantain - Plantago major
Sago weed/small plantain - Plantago varia [a native of the Cumberland
Plain and Blue Mountains (rare), probably extinct since last time I looked the Cumberland Plain was covered with unsustainable housing developments]
Tussock grass - Poa labillardieri
Self-heal - Prunella vulgaris
Bracken - Pteridium esculentum
Sorrel - Rumex acetosella
Chickweed - Stellaria media
Buffalo grass - Stenotaphrum secundatum
Broughton pea - Swainsonia procumbens
NZ spinach - Tetragonia tetragonioides (a native, despite the common name, extends to oceania)
Salsify - Tragopogon porrifolius
White clover - Trifolium repens, and 8 other species of clover, including Subterranean clover - Trifolium subterraneum Cumbungi - Typha domingensis

You will note there are many plants listed that are useful as accumulators, food, fodder and first-aid e.g. bracken, an indigenous member of forest communities and healing plant, marvellous for ant bites. I was certainly surprised to see lucerne and "sub" clover in there. Apparently lucerne is considered a weed in irrigated vineyards
and citrus orchards of the Murray River system. Due to oestrogenic activity, "sub" is apparently troublesome in potato crops where it reduces the yield and slows down harvesting.

Therefore, the answer to "what is a weed?" depends firstly on who you are, and leads to the next question:

WHO ARE YOU?
The greenkeeper or home gardener who weeds, feeds, waters, snips and mows his treasured lawn of couch, kikuyu, buffalo, or all 3 together, is often blissfully unaware that they are aggressive weeds of bushland, roadsides and other places (like community eco gardens), while they
consider anything with a broad leaf to be a weed of lawns and/or turf.

Corporate scientists, particularly geneticists, appear to consider anything that is not GE Canola, BT corn, rice, wheat, RR soya beans or cotton, needs weeding out and may even believe they can feed and clothe the world with these 6 plants. This is total nonsense of course. Of the billions of tons of biocides that are sprayed annually on these and other agricultural crops, approximately 1 per cent reaches the target organism.

Horticulturists are actively cultivating known weedy species for sale to home gardeners as "ornamentals", as we speak.

Bush regenerators think (rightly IMO) all exotics growing in bushland are weeds.

So everybody has a different interpretation of a weed, depending on where it is grown, where it originated, what plant it is, who is growing it and why. The classic case is Paterson's Curse [Echium sp.] which is called Salvation Jane by sheep farmers in arid regions of South Australia. Apparently it can sustain sheep through a drought, is
a source of great honey and the seeds have now been found to contain Omega 3 fatty acids. Another Echium sp. is a known cure for snakebite.

WHERE DO WEEDS ORIGINATE?
Evidence in the form of pollen profiles indicates that weeds are the creation of agricultural man.

It seems that only the English language has a specific word for them.
The Aborigines knew nothing of weeds until the arrival of white man.
The Chinese term for weed translates to something like "wild grass", the French say "mauvaise herbe" [bad grass/herb] and the Spanish "mala hierba" [ditto], plural [weeds] is "ropa de luto" [clothing of mourning]. Interestingly, Germans use the word "Unkraut" [the opposite
or antonym of "Kraut"] meaning anti- or non-plant. I would be interested to hear of any others.

The word "weed" is evidently derived from "woed", a corruption of Dyer's "woad", Isatis tinctoria which was used by warring medieval Britons to stain their skin blue.

WHEN DID WEEDS FIRST APPEAR?
Evidence of weeds goes back as far as Neolithic times (about 3000 BC) when the elm decline occurred and for a long time it was believed that this was due to climate change.

However, work by Iverson, Troels-Smith & Jorgenson (1949) examining pollen profiles in the mud beds of Danish lakes suggests the elm decline began when agricultural man fed elm branches to newly domesticated cattle and cleared forests in order to grow primitive cereals. Their evidence shows that the decrease in elm pollen was associated with charcoal layers. You guessed it. Neolithic man used
fire to clear the forests. Further experiments revealed that 3 men could clear 500 sq. metres in 4 hours using polished Neolithic axes.

Previously inconspicuous pollen grains began to appear above the charcoal layers, together with cereal pollens and the first weed to show up was plantain or ribgrass, Plantago lanceolata, qualifying it as the "first weed of European agriculture". The North American Indians
certainly knew where it came from and so dubbed it "white man's footprint".

WHY DO WEEDS MATTER?
Weeds are economically significant and inconvenient in agriculture yet agriculture creates them. The problem suggests the solution and we all know what that could be.

Russ wrote:
> Finally, there is the age of the guilty Permaculture book
> bearing the notorious list - it is now 30 years old,
> though I have not seen the most recent editions and it
> would be good to get feedback from others on this
> listserver as to the status of the list in these recent
> editions.

HOW CAN PERMACULTURISTS HELP?
The word "weed" itself has such a negative aura that I don't even like using it. I try not to, but it just rolls off my tongue like waves on the beach especially when faced with acres of recalcitrant couch and kikuyu.

I suggest for a start that we come up with a new and more satisfactory definition of a "weed". Maybe something like: "an adaptable, vigourously recurring, dominant, aggressive and/or tenacious plant with non-ecological and/or anti-social behaviour and the disgusting habit of
reproducing itself sexually, bisexually and/or asexually ".

We may also need to prepare our own lists of potentially weedy species, classified into bioregions.

Any more ideas?

Robyn

CONTACT DETAILS:

Robyn Williamson
PDC, Urban Horticulturist
Hon Sec, Fagan Park Community Eco Garden Committee
Local Seed Network Coordinator
NORTH WESTERN SYDNEY COMMUNITY SEED SAVERS
mobile: 0409 151 435
ph/fx: (612) 9629 3560
email: rz.williamson@optusnet.com.au
http://www.communityfoods.com.au
http://www.au.gardenweb.com/directory/fpceg
http://www.seedsavers.net/lsn/32.html
http://www.sydney.foe.org.au/water

(Note for Robyn W: Tagasaste and Leucaena are different species, they fill the same niche (tree fodder) in temperate and tropical regions respectively, Leucaena is frost sensitive.)

Here is Robyn Becket comment.

Hello Robyn,

I found your article very interesting.

I love to hate weeds. (The sort that invade bushland and my food garden) I think its interesting that for me and plenty of others weeding is a therapeutic activity. Perhaps if there were no weeds I'd just spend more time planting and watering and harvesting.

Also I am a bush regenerator, who tries to live holistically. I expect to be paid for some of my bush regeneration work, not all. My knowledge of permaculture design principles is limited, but I think I get the gist and with my knowledge of bush regen I can integrate the two. I do plan to learn more about Permaculture design, and watched the film at the Peats Ridge Festival.

I have visited Bill Mollison's place in N. NSW and didn't like it much.

Primarily there was a difference in ethics and from the people there at the time a defensive attitude about plants escaping from the farm and growing as ferals in the bush. I didn't like the attitude that it didn't matter.

My philosophy is that in providing for ourselves we shouldn't have a negative impact beyond our borders, and if we make a mistake in our experiments and plants escape we are responsible and must deal with them. We need to be aware of the plants likely to go feral and not use them.

At Bill Mollisons the tree Tipuana (I can't check proper name, I'm using a computer away from my books) used for nitrogen fixing was going feral. It is rapidly becoming a problem in bushland and has been hugely promoted by Permaculture practicioners.

I think it has been a huge mistake to promote Tipuana in Australia and the people who did should address the problems they have created. What amazes me is that the local native nitrogen fixing plants that would already exist on many properties are not acknowledged at all.

This message is getting a bit long, and I hope I'm not being too negative, but I'm glad for the opportunity. I'd be interested to see what you think about my comments.

Regards,

Robyn Becket

Here is my reply comment.

Robyn B

While using local native nitrogen fixing plants would be great, I personal could not recommend them to anybody.

The problem is legal. The use of local natives in any (permaculture or not) system, risks these elements of the system being classified a 'remnant' vegetation, and all the inflexibility/problems with current 'anti-clearing' laws. This varies so much between the states.

The devaluation of land that occurs when isthe usage condition are made less flexible is real. The state government have drafted these law in such a way, that generally compensation is not available for the holder. So I in good faith won't use native legumes in my guilds/mass plantings etc. This is really a pit, a large region in the northern half of the eastern Australian grain belt has a leguminous native is one of it's dominant species, a farmers wont let is regrow and increase N levels for this reason.

This issue is stopping farmers from developing ultra long term crop/pasture/woodland rotation systems more suited to Australian dryland areas, than the current modified 'imported' practices.

What good are nitrogen fixing woodlands (to the farmer), if you can't clear it for rotate it back into crops. In PNG they have been doing 70+ year rotations for over 10,000 years.

Dumb politically driven law making usually generates some silly results.

With regards to permies not caring an about escapees, for me it's a matter of priorities. The centre of me attention currently (and for years to come I suspect) is Global Warming and Peak Oil.

What use is stopping directly human caused plant invasions, if the whole ecosystem disappears.

Global Warming is/will drive far more plant (and animal & diseases) invasions than invasions directly caused human plant prorogation. As climates change, the plant and animals move generally uphill and towards the poles. Greatly increase rates of invasion at most every ecosystem edge!

Now that I've finished my rant, in truth, I will use native legumes. But only in Zone 5 and parts of Zone 4 that will never be rotated into another Zone at some stage in the future. Get rid of the bad laws and I would use them in all zones.

Good leadership requires planning for change, good planning requires flexibility. Flexibility is undervalued by most.

Gnoll110
http://www.gnollsinspace.blogspot.com/

Now I want to expend on my comments in two area.

One, what legal environment would I like to see. The problem is the the current set of laws is design to serve 3 master! 1/ Bio-diversity presivation, 2/Carbon freezing and 3/ City vote retension!

We all know what they say about serving two (or more) masters!

I outline where I think the law should be, in a post on the ABC's Four Corners forums and the "A-Team" story.

Where is the science that says what is needed to really preserve biodiversity?

This is politics.

If there was real science, there would be two sets of laws.

A 'Biodiversity Preservation Act' to do what the name says.

And a 'Biomass Act', with the aim of maximizing the net reserves of carbon while maximizing Biomass production for energy production, thus reducing the burning of Oil, Gas and Coal.

The 'Biomass Act' would replace the various anti-clearing laws, with all their faults.

When Global Warming & Peak Oil meet, something must give!

Any given piece of land would be subject to one to one Act or the other. It either being managed to preserve biodiversity OR mitigated Global Warming!

Note 'Carbon freezing' is a knee-jurk reaction, what is needed are systems that both store the large amounts of Carbon while cycling Carbon to mitigate Global Warming.

Also note in the same thread I question the Green Lobbies preoccupation with Hemp! As it's an annual crop, my knee-jerk reaction is that it should be less environmentally sustainable than wood chipping done right. See David Holmgren's "BIOMASS FUELS FROM SUSTAINABLE LAND USE: A permaculture perspective" page 2.



Someone needs to do the EMergy calculations for both.

Is Hemp a solution.

Or would it just be an Oil to Paper converter.

The problem the modern intense cropping is that about as much energy (as Oil) is consumed as is produced as embodies in the paper.

To get more embodied energy out, you need to go to use perennials, and the longer the perennial grows, better the energy input:energy output ratio.

This is why permaculture use lots of food forests, timber forests etc.!

Please note I was not the only 'Ned' on the forum that night, so only some 'Ned' posts are mine!

Two, the native legume I refered to above is Acacia harpophylla, commonly known as 'Brigalow'. The soil region where it grows is commonly called the 'Brigalow Belt'.

Technorati:
global+warming peak+oil permaculture weeds native+legumes anti-clearing+laws ecoliving+centre four+corners bill+mollison david+holmgren tipuana tagasaste leucaena brigalow acacia+ harpophylla brigalow+belt biomass biodiversity emergy