Regular commentator at this blog Ian Mott sent me the following email:
Hello Jen,
We have all grown accustomed to the notion that it is the removal of trees from the landscape that causes salinity. But recent research from the Argentine Pampas indicates that the addition of trees to a natural grassland can also increase the salinity of groundwater flow systems (GFS).
This could have major implications for the management of salinity in the Murray Darling Basin, particularly in rangeland areas where major thickening events have taken place or where existing small clusters of forest have expanded onto grassland ecosystems.
The study, by Esteban G. Jobbagy and Robert B. Jackson, published in Global Change Biology compared 20 paired plots of forest and grassland and found a significant increase in groundwater salinity under the forested plots. "Afforested plots (10-100 ha in size) showed 4-19-fold increases in groundwater salinity on silty upland soils but less than twofold increases on clay loess soils and sand dunes."
While this study has been limited to planted forest plots on previously grassland ecosystems, the same causal factors are at play whenever forest vegetation expands on grassland. And it logically follows that the same causal factors will be at play when, for example, a 10% canopy woodland thickens to become a 60% canopy forest.
Jobbagy & Jackson have concluded that "Soil cores and vertical electrical soundings indicated that ...salts accumulated close to the water table and suggested that salinization resulted from the exclusion of fresh groundwater solutes by tree roots."
To which the average farmer would say, "Well, they would do that, wouldn't they".
The extensive, 1400 plus, rangeland sample plots done by Bill Burrows confirm that more than 60 million hectares of rangeland in Queensland is subject to thickening at an average rate of circa 0.25m2 increase in basal area per hectare. There is a further estimated 30 million hectares in NSW. And there are also numerous landholder reports of properties that had only 3,000 ha of Gidgee in the early 1900's but have in the order of 50,000 ha today as a result of major encroachment onto grassland.
And this poses an interesting question for the publicly funded anti-salinity industry and the policy arms that have focussed so much public attention on the removal of trees as salinity causal agent. If the lowering of a water table by excess bore irrigation can be widely recognised as a causal factor in increasingly brackish ground water resources, why has it taken so long to recognise that a similar lowering of a water table by the addition of trees can produce the same result?
It certainly invites the question, is there any similar research conducted here in Australia?
Clearly, the political exploitation of salinity appears to be sinking deeper and deeper into murkier water.
Regards,
Ian Mott
Thanks Phil; I knew a lad who helped build some of the info systems behind our RFA agreements, 20/20 vision etc. Zeroing in on some old haunts it gets a bit complex. Bet that’s why he moved on! I used to say he was just another tree counter.
http://adl.brs.gov.au/mapserv/intveg/index.html
Taz - I would interested to hear your experiences with radio and vegetation etc.
In terms of visual effects in art depicting Australia - Russel Drysdale is interesting - how earlier pictures with happier days, greener grass and blue skies become barren, red dusty skies, desolate and isolated. e.g. Dead Bullock, Desolation, Red Landscape, The Crucifixion and alone as Woman in the Landscape.
His exposure to the 40s droughts I guess.
Also in the Jill Ker Conway's book "The Road from Coorain"
Phil: With no stretch of the imagination a few of us can challenge this new age dependence on science, the policies and the attitudes from other well established sources such as art in relating to change, in particular mans impact on this continent over the last say 150 years. But perhaps our greatest problem today is the people who depend on their rhetoric for solutions. By that I am simply offering to share visual impressions built over decades. This is how I model most dilemmas.
Notice I don’t usually refer to other people’s web pages either in our discussions. That said lets move on.
Trees and landscapes can be studied in many ways, none the least is photography but other art will do too. Early English land lords brought their views with them literally and their concept of rural exploitation applied all over this country. Pioneers extended their influence deep into our hinterland and that is what I look for in all our early records. But the records also remain in old trees and that is your best clue to what was.
There is another aspect. As one team struggled to put a model of our entire radio communications system into a computer and associate every aspect with some legal jargon about interference and compliance, I was still studying all the contour maps and wondering how the aborigines got on with their smoke signals way outback, I mean before us and our processes of understanding. We do kid ourselves at times.
BTW vegetation in all its forms affects radio propagation over long distances. So does water and salt. QLD’s old DRCS was a particular interest as we extended the boundaries of other services
Dear Roger
I think you may have posted this in the wrong place. I know it wouldn't be a diversion so I assume it's an slight error.
Regards
Phil
yep, you cant believe what any of these government employees say;
http://news.independent.co.uk/environment/article345926.ece
Dear Roger
I also refer you to this more useful earlier national survey for a national perspective.
ftp://ftp.brs.gov.au/outgoing/longterm/lw/lcc_report.pdf
from
http://www.affa.gov.au/content/output.cfm?ObjectID=D2C48F86-BA1A-11A1-A2200060B0A06037
I do suggest you be most circumspect in use of ABS and AGO data.
Regards
Phillipe
Dear Rog - I think you ought not be calling myself a penis as you are most incorrect and the term is not polite anyway. You are most incorrect to write your post. I am surprised as I thought you were quite knowledgeable in Australian natural resources issues.
The Qld satellite data are definitive - highly ground truthed and 95% accurate. NSW numbers have been small in comparison for a long time. Other states very small.
ABS are farmer surveys and I don't read Greenleft Weekly. ABS for example had one million hectares for a Queensland figure actually below half that number. About as good as their Agricultural census. Both ABS and the AGO are not expert in these matters. The AGO are uncertain as they do any ground-truthing out of the ACT.
Regrowth clearing is included and can be estimated. But clearing for cropping is still small.
Woody vegetation can have a phenological description of basal area, foliage cover or crown canopy. Or the analysis will be qualified down to a detection level. Of corse MODIS imagery using angular instead of spectral patterns and microwave imagery may give us information to detection differences in vegetation structure which will identify regrowth more clearly.
Have a look at any state of environment report, state survey and convince me that the NSW number is higher or even high !
Where are the vast new areas of cotton or wheat production?
And just so we don't get silly - we are talking the last 10-15 years - not since settlement.
You may ahve found yourself in a large cleared paddock and felt it was quite large but Queensland like the universe is much larger.
Ask Ian's opinion?
I hope you don't see my correction of your refutation as offensive.
Best wishes
Phillipe
Taz - I think it depends where you are in Australia. Certainly the coastal strip is heavily cleared in parts. SE Qld about 50%. Most of NSW wheat belt is obviously cleared. I guess Ian could inform on the Big Scrub between Grafton & Brisbane.
But we have areas where the reverse has occurred too - woody infestation or thickening up - Pilliga Scrub, Cobar woody weeds patch, SW Qld Mulga forests, central Qld eucalypts.
Actually cities are very interesting - South Brisbane is now a sea of concrete, asphalt and houses - on the city side there is a freeway - compare with this description.
http://www.health.qld.gov.au/pahospital/docs/general/Ab_History_Ros_Kidd.pdf
You really are a total tool Phil.
*There may some clearing for cropping but is relatively a smaller number*
In your inexpert opinion of course.
From the ABS (not GreenLeft Weekly);
"UNCERTAINTY OVER THE ESTIMATES
Knowing how much clearing is occurring is problematic, and these figures, from the Australian Greenhouse Office, are uncertain estimates. The most reliable figures are provided by government research agencies using satellite imagery, but data collected in this way are not available for every State over the past ten years. The accuracy of estimates is expected to improve over time.
The figures used include information about land that has been cleared for the first time as well as land that has been re-cleared. They do not distinguish between the kinds of vegetation that has been cleared - for example, whether it formed part of a healthy or a degraded ecosystem. Thus the figures cannot be used to measure the net or quality-adjusted change in vegetation cover. Both clearance and re-clearance of native vegetation have environmental impacts.
There is a long history of attack on our hapless trees. There is a museum piece of engineering, a thumping great tractor that clumped along on wooden shoes like posts. This pioneering monster was used to pull scrub around our southern flats for years, about the same time dust storms used to choke Melbourne.
In my study I keep a battered copy, “Glimpses of Australia” V2, 1897. On page 229 is a good photo of Black Swan Lagoon near Warwick QLD, “one of the richest bits of country in the world”. It is sparsely treed but I am suspicious it was heavily cleared by then. I wonder how that block fairs today in global fertility stakes.
On page 233 is the Torrens Weir, it looks rough country. ‘ “In the early days of Adelaide the Torrens was BIG river but as the settlement extended and forest was cleared away, the river dwindled down until it became a small stream meandering along the bottom of a big depression”.
On page 234 is the Ovens River – “Germantown” but the description is remarkable in that it connects half of Victoria on the river’s way from the Alps to somewhere south of Geelong. The photo however shows a pretty stretch of river flats between the hills as a very woody place.
From the “Meat Works” near Grafton p251 to “A Bush Workman’s Home” Gippsland p268, we can clearly see that the country was wooded every where. P 268 in particular gives a glimpse of original bush on the far side of a fresh farm and a vast area of ringbarked timber on the near side.