What I did on my holidays

[Tannin]

Some of you might have noticed that I've been off the air these last couple of days. I thought I'd tell you all why.

Belinda and I left Ballarat after work on Friday and drove about 300 kilometres more or less east and arrived in Benalla just before 10 o'clock. Most of the others were camping or driving up from Melbourne on the Saturday morning, but we decided to do out trip in luxury style, and checked into the first motel we found open.

Benalla isn't marked on that map, but you can see Ballarat to the west of Melbourne. Now look about that same distance north-east of Melbourne and you will see Mansfield and Wangaratta. Benalla is near Wangaratta.

The next morning we were up early (early by my standards anyway) and at the Benalla Post Office to meet the crew at 9:00. After a little of the usual "is everybody here" stuff (a very little - these guys are nothing if not organised) we set off in convoy. We drove for 15 minutes or so through typical degraded box ironbark country.

This is one of the moderately fertile parts of Australia: in the natural state it was open forest, criss-crossed with wild rivers. In the summer they were just languid, slow-flowing streams; in the winter and the spring, mighty rivers taking the rain that blows up from the Southern Ocean to fall on the Great Dividing Range on the first part of its long, slow journey to the sea. The Broken River, for example, flows 500-odd kilometres from the Mansfield area up north through Benalla (away from the coast) to meet the Murray near Woodonga, then via the Murray another fifteen hundred kilometres or more to finally reach the sea in South Australia.

(On the map above, you can see where the Murray has its outlet, more-or-less under the "S" in "South Australia". You can trace its course from the orange line along the Victoria - New South Wales border. As a matter of interest, at almost 4000 kilometers, the Murray-Darling system is the third longest navigable river in the world and drains 14 percent of the continent - that is quite astonishing when you remember how flat this place is: with the highest mountain in Australia a mere 7000 feet and very few places being more than 1000 ft up, it's a long, long way for a river to flow. At Wodonga, the Murray is just 531ft above sea level - and it has 2100 kilometres still to go! The headwaters of the Darling reach right up into Queensland. Alas, on a volumetric flow basis, the Murray wouldn't rank in the top 1000 - we only think it's a big river because this place is so dry. On any other continent it would barely be worth thinking about.)

"Box ironbark country" is called that because of the two dominant species of eucalypt that grow there: Box on the lower, more fertile parts, Ironbark on the hills and higher country. Both are magnificient trees when they are healthy, and they form a dry, open forest, with many, many other species growing in between and underneath them to form a rich and varied habitat. Both are very drought-tolerant, as they need to be, for apart from the riverbanks where the River Red Gums grow, they must depend on rain and though the typical rainfall is about 25 inches a year, nearly all of that is in the winter months. Summers are long and hot and often very dry.

Once you take the trees away, everything changes: rainfall decreases (because you are changing the microclimate), runoff becomes more rapid (because there are no trees to hold the water in the soil and protect it from the sun), erosion increases dramatically and carries away the thin layer of fertile topsoil (because there are no trees to hold the soil together), and on the flatter parts (like most of the Benalla district) the water table rises (because there are no large trees to drain the sub-soil).

It is this last factor which is perhaps the worst of all. On first sight, it sounds absurd. How can more water in the soil be a problem? Simply, because ground water has got where it is by percolating slowly through the soils and rocks, and on the way it disolves all sorts of minerals, in particular, salt. And nothing grows in salty water. Once the water table has risen, you can no longer plant new trees to lower it, because they won't drink salty water. The bigger they get, the deeper their roots go, and the worse their health becomes. Before too long, they die.

The only way to deal with salinity is to replant trees on the higher places (well above the water table) so that they can hold the rainfall in with their root systems and allow it to gradually percolate out through the topsoil into rivers and streams.

Salinity is a terrible problem in many parts of Australia. Vast tracts of once productive agricultural land are already dead, and much larger tracts are seriously threatened. We drove through several saline areas on the way to Benalla but, thus far, salinity does not seem to be the huge problem there that it is in other parts.

But back to box ironbark country. Here is a typical bit of it - after clearing, of course, with just the odd tree left standing to provide shelter for livestock. That's my sister in the foreground. I'll explain what she is doing there and what she is carrying in a little while.

Now look a little more closely. Look at the trees. See how many of the growing tips are scraggly and dead? That's called "die-back" and it's what a tree does when it's severely stressed. All seems green and healthy on first sight, but don't forget it's the middle of winter here, which is our rainy season, and although the last few years have not been good ones, they have not been terrible ones either. Aside from all the factors I mentioned above, the standing trees are having to cope with soil compaction from stock (native wildlife does not compress the soil and squeeze the air out of it the way that sheep and cattle do, and our soils are far older and more fragile than most norther hemisphere ones). I'm not sure how important this last factor is - probably insignificant compared to loss of topsoil from wind and rain erosion. Almost everywhere we went the trees were clearly stressed. We Australians have become used to this, it seems; we tend to think of native forest as scraggly, untidy stuff, much less attractive than the lush green rows of oaks and beech and conifer that we see on TV shows anout northern forests. But, of course, a great deal of the scraggly, down-at-heel look that we associate with Australian trees is simply that so many of the trees we see are unhealthy ones, grimly holding on to life and ever so slowly dying.

 

[Tannin]

This is where we ended up:

And this little fellow is why:

"Ahhah!" you all say, "Tannin has been out birdwatching again." Nope. We didn't see a single Regent Honeyeater. In fact we didn't even go looking for one. Why not? Because there aren't any, not in this part of the world anymore. In fact there nearly aren't any at all. It's thought that the once common-as-mud Regent Honeyeater is down to about 1500 to 2000 individuals now - and the reason is simple. The Regent Honeyeater eats nectar, and the nectar of the Ironbark tree is crucial to him - and there just aren't enough healthy trees left to keep the Regent Honeyeater going.

What trees do remain - about 17% of the original cover, and that 17% is all the worst, most infertile land, of course - are spread far and wide. An island of trees on its own is useless, for the birds (and all the other creatures) have no way to get from one place to another. Wildlife can survive in surprisingly small patches of healthy forest, but only if it is able to move about so that when an Ironbark stand finishes flowering (for example) it can move by easy stages to another place where the season is a little later (because it is on the south side of the hill, perhaps) or to where there is Yellow Box in flower. And so on. According to the experts, this ability to move about is cruical, and the single most important thing we can do for our wildlife. Not only does it allow the survival of particular individuals, it also allows a healthyy cross-fertilisation of bloodlines, so that isolated remnant pockets of this species or that do not become inbred and weak.

So that was our task: to provide a corridor of regenerated bushland between two existing stands of remnant trees. And here is how we did it:

The scheme works like this: one man runs the whole thing on a shoe-string. He is government funded, with a tiny fraction of the money he deserves for a task like this. He organises seed-gathering (in itself a critical task, for it's vital to make sure you choose seed from the local sub-species, if you can still get it, otherwise you throw the whole thing out of whack). He has got sixteen local primary schools working with him: the kids do the lion's share of the sewing in seed-trays, and then pricking out the seedlings into tubes (plastic pots about an inch square and four inches long). Local landowners and semi-government bodies can be persuaded to make bits of land available (it is in their interest, long-term, of course, but first you have to do a hell of a lot of education). And then you need to find the money to get a contractor to come along and spray the area with herbicide, and another one to go along with a ripper to cut a deep furrow into the iron-hard earth. (You can see the rip lines in the picture above.)

Then it's time to gather every willing hand you can get hold of and put the trees in. That was our part. About 90 of us rolled up and spent the weekend digging holes - you need a deep hole, for these little trees won't get watered until it rains, if it rains - and putting trees in them. Or rather, a mixture of trees and shrubs, 20 or 30 different species, in more or less the proportions that they would occur in nature.

Swinging a pick doesn't sound like a whole lot of fun, but it is. You are working with a great bunch of people, all ages, all walks of life. This particular planting weekend it was mostly people from the Melbourne Bicycle Club and the Melbourne University Practical Conservationists Club, plus a good smattering of ring-ins like us. So I'd swing the mattock for a half-hour or so, digging holes until I was buggered, then take a turn planting, or carrying trays of trees around to the right places, then take another turn at the mattock, and when I was too tired to do that anymore, hand it over to another volunteer and use a shovel to exercise some different muscles for a while. Others were making themselves useful laying out the trees along the rip lines, or putting down the tree-guards ready to be placed around the seedling to stop the rabbits eating them.

(That's what you can see my sister carrying in the first picture - an armful of tree-guards. They are actually cardboard cartons with the bottoms cut out of them - the sort of thing you buy milk or fruit juice in, and by the time they rot away the tress will be big enough to make it on their own.)

It's simply astonishing how much work 90-odd people can do in a day!

And amazing too the way that everybody finds a way to make themselves useful: there was a girl on crutches who couldn't swing a pick but could get around on her knees to put the trees in, two or three elderly people with bad backs who can't plant trees but sure make themselves invaluable by preparing meals for 90 tired, hungry people, and old retired engineer who ekes out the project's timy budget by making mattocks out of salvaged scrap metal (darn good mattocks too - lighter and sharper than the ones you buy in shops), and the local scouting people who make their hall available for the low-budget volunters (especially the uni students) to sleep in, the local hotel that donated a great big 90-person serve of roast potatoes. And so on.

 

[Tannin]

So what is the herbicide for? And the ripper?

The ripper is a variation on the plough theme, a single very heavy tine pulled along behind a tractor to make a deep cut into the earth along the contour line. It goes down quite a long way, almost a metre. This creates a sort of "mini-dam" to help catch whatever rain might fall before it flows away, loosens the soil down a fair way so that the young tree can easily develop nice deep roots before the next bad season, and makes it a lot easier for the guys on the picks and shovels.

The ground is barren - no real topsoil left, remember - and thickly covered with grasses, nearly all introduced species, and in the worst places (I neglected to take a photo of any of those) mostly noxious weeds - that South African curse Capeweed prime among them. To give the young trees a chance to recover from transplanting and get up to a reasonable size - say a foot or two tall - you have to kill off the competition for a while. So they spray herbicide along the rows a couple of weeks before planting day. But this only kills the weeds that are alive at the time. The top couple of inches of soil are full of weed seeds, and they will germinate as soon as it rains, so the they have to come off

That's where we come in: the diggers first clear away the top two or three inches of soil from an area about two or three feet square, and put the soil to one side, as that is full of weed seeds. It also happens to be, most of the time, the only half-decent part - the actual proper topsoil is very, very shallow in this degraded country, but that can't be helped. Then you dig a nice deep hole and move on to the next one. (Someone else has gone along laying out the shrubs and tree-guards in advance.) One of the planters comes along behind you and plants the tree, then fits the tree-guard over it, and finally anchors it firmly so that rabbits and kangaroos can't knock it over too easily in order to eat the young tree - it's only tiny, somewhere between one and six inches tall.

(Here you can see some completed rows - you can't see the trees just yet, only the white tree-guards. In the distance you can see the main body of diggers and planters nearly at the end of the corridor and ready to hop over the fence and start coming back the other way, on the northern farm this time. By the end of the day, there would be a good wide corridor. It needs to be quite wide - 40 metres is the rule-of-thumb - otherwise the agressive species will drive out the shy species and it serves little purpose. If it's wide enough, there is room for the shy ones to sneak past the bigger, more assertive species. I'm not just talking about birds here, of course. There are Squirrel Gliders still surviving somehow in the little patch of bush at one end of the corridor we made.)

(These little cuties are a tiny member of the possum family. You could hold one in the palm of your hand. They come out at night to feed. They eat Wattle sap - or drink it, rather - by biting a tiny hole in the bark. Astonishingly, that's all the nourishment they take - they don't ever drink water, not even in high summer. As you can see, they glide from tree to tree using the loose skin between their legs.)

When you first start in the morning or after a break, the diggers go racing off and get two or three holes ahead of the planters. But before too long they start to tire, and the planters catch back up again. Then everybody starts to switch around.

It's quite astonishing how much the soil varies from one hole to the next. This one is soft and almost loamy, that one just a few metres away is heavy clay (which is much easier with a shovel than a mattock), the next one might be stony, and the next one again hard as the hobs of Hell - that's when you wish you were using a mattock instead of a shovel - even with a mattock it is slow and sweaty going.

At the end of the day, we all piled back into our cars and returned to Benalla for showers and clean clothes, then met at the local high school hall to enjoy a meal, a glass of wine or three, and good company. After that the younger ones went off to a bush dance (Aussie folk dancing, I gather - not for us - we went to bed). And in the morning, up, a little stiff but not too sore, to do it all over again.

It might sound silly, but it was a really fun weekend. I'm just a smidgeon stiff tonight, but satisfied with my weekend's effort, and no doubt a little fitter than I was. I have no idea how many holes I dug, but I made every one a good one. Those tiny little trees have just three months before they have to face a summer without water, so they need all the help they can get.

And between us, on the weekend we planted 3,334 trees.

 

[Tannin]

It's quite astonishing how much the soil varies from one hole to the next. This one is soft and almost loamy, that one just a few metres away is heavy clay (which is much easier with a shovel than a mattock), the next one might be stony, and the next one again hard as the hobs of Hell.

I forgot to explain why this is. I was puzzled by it and asked the guy who leads the project. My thought was that perhaps this is the normal arrangement and I am just too used to digging in suburban gardens which have been turned ove a thousand times before, or up here in the Ballarat district which, like parts of California no doubt, was all turned upside-down during the Gold Rush. Nope. The explanation is far simpler than that: all the original topsoil is missing, washed off and blown away down the hill: we were digging in subsoil that, until quite recently, have been a couple of feet underground. Here there is an ancient drainage channel full of sand and stones, there a patch of soft topsoil from further up the hill, in-between just the hard, unyeilding clay.

On the way home we stopped to look at the Goulburn River. The Golburn is the biggest river in Victoria, and a major tributory to the Murray-Darling system. It has been dammed long since, of course, and Lake Eildon is one of the largest water storages in the country. Here is how it looked in 1962:

But with decreasing rainfall and the progressive soil degradation, there is less water flowing in now (cleared land makes poor catchment, you get less water and what there is has a high silt content), and more flowing out to provide water for the vast irragated area downstream. Here is that arm of Lake Eildon again - same place, but a recent photo:

Down on the flat, we drove through empty fields with odd-looking narrow paddocks. Why would anyone want to divide their land up into such long, narrow paddocks? After a while we realised what they were: they were once apple and pear orchards which, because of the rising salt levels and the ever decreasing availibility of water have been abandoned, the trees grubbed out and they are just used for grazing now. If the salt rises any higher they won't be much good for that either - grass is shallow-rooted but it won't survive in salty soil. We saw patches of Spiny Rush - the one thing that will grow in salt-damaged land. It's no good for anything, you can't eat it, stock can't eat it, and even the Spiny Rush can't survive if the salt gets too bad.

Then we crossed the Gouburn. Here it is:

Looks pretty enough. Now look a little harder: what month is it? August - the wettest month of the year, or as wet a month as you get anyway. See the Red Gums on the left- hand bank? See where they start - way up above the water-level? (The ones on the other bank are the same, of course, but hard to see in that picture.) River Red Gums grow right at the water's edge, quite often actually in it.

The small Wattle tree on my right (it's in bright yellow flower) is young, perhaps ten years old. It's growing in the actual riverbed. (Wattle trees don't grow in water: if the river ever returns to a normal winter flow, it will die.) Usually at this time of year, the only way to sit where I am would be to use an aqualung. But the river has been so low for so long that not only is the sand of the riverbed covered in grasses and weeds, that ten-year-old Wattle has had time to grow and get established. Here is a shot that might show this a little more graphically:

See the white mark on the depth-guage where it says "1974"? That was a flood, but you get the general idea. This dirty little brown stream is all that is left of the greatest river in Victoria. It's when you see the massive scale of the devestation that we have inflicted on this once-beautiful continent that you start to feel that 3000 trees is meaningless. It will take a hell of a lot more than that to make any significant difference, to even slow the rate of damage, let alone start to claw back some of the productivity and the beauty that we have so stupidly destroyed. But it's a start.

 

[Tannin]

Damn! Here is 1962 again.

And present.

 

[CougTek]

Blame it on the Europeans and the Chinese. They keep all the water for themselves, the bunch of Scrooge.

 

[jtr1962]

Tannin,

Thanks for some very interesting reading and the history lesson. It sounds like a fun way to spend a weekend to me, and you're helping the ecosystem besides.

Although I've never been to Oz, I know all about hard soils. Shortly after I got out of college, my mother and I got the idea to start a vegetable garden on the small plot of land that my parents' house it on. To give you an idea, the total size of this plot is 40' x 100', the front yard is about 20'x25', and the backyard about the same. We adopted a square foot gardening technique and reserved a piece of land of about 75 square feet for our garden. In order to properly prepare the plot, I had to remove all the grass, and properly prepare the first 18 inches of soil. After the first few shovelfuls, I knew it wasn't going to be easy. The soil here is mostly clay, and full of stones. It's no exaggeration to say I probably removed about two tons of stones from that small plot, including three that I need a car jack to get out. The largest(still in my yard as a decoration) is about 3 feet in diameter, more or less, and probably weights close to a ton. I remember wedging the jack in the hole, jacking one side of the boulder a few inches, putting soil under to keep it there, repeating on the other side, etc. It took a few hours to get the thing to ground level, and three of us could barely roll it to where it remains today. Makes me appreciate what the Egyptians went throught to build the pyramids.

Anyway, once the soil and large stones where removed, I filtered the soil through a 1/2 inch mesh to get out any smaller stones. I then added large quantities of compost, vermiculite, peat moss, and fertilizer. The whole process took a few weeks, and the garden has been a rousing success. Due to the limited space, we grow vining crops on a trellises I made with electrical conduits. About eight years ago, I replaced the brick border, which constantly shifted in the winter and let the grass in, with a concrete one. This coincided with a whole series of home improvements that my father made-new windows, new sidewalk and driveway, new roof, so I figured why not do something nice for the yard as well. I also extended the border around the entire backyard, set the garden path blocks in concrete so they wouldn't shift, and made a nice path on the side of the house with concrete blocks molded to look like a stone path(using one of those DIY plastic molds). Of course, I was stuck digging through our hard clay soil to make all these projects, but at least I know the concrete won't shift much since the soil is already very compacted.

This summer we've been making our own compost, and I'm getting started on a small portion of the front where some shrubs are. Two bins of compost(~20 cubic feet) were added to only about 20 square feet of hard clay soil, and I can tell much more digging and hard work is going to be needed.

 

[Groltz]

Tony, in direct counterpoint to your lengthy dissertation, let me simply offer this:

Cheers on participating in a noble cause.

--Steve K

 

[flagreen]

Well done Tannin! I can sympathise with your situation there in Oz. We have a terrible problem with salt water intrusion here in Florida. The water table has dropped considerably and consistently over the last 20 years to the point where saltwater has intruded and spoiled virtually all of the fresh water wells along the coast. The problem stems from not only excess demand but also from rain fall shortages. Reverse osmosis plants are under construction all over the state but the economics of desalinization aren't quite there yet. So most municipalities use a mixture of RO and natural fresh water reserves to keep the cost of water reasonable. In addition, all of the major urban areas now recycle their waste water for use in watering lawns which has helped. And of course water restrictions are in effect state wide now.

Twenty years from now I would imagine desal technology will have progressed to the point where it is cost effective so that 100% of the potable water used will come from the sea. I hope so anyway. Either that or that they are going to have stop folks from moving up north to Florida.

Bill

 

[Buck]

All of this work and no Mai Tais? phooey

 

[slo crostic]

Great post Tannin, and nice work too. It's good to see people being concerned about the environment, and actually doing something about it, rather than worrying about when their next pay rise is coming, or whether to holiday in the bahamas or the mediterranean next spring.
On the salinity issue, there is a plant commonly known as a salt bush which can be grown in areas of high salinity and be used as fodder. The orange farmers around Mildura have been experimenting with it for a few years now to try removing salt from the soil, but I haven't heard any more about it for quite a while. Just wondering if you have heard of this approach at all and if it is viable in your field, or if it is more useful in agriculture.
btw, who are these planting days organised by?

 

[flagreen]

Hmm... Tannin looks like great croc bait sitting on that bank!

 

[Pradeep]

Hmm... Tannin looks like great croc bait sitting on that bank!

Looks to me like is is pondering the foolishness of leaving the bog roll at home

Did you see any foxes whilst you were on your outing Tony? $10 bounty for each one now.

 

[Mercutio]

Lest anyone think Oz and Florida are the only places with water problems... Lake Michigan, the largest inland body of water in the USA, is down something like four feet from its normal crest.

And several states in the US were on draught water provisioning throughout the winter (ie, the time in most of the the US when there is supposed to be snow all over the place).

I can very easily see a future in which water is ration just about everywhere.


And to make things even more cheery for everyone, I was reading just a few days ago that some group of scientists decided that we passed the point where human beings are consuming more of the Earth's renewable resources than it can replace, about seven years ago - we're to the point where everything we do is living off the principle, instead of the interest.
Somehow I doubt that's a good thing.

 

[Buck]

I read that there is a group of scientists that expect another minor ice age in about 50 years. The last minor ice age lasted from 1300 to the 1850.

The New Ice Age
Worried about global warming? Talk to a few scientists at Woods Hole. Oceanographers there are seeing big trouble with the Gulf Stream, which warms both North America and Europe
By Brad Lemley

William Curry is a serious, sober climate scientist, not an art critic. But he has spent a lot of time perusing Emanuel Gottlieb Leutze's famous painting "George Washington Crossing the Delaware," which depicts a boatload of colonial American soldiers making their way to attack English and Hessian troops the day after Christmas in 1776. "Most people think these other guys in the boat are rowing, but they are actually pushing the ice away," says Curry, tapping his finger on a reproduction of the painting. Sure enough, the lead oarsman is bashing the frozen river with his boot. "I grew up in Philadelphia. The place in this painting is 30 minutes away by car. I can tell you, this kind of thing just doesn't happen anymore."

Full text of this article can be found in the current issue of Discover Magazine.

 

[flagreen]

As regards water only. I once heard that every drop of water ever placed upon the earth is still with us billions of years after it's arrival. It can be contaminated of course, but fortunately never "used up". Where the hell is it going to? Has to be elsewhere on earth.

 

[jtr1962]

As regards water only. I once heard that every drop of water ever placed upon the earth is still with us billions of years after it's arrival. It can be contaminated of course, but fortunately never "used up". Where the hell is it going to? Has to be elsewhere on earth.

That's not 100% true. There is a certain amount that goes into space, and the hotter the earth is, the greater the amount. Lighter gases, such as hydrogen, have long ago left the atmosphere except in trace amounts because the earth's gravity is too weak to hold them. The exact rate that a gas goes off into space depends upon its molecular weight, the planet's gravity, and its average molecular speed(or temperature in layman's terms). I don't remember the exact equation off hand, but if you're curious I'm sure you can find it somewhere on the Internet.

While we won't "run of out water" at any forseeable time, the only source of it soon may be desalination plants or atmospheric condensors, both currently very expensive means of extracting water.

The whole picture in Australia is really very depressing. I do hope they are able to reverse the damage inflicted by human habitation.

 

[Cliptin]

That's not 100% true. There is a certain amount that goes into space, and the hotter the earth is, the greater the amount. Lighter gases, such as hydrogen, have long ago left the atmosphere except in trace amounts because the earth's gravity is too weak to hold them.

mm-hmm. How much left? Why didn't you stop it? As any third grader knows, the equation for the gravitational pull between two bodies is

                                  G=m1m2
                                    -----
                                     r^2
             , where the ms are the masses of the two bodies and r is the distance between them.

I don't see temperature in the equation anywhere. Do you? Really only the weak hydrogen has been dragged out of the earth's atmosphere. We're now left with the beefier, stronger Hydrogen. And we're better for it.

PS. I never really get cranky so sometimes I have to fake it. Plus, I miss Helldiver. *sniff*

 

[Cliptin]

Tannin, I applaud your efforts at reforestation. If everyone would just do small things, things would be a lot better.

You might get into contact with the belgians. They seem to have been able to push back the sea with dikes and use the exposed land for farming. There had to be salt in that soil.

As a last resort, you could move to Italy. This country is having a current population implosion. In 2002, an average of 1.3 children were born to the statistically average woman in Italy.

In the late 1990s, Italy became the first society in world history with more people above the age of 60 than below the age of 20. This brings a whole new visual to PWs trips to the beach.

 

[Dozer]

In the late 1990s, Italy became the first society in world history with more people above the age of 60 than below the age of 20. This brings a whole new visual to PWs trips to the beach.

ROFL :lol:

 

[Cliptin]

                                  G=m1m2
                                    -----
                                     r^2
             , where the ms are the masses of the two bodies and r is the distance between them.

Oops, typed too fast. Should be:

                                  F=Gm1m2
                                    -----
                                     r^2
             , where the ms are the masses of the two bodies and r is the distance between them and G is the gravitational contant.

 

[Cliptin]

A little old (December 6, 2001) but relevant especially considering Austalia's history as recounted by Tannin (lots of tree and brush burning).

http://www.nsf.gov/od/lpa/news/press/01/pr01100.htm

 

[flagreen]

Clipton,

I don't know all that much about physics but wouldn't a gas get lighter (expands) as it gets warmer? And doesn't it's weight (density) determine it's mass? If so that would explain the phenomenon mentioned earlier.

Bill

 

[jtr1962]

                                  G=m1m2
                                    -----
                                     r^2
             , where the ms are the masses of the two bodies and r is the distance between them.

Oops, typed too fast. Should be:

                                  F=Gm1m2
                                    -----
                                     r^2
             , where the ms are the masses of the two bodies and r is the distance between them and G is the gravitational contant.

That equation is only part of it. Here's something I found related to the discussion at hand:

http://www.wikipedia.com/wiki/Boltzmann_distribution

The Maxwell-Boltzman equations determine the distribution of velocities that gas molecules have at a given temperature. In case you can't follow the equations, what they say is that at a given temperature, the molecules of a lighter gas move faster on average than the molecules of a heavier gas. Hydrogen is a very light gas(only one proton and one electron per atom), therefore its molecules move very fast compared to, say, oxygen. If a significant percentage of molecules move above the escape velocity of the planet, then they fly off into space. In the case of earth, this a ~25,000 mph at the surface, so if even a fairly tiny fraction of hydrogen molecules are moving faster than this, over millions of years nearly all of the hydrogen will have flown off into space. This also explains why a planet with a very low escape velocity, like the moon(~3600 mph), has no appreciable atmosphere. Mars isn't much larger than the moon, but since it is farther from the sun, and the gases in its atmosphere are therefore colder(and move slower), it has managed to hold onto a very thin atmosphere. Naturally, this discussion is irrelevant once a planet is cold enough that a gas liquifies. If the moon were at Pluto's distance from the sun, it would have retained all of its primordial atmosphere, only it would be in solid or liquid form. BTW, helium is the only element that doesn't freeze, period, even at absolute zero. It also exhibits some very strange behavoir at low temperature, including zero viscosity. It can therefore creep out of a flask in a very thin layer, and to the casual observer it looks like it goes through the walls of the flask.

 

[time]

That's great jtr1962, but Mars has a mass about an order of magnitude greater than Earth's moon.

 

[Fushigi]

To add to jtr's comments, atoms near the outer egde of our atmosphere are also affected by gravitational pull from the moon. Most planetary histories note that the moon has been responsible for skimming off the top of the atmosphere and that the diameter of our atmosphere is smaller than it was in the time following the earth's formation.

- Fushigi

 

[jtr1962]

That's great jtr1962, but Mars has a mass about an order of magnitude greater than Earth's moon.

That's true, but the diameter is also a bit larger. The escape velocity of a planet is proportional to the mass and inversely proportional to the radius. In fact, the equation is Vesc = (2 * G * M / r)1/2

Here's a table of planetary properties:

Note that the escape velocity for Mars is 5 km/sec, or 11,200 mph. Actually, the earlier figure I quoted for the moon of 3600 mph is incorrect. That was the circular orbital velocity. The escape velocity is 5324 mph. Since the escape velocity of Mars is more than double that of the moon, and it is colder to boot, it can retain a very thin atmosphere about equivalent to what exists on Earth at 100,000 feet.

Looking at the table, it is interesting to note that the atmosphere of Mars is nearly all CO2, a fairly heavy gas. All of the lighter gases long ago escaped into space. Also note that the four gas giants have very dense atmospheres composed mainly of the two lightest gases, hydrogen and helium, due to their very high escape velocities and very cold temperatures. The escape velocity of Jupiter is 60 km/sec(135,000 mph). Am I the only one who thinks it would be fun plunging into Jupiter's atmosphere in a well-shielded spacecraft? That would be the ultimate roller coaster ride.

 

[time]

That's true, but the diameter is also a bit larger.

Well, it's double, which is what I was trying to point out. You keep saying "a bit", making it sound like they're of similar size.

 

[Buck]

Tannin, those pictures you show look similar to the natural state of where I live, except you have more trees (yes, your barren forest is better populated then my natural surroundings). However, because I live in this place they call Southern California, everything has been manicured. We've arrogantly tapped into the Colorado river, channeled most of its water to our area so that it no long flows into the ocean, and turned our near-desert condition into a veritable Disneyland larger then most states in New England.

 

[jtr1962]

That's true, but the diameter is also a bit larger.

Well, it's double, which is what I was trying to point out. You keep saying "a bit", making it sound like they're of similar size.

Well, that's true. The thing is when I talk about astronomy I usually tend to use the words "a bit" unless one thing is larger than another by an order of magnitude. Two orders of magnitude is much larger, etc. This is because there is such a huge range of scale once you study the universe. Compare the distance to the moon to the distance to, alternately, Mars, Jupiter, Pluto, the nearest star, the center of our galaxy, the next galaxy, the nearest galactic cluster, the next group of galactic clusters, the closest quasars, and the farthest quasars. Kind of boggles the mind, doesn't it?

 

[time]

Our galaxy itself contains a hundred billion stars;
It's a hundred thousand light-years side to side;
It bulges in the middle sixteen thousand light-years thick,
But out by us it's just three thousand light-years wide.
We're thirty thousand light-years from Galactic Central Point,
We go 'round every two hundred million years;
And our galaxy itself is one of millions of billions
In this amazing and expanding universe.

I usually tend to use the words "a bit" unless one thing is larger than another by an order of magnitude.

Mars has a mass about an order of magnitude greater than Earth's moon.

Apologies to Tannin for hijacking such an excellent thread. Awesome words, pictures and deeds. :wink:

 

[Tea]

Our universe itself keeps on expanding and expanding,
In all of the directions it can whiz;
As fast as it can go, that's the speed of light, you know,
Twelve million miles a minute and that's the fastest speed there is.
So remember, when you're feeling very small and insecure,
How amazingly unlikely is your birth;
And pray that there's intelligent life somewhere out in space,
'Cause there's bugger all down here on Earth!

Eric Idle

I shouldn't think Tannin would mind, Time.

 

[Tea]

I was reading the Melbourne Age today. There was an article written by their economics editor - no raving greenie, a cold, hard numbers man. It had some truly astonishing figures in it, ones fit to make any rational man weep for the stupidity that drives this country ever deeper into self-destuction.

Did youi know that, on an average runoff per unit of surface area basis, Australia is six times dryer than the other continents? And if you discount the flow of rainwater into the Gulf of Carpenteria and seas nearby (i.e., the little bit up the top end where it's just jungle) then the figure is twelve times dryer than average. In addition, of course, Oz suffers from the ENSO climate cycle which makes our rainfall much less predictable than it is in other parts of the world. (All climates vary, the climates of Australia and Chille, sitting as they do on either side of the South Pacific and both being subject to the El Nino Southern Oscilation (ENSO), vary a lot more. Where most countries have very wet or very dry years from time to time, we get dry decades every so often.

But the thing that makes you cry with frustration is the incredibly stupid waste we carry on with. Fully ten percent of our usable water goes to growing, of all things, bloody cotton! Cotton from the upper Darling river system (up around the Queensland-New South Wales border) accounts for less than 0.1% of our GNP, and it uses 10% of our water. We don't need to grow cotton. There are any number of countries in the world who would be only too happy to sell us the little bit of cotton we need, or swap us for something that our country is good at producing, such as wheat, wool, barley, beef, dairy products, flax, hemp, oil seeds, apples, oranges, peaches, potatoes, corn, or timber - something that we could produce in any required quantity with a minimum of fuss and without buggering up our environment.

But we continue to provide one-tenth of our priceless water to a handful of greedy cotton growers in case they happen to vote against someone, and at a price such that the incredible amount of water that they waste costs them less than two percent of their total on-farm budget. We complain about not having enough water to avoid restrictions in the summer, and here we are, out in the middle of the desert growing bloody cotton!

(This is the normal vegetation of the area, sans irrigation - it lives somewhere on the borderline between marginal grazing land and desert.)

Meanwhile, the Darling is a tiny trickle of mud in a vast bed of once-fertile watercourse, the city of Adelaide has serious concerns about being able to provide sufficient tap water to its citizens (let alone decent quality water - for the pitiful trickle that runs down the Murray-Darling is insufficient to flush away the nutrients that run off farms and needs a good deal of treatment before you can safely drink it), and the Murray delta has silted up because the flow of water out of it is no longer strong enough to wash away the sand that the ocean tides bring in.

Rice is second only to cotton as a water waster, and is an equally stupid crop to try to grow on the most barren continent on earth. Rice uses seven percent of our water and contributes little to the nation. Like cotton it is something we could buy from any number of other nations, nations that are desperate to find some foreign exchange earnings and have water to burn. We could swap a Thailand or a Cuba three tons of wheat for each ton of rice they grow for us and not even notice that that smal amount of wheat was missing.

Rice growing uses almost as much water as the domestic consumption of the entire twenty million citizens of Australia. Cotton growing uses more water than it takes to flush every toilet and water every rose garden and wash every car in the country.

It's time our useless politicians stopped jumping up and down on the sidelines of a war in which we can and will play no significant part and which might not even be a war yet, and started doing something useful to justify their salaries.

 

[Prof.Wizard]

Hmm... Tannin looks like great croc bait sitting on that bank!

Mwahahahaahaha! Indeed...

Great work Tannin, I really enjoyed your photos/text.

 

[slo crostic]

Good post Tea! You're absolutely right to be annoyed about the massive amounts of water the cotton industry wastes but this is only a minor part of the whole cotton farming problem. The truth is cotton is an unsubstainable crop in many other ways too.

The following is a quote from this website.

Hemp vs. Cotton For Clothes & Textiles

"Hemp fiber bundles are up to fifteen feet long, while cotton fibers are a mere three-quarters of an inch, which reportedly gives hemp eight times the tensile strength and four times the durability of cotton. Hemp has a natural luster and takes dyes beautifully, due to its superior absorbency.

"Much of the groundwater tested in agricultural regions around the world has been contaminated by runoff from pesticides, herbicides and fertilizers. Already 15,000 lakes in the United States are so contaminated that nothing can live in them.

"The pesticide king is cotton. Cotton is adapted to a wide range of uses, and it spins easily, but the environmental costs of cotton cultivation are incalculable. Cotton is grown on 3% of the earths best arable land and uses a whopping 26% of the worlds pesticides. It is a demanding crop that requires heavy irrigation and consumes more than 7% of the fertilizer used annually. It exhausts the soil, but is widely grown by developing countries desperate for a cash crop to pay international debts.

"An acre of land will produce about 1000 pounds of primary hemp fiber, about 2 or 3 times more fiber than cotton. Fiber comes right off the plant ready to comb and use.

"With few insect enemies and little competition from weeds, hemp is a much better candidate than cotton to produce a high quality, sustainable and organcially grown fiber."


Why does anyone insist on still growing this wasteful crop when there is clearly a much better alternative? Is it just because of fear of the evil drug marijuana? Or is it due to the cotton/wool/paper tycoons greasing the palms of our politicians to protect their own interests?

 

[P5-133XL]

Why does anyone insist on still growing this wasteful crop when there is clearly a much better alternative? Is it just because of fear of the evil drug marijuana? Or is it due to the cotton/wool/paper tycoons greasing the palms of our politicians to protect their own interests?

People grow cotton because consumers demand cotton. If the manufactures could produce Hemp equivilents to cotton garments at a cheaper price then they would, because they make more money. Unfortunately hemp is not equivilent to cotton: Specificly in its ability not to wrinkle and its comfort: Long fibers differ than short fibres. Long fibre's feel hard and short fibres tend to feel soft. These characteristics make it much less desirable to the consumer that is concerned with comfort and not having to Iron their clothing.

This is not to say that one can't manipulate the hemp to make it more desirable as a commonly used fibre. However, it will be needed to manipulate it and thus the goes the profit margin as manipulation cost $$$.

 

[slo crostic]

Hemp fibre can produce garments as fine as silk with relatively small amounts of "manipulation". The many uses for hemp biproduct (oil, paper, stockfeed, plastics, high protein seeds, etc...) would more than offset the costs involved in processing the raw fibres. The hemp paper industry alone would help to cut greenhouse gases on a massive scale due to the ending of huge amounts of deforestation for wood pulp. An acre of hemp produces 4 times as much paper as an acre of trees, and all in a 12 week turnaround period.

It's time the world woke up to the virtues of hemp, our ancestors knew it, why can't we learn from them?

 

[Mercutio]

Anyone here ever seen Koyaanisqatsi or Powaqqatsi?

Possibly more the latter than former, both movies endevour to show the changes modern civilization has wrought on nature. Most of the images look almost unreal but at the same time utterly prosaic. I'm watching Koyaanisqatsi right now.

Beachgoers laying yards from a chemical plant (replace chemical plant with steel mill and you have Lake Michigan), desolate industrial complexes, a cityscape with cars as a circulatory system... and a movement from the natural valleys between mountains to the manmade centers of huge cities.

It's oddly enthralling.

 

[Cliptin]

... and a movement from the natural valleys between mountains to the manmade centers of huge cities.

...to the unnatural valleys between skyscrapers.

 

[Tannin]

You will be pleased to see, Slo, that my picture in the "what do we all look like" thread, features me wearing a 100% pure hemp tee-shirt.

http://www.storageforum.net/phpBB2/viewtopic.php?t=781&start=265

Unfortunately, the ironing lets me down a little.