Removing willow for water Thursday, 02 December 2010 CSIRO Weeping willows lining the banks of the Murray River near Mannum, South Australia Image: Tanya Doody, CSIRO Removing willows growing in the stream bed of creeks and rivers could return valuable water resources to river systems, new CSIRO research has found. A CSIRO study into the water use of willows found more than five and a half megalitres of water could potentially be saved annually per hectare of willow canopy area removed, where trees were in-stream with permanent access to water. “One megalitre is one million litres – the volume of water used by three average households in a year. So the evaporative loss of one hectare of willows is enough for about 17 households each year,” says project leader, Tanya Doody. https://www.sciencealert.com.au/news/20100212-21650.html
“However, if the net overall benefit of willow removal from creeks and streams is to be properly evaluated, the various other benefits and disadvantages of removal must also be understood and included in decision making,” Ms Doody said. Well, that is a relief... how much do willows stop evaporation from open streams as compared to the evapotranspiration they contribute to? How much do they add to the small water cycle slowing water and storing it in the local environment rather than rushing its way further downstream? How much soil will be lost in their removal and what preventions will be taken to stop other such deemed weeds taking advantage of the open sunlight? Are there advantages of stockfeed in the willows, and could money be spent on better overall management and a more longterm, successive approach?
Tanya should do more for society and remove herself from the debate. They could of course suspend plastic screens over the rivers and creeks to shade the water - am effective use for petrochemically based products?
Why is the usual knee-jerk reaction always all-or-nothing? Why not consider balance for a change? I know it's not politically correct, but... If the willows draw up the water and transpire it into the atmosphere, and the moisture is dumped into the sea via rainfall, it isn't doing the soil much good, is it? Trees have historically been used to drain swamps. In some places, the shading of the area by the trees is a moot point, since the water is hidden underground, but willows can still find it. If the removal of the trees causes erosion of the land and destruction of the water source, that's not of much benefit, either. If surface water is subject to massive surface evaporation, maybe replacing the willows with a plant that is less of a water hog could be an advantage. Or deepening pools so the water collects there, offering less surface area to evaporation. Thinking and taking in the whole picture isn't against the law... yet. Sue
Hmmm, let the willows use it so they protect the stream and increase the chances of downwind precipitation or let it run through to be used in the nearest major city to water lawns and wash cars and driveways. Decisions, decisions...
There's also the problem of trying to grow natives in open ground if you remove the willows first. Best to leave the willows there until the native trees are large and an alternative ecosystem is established. Personally I think willows along rivers are an asset, especially in the hot dry barren because we favour grass in stead of trees place that I live in. You need a bloody good reason to chop down a willow. Peter Andrews, Hakai Tane and others are doing lots of work showing how valuable willows are in restoring landscapes. I doubt that willows are a problem in most places if you are working holistically with the whole land*. I haven't seen the research yet, but there are people saying that willows hold water in the ground and are therefore a much better proposition than bare land or in some cases bare land that's trying to grow natives. I'd like to see the CSIRO research itself, to see how they actually measured the water and why they came to the conclusions they did. *If on the other hand you want to pull lots of water out of the ground for inefficient above ground irrigation schemes and you consequently find you don't have enough water in your rivers I can see how demonising willows as the problem might make one feel less scared about the water situation.
I'm sure I'm on a couple of lists of the sort David Holmgren was running a campaign about willows down in Victoria in regard to Spring Creek, some references here: https://www.holmgren.com.au/frameset.html?https://www.holmgren.com.au/html/OurPlace/ourplace.html He's also got an interesting book review on the status of weeds: https://www.holmgren.com.au/DLFiles/PDFs/InvasionBiolReview.pdf
Oh this topic makes me so sad and so angry. I went on a camping trip a couple of years ago to Wee Jasper, which is south west of Canberra, ACT, Australia. For as far as the eye could see in some places, were the charred stumps of willows lining the river beds. Nothing else lived, except brown grass and dirty hungry sheep. The senseless destruction was so depressing I found myself crying often as we drove through it. Attending a course with Darren Doherty a few months ago, he showed us an example at a very exposed place in a river at Bedigo. On one side of the river, was a river red gum. Its roots were very exposed, there was no soil around them at all. It certainly did nothing to hold the river bank together. Directly opposite was a weeping willow. The river bank was fully in tact, the roots were not exposed. I took pictures to prove it. Slowing the water down with willows is a tremendously beneficial thing to do.
At Mulloon Creek Natural Farms, we did a walk down the creek, where they are using Peter Andrews' methods to rehab the creek zones. One of the "leaky weirs" had a stand of willows either side, to prevent erosion when the creek overflowed the weir. Casuarinas were starting to push the willows out and survive, where, earlier experiments with the casuarinas on their own, had failed miserably. So in this case, the dreaded willows were acting as the nurse species for the natives. The stupidity of some people in this (and other) areas, makes you believe that their mothers must have been the most patient, sainted women on earth, because it would've taken them weeks to teach their dumbass kids to suck!
https://www.csiro.au/news/Water-savings-from-willow-removal.html Ms Doody will be presenting the results of her research at a seminar at the Christian Laboratory, CSIRO Black Mountain, Canberra, on Friday 3 December at 2:30pm (with afternoon tea beginning at 2pm). Not a lot of angst about (yet another) lapse in biosecurity either:- https://www.csiro.au/resources/Willow-sawfly.html
Am I the only one who saw this passage in the link you provided, MA? (My emphasis) "However, in New Zealand N. oligospilus has caused severe damage to willow plantings used for river bank stabilisation to a point where authorities are investigating resistant varieties or use of alternative species.: Them damn Kiwis are stealing a march on us (environmentally), again!
Confirmatory bias? Well of course they know which side their bread’s buttered, and won’t bite the hand that feeds them (hmm, getting peckish … ).
https://www.aabr.org.au/index.php?o...ia&catid=94:seminarconference-notes&Itemid=74 The bark is an excellent, anti inflammatory herbal remedy
The environmental and economic sustainability of potential bioethanol from willow in the UK Stephenson A.L., Dupree P., Scott S.A., Dennis J.S. Bioresource Technology 2010 101:24 (9612-9623) In vitro anti-proliferative effects of the willow bark extract STW 33-I Bonaterra G.A., Kelber O., Weiser D., Metz J., Kinscherf R. Arzneimittel-Forschung/Drug Research 2010 60:6 (330-335)
i like willows they hold the banks together they reinforce my gabions they supplament my livestock in times of drought the best murray cod are caught near willows