The War on Willows

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Shirley Henderson
Posts: 356
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Location: Thirlmere

Re: The War on Willows

Postby Shirley Henderson » Wed Dec 15, 2010 9:48 am

Image

This picture shows the ferns surrounding the base of the privet. We have had a lot of rain through here recently and I mean a lot! I am surprised that these bush regenerators chose to remove the Privet and their stabilising roots, especially during these extreme rain events.
Live and learn I suppose this is not my area but I will be watching with interest what happens next.
Last edited by Shirley Henderson on Thu Dec 16, 2010 6:49 am, edited 2 times in total.

sceptic
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Re: The War on Willows

Postby sceptic » Wed Dec 15, 2010 10:50 am

Well, this is all quite interesting, in response to Shirley's question, some links you might find interesting (which say pretty much what I have been saying):

http://tasfish.com/index.php?option=com ... Itemid=115

Alterations of typical pool-riffle sequences in rivers is another feature of willow impacts. As the dense mats of willow roots and even the trees themselves invade shallow riffles, the altered flow may result in the surface flow between pools to decrease, even become disconnected. Needless to say such invasions in to rivers may limit access and cause danger to boaters on the water.

Typical native riparian vegetation is evergreen, shedding old or dead foliage throughout the year. In contrast, the willow is deciduous loosing all of its leaves in autumn, gaining them again in spring. The implications are higher autumn and spring water temperatures for rivers impacted by willows due to the lack of shading (DWMS) which can alter algae / lichen (epilithon) biomass on the riverbed (Read, 99).

High nutrient loads on the riverbed caused by leaf litter can lead to an increased oxygen demand as the leaves breakdown leading to decreased water quality. Reduced surface water flows across riffles can also reduce the amount of re-oxygenation occurring. As willows impinge into the river channels and trap sediments, sand and gravel beds, the depth (capacity) of the river channel decreases, increasing its propensity to flooding. As the river capacity decreases, normal flows as well as any additional flows (e.g. floods) are diverted to the banks and cause erosion in an attempt to widen the river and compensate for decreased capacity (previously in the form of depth).

As any fisherman will testify, where there is one willow there is likely to be a hundred. This feature is referred to as a “monoculture” where a single species spreads and dominates, and obviously for ecological biodiversity this is extremely bad. The willow tree monoculture is detrimental to surrounding flora and fauna biodiversity eventually creating an area where nothing but willows grow (Meander Valley Weed Strategy).

Impacts on River and Riparian Ecology

Large woody debris is important in our rivers for shelter, spawning sites and as a source of food items etc. An example of the importance of woody debris is to the native Tasmanian blackfish (Gadopsis marmoratus) that relies of LWD for shelter and as a spawning site. (The blackfish lays its eggs in the hollows of logs (IFS pamphlet)). Whilst there is no doubt that the willow contributes woody debris to river ecosystems, the quality of willow LWD is inferior ( different in form, texture and longevity (DWMS)) to the quality of the LWD of native vegetation. Numbers of native species such as the blackfish that relies on appropriate LWD for spawning and the Giant Freshwater Lobster (Astacopsis gouldi) that feeds on decaying wood would therefore likely be detrimentally affected by willow tree invasion. The monoculture of willow trees along riverbanks and riparian areas leads to dense canopy’s and sparse under-stories due to shading. This leads to the suppression of most native species which through the food chain may effect the whole food web.

A small unpublished Rivercare study in the North Esk Catchment noted a lower diversity of birdlife compared with native sites demonstrating the effect of willow monoculture upon the foodchain. As noted by the DWMS, willow trees do not develop hollows suitable for native bird or mammal shelter.



http://www.weeds.org.au/WoNS/willows/do ... _Sect1.pdf

and some interesting work on large woody debris
http://www.hcr.cma.nsw.gov.au/uploads/r ... 032007.pdf
The truth is out there.

ghosta
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Re: The War on Willows

Postby ghosta » Wed Dec 15, 2010 11:00 am

duane wrote:Ghosta in reply to your query
you havent explained what changed to make certain willows a problem.


Try this:
It is invasive.
It spreads too quickly
It's residue fails to break down.
Its a monoculture.
It's killing ALL of our catchments.
It prevents biodiversity from growing beneath it.
It takes more water out of our waterway systems than native plants
And the landscape condition has deteriorated SO much that the area and the job willows have to cover has increasingly got bigger.

All reasons for putting it on the WONS list.


Well some of the reasons you have given are correct. But its not "It's killing ALL of our catchments." And the statement " the landscape condition has deteriorated SO much that the area and the job willows have to cover has increasingly got bigger" is certainly questionable given that other plants can and will be doing this job in future.

The thing that HAS changed is the widespread use of hybrid willows from the 1980s on.
from http://www.aabr.org.au/index.php?option ... &Itemid=74

"Generally, willow seed is very small, very short-lived (2-4 days), produced in massive quantities over several weeks, highly fertile, capable of dispersal over very large distances by wind, and very specific about the characteristics of a suitable seed bed. This means that usually most seeds do not survive but, when conditions are suitable, hundreds of thousands of seedlings can establish.

As willow seed is very short-lived, all of the early introductions of willows were made as cuttings or pot plants. This meant that most of the plants of any species, or at least the plantings at any one site, were derived from one or very few individuals. As willows are mostly either male or female this has meant that most of the clones were unisexual and plantings rarely produced seed or seedlings. Seed was only possible from hybridisation of two different species where the correct sexes were present; the flowering times overlapped; and the trees were closer than about 3-500 metres, (about the maximum effective distance for the pollinating insects.) The sparcity of plantings, other than massed single-clone plantings, and the lack of overlap of flowering times for the different species has meant that seeds were hardly ever formed.

Over the years more species and cultivars have been introduced. Some of these cultivars were hybrids between other species, often very rare. If such hybrids are planted, and either or both parent species are around, they can overcome the problems of non-overlapping flowering times, and also reduce the inter-species fertility barriers. There is now an increased opportunity for fertile and viable seed to be formed. As trees aged, the longer they tended to flower and the more likely that overlaps occurred. All such situations have occurred and there are now areas where there has been mass colonisation by seedling willows. Although these are, so far, usually serious to the 1ocal area only Salix cinerea, (a Pussy Willow), has proven to be a serious problem over large areas to date. It is a serious problem in Victoria, becoming a problem in southern N.S.W., but we now also have a population producing seeds around Sydney."

The dilema for followers of NSF is that willows can be used sucessfully to achieve the aims of the landowner, often with no effect that is seen as detrimental to him/her. The fact that willows dont provide much habitat for native species may be completely irrelevent, as an example.

Willow spread may be completely under control at present due to the lack of suitable cross pollinating stock. But there is certainly no guarentee that it will remain this way, all it would take is for a neighbour to plant a willow of a differnt sex or variety which allows cross pollination and the someone is likely to have a problem...it may or may not be you.

Governmet authorities have chosen to act to minimise the chances of this happening and to fix existing problems.

Fortunately there are other species of plant that can do the job that willows can do- perhaps not as easily, but taking "problem" willows out of the NSF toolbox does not mean the end of this approach to farming. In my view NSF advocates should not be at war with authorities, rather they should be demanding some of the funding be used to find the most suitable alternative species for their particular situation.

Shirley Henderson
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Re: The War on Willows

Postby Shirley Henderson » Wed Dec 15, 2010 11:13 am

Image
I saw these willows accross the road from the reserve I was photographing so decided to go over and have a look around them. Note that there are many trees and shrubs surrounding the Willows as well.

Ps Ghosta, I have read most of what has been written on willows but pursue new ways of thinking, using and accepting our introduced plant to the benefit of us, the wildlife and the country. Willows are one of the best for waterways that there is. I could go on forever quoting everyone elses work (might I add quoting others work as your own is illegal also).. You seem to think that we do not read, or research or find out why Willows are so disliked. I look for myself and find that it has just become a legal malarkey of a lot of people that are well intentioned but do not understand the implications of the long term removal of Willows and the benefits that could be had by keeping them. I am aware and have stated many times on this site that Weeping Willow is not on the noxious weed list so this is not "New" information. Read the whole site and you will find this argument raised time and time again. Think through the answers that have arisen and the opportunities to be had. Many of us here have tried to discuss with you the benefits of not categorising plants as good and bad but understanding them better. We have tried to answer your questions fully and along the way we have posed quite a few to you that you do not reply to. Take some time out and think things over. Kind regards

Shirley

Shirley Henderson
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Location: Thirlmere

Re: The War on Willows

Postby Shirley Henderson » Wed Dec 15, 2010 11:17 am

Image
Now hasn't there been a statement somewhere along the line that nothing will grown under Willows. This is surely good habitat. Now I know where I would rather be on a hot day.

Shirley Henderson
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Re: The War on Willows

Postby Shirley Henderson » Wed Dec 15, 2010 11:22 am

Image
Ahaa! What this? Causarinas growing from seed. Coming up from underneath the willows! :D

Shirley Henderson
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Re: The War on Willows

Postby Shirley Henderson » Wed Dec 15, 2010 11:25 am

Image

and in the water.....Native wetland plants (Persicaria) amongst a soup of organisms. Some like it hot..some like it cool! 8)

Shirley Henderson
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Re: The War on Willows

Postby Shirley Henderson » Wed Dec 15, 2010 11:30 am

Image
This one may be a bit hard to distinguish but if you look to the left of the picture you will see a Casuarina growing out through, over and above the Willow. The casuarina is filling the complete height in the photo. The willow is now underneath it! :o

ghosta
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Re: The War on Willows

Postby ghosta » Wed Dec 15, 2010 12:10 pm

Thank for posting the photos Shirley. It will be interesting to see if the casurina actually does shade out and kill the willow beneath it (in your last photo). It would be worthwhile knowing if the sucession idea actually works, and if it does which species do it the most effectively.

Interesting that the "well read" posters who have adopted a pro willow stance did not mention the importance of hybrids and seeding in their "replies" to the questions I posed.
Perhaps the concepts are not well recognised by the ordinary man in the street; having an environmental science background I'll admit I sometimes make the mistake of thinking that such matters are commonly understood by everyone. Thats certainly not any attempt putting anyone down; people learn different things according to their trade and life experiences.

Shirley Henderson
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Location: Thirlmere

Re: The War on Willows

Postby Shirley Henderson » Wed Dec 15, 2010 12:33 pm

Yes Ghosta, I will be following this little plot a long to see how it goes. I will keep things posted as time goes on.
Others too. I am very interested in the subject of plants and the life they support.
ps I am also a hoticulturalist and understand the hybridisation of willows.
As and environmental scientist I am sure you would be open to the idea that laws and present theories are open to change if the human race is to evolve.
Last edited by Shirley Henderson on Thu Dec 16, 2010 6:58 am, edited 1 time in total.

Shirley Henderson
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Re: The War on Willows

Postby Shirley Henderson » Wed Dec 15, 2010 1:06 pm

Image

Please click on the photograph to see a short slide show on weeds as habitat. :mrgreen:

duane
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Re: The War on Willows

Postby duane » Wed Dec 15, 2010 8:50 pm

Its simply a matter of doing a search on the internet or reading some of the publictions put out by authorities urging control of willows.
Perhaps the defenders of willows posting here dont want to know the reasons, or dont want the reasons outlined here.
said Ghosta.

Let's see if anyone here on this thread has read the paper I alluded to earlier on in this thread. The paper has been written by Dr Michael Wilson, an emminent scientist and willows expert.

No one has commented, I believe, on the balance Dr Wilson's paper brings to this debate. Is that because no one has read it? or because no one wants to refer to it?

My challenge is to all those sceptics out there to give us their summary on the work presented in that paper.

Dr Michael Wilson's paper WIllows - viewtopic.php?f=1&t=831&start=15

ghosta
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Re: The War on Willows

Postby ghosta » Thu Dec 16, 2010 8:05 am

There are not a lot of "sceptics" about willow removal posting here so perhaps thats one reason why the response has been limited, but to be fair Shirley has taken on board the sucession concept with her keen observation (and photo) of succession happening.

Dr Wilsons paper is a little short on detail and its difficult to know how to interperet some aspects of his work in a more general sense.

He does not state what method of willow removal was adopted, one would expect differences if the willows were poisoned compared to bringing in a bulldozer or excavator to rip the willows out by their roots.

The species of willow he studied has not been identified. This is important- the fact that the willows have been there for over 40 years tends to indicate they are not the more vigorous hybrid species which are actively seeding and spreading. The reason for willow removal has not been identified, we know the area studied is a reserve, he may be removing weeping willows or cloned same sex species.

But his studies do identify the potential consequences of willow removal, and hence the need to exercise care when planning a removal project. Options other than mechanical removal need to be considered.

He raises the idea of sucession by underplanting as an option, but other than saying "This is observable already in old stands" he has not attempted to research this further in this paper. We are not sure what is actually being observed, is it the vigourous growth of underplanted species and the wilows have been supressed and will eventually die, or have they been killed quickly outright? Would this technique be usefull with the more vigorous hybrid species which already outcompete native vegetation and it would be expected that etablishment of underplants would be difficult. Also this concept ignores the implications of cross breding and seeding; if it takes 20 years to kill the willows but during this time further areas have been infested, perhaps hundreds of metres away then his conclusion "Clearly a better way is needed and that is succession" is simply not valid in the absence of evidence.

Nor is their any inducation of the success rate, it would be useful to know if this technique could be developed to the degree that it has a 100% sucess rate, and obviously more research is needed.

But I do believe he is has identified a tool worth persuing. In suitable willow species and where they are of the same sex, underplanting may be the first step. This is followed up by an assesment of the effectiveness of the operation with followup plantings for maintenance. Where underplanting is unsucessfull, then other techniques (poinsoning,mechanical removal etc) may be needed to complete the job, but such a program would have benefits to the enviroment generally, over some alternative techniques.

It would mean a change in community expectations ie the willows would take years to remove, and also a change of thinking for funding authorities. There is a tendency for grants to be made avaiable for specific tasks and a short timeframe for spending this money, and the reason a grant has been made may be supported by some particular political motive which is present only for a short period.

Jodi James
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Location: Avon West Australia

Re: The War on Willows

Postby Jodi James » Thu Dec 16, 2010 11:38 am

Thanks Shirley,

Great Pic....Wake up Australia, we should be promoting all plants, we need green stuff! Green stuff makes Rain! who cares about weeds, they grow to repair the soil, they only grow because the soil is unbalanced....most of the time its because the calcium to magnesium ratio is unbalanced.

Perhaps they should do some longterm research in what fertiliser is doing to our soils, put the weeds on the backburner for a bit. We want Green carbon! Living Pumps, who cares what species they are. It's better than erosion and dead landscapes. If it grows there then let it grow! God created it for a reason, we all spend our lives killing everything, instead of promoting green stuff!

It will take years to have trees grow to the size the willows are. Let them be! at least they are using up Co2 and making carbon. Carbon isn't that what everyone is crowing about at the moment? The next big gravy train of the century, who can make the most money out of that new enterprise! another monsanto?
Open mindedness opens wisdom

Jodi James
Posts: 23
Joined: Sun Aug 19, 2007 1:36 pm
Location: Avon West Australia

Re: The War on Willows

Postby Jodi James » Thu Dec 16, 2010 12:00 pm

What a load of claptrap,


It is invasive.
It spreads too quickly
It's residue fails to break down.
Its a monoculture.
It's killing ALL of our catchments.
It prevents biodiversity from growing beneath it.
It takes more water out of our waterway systems than native plants
And the landscape condition has deteriorated SO much that the area and the job willows have to cover has increasingly got bigger.

All reasons for putting it on the WONS list.


Get off your backside and get out of your office and go look! There is Biodiversity growing beneath,invasive, look at your gum tree species,I would call them more invasive. Willows only grow there to fix the soil, when somehing else grows beneath they will eventually die out anyway. Maybe you should consider eucalyptus on your WONS list, they are a threat to mandkind, a major fire fuel danger., and a soil killer

Shirley fantastic! let them eat humble pie!

They all grew quite well together before we came and ruined the planet.

I would rather look at that beautiful piqturesqe landscape than some of the plantations mankind are trying to put together. How can they get nature right?
too many people playing god.
Open mindedness opens wisdom


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