Willows: weeds of retention

Summary Removal is the dominant strategy advocated and implemented by management authorities when confronted by willows, the majority of which are Weeds of National Significance. There is much discussion and debate over possible effects of willow removal on stream ecosystems. In this paper I present research that demonstrates that a cleared reach has significantly worse ecosystem benefits than either a willow lined or mature native vegetation lined stream. The only benefit of removing willows, other than where vegetation of any type would be removed for infrastructure protection, is that native trees and shrubs are easily planted. This does not compensate for the potential negative consequences of clearing. In the streams we have studied, clearing will mobilise sediment, nutrients and organic matter, will make heterotrophic streams more autotrophic, will threaten habitat values for invertebrates and fish and will threaten pool-riffle sequences. There is a better way to manage willows; succession. Existing stands can be retained and native vegetation (or whichever species mix is preferred) can be planted alongside and under the willows. The shade intolerant willows will be out-competed over time. This strategy can be immediately implemented, as current funding and vegetation establishment techniques are suitable. The fact that a stream ecologist and a farmer (Peter Andrews, Natural Sequence Farming) have independently arrived at the same conclusion in relation to willows is noteworthy. A good understanding of the ecological values associated with retention of materials, energy and nutrients in streams would compliment hydrological studies in Natural Sequence Farming systems and help shift public policy and perceptions away from simplistic approaches to weeds.

bluegreen said:

Willows: weeds of retention

Summary Removal is the dominant strategy advocated and implemented by management authorities when confronted by willows, the majority of which are Weeds of National Significance. There is much discussion and debate over possible effects of willow removal on stream ecosystems. In this paper I present research that demonstrates that a cleared reach has significantly worse ecosystem benefits than either a willow lined or mature native vegetation lined stream. The only benefit of removing willows, other than where vegetation of any type would be removed for infrastructure protection, is that native trees and shrubs are easily planted. This does not compensate for the potential negative consequences of clearing. In the streams we have studied, clearing will mobilise sediment, nutrients and organic matter, will make heterotrophic streams more autotrophic, will threaten habitat values for invertebrates and fish and will threaten pool-riffle sequences. There is a better way to manage willows; succession. Existing stands can be retained and native vegetation (or whichever species mix is preferred) can be planted alongside and under the willows. The shade intolerant willows will be out-competed over time. This strategy can be immediately implemented, as current funding and vegetation establishment techniques are suitable. The fact that a stream ecologist and a farmer (Peter Andrews, Natural Sequence Farming) have independently arrived at the same conclusion in relation to willows is noteworthy. A good understanding of the ecological values associated with retention of materials, energy and nutrients in streams would compliment hydrological studies in Natural Sequence Farming systems and help shift public policy and perceptions away from simplistic approaches to weeds.

This is a subject close to myself as I have been regenerating the banks of willow lined irrigation canals. I’ll show some hpoto’s but they’ll have to wait until a week or so as I’ll be away this week and my car will be in dock next week but I’ll try to get some photos together to discuss this.

Firstly though I will agree that natives(ie; Red Gum) may eventually outstrip willows but I will disagree that they can be planted under the willow. Meanwhile, such intricate transplanting work requires hand work and hand watering maintenance for the first few months at the least and possibly for the first two years. The pace of such work is slow, meanwhile the willows are continuing on spreading themselves. To achieve this theory it would require massive work for the dole type projects and would give all unemployed a chance of a job yet still wouldn’t move quickly enough.

it would be good to hear your input roughbarked, being on the “cutting edge” so to speak. I see two polarised views emerging these days. The traditional one of weed eradication, and a new one emerging that says use them, don’t kill them.

In my childhood home there was a willow by the creek that ran alongside our block. Every year my father would go down and cut away thick mats of roots that had encroached into the creek to allow it to continue to run freely. I don’t remember there ever being seedlings from it. Now the whole creek has been piped (it was in suburbia) so there is no relevant ecology at all now.

Thanks. I was going to keep mine anyway LOL!

Two points raised bluegreen..

roots and seedlings willows don’t make seedlings as often as they make cuttings

their roots clog the stream.. they also drain the stream outside its banks and the roots themselves choke out possible competing plants.

These things aren’t always necessarily bad nor good.. they unfold and lock up as they do with the power of whatever water flows down the stream or not.

weeds are native somewhere.. they are only weeds where we don’t want them.

and this is the fact we should focus upon.

Driving to Melbourne I came upon a patch where I was heard to say; “Poplars should be next on the weeds list by the looks of that.”

the title of this thread is a misnomer.. you cannot keep your willows.. you must either remove them or plant natives to out compete them.
Nurseries are no longer allowed to supply them.

ie: if there is a possible chance that willows will escape. Then efforts should be made to prevent that happening.

Has anyone seen the cricket bat willow plantation?

What gets me is, Australia has it’s own native trees with droopy habits, that have evolved to sustain waterholes, billabongs etc…they look just as stunning and, to my mind, more attractive than the “English” willows…but what would I know, I was born in Australia and have never been to England…

Dinetta said:

What gets me is, Australia has it’s own native trees with droopy habits, that have evolved to sustain waterholes, billabongs etc…they look just as stunning and, to my mind, more attractive than the “English” willows…but what would I know, I was born in Australia and have never been to England…

Yes you are absolutely correct.

two willows may be useful.. basket willow or cricket bat willow.

the rest of them are useless as trees., in Australia.

Mind.. one would say .. on a hot day that a wllow provides shade. Maybe also one may say the colour green may be a sight for sore eyes in our dehydrating climate.

There are many Australian natives that easily may replace the introduced trees.

My philosophy is still the same after a lifetime of cultivatin trees for all purposes.. yes including willows., is this: If you can’t eat it, if it isn’t there for a useful purpose then it should be a native plant. ie: We could make asprin out of all the willows as we harvest them. We could farm them for such a purpose but planting them near any watercourse however dry it looks is not only a wasteful usage it is an environmental calamity.