Right as Rain: Part 2

Please feel free to ask questions or make any comments concerning the content of this program.
Peter is the only person ever to have 4 ABC Australian Stories and the previous 2 broke all records.

This tells us that Australians are interested in NSF and want to know more about it.

Our forum is your chance to do that. Some of those who know much about NSF may respond to your posts so please take part in this discussion.

Thanks for visiting us and be sure to join our mailing lists.

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Right as Rain: Part 2

Postby duane » Mon Jul 13, 2009 8:39 pm

Everybody knows my bias.

Right as Rain Part 2,was a great program, about a great Australian, whose brilliant insights into the unique efficiences of the Australian landscape will provide landscape and water solutions and a legacy to all Australians, now and into the future.

Well done to everyone at Australian Story!!

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Wheel re-invention

Postby RiparianMan » Mon Jul 13, 2009 10:19 pm

I've loved all the publicity re. gully/stream/river rehabilitation - but the simple truth is it's all been done before! Leaky weirs are just slightly dodgy bed control structures, the role of which has been well understood for many a long year. Funny how we just seem to need to endlessly re-invent things. I was working with landcare/rivercare groups in the mid-90s doing exactly this sort of work.

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Postby duane » Tue Jul 14, 2009 1:46 pm

Hi Rick

It would be good to inform the forum of the work you have/are doing in this area and to see where there might be similarities, differences and add to the body of knowledge about the unique features of Australia's hydrology.

IT WOULD BE GREAT to engage this forum.

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Postby RiparianMan » Tue Jul 14, 2009 4:59 pm

Hello Duane,
Working as a landcare co-ordinator on the mid-north coast of NSW from 1995 onwards I was involved with numerous projects dealing with the issue of river bed & bank erosion. I then went on to work for the old DLWC's Rivercare program. Channel bed lowering, & its impact on floodplain hydrology (not to mention bank erosion) was well understood. Many bed control structures were designed & trialled - with the specific aim of raising the bed level in degraded creeks etc. Some of the first of these were built in the Nambucca River in the early to mid 90s. Designs built from both rock (eg "rock ramps") & timber (eg timber V-weirs) were perfected in the following years - although with the demise of DLWC (& the old state-wide Rivercare program) much of this work seems to be have forgotten, or is being re-learnt by the current CMAs.

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Postby duane » Tue Jul 14, 2009 9:03 pm

Rick

Thank you for your reply. I am really interested to hear a lot more about this work that was done in those times and the comparisons with the present River Styles system many of the CMA's are using today.

I would love to hear about the methodology, the rationale used for placement of bed control structures, the proposed outcomes and the real outcomes, the attempted 'bio-mimicry' materials and methods used, the successes and the failures.

This would be am invaluable learning experience for everyone who visits this site.

I for one would value your experience and expertise.

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Postby duane » Wed Jul 15, 2009 2:38 pm

Both the recent second program on Australian Story, Right as Rain Part 2, and extended interviews are available to watch online at http://www.abc.net.au/austory/

I would love to hear some more feedback from people on what they thought of the two programs and what we should be doing to make it all happen.

People can also go online at the Aust Story Guestbook to read posts there as well as registering and posting any messages they may like.

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Australian Story feedback

Postby swampy » Thu Jul 16, 2009 4:34 pm

Congratulations to the ABC for presenting as best they could a balanced story on Natural Sequence Farming. It was unfortunate that the naysayers could not be coaxed onto the screen but following the full interviews with all participants it is pretty obvious where the disagreement with Peter's approaches and "establishment" lie. Those differences {the use of Willows for creek stabilisation and weeds for pasture improvement} need further debate.

Contrary to Tony Coote's observation that willows did not propagate on waterways on his land, the general observation travelling throughout Australia is that these are aggressive colonisers and have spread far wider than their original plantings. Blackberries are an enormous nuisance, tying up large tracts of bush where they have been allowed to grow unhindered. I do find it hard to accept that these plants should be part of a solution.

The sequence of transition that Tony suggested that willows make way for other more suitable species, like Casuarina is a very important theory that needs clarification. If it does happen then this may be acceptable. However, from my observations it doesn't. Willows just take over and dominate a stream once they have gained hold and rarely relinquish their stranglehold.

However, the idea of hydrating the land by slowing down the flow of water and using natural structures and vegetation to achieve this is a basically sensible idea. I have an idea which may be more compatible with the overall desire to re-hydrate but using vegetation that is more in harmony with the native landscape.

What about using vegetation that is native and does a good job of forming dense fibrous root systems that cope with some flooding, in particular bullrushes? These are native, low growing plants that thrive in wet conditions and leave some open water for fish-life to proliferate as well as water plants which do require sunlight. A dam could be constructed so that a wall within a wall would exist where the bullrushes are fed the first bit of water entering a pond in a low mound constructed around both margins of the pond.

This ring pool would receive the first amount of water to flow into a dam following a dry period and would help to keep the border of the pond moist throughout the year. Once sufficient water entered the pond, this boundary wall would be over-topped and the main pond filled from the edges in and not the single entry point of the in-flowing stream. The result would be a permanent ring of vegetation {bullrushes, melaleucas, casuarinas etc - native plant species and all naturally occupants of river systems in Australia}.

This wet edge would allow vegetation to continually grow on the margin of the pond, even though at times the centre may become completely dry. It is this vegetation that gives the pond wall its strength, along with soil that is only rarely over-topped.

Another thought is that most of the structures that are shown involve handling excess water by allowing it to rise above an engineered lip and then flow over the top and downstream. Whether this is through a "leaky" bed of rocks or a concrete wall it still means that once flows reach a certain level they go over the top and in doing so gather momentum as they tear over the wall and tumble into the next pond below. Sometimes they erode their way through the substance of the wall as well, destroying the pond.

What about as an alternative of making a submerged drain that has a graded inlet, covered in mesh and in turn covered in gravel - nature's perfect sieve. The drain could be V-shaped so that with low water levels a trickle goes down and as inflows increase, so does the width and depth of the drain which can hopefully handle a flood.

The outlet could be placed deeper in the downstream pond so that the agitation is reduced, preserving the structures there. The outlet could also travel away from the stream, fill up a side depression forming a shallow bog and wetland and from there water could trickle back down into the main stream. This way, over time the wetland so created is widening, further enhancing the effect of hydrating the whole flood-plain and not just the main channel.

The big problem with my idea is that in a flood it all gets over-topped and that is where the damage occurs. I guess I was hoping that the plumbing, being kept clear of choking vegetation by being behind a gravel sieve will never get blocked and as long as its dimensions are fine, would handle all but the most extreme inflows.

I would be interested to hear how this is received.
Peter Marsh

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Postby RiparianMan » Thu Jul 16, 2009 7:50 pm

Ok there is way too much going on here to cover it all properly, but here's some "rules of thumb":

Choosing vegetation for erosion control is a major issue. The idea of "tractive stess" needs to be considered. This is a simple concept - some types of vegetation/species have evolved to cope with the force of flood waters & some have not. Unfortunately many of the common riparian weed species, e.g. Blackberry, Lantana & Privet, can handle only low to moderate levels of tractive stress. Consequently, when these species come to colonise parts of the channel that experience high tractive stress loadings during floods they just wash out leaving bare, exposed banks. Weed control for channel stability should therefore focus on removing these weeds from erosion prone sections of channel first.

Bed control structure design always has to include consideration of any downstream scour that may be caused by the structure itself. There are computer models that help predict this - but it's really not that hard to work out. The higher the bed control the bigger the drop on the downstream side so the bigger the scour. Several small structures through a river reach are therefore much better than one large one because the scour problem is kept to a minimum.

I know of heaps of places where these structures were installed 10 or more years ago so if anyone has some $ to put on a field trip I'd be happy to make an itinerary!!!

Yeah, and by the way, the willow - casuarina vegetation succession thing is very suspect. Plenty of sites were planted with willows back in the 70s & guess what? Yep - they're still willow infected today.

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Postby duane » Sun Jul 19, 2009 6:19 pm

In Nature, in the Plant Kingdom there is a universal process known as 'plant succession'.

'Succession' also exists in the animal world......my thesis was on the succession of insects in the role of carrion decomposition.

Here is Prof Haikai Tane's post from another blog. Many ecologists seem to be totally unaware of this natural process of succession.

As a 'bidgee boy" from the sixties - many a happy holiday was spent wandering the river banks, swimming and snorkling the river pools and watching the platypus at play from up near Cooma down to Burrenjuck . It was during these years - when I was studying honours biogeography at the ANU - that my ecological studies of rivers and floodplains began.

I note from the "Bidgee Buzz" newspaper, undertones of anxiety about "exotics' in the river corridor. Research on riparian biota indicates there are proably greater grounds for concern about the phytotoxicity of Australian red river gums! Please be aware that the International Convention on Biodiversity specifically embraces all biota. Since the 1968 UNESCO international conference on "Use and Conservation of the Biosphere" in France, the UN position has remained unchanged:

"there is no fundamental difference between natural, wild or modified, sem-natural or developed, domesticated or purely artifical vegetations. The laws governing these ecosystems are identical"

When UN Agenda 21 was adopted by member states at Rio in 1992 - and subsequently became international law - the biodiversity concept was excluded from the key list of 27 principles defining sustainable development and environemtnal protection. Biodiversity is still only a convention because biologists have been unable to demonstate that there is a functional relationship between the Linnaen classification of species and environmental performance. It may come as a surprise to some that the Australian concept of native biodioversity is inconsistent with the international biodiversity convention. It is more about personal beliefs and conservation funding programs than the ecological integrity of watersheds and their environmental performance.

Peter Andrews has demonstrated clearly that the UNESCO position on vegetation, ecosystems and environmental performance is the safe and sound one. Aguably, willows are the world's premier riparian plants - they are used in every continent except Antarctica for riparian and stream restoration works. I have noted from my work in the River Murray, Billabong, "Bidgee and Shoalhaven watersheds that Australia willow communities are excellent nurse crops encouraging the natural regeneration of casuarinas as well as providing prime habitat for water dragons, marsupial water rats and platypus; and from beneath the water perspective, willow root plates are veritable supermarkets of macroinvertebrates, yabbies and fish.

Nature does nothing useleslly noted Socrates, a fact worth pointing out to readers in the Bidgee Buzz. You might also add that Nature is an equal opportunity employer - she does not discriminate on the basis of race, genera or species. That is a human failing. A few years ago, I was advised by the leaders of a German Parliamentary Delegation on Conservation and the Environment visiting New Zealand - while here they investigated "native biodiversity programs" - that in Germany they call native biodiversity "ecofascim" because it is based on the same nativist principles that underpinned Hitler's Fascism.

Now that Peter Andrews has shown Australians that exotics are indeed necessary for rehabilating Australian rivers and streams, as well as sustainable farming and ecoforestry, perhaps the Bidgee Buzz can take the lead and expose the "exotics are pests" mentality as a sadly misinformed ecocolonial myth doing more damage than good. It is far, far better to teach your community to observe and enjoy the exciting dance of ecosynthesis uniting native and exotic biota in new and improved riparian ecosystems.

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Postby duane » Sun Jul 19, 2009 7:40 pm

More scientific documentation on NSF.

This extract taken from the studies undertaken at Lake Cowell.
See http://www.lakecowalfoundation.org.au/i ... 0E6A55858F

Natural Sequence Farming
Home
Natural Sequence Farming (NSF) is an innovative technique that restores the functionality of riparian systems and their floodplains. The result is significant improvement in ecological and economic productivity. Seven landholders along Spring Creek are involved in ‘rehydrating’ 10km of Spring Creek, Lake Cowal.

Under the supervision of Peter Andrews, pioneer of NSF we commenced constructing the leaky weirs on the 23rd October 2006. Since this time all of the weirs were completed, an extensive revegetation programe is underway and two Masters students from the Australian National University (ANU) have done researon on this project.

In 2009, Nick Streeton from ANU, sponsored by the LCF completed his masters on the development of an upstream sediment budget for Spring Creek. This is an interview with him at the completion of this Masters.

The video clip is nearly 9 minutes long and contains valuable insights about the implementation and continued management of NSF principles on Spring Creek. The clip should only be played if the viewer has a broadband internet connection. If the clip "stops and starts", pause it, and wait for the download bar to progress before you click on the play button to resume viewing the clip. Click on the link to see video http://www.lakecowalfoundation.org.au/i ... 0E6A55858F

This next section can be seen in its entirety at http://www.lakecowalfoundation.org.au/i ... 46E520BEBD

Natural Sequence Farming - catalyst for riparian restoration in semi-arid Australia
Home / Our Projects / Major Projects / Natural Sequence Farming - catalyst for riparian restoration in semi-arid Australia
This project is a partnership between the Lake Cowal Foundation, Natural Sequence Farming Incorporated, Bland Shire Council and seven local landholders who own properties situated along “Spring Creek”, Lake Cowal.

Natural Sequence Farming (NSF) is a holistic land management initiative developed by Mr Peter Andrews in the Upper Hunter Valley in the 1970s that seeks to reintegrate stream flow and floodplain processes to sustainably drive production and nature conservation outcomes. A CSIRO expert panel commissioned by the Deputy Prime Minister, Hon John Anderson, reported favourably on the scientific basis and effectiveness of NSF (CSIRO 2002) and recommended that it be trialled in other land systems in Australia. Currently no trials are being conducted in the Australian semi-arid zone. It is now recognised that NSF recreates pre-European chain-of-ponds, swampy-meadow complexes (Andrews et al. 2005). This project will:

Trial the implementation of NSF in a typical incised, ephemeral and degraded stream (Spring Creek) in the semi-arid Lake Cowal catchment, 40 km northwest of West Wyalong, NSW;
Functionally reconnect Spring Creek and its floodplain by the cost-effective construction of 20 leaky weirs at stable choke points. The weirs will be constructed from rocks, logs and debris. Where necessary one or more additional side channels will be constructed to mimic pre-European multi-channelled floodplain (NB following a fresh flow, leaky weirs help to de-energize water movement, trap nutrients and sediment, facilitate floodplain recharge, create ponds that ameliorate salinity, drive vegetation succession and create an ongoing baseline flow as discharge from the recharged floodplain continues);
Manipulate plant succession using predominantly native grasses on the floodplain and a range of local provenance rushes, sedges and wetland plants in association with leaky weirs to optimise production and nature conservation outcomes;
Develop low cost monitoring strategies to assess changes in stream and floodplain health (e.g. carbon, salinity, ground cover, biomass, nutrient cycling and baseline flows);
Host field days to demonstrate the principles and benefits of NSF and encourage a better understanding of Australian landscape function.
Spring Creek (also known as Billy’s Lookout Creek) is a small stream originating on a skeletal ridge called Billy’s Lookout. It flows approximately 10km through cleared agricultural land before terminating in Lake Cowal. The methodology proposed includes the following activities:

Careful appraisal of stream suitability and potential, catchment area, mean annual flow, landuse, land degradation, geomorphology and soils;
Identification of critical choke points along Spring Creek through survey and search procedures;
Training of at least two landholders and one Lake Cowal Foundation staff in NSF practices;
- Negotiations with DIPNR, DEC, Fisheries and the Lachlan CMA to gain appropriate approvals for stream-related activities;
Installation of approximately 20 leaky weirs at selected choke points;
Construction of at least one additional floodplain channel to enhance recharge under fresh conditions;
Erection of approximately 20 km of fencing in sensitive areas to restrict livestock access;
When a fresh flow occurs that initiates partial or complete recharge, establishment of a seed bank of nursery plants that will enable rapid growth on the floodplain (grasses, shrubs, trees) and at choke-pool areas (reeds and rushes), including planting 10,000 local provenance native trees and shrubs concentrated in areas where native vegetation is currently absent and 100,000 wetland plants and native grasses.
Collect baseline data such as soil carbon, soil formation, ground cover, ground biomass, underground biomass, soil bacterial activity, water retention, water quality, oxygen levels, saline leakage and salinity levels;
Host field days to engage community in awareness of Australian landscapes and encourage adoption of NSF (and other sustainable land use practices).

In the longer term:

Record and monitor changes such as soil carbon, soil formation, ground cover, ground biomass, underground biomass, soil bacterial activity, water retention, water quality, oxygen levels, saline leakage and salinity levels;
Manipulate stock or equivalent to spread fertility over valley floor;
Implement adaptive management procedures based on scientific evidence to optimise outcomes; and
Host field days to engage community in awareness of Australian landscapes and encourage adoption of NSF (and other sustainable land use practices).
This project addresses multiple objectives of the NLP but is focusing primarily on repairing the hydrology of a dysfunctional landscape. It addresses a broad range of NRM issues and has significant beneficial implications for future landscape management. Some outcomes this project aims to achieve include:

Retention and storage of water in the catchment;
Reconnection of creek and floodplain ecosystems;
Protection and restoration of endangered landforms (the ‘chains-of-ponds’ and swampy meadows);
Improved water quality
Increased biodiversity;
Reduced erosion and loss of nutrients;
Reduced effects of dryland salinity;
Increased agricultural productivity; and
Increased knowledge and awareness in the local community of sustainable natural resource management procedures.
All of the factors described above will make a substantial contribution to ecosystem function that results in increased agricultural productivity and better economic and conservation outcomes. Communication of the information derived from understanding the connections and successional process occurring in the catchment will potentially have significant effects on our ability to manage our natural resources.

After gaining support from the relevant landholders we submitted an application for funding of $141 880 to the Natural Resource Innovation Grants 2005-06 (under the National Landcare Program) to undertake a Natural Sequence Farming project along Spring Creek. On the 8th February we received confirmation of funding approval from the Minister for Agriculture, Fisheries and Forestry, Peter McGauran for this project. Project partners include G & H West, P & V Barber, G & A Davies, C. Lee/J. Worner, H & B Mangelsdorf, M. Wilson, Lake Cowal Foundation, Bland Shire Council and Barrick Australia Limited.

Peter Andrews and landscape ecologists conducted site visits during March 2006 to undertake a careful appraisal of Spring Creek. A management plan has been developed and a section 3A approval has been issued by the Lachlan Catchment Management Authority (c/- Department of Natural Resources) in June. Approvals were also obtained from the Department of Lands, State Rail Authority and NSW Fisheries. Condobolin Rural Lands Protection Board was informed of the project although no projects works were undertaken on RLPB lands. All management have been signed by the participating landholders.

Under the supervision of Peter Andrews, pioneer of NSF we commenced constructing the leaky weirs on the 23rd October 2006. With assistance from the Bland Shire Council, the concrete structure was lowered and secured in place, and the series of leaky rock weirs were constructed.

The 15.7 km of fencing and the deep ripping were completed by April 2007. As part of the monitoring program, 42 piezometers were also installed so changes in the watertable can be readily monitored. These required individual licenses from the Department of Environment and Climate Change.

After a reasonable rainfall event in July 2007, 2,385 tubestock were planted with a further 681 for 2008, however the continued drought conditions prevented the planting of remaining 9,744 tubestock. There is still 19 km of direct seeding and 22,400 aquatic plants and native grasses to be planted when climatic conditions improve. Apart from the tree planting, the NSF project is now complete. Two major reports are being written about how the project was planned and implemented along with the monitoring methodology and baseline data which has been collected. These reports will provide valuable guidance to others wishing to undertake similar projects.

A Master of Environment research project is presently being developed in co-operation with ANU’s Professor Richard Greene and Landscape Function Analysis (LFA) practitioner David Tongway aimed at reviewing baseline data sets to assess the performance of the leaky weirs in relation to the condition of Spring Creek. The study investigated the development of an upstream sediment budget which could assist in calculating the total sediment budget from Spring Creek allowing determination of the effective lifespan of the leaky weir structures. An interview with Nick Streeton can be found by navigating to the section "University Students".

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Postby duane » Sun Jul 19, 2009 10:24 pm

Dr Michael Wilson is with the MDBC and did his PhD on willows and spent 16 years studying their effects on incised and eroded streams in Australia.

Here is a paper he presented to the NSF Workshop back in 2006.

Willows: weeds of retention

by
Dr Michael Wilson


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.
Outline
In this paper I synthesise findings from research conducted by my students and myself over the last decade. I utilize a simple diagram that compares three stream reach types: willow-lined, cleared and native vegetation-lined reaches. The diagram relates directly to the primary management strategy advocated under the Weed Management Guide for Willows prepared by the CRC Weed Management for established trees in farmland (available www.weeds.org.au/WoNS/willows). It is generally suggested that willow infestations be cleared and native seedlings (or seed) planted. Not withstanding the logistical and financial costs of this strategy, there is a wide-spread acceptance that removal of willows is beneficial per se and that even without replanting positive environmental outcomes have been achieved. This manifests, for example, when Catchment Management Authority (CMA) funding and key performance indicators are related to “kilometers of willows removed”.
Each parameter evaluated during our research has been measured directly within each of the three reach types or has been estimated based on literature and other research. Where the value presented is an estimate based on other people’s work a question mark (?) has been used. This does not necessarily imply that the estimated value is unknown, simply that the value was not directly estimated in the context of the particular research being presented. The methods used to evaluate the parameters are often complex and their documentation is beyond the scope of this paper. Much of the research has been documented in detail in theses and publications which are cited in the references. Similarly a literature review is beyond the scope of this paper and readers are directed to Wilson (2001) and Zukowski & Gawne (2006).

Sediment and organic matter retention
Aggradation (storage of sediment and organic matter) appears to be a key feature that distinguishes willow and native-vegetation lined streams (Figures 1 - 3, Wilson 1999, Wilson 2001, Boyer 2003). In central Victorian stream reaches there was an estimated 187t more sediment (Figure 1) and 30t more organic matter (Figure 2) stored per kilometre of stream in willow-lined reaches than those lined by native vegetation that regenerated following the 1850’s gold rush. All study reaches have been in a nature reserve for about 100 years and the native vegetation was multi-strata dominated by eucalypts, Acacia and Pomaderris with a grass, herb and fern groundcover. For reaches cleared of riparian vegetation I have assumed the amount of sediment and organic matter stored would be even lower (Figures 1 and 2) as there would be no vegetation control on material retention. For ‘reference’ reaches I am again making an assumption as there were no comparable reaches in the Ballarat district that had not been cleared in the gold rush or for forestry or agriculture.
A reference reach was assumed to contain complex native vegetation, a heavy load of large woody debris and a dynamic balance between sediment source from the landscape and stream power. Under these circumstances it was expected that the stream beds would store a substantial amount of sediment and organic matter. Evidence for this assumption comes from observations made by geologists and others in the gold rush (discussed in detail in Wilson 2001). For example Howitt (1857) wrote that in Sailors, Wombat and Spring creeks
“The old ground has been worked so often that vast quantities of sludge have accumulated in many places; and when sometime back a flood carried away much of the sludge and tailings, and opened new courses, the miners took advantage of the changes thus effected and worked the lower stratum, which was found to contain a great deal of gold”.
I studied these exact same reaches and 150 years after Howitt made the above observations, all channels except those lined by willows are bedrock and boulder dominated (Figures 3a and b). In the non-willow reaches there was an average of only 5cm of finer sediment and organic matter overlying the bedrock. Gold fossickers still visit these creeks and are able to pan these small accumulations very quickly and there is no possibility of floods revealing a ‘lower stratum’ as described by Howitt (1857). So I contend that the reaches that now appear as in Figure 3b were so deep with in-fill sediment that they were worked by miners in two separate phases. The stone walls built up by the miners to affect this work are still visible above the current bed level in native-lined streams, but are below the bed level in willow lined reaches. They would have been constructed below the pre-gold rush sediment levels to hold back bank sediments during works. (Interestingly, I believe Heritage Victoria recently suspended willow removal work in Spring Cr due to destruction of these gold rush stone walls).

Figure 1. Sediment storage per km of stream length estimated for willow-lined, native vegetation-lined, cleared and reference streams in the Ballarat district, central Victoria. Adapted from Wilson (1999)
Figure 2. Organic matter (OM) storage per km of stream length estimated for willow-lined, native vegetation-lined, cleared and reference streams in the Ballarat district, central Victoria. Adapted from Wilson (1999)


Figure 3. Willow-lined (a) and native vegetation-lined (b) reaches in adjacent catchments with nearly identical gold rush(1850’s) disturbance history, geology and current catchment land-use. Both reaches are in the same nature-reserve (Wilson 2001). a) Willow channel infill with surface stream channel now ‘perched’ on 40 cm of aggraded sediment stabilized by willow roots b) Incised and bedrock-boulder dominated native vegetation-lined channel.
I conclude that willow-mediated aggradation in these channels is converting them from incised channels (Figure 3b) to in-fill channels (Figure 3a) that are more characteristic of pre-European conditions. This conversion has occurred in 40 years (the time since local willow colonisation) and there is no evidence that after 100 years native vegetation protected in a nature reserve can achieve the same conversion. I am not suggesting that willows be planted in nature reserves to achieve this aim, I am simply stating that if eucalypt-Acacia dominated native vegetation lacks transformative power in a nature reserve then in urban and agricultural landscapes it alone will not mediate conversion of incised channels to in-fill channels.
Willow removal, even if followed by planting of tube-stock eucalypts and Acacias has the potential to release hundreds of tons of sediment and tens of tons of organic matter per kilometre as the material trapped by willow roots is released as they breakdown. If the sediments, organic matter (and the nutrients such as phosphorus contained with in them) can cause harm to downstream ecosystems then their capture by willows is beneficial. If the sediments that are captured are restoring channel morphology to something akin to reference condition then this is beneficial. If the sediments are sourced from ‘leaky’ agricultural and urban catchments, then their capture and long-term stabilisation where they are needed (in-filling incised channels for example) is more beneficial than their continued journey downstream to where they might cause harm (for example by contributing to siltation, sand-slugs or reservoir eutrophication).

Litterfall
Willows and eucalypt-Acacia dominated native vegetation contributed the same amount of litter to streams in Central Victoria. The values are in the range documented for upland streams flowing through native vegetation in south-eastern Australia (see Wilson 2001 for references). The timing of litterfall is very seasonal in both vegetation types. Native vegetation exhibited a strong seasonal pattern with 50% of litter falling in summer. Willow riparian vegetation was less dominated by a single season with 40% of annual litterfall in both summer and autumn (Table 1). Depending on season a greater or lesser amount of willow leaves will fall in summer as drought can cause willow leaf drop. The key point is that both native vegetation and willows yield a pulse of litter through summer and autumn.

Figure 5. Annual total litterfall, excluding large woody debris (diameter >10cm) for willow-lined, native vegetation-lined and cleared streams in the Ballarat district, central Victoria. Adapted from Wilson (2001), mean ± SE.

It is often argued that native vegetation supplies a sustained supply of litter throughout the year whereas willows drop all their litter in autumn. This seems logical as there are leaves present throughout the year in the evergreen native forests. However, empirical data shows a much more complex pattern (Table 1). There was a four-fold difference between the seasons of maximum and minimum litterfall in native vegetation, and an eight-fold difference in willows. In native vegetation, autumn, winter and spring each contributed 20% or less of the total. In willows two seasons contributed about 40% each, one season 20% and one 5%. So it is not reasonable to say that willows drop all their litter in autumn, rather they supply a sustained amount of litter over summer and autumn, the same amount of litter as native vegetation in spring and half the amount in winter.
The annual weight of leaves, twigs, bark and flowers was very similar at the willow and native sites. Leaves constituted 41-58% of the dry weight of litter at all sites, but were least important at all but one site (10-21%). The exception was at a site with a dense Tea-tree and Bottlebrush understorey where leaves constituted 46% of the winter litter. Twigs dominated winter litter at all other sites and were the next largest component of annual totals (16-25%). Bark, flowers, capsules and leaf scales constituted between 1-19% of annual totals, with flowers and leaf-scales sometimes quite important in spring (particularly spring catkin fall from a member of the Salix cinerea complex).
The story of litterfall in willow stands is far more complex than that portrayed by typical weed fact sheets and willow management plans. An analysis of litterfall literature in Australia shows that the seasonal pattern at willow sites was similar to that observed in an Australian cool temperate Nothofagus forest (Turnbull and Madden 1983) and wet sclerophyll forests (Ashton 1975). The willow and native sites had similar proportions of non-leaf litter (42-59% of the annual total at all sites, Wilson, 2001), which is a recognised characteristic of Australasian warm temperate forests (Bray and Gorham 1964, Campbell et al. 1992). As expected there were strong contrasts in the litterfall pattern in native vegetation with understoreys dominated by tea-tree-bottlebrush compared to Acacia-Pomaderris. In winter these contrasts were far greater than the contrast between willows and natives.

Daily litterfall (% annual total)
Spring Summer Autumn Winter
Mean native 20 51 16 12
Mean willow 19 37 41 5

Table 1. Seasonal pattern of litter fall as percentage of total litter falling in each season for five stream reaches characterized by native (n=3) or willow (n=2) riparian vegetation communities in the Ballarat district, central Victoria. Adapted from Wilson (2001).

Why is litter important? The main reason is an energetic one – the majority of the energy driving aquatic ecosystems in shaded streams comes from litter. So everything from the microbes, the invertebrates, the fish and the platypus are ultimately dependent on the litter. In the next section I look at some work we have done on stream energetics.
Community Metabolism
There are many parameters that can be used to describe the energetics of a stream but I chose community metabolism which is a single over-arching measure of the total photosynthetic and total respiratory activity of every living organism in the study reach. The ratio of photosynthesis to respiration is called the P/R ratio. When this ratio is above one (>1) it tells you that the stream is producing more organic matter from photosynthesis than it is using up in respiration i.e. it is a ‘producer’ (or autotrophic) stream. A ratio less than one (<1) tells you that the stream is using up more energy in respiration than it is producing in photosynthesis i.e. it is a ‘consumer’ (or heterotrophic) stream. A consumer stream gets the extra energy required from litterfall and other external sources (e.g. organic matter in run-off and soil water flowing into the stream) though these are typically small in relation to litterfall.
Our results are consistent with common sense. A willow canopy and a native canopy both shade the stream and this limits photosynthesis, resulting in ‘consumer’ reaches under both canopies. In Figure 6 this is indicated by P/R ratios of 0.2 in both these types. As shown earlier the willow and native canopies deliver a similar annual total of litter to the stream and both heavily shade the stream in the seasons of maximum productivity so the overall energetics are very similar. Heavily shaded, heterotrophic streams would have been the norm for the study streams prior to catchment clearing for gold, forestry and agriculture.

Figure 6. Photosynthesis to respiration ratio (P/R) for willow-lined, native vegetation-lined and cleared streams in the Ballarat district, central Victoria. Adapted from Major (2001) and Wilson (2001).
Reaches with no canopy are radically different. There was enough light reaching the stream to increase photosynthesis 10-fold. The consequence for overall stream energetics was that open reaches had P/R ratios of 0.6. The reaches with a canopy were strongly heterotrophic but those without a canopy become weakly heterotrophic. Clearing of a canopy regardless of whether it is willow or native results in a fundamental shift in energetics towards autotrophy. This is commonly seen with large strands of filamentous green algae in cleared reaches. Flow-on effects of this energetic shift would be expected through the whole ecosystem but have not been studied in relation to willow clearing. However, we have done some work on macroinvertebrates and fish habitat that are reported in the next section.

Invertebrates and Fish
Chandramali Jayawardana completed her PhD studies last year where she looked at macroinvertebrates in willow, Phragmites, tea-tree/bottlebrush and bare bank habitats (in a fully replicated spatial design across all seasons where all habitats were present in each site, sites were nested within rivers and rivers were replicated). She has published a couple of papers comparing willows, Phragmites and bare banks (Jayawardana et al 2006a, 2006b), but her overall conclusions come from her thesis. She showed that the willow and Phragmites habitats had similar macroinvertebrate assemblages and were richer than the bare bank and tea-tree/bottlebrush habitats. During winter high flows the differences between the two rich habitats and the two poor habitats were even greater, suggesting that the complex root mats of willows and the dense stands of Phragmites were important habitats for macroinvertebrates under high flows.
Minal Khan (2004) completed a PhD in 2004, investigating fish communities in streams of the Ballarat district. She focused on River Blackfish (Gadopsis marmaratus), a nocturnal ambush predator, which remain the dominate species in Birch Creek – a regionally significant population of this vulnerable species. In various studies Minal found that undercut banks constituted 4-19% of the available habitat, but 60-70% (Khan 2004a and 2004b) of Blackfish used these as day time refuges. Virtually all these undercut banks were below willows.
In an effort to better understand these undercut banks Paul Jaskerniac (2003) completed a Third Year major project, describing their form. He showed that they had an overhanging cover of sediment and organic matter reinforced by dense willow roots (Figure 8). There was a willow rootlet fringe that was characteristically pink in spring. But the big surprise was the abundance of deep complex ‘tunnels’ up to 1.84m deep running perpendicular to the stream bank. The tunnel entrances were up to 20cm in diameter. Platypus are also known to be associated with willows in the Shoalhaven River, NSW (Tom Grant, University of NSW pers com Oct 2006). The complex physical structure of willow lined banks appears to be suitable habitat.


a b
Figure 8. Cross section (a) and plan view (b) of tunnels and overhangs under willows in Birches Cr that are the dominant day-time refuge for River Blackfish. Adapted from Jaskerniac (2003).

Interestingly the literature shows that in low disturbance streams River Blackfish are strongly associated with debris dams and large wood in the stream (ie large woody debris). In agricultural streams, where there was almost no large woody debris, River Blackfish were associated with undercut banks. This suggests that there is some breadth in their habitat requirements and that willow undercuts can be valuable in the absence of large woody debris.
We studied the volume of large woody debris per area of channel under replicate willow-lined and native-lined channels. There was a greater load of large woody debris in native vegetation-lined streams than willow-lined streams (Figure 9). The data were from streams where the willows had been present for about 40 years, with gold rush clearing and channel stripping and then domestic grazing preceding the willows. The native vegetation was about 100 years old having colonised following the gold rush. We would predict that loads at a cleared site would decline to zero, as there would be no new supply of wood. We would expect a site with no gold rush or other clearing to have much higher loads than those found in streams under 100 year old forests; after all 100 years is middle-aged for many eucalypts and limb fall and senescence may be more common in older eucalypts. So under 40 y old willows there was a load half that under 100 y old native forests, which we presume was a much smaller load than under centuries-old native forests.

Figure 9. The volume of large woody debris (all pieces of wood with a diameter > 10cm) per square metre of channel in willow-lined and native vegetation-lined streams in the Ballarat district, central Victoria. Also the presumed load for cleared and ‘reference’ streams (i.e. those undisturbed by post-European catchment or riparian clearing). Adapted from Cameron (2000) and Wilson (2001). Mean ± standard error.
Pool-Riffle Sequences
Pool-riffle sequences, like large woody debris and undercut banks, are important habitats for aquatic organisms. The relatively still pools contrast with the turbulent flowing riffles and the alternating pattern of these two habitats is considered a healthy attribute of many upland streams. In 2003, Julie Boyer undertook her honours research on the pool-riffle sequences along the Yarrowee River and Jim Crow Creek in the Ballarat district. She mapped the vegetation types along tens of kilometres of these streams and then mapped the pools, riffles and runs in each reach. By matching the vegetation type to the stream habitat type she could explore their association (e.g Table 2 from the Yarrowee River).

Vegetation type
Willow Native Grassland
% total stream length 76 20 4
% total habitat length associated with each vegetation type
Pool 91 7 2
Riffle 91 6.5 2.5
Run 60 33 7

Table 2. The associated between pools, riffles and runs associated with three riparian vegetation types; willow, native vegetation (eucalypt-Acacia dominated) and grassland (exotic pasture dominated) along the Yarrowee River, Ballarat (Boyer 2003)
The key point is that there was a disproportionately large association between pool-riffle sequences and willows. Native vegetation and grasslands together lined 25% of the stream but were associated with only 10% of the pool-riffle sequences. The association was statistically significant (G-test P<0.001, Boyer 2003). An association between two things does not always mean that one thing caused the other. So Julie undertook a second study to survey the stream bed to see what channel features were associated with the pools (Figure 10). Virtually every pool studied was formed by a debris weir at the downstream end. By laser survey, Julie showed that the weirs rose above the surrounding channel bed height, forming a pool. Excavation and probing of the weirs showed them to be constructed of debris and sediment armoured by willow root maps. A fallen branch or piece of large wood was sometimes a major component of the weir and the root mat and sediment accumulated and cemented the wood in place.
The Yarrowee River receives the bulk of Ballarat’s storm water (from a population of approximately 80 000) and the hydrological conditions in the channel are extreme. Yet under these conditions, willow-armoured weirs were creating beneficial habitat patches. This is entirely consistent with our other findings on sediment and organic matter retention discussed earlier.
This research is compelling and carefully documented evidence that supports some observations by Peter Andrews (2006). He states that plants are fundamental to repairing the degraded landscapes he is concerned with, even when the plants are considered weeds. He pays particular attention to willows in terms of channel-floodplain restoration. Our research simply places observations of landscape self-repair in a scientific context, and there should be no surprise that these observations match those of a practitioner of landscape repair. The ‘leaky weirs’ advocated for use in channel-floodplain restoration by Natural Sequence Farming (Andrews 2006) appear to have much in common with the weirs created by willows in the Yarrowee River and Jim Crow Creek. Julie Boyer’s research was motivated because pool-riffle sequences are extremely valuable habitat and on that basis alone it is worthwhile. But it becomes even more valuable when it can contribute to ideas focused on restoring the whole of the floodplain complex in agricultural landscapes.

Figure 10. Longitudinal cross section of a 140m reach of the Yarrowee River, Ballarat showing a pool-riffle sequence. The arrows indicate debris weirs, R = riffle. Note the vertical exaggeration, both axes are in metres (Boyer 2004).

Conclusions

Willows are clearly powerful ecosystem engineers. They are not the same as native plants, just as native plants are not the same amongst themselves and conclusive differences can be shown between reaches lined by willows and those lined by native vegetation. However, the fact that they are different is a completely different issue as to whether they cause harm. I believe that the presence of willows along streams in agricultural zones can be shown to be almost universally preferable to cleared streams in those zones. I would also suggest that even relatively low-disturbance eucalypt-Acacia dominated riparian vegetation may not have compelling benefits over willows under many circumstances. Willow invasion of pristine, rare or clearly self-repairing native ecosystems can be dealt with through well-accepted bush regeneration techniques.
However, our current willow management strategies advocate clearing willow-lined streams. The evidence presented in this paper suggests that would be catastrophic. It is possible that clearing willows makes room for planting of native trees and shrubs, but I can foresee no other immediate or even medium term benefits. In all the streams we have studied, clearing will mobilise sediment, nutrients and organic matter, will make heterotrophic streams more autotrophic, will threatening habitat values for invertebrates and fish and will threaten pool-riffle sequences. Native vegetation planted where willows are cleared will take many decades if not hundreds of years to mature, for the canopy to recluse and for significant limb fall to occur.
Figure 11. A diagrammatic representation of succession (the solid arrow) that is demonstrably preferably to willow clearing and revegetation.
Clearly a better way is needed and that is succession (Figure 11). There is no need to clear willows – I contend that it is the absence of complex vegetation across our landscape that is the problem, not the presence of willows. Willows can be left to continue to restore the channel and we can plant a native forest (or whatever species mix is required for production, aesthetic and habitat values) next to and under the willows. Willows are intolerant of shade and will be displaced over time. This is observable already in old stands. It is immediately implemented under current funding arrangements for riparian fencing and restoration.

-------------------------------------------------------------------------------------
Peter Hazell and Duane Norris, Proceedings of the first Natural Sequence Farming Workshop, Natural Sequence Farming- Defining the Science and the Practice, held at Bungendore, NSW, Australia on the 31st October and 1st November 2006, SRCMA. Page 1*Dr Michael Wilson, Research conducted whilst at the Centre for Environmental Management, University of Ballarat
Current address: Murray-Darling Basin Commission, PO Box 409, Canberra, ACT 2601, michael.wilson@mdbc.gov.au





References
Andrews, P. (2006) Back from the Brink. ABC Books, Sydney.
Ashton, D. H. (1975) Studies of litter in Eucalyptus regnans forests. Aust. J. Bot. 23, 413-433.
Boyer, J. (2003) Willow Influence on Aquatic Habitat in the Yarrowee River, Ballarat.Unpublished Honours thesis, University of Ballarat, Ballarat.
Bray, J. R. and Gorham, E. (1964) Litter production in forests of the world. Adv. Ecol. Res. 2, 101-157.
Cameron, H. (2000) Large Woody Debris in Willow and Native Vegetation Lined Streams. Unpublished Third Year Project Report, University of Ballarat, Ballarat.
Campbell, I. C., James, K. R., Hart, B. T. and Devereaux, A. (1992) Allochthonous coarse particulate organic matter in forest and pasture reaches of two south-eastern Australian streams. I. Litter accession. Freshwater Biology 27, 341-352.
Howitt, W. (1857) Land, Labour, and Gold, or Two Years in Victoria. Publisher unlisted, London.
Jaskerniac, P. (2002) Structure and Stability of Burrow Network within the Willow (Salix fragilis var fragilis) Root-mat as Habitat Sites for River Blackfish (Gadopsis marmoratus Richardson). Unpublished Third Year Project Report, University of Ballarat, Ballarat.
Jayawardana, et al (2006a) Macroinvertebrate communities in willow (Salix spp.) and reed beds (Phragmites australis) in central Victorian streams in Australia. Marine and Freshwater Research 57, 429-439.
Jayawardana, et al (2006b) Macroinvertebrate communities in Phragmites australis (Cav.) Trin. ex Steud. reedbeds and open bank habitats in central Victorian streams in Australia. Hydrobiologia 568, 169-185.
Khan, M (2004) Unpublished PhD thesis, University of Ballarat, Ballarat.
Khan, M. T., Khan, T.A. and Wilson, M.E. (2004a) Habitat use and movement of river blackfish (Gadopsis marmoratus R.) in a highly modified Victorian stream, Australia. Ecology of Freshwater Fish 13, 1-9.
Khan, M. T., Khan, T.A. and Wilson, M.E. (2004b) Movement and use of added hollows by River Blackfish Gadopsis marmoratus R. in an agricultural catchment stream. Victorian Naturalist 121(6), 244-253.
Major, P. (2001) Impacts of Riparian Clearing on Community Metabolism within a Victorian Upland Stream. Unpublished Honours thesis, University of Ballarat, Ballarat.
Turnbull, C. R. A. and Madden, J. L. (1983) Relationship of litterfall to basal area and climatic variables in cool temperate forests of southern Tasmania. Aust. J. Ecol. 8, 425-431.
Wilson, M. E. (2001) Organic Matter Dynamics in Willow and Eucalypt Lined Central Victorian Streams. Unpublished PhD thesis, University of Ballarat, Ballarat.
Wilson, M. E. (1999) Post gold rush stream regeneration: implications for managing exotic and native vegetation. In: Rutherfurd I. and Bartley, R. (eds) Proceedings of the Second Australian Stream Management Conference, Adelaide. Vol. 2: 725-730.
Zukowski, S. and Gawne, B. (2006) Potential Effects of Willow (Salix spp.) removal on Freshwater Ecosystem Dynamics: a Literature Review. Report prepared for North East Catchment Management Authority, Murray-Darling Freshwater Research Centre.

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Postby webmaster » Sun Jul 19, 2009 11:06 pm

Here is the actual document referred to in the post above.

Dr M Williams - Willows
The Forum for Peter Andrew's Natural Sequence Farming

RiparianMan
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Death by information overload

Postby RiparianMan » Mon Jul 20, 2009 7:41 pm

Very interesting to see where this discussion is going.

"Many ecologists seem to be totally unaware of this natural process of succession" - Duane, are you really sure about that statement?!!!

Willows - yep, many of the CMAs etc do have rather simplistic programs that involve the wholesale removal of willows with little consideration of the overall impact. Willows can significantly alter geomorphic processes & combining River Styles type assessments prior to developing Willow removal programs is a good idea.

I watched that Lake Cowal video - life is strange isn't it? Funny how good old basic stream/gully incision & the various bed control methods that are available to deal with this issue have suddenly become labeled "NSF" & trumpeted as groundbreaking & new. There's absolutely nothing new about this sort of work. New, maybe, to the current cohort of interested parties, but, frankly, these issues have been well understood for many, many years. Winding the clock back to "year zero" was Pol Pot's angle during the disastrous Cambodian Khemer Rouge years - let's not do that here in Australia with respect to stream management!

Shirley Henderson
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work, work, work

Postby Shirley Henderson » Tue Jul 21, 2009 9:48 am

Hello Rick, I have had a look at your website and it seems that you do a very good job. I also love being paid to restore, regenerate or recreate functioning riparian corridors. It is paid work however and the scale and state of Australian waterways does not have the skilled man power or the funds to cover it. Even if the funds were avaiable do you think that it would be allocated to such a task as no one can even agree on the correct action to take. Quote from your website: Without active management, it is not unusual for riparian areas to become completely dominated by exotic vegetation. End quote.
I often say when a bird drinks nectar to survive or feed it's young, do you think the bird cares if the plant is native or introduced? A barren landscape without vegetation maintains none or very little life. Any plant that can provide shade, shelter, breeding ground, warmth, structure, organic matter and life to the soil has to be a welcome relief from nothing. A place for growth beginning and a chance for restoration. All this happens for free.

RiparianMan
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Postby RiparianMan » Tue Jul 21, 2009 8:58 pm

Hi Shirley,
Mt Annan eh? What a fantastic place to live.
Yep - there seems to be endless argument about what is the "correct" action to take with respect to developing & implementing riparian rehabilitation projects. There are many reasons for this - one of which is the way that most of the "professional" government staff are on short term contracts. Consequently, we (as a society) continuously "leak" knowledge & experience.
With regard to the weed thing - sure, I am not a wholesale weed "Nazi". There is a case for accepting that in some catchments/sub-catchments etc. the weed battle is lost. It's all about the BIG CAPITAL "P" - PRIORITISATION! The River Styles method helps here with respect to geomorphology i.e. in a structural sense, is this creek/river reach recoverable? As far as weed control goes, it gets far more complicated. The idea of "environmental triage" is helpful here. Some areas are just not worth the rehabilitation effort in terms of weed control. Accept that they are altered, weed-infested systems & live with it (& yes, they will always provide habitat for something). But other areas are worth rehabilitating - including preventing weeds taking over. I sit here now, having just come in from a day working on the Lower Ovens in NE Vic. - & this is definitely a river reach that is worth every effort to keep weed free because the effort required is not great but the consequence of inaction would be huge (as demonstrated by the few areas that have been neglected).
With regard to the bird habitat - yes this must be factored in. On the project I have just finished we removed Hawthorn & Blackberry but replaced them with local native plants that provided similar structural habitat i.e. compact, spiky shrubs (Tree Violet & Hedge Wattle).
Thanks for your comments/feedback Shirley & keep up the good work looking after that mountain! (PS I love the Botanical Gdns!)


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