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Thursday, 19 August 2021 10:09

Wetland restoration under the microscope

Restored wetlands on private farms deliver ecosystem services and increase diversity, with varied results, a recent study has found. Shannon Bentley, a master’s student at Victoria University and the first recipient of a Wetland Care Scholarship funded by Ducks Unlimited NZ, is studying how wetland restoration on farms changes plant, soil, and microbial characteristics. In 2018-2019, as a part of the research group, Wetlands for People and Place, she sampled 18 privately restored wetlands and paired unrestored wetlands on farms in the Wairarapa.

For her master’s thesis, she analysed the wetland plant communities, soil physiochemical characteristics, and soil microbial communities to understand how they change with restoration. She found that wetland restoration on private property shifts plant, soil, and microbial characteristics towards desirable remnant wetland conditions. She also showed that the outcomes of wetland restoration varied within and between wetlands.

More than 40 per cent of New Zealand is held in private ownership, and private property holds huge potential for wetland restoration, containing 259,000km of stream length (Daigneault, Eppink, & Lee, 2017). Additionally, wetland degradation is extensive in lowland environments which are primarily in private ownership.

The outcomes of wetland restoration undertaken by landowners’ own prerogatives are poorly tracked. Private restoration is driven by personal preferences and finances, so the extent and form of restoration are varied. For example, the 18 wetlands sampled in Shannon’s study were restored in many different contexts and using many different techniques.

Wetlands differed in time since initial restoration (6 months to 42 years ago), size (0.4ha to 33.7ha), upstream watershed area (4ha to 2,263ha), dominant plant community (woody v herbaceous), and the number of restoration techniques used (2 to 8).Wetland restoration is beneficial for a number of reasons, but particularly for regaining wetland ecosystem services and increasing native biodiversity. Ecosystem services are ecological processes and functions that have beneficial outcomes for humans.

Compared with all other ecosystems, wetlands produce the highest levels of ecosystem services per unit area. This high production of ecosystem services is due to wetlands’ unique biology and geology resulting from their position at the interface of water and land. Wetlands are particularly effective at producing the ecosystem services of water purification, flood abatement and climate regulation through carbon sequestration.

Shannon found that with restoration, soils regained wetland traits, providing more ecosystem services. The restored soils had higher carbon content, lower bulk density, and lower plant-available phosphorous. Increased soil carbon content shows the carbon sequestration potential of soil expands with restoration.

Additionally, reduced plant-available phosphorous indicates restored wetlands can take up phosphorous and improve downstream water quality.

And finally, with increased carbon and reduced bulk density, water moves through the wetland soils slower to reduce peak flood heights.

Shannon found wetland soil microbes increased in biomass and fungal dominance after restoration. These changes, in part, explained the increase in capacity for wetlands to deliver ecosystem services.

Soil microbes are responsible for decomposition and nutrient cycling. A greater mass of microbes means restored wetlands have more capacity for biogeochemical cycling and decomposition, which can accelerate processes such as carbon burial, as
seen with the increased carbon in restored wetland soils compared with unrestored soils.

The presence of arbuscular mycorrhizal fungi (AMF) also increased after restoration. AMF help plants survive and reduce phosphorous in soils, thus contributing to cleaner waterways.

Each restored wetland showed a lot of variability of soil and microbial responses within and across wetlands. Because wetlands are found along a hydrological gradient between saturated soils and drier, upland soils, the microbial and soil properties differed according to the landscape position.

Soils close to the water’s edge, as a result of being saturated, had more carbon, microbial biomass, and more fungal biomass, and were less dense. By examining the plant communities, Shannon found that, after restoration, plant diversity increased within the plot and across the landscape. This means that with restoration, habitat heterogeneity increases, a beneficial outcome that increases ecosystem stability and the number of ecosystem services produced.

Additionally, she found that wetland soils and plant and microbial communities showed different levels of recovery that were not consistent with the length of time that they had been restored.

Some projects’ soil and microbial characteristics recovered faster than others. The main difference between fast and slower-recovery wetlands was the hydrological regime.

Restoration projects that occurred on isolated hydrological systems such as depressional, rainwater-fed wetlands took far longer to re-establish remnant wetland conditions. Projects undertaken on flowing hydrological systems such as springs and streams underwent successional processes faster to establish wetland conditions that have a higher production of ecosystem services.

The study has shown that restoring wetlands on private farms increases the ecosystem’s ability to simultaneously produce multiple different ecosystem services and support more biodiversity.

As food production demands continue to rise simultaneously as land becomes more scarce, agricultural systems are becoming more industrialised and intensive. This is placing pressure on natural ecosystems, as seen by reduced water quality, native habitat, and changing landscapes from carbon sinks to sources.

There is increasing recognition that we need mixed agroecosystems so food production does not compromise other ecosystem services.

Wetland restoration is gaining significant traction as a solution to issues surrounding water quality, climate regulation, flooding, and loss of native habitat, and this study has shown that private restoration is effective tool to do just this.

Shannon concludes her report by saying: “I would like to thank all the landowners that generously allowed us to sample their wetlands; each site we visited was so beautiful and unique.

“I thank Ducks Unlimited for the funding that allowed me to do this research. I also thank the Holdsworth Foundation, the Sir Hugh Kawharu Foundation, Wairarapa Moana Trust, and Victoria University for the financial support I have received.

“Finally, I would like to thank my supervisors Dr Julie Deslippe and Dr Stephanie Tomscha for their guidance and help in producing this research.”

Published in Issue 181
Friday, 28 May 2021 22:16

Restored wetlands bring diversity

DU's inaugural scholarship recipient Shannon Bentley is in the final stages of analysing data for her thesis on wetland restoration.

She says she is exploring how restoring wetlands from pasture changes plants, microbes and soil.

"Restored wetlands are home to more diverse native plant communities and soil microbial communities than pastures, preliminary results show.

"This diversity produces a wide variety of benefits for people. For example, restored wetland soils have an increased capacity to store carbon, attenuate floods, and remove excess nutrients. "However, restoration creates a wide variety of responses, with every restored wetland being different."

More to come from this space, she says.

Published in Issue 180
Monday, 25 January 2021 16:53

Wetland restoration methods studied

Victoria University student Shannon Bentley is the recipient of DU’s first Wetland Care scholarship.

Shannon, who is from Upper Hutt and Carterton, has a bachelor of science degree and is now studying for a master’s in ecology.

She is looking at facilitating effective wetland restoration in the Wetlands for People and Place research group.

“This project looks at wetland restoration in the Ruamahanga  catchment, and my role in the project (in part) is to find the ecosystem services gained from wetland restoration,” she says.

“This project has been an amazing opportunity to contribute to the Wairarapa’s environment and clean up the Ruamahanga River.

“In the Wairarapa, farmers have been undergoing wetland restoration on private property. Farmers have used different restoration techniques to re-establish a wetland ecosystem,” she says.

“Wetlands produce services such as water purification, flood abatement, carbon storage, and species habitat.

“My master’s research asks how restoration, species diversity and ecosystem services interact.

“Specifically, I will ask how does restoration affect the biodiversity of plants and soil microbes? And how do biodiversity and restoration treatments affect the ecosystem services?

“With this information, I hope to be able to advise which wetland restoration techniques are effective at restoring ecosystem services.”

Her goal is to quantify the gain in nutrient retention, flood abatement, carbon storage, and plant and microbe diversity in 18 restored wetlands of differing ages in comparison to 18 unrestored wetlands.

“By measuring how wetlands are functioning (via ecosystem services) after they have been restored, and looking at what restoration treatments are effective, this project will be able to determine how effective our current restoration efforts are,
and which restoration techniques are working.”

DU Director Jim Law says, of Shannon: “She is exactly the kind of person that our scholarships are directed at. She is a bright, passionate young Kiwi.” Shannon’s supervisors are Dr Julie Deslippe, assistant director of the Centre of Biodiversity and Restoration Ecology at Victoria, Dr Stephanie Tomscha, head of the Wetlands
for People and Place project and a postdoctoral research fellow at Victoria, and Ra Smith.

Ra Smith is an environmental iwi liaison for Shannon’s iwi, Ngāti Kahungunu, and a whanaunga (relative). He is involved in the effort to clean up Lake Wairarapa.

Published in Issue 179
Monday, 23 November 2020 22:38

Good timing for get-together

President Ross Cottle welcomed DU members to the 46th Conference and AGM in Gisborne – the first time it has
been held there.

He said the turnout was better than expected after the Covid-19 lockdown. The timing of the conference, on the weekend of July 31 and August 1, turned out to be fortuitous, with the country facing further lockdown restrictions from August 11.

Ross thanked Kees and Kay Weytmans for organising everything at the Gisborne end.

Ross said it had been another relatively quiet year of activity, not helped by Covid-19.

Wairio continued to be a major focus for DU in the Wairarapa. The attempt to get a permanent water supply from Matthews Lagoon had not been very successful, with the wall of the  diversion canal blowing out last winter.

It was yet to be reinstated although DU hoped it would be completed next summer.

DU was still seeking opportunities to advocate for wetland construction, and the promotion of environmental issues where needed.

"Our membership is holding, although there is noticeably more grey hair, and in some cases no hair at all, showing up to events each year," he said.

It was reported at last year's AGM that the Board had decided to offer scholarships to university students studying in the
wetland environmental area.

There had been a much slower uptake than expected, but in July, Adrienne Longuet-Bushell, Jim Law and Ross presented
Victoria University student Shannon Bentley with $5000 to continue her studies in carbon sequestration in wetlands.

Ross concluded by thanking the Board members for their work over the past 12 months.

Donations have come from the Wetland Trust, the Pharazyn Trust and Treadwells, and a one-off private donation.

Members' subscriptions and donations, along with last year's raffles and auctions contributed to the rest of the income, Treasurer John Bishop said.

DU accumulated $75,000 for the year and, once expenses were deducted, it was left with a surplus of $30,765, though a big portion of this is earmarked for work at Wairio.

John was this year’s Bill Barrett Trophy recipient.


David Smith said that at the end of the trust's financial year, which is on December 31, it recorded its highest net assets at $522,000, but then there was Covid-19.

On March 23, the funds had taken a dive of just over $72,000, though this was also partly because of Donald Trump's trade war with China.

The trust sat tight and, as at July 22, the trust's funds were back to $505,000 as sharemarkets recovered much of their losses.

Three Board members – Adrienne Longuet-Bushell, Gill Lundie and Emma Williams – had completed their two-year
terms. All were re-elected unopposed for a further two years. Liz Brook has retired from the Board.

DU assisted with two projects this year, both in the Masterton area.

Matt Wyeth, of Spring Valley Enterprises, is creating a wetland and pond of about 2 hectares which will complement the already extensive areas created in the past 20 years.

The cost would be more than $10,000, and DU would contribute $5000 towards it. It was due to be completed but had been delayed by Covid-19.

John Murray, of Kainga Mauru Trust, has also created an approximately 2ha wetland and pond. DU has contributed $5000 towards the $10,000 work required to do the excavations.

Will Abel said that sadly, there was nothing more to add this year, with no swans available.

"The breeding birds we have had over the years have departed the scheme, and we are having no success in replacing
them," he said.

"Even our strongest suppliers, Peacock Springs, are now needing breeding stock. We don’t really have any ideas how to
reverse the trend as importing birds is still not possible."

About 10 pairs had been seen on Henley Lake in Masterton, but there was no easy way to capture them.

Ducks Unlimited is stable with 275 members, of which 80 are non-paying or life members.

Reminders will be sent to those with outstanding subscriptions.

The website is now mobile-friendly and the number of people accessing the site through their phones is nearly as high as those using desktop computers.

More copies of Flight magazines have been added to the website with 100 issues now online.

Jim Law said the Wairio project was moving from a development stage to maturity.

The site was being visited by more people taking advantage of the grassed walkway around the wetland.

"Just watch your boots" because waterfowl are fond of parking up on it, he said.

DU continues to work with iwi who will be more involved with the management of Wairarapa Moana once their Treaty settlement is signed. "Our relationships with them are very good," Jim said. Greater Wellington Regional Council had taken over responsibility for the Matthews Lagoon and Boggy Pond reticulation project, but it had failed.

"We believe it will be fixed this summer." There was also debate within GWRC about the need for a fish passage at the site and this needed to be resolved.

The fantastic partnership with Victoria University was continuing, with students regularly working on Stage 3 at Wairio.
In July, the first Wetland Care scholarship was presented to a Victoria University student. The university also has another student who is likely to apply for a scholarship in the next two to three months.

DU has a five-year Wairio strategy which now needs to be updated. Also, its management contract with DOC expires in December 2021 so next year members will be asked about whether to continue that contract.

"There will be less work – we are just waiting for the trees to grow, some repairs and some planting. Our preference is most likely that we would continue," Jim said.

Ross applauded Jim's negotiation skills in dealing with the different Wairio partners.

Di Pritt asked the meeting to record a huge vote of thanks to Jim, Ross and the Wairio committee for their work. She said when they first visited the wetland 15 years ago, their first reaction was: "What are we doing?" 

"It was the bleakest place – Siberia had nothing on it", and now it is a significant wetland, she said.

Fred Bailey asked how to access funds for predator control. It was generally thought regional councils should be the first point of contact.

Guest speaker Sam Gibson suggested contacting DOC's local relationship officer to tap into the DOC Community Fund and Jobs for Nature funding.

John Cheyne said Hawke's Bay Regional Council was the greatest source of resources in his region, as well as the DOC Community Fund.

Published in Issue 179
Friday, 13 March 2020 08:56

DUNZ Scholarship awarded

The first Ducks Unlimited scholarship has been awarded to Shannon Bentley who is studying for a master’s degree at Victoria University of Wellington. Shannon’s research will include field work at the Wairio wetland.
She is originally from the Wairarapa.

DU is planning a small presentation at the university to award the scholarship to Shannon in March 2020.

Published in Issue 178
Sunday, 15 September 2019 18:21

Pekapeka wetland earns Pride of Place award

One of the areas to be visited during the AGM weekend.

Hawke’s Bay Regional Council was  delighted to receive a Distinction Award from the New Zealand Institute of  Landscape Architects at the NZILA Resene Pride of Place Landscape Architecture Awards for 2013 in April.

The citation for the award states that Pekapeka Wetland provides a range of  experience opportunities for users and  acknowledges the contributing work of Shannon Bray Landscape Architect.

Stephen Cave, HBRC’s Operation  Environmental Manager said “This is one of three awards for Pekapeka Wetland  since 2009, realising its champion value and raising the awareness of wetlands throughout Hawke’s Bay.

“The award from NZILA is a great  reflection on the restoration work  happening in Hawke’s Bay and we are  very honoured. It is estimated this award puts Pekapeka Wetland in the top five  percent of landscape architecture projects undertaken throughout New Zealand in  recent years.”

The award recognises Pekapeka Wetland as a high quality interpretive site for wetland restoration. It is noted for integrating public accessibility with educational  features, using local materials and stories.

Stephen is quick to acknowledge a number of the project’s key supporters, particularly Shannon Bray, Waa Harris, Peter Dunkerley, the Community Foundation, Rotary Club of Stortford Lodge, Eastern and Central Community Trust and the preliminary work of Titchener Monzingo Aitken Ltd.

Iwi groups plus many children from schools (particularly Pukehou School) and Kiwi Conservation Club all played a key role in planting areas around the swamp.



Published in Issue 156