Ducks Unlimited
Tuesday, 02 April 2019 07:49

Wings over Wairio project

Victoria University master’s student Patrick Hipgrave is using drones to map wetland vegetation for his project on geographic information systems (GIS).

The project

What changes in vegetation cover over time are evident at Wairio?

To what extent is the accuracy of the image classification process improved with the addition of ancillary data?

This project investigates the use of image classification techniques to create detailed maps of wetland areas based on aerial photographs. 

The project uses an emerging set of analysis methods called ‘object-based image analysis’ to investigate the applications of remote identification techniques calibrated to detect selected native and invasive species. 

An additional objective is to compare and contrast the improvements that including ancillary data into the classification process, such as 3D digital surface models (DSMs) or near infrared imagery, may have over classifications based solely on true-colour images.

The processes being evaluated by this project may allow teams with limited budgets or time to quickly and accurately convert imagery into maps with much greater levels of details, which will improve their ability to detect and track specific plant species. 

This is especially useful in the case of wetlands undergoing restoration as they often exhibit significant changes over time, and the target species would normally be challenging to differentiate from one another in an aerial photograph.

Results to date

Though the study is ongoing, with flights every three months, the initial results would appear to confirm that a ‘true-colour only’ classification would perform poorly compared with ancillary data. The improving effects of including infrared imagery will be tested once that has been gathered. 

The classified images contain between 18 and 20 distinct classes.

Study area

The Wairio wetland was drained and converted into farmland in the 1960s.

Since 2005, it has been undergoing a managed restoration programme to return it to something approaching its natural state.

Several plantations of native plants have been established, and a weed eradication programme to control invasive species such as Bidens frondosa is in progress.  This project can assist this effort by tracking the distribution of natives and weeds.

Object-based image analysis 

Object-based image analysis works on the principle that different types of surface cover have unique properties, such as colour, texture or shape. 

For instance, weed species might be distinguished from grass as the weeds may be a different shade of green to the surrounding grass, or present a unique textural pattern owing to differently shaped leaves.

 

 The sensors being used in this project are the DJI Phantom 4 Pro Camera, to collect true colour imagery, and a Micasense RedEdge-M, a multispectral sensor for collecting near infrared imagery. The software is ArcGIS Pro 21, ENVI 5.4 and PrecisionMapper 3.32

 

 

Published in Issue 176
Sunday, 20 January 2019 03:53

Ramsar officials visit

Ramsar officials visited the Wairio wetland in March during their visit to Wellington, the host city for the Oceania preparatory meeting in the lead-up to the 13th Conference of the Parties (COP13) to be held in October 2018 in Dubai. 
 
The meeting in March was attended by eight contracting parties in the Oceania Region, an observer from Vanuatu, which is in the process of accession, and observers from international and national organisations that work on wetland-related issues. 
 
Ramsar officials said the Pre-COP meeting was an opportunity to discuss and give feedback on draft resolutions to be considered at the Ramsar COP13. It was also an opportunity to share experiences, information and 
knowledge on wetland issues common to the region and identify opportunities for cooperation, learning and improved implementation of the convention. 
 
The delegation thanked Ngati Hinewaka and Kahungunu ki Wairarapa, Greater Wellington Regional Council, Ducks Unlimited and the Department of Conservation for hosting the visit. 
 
The Convention on Wetlands of International Importance holds the unique distinction of being the first modern treaty between nations aimed at conserving natural resources.
 
The signing of the convention, now known as the Ramsar Convention, took place in 1971 at the small Iranian town of Ramsar.
 

 

Published in Issue 175
Thursday, 23 August 2018 22:09

Wairio under scrutiny

Ecological restoration of Wairio Wetland, Lake Wairarapa

The response of native wetland vegetation to eutrophication and re-vegitation management strategies.

Abstract: Aprille Gillon.

Wetlands are highly productive ecosystems that support abundant native fauna and flora and provide many essential functions and services, for example, water purification, erosion stabilisation, floodwater storage, groundwater recharge, peat accumulation and biogeochemical cycling. 
 
Despite the vast benefits wetlands provide worldwide loss and degradation still continues, mainly due to agriculture, urban development, population growth and exploitation. 

Wetland disturbance can cause altered hydrological regimes, invasive species introduction, soil and water eutrophication, habitat fragmentation  and reductions in native fauna and  flora leading to an overall reduced functionality. 
 
Ecological restoration is an active practice commonly undertaken in degraded wetlands to re-establish ecosystem functioning, and most commonly includes revegetation, reconstruction of hydrology, weed control, pest management, and native species reintroductions. 

Wairio Wetland on the eastern shores of Lake Wairarapa forms a part of Wairarapa-Moana, the largest wetland complex in the lower North Island. Historically Wairio was an abundant kahikatea swamp forest, with a diverse range of waterfowl, waders and freshwater fish. However, the wetland was adversely affected by a draining scheme during the 1960s and 1970s, the construction of Parera Road, and the invasion of willow trees planted for erosion control. 

Draining of the wetland, division from nearby lagoons and ponds, nitrogen and phosphorus build-up in waterways and exotic weed invasion all contributed to the poor state of the wetland. In 2005, Ducks Unlimited (DU) in conjunction with the Department of Conservation (DOC) and members of the local community formed the Wairio Wetland
Restoration Committee to manage and restore the wetland to its presettlement state.
 
Restoration undertaken at the site have included native tree planting, earthworks, weed control, pest management and fencing sections of the site to exclude cattle, have met with mixed success. 

This thesis reports on two studies undertaken at Wairio Wetland with aims to inform future restoration efforts. 
 
There had been a proposal to divert nutrient rich water from Matthews lagoon into Wairio Wetland to increase filtration and improve 
the water quality of Lake Wairarapa. The outcomes of the effects of nutrient loading on established plant communities remain unknown. Therefore, the first study conducted between December 2012 and May 2013 in  Stage 2 of the wetland, examined the effects of fertiliser addition on biomass, structure and diversity of a wetland plant community. 
 
Different levels of phosphate and nitrate fertiliser were applied to 50 plots (4m2) of vegetation at the site with percent cover and the average height of respective species recorded every four to five weeks. Results showed the addition of phosphorous and/or nitrogen had neither a positive nor negative effect on the plant community at Wairio with no significant changes in the 15 species recorded at the site. These results contrast other studies that have reported increases in biomass, reductions in biodiversity and common/introduced species out competing rare/native species. 

The short duration of the experiment and summer drought conditions may have obscured the above-ground visual responses of the plant community to nutrient addition: therefore, further continuation of this experiment is advised. Variable survival rates of previous plantings, and uncertainty about the most cost-effective practice under current site conditions, provided the impetus for this study.

Therefore the second study, conducted between July 2011 and January 2014 in Stage 3 of the wetland, further investigates the effects of various management treatments on establishment of native woody vegetation.

Note: Both the experiments described in the above thesis are on-going. Stephen Hartley who is Deputy Director for the Victoria University Centre for Biodiversity and Restoration Ecology and is a Senior Lecturer in Conservation and Ecology, will continue to monitor the growth of trees in Stage 3, and a Belgian intern student will re-survey the nutrient enrichment plots in Stage 2.

To view Aprille Gillon’s full thesis go to:-
http://researcharchive.vuw.ac
handle/10063/3648
The study involved monitoring 2368 planted trees of eight native wetland tree/shrub species, including: Cordyline australis, Dacrycarpus dacridioides, Olearia virgata, Podocarpus totara, Coprosma robusta, Coprosma propinqua, Leptospermum scoparium, and Pittosporum tenuifolium. The trees were subjected to various planting treatments, including the excavation or retention of topsoil, presence or absence of weed mats and presence or absence of nurse trees with spacing of 0.75m or 1.5m. Survival and growth of each tree was measured every six months over the 30 month experimental period. 

Results showed that interspecific competition and hydrology appeared to be the main processes influencing the establishment of native plantings at Wairio Wetland, with plant mortality greatest in the first year after planting. Water logging, in particular, was detrimental to establishment of all species at the site except D. dacridioides. Topsoil excavation and the planting of nurse trees at 1.5m spacing was the most effective management treatment combination promoting survival of plantings at Wairio. 

However, the success of management treatments varied greatly between species at the site and had different impacts on plant growth. Topsoil excavation was beneficial to survival of D. dacridioides and C. robusta but detrimental to growth of C. australis, O. virgata, C. propinqua, Ptenuifolium and L. scoparium. 

The concurrent planting of nurse trees with focal trees was beneficial to the survival of D. dacridioides, growth of P. totara, and survival and growth of C. australis. The planting of nurse trees further apart at 1.5m compared to 0.75m had a positive effect on the survival of C. propinqua and P. tenuifolium, and survival and growth of L. scoparium. Weed mats were beneficial to survival of O. virgata and growth of L. scoparium but detrimental to growth of D. dacridioides. These management treatments can be used in future revegetation efforts at Wairio Wetland and potentially in other wetland restoration projects throughout New Zealand.
 

 

Published in Issue 162
Monday, 19 March 2018 07:22

Boggy Pond April rounds

Last April, I was able to complete the servicing round down at Boggy Pond, Mathews and the Wairio Restoration Block. The total predators trapped there for the month was :
 
1 cat, 5 ferrets, 1 weasel, 9 rats, 29 hedgehogs, 6 mice and 1 hawk.
 
While there I GPS’d another eight potential trapping sites on the new bund wall that was recently created.
 
A Timms trap was missing from the trap site by the Bridge to No Where and a Timms/ DOC 250 was missing past the second bridge  leading to the Viewing Hide. I suspect these  have been stolen as they were there when I serviced the gear in February. These missing traps will be replaced after duck shooting season. I am wary that more may disappear during that time with the influx of hunters to the area.
 
Steve Playle.
 
 

 

Published in Issue 164
Monday, 19 March 2018 07:07

Working in the edge of the wetlands

Boggy Pond, Matthews lagoon, Wairio Wetlands, JK Donald Reserve and Barton’s Lagoon. These areas in the east and north of Lake Wairarapa are regarded as the best examples of native wetlands left at Wairarapa Moana.
 
All are on public conservation land and have infestations of pet plants to some degree – alder, willow, hornwort, tall fescue, aquatic weeds, and more. The pest plants have changed the natural character of the wetlands and made it difficult for some native plants and animals to thrive and also made it difficult for the wetlands to act as sediment and nutrient filters. Some money and time will be spent dealing with the pest plants in these areas and planting to enhance the native ecology already there.
 
The Wairarapa Moana Wetlands Project began in 2008 to enhance the native ecology, recreation and cultural opportunities on the public land in the area. Project partners are Greater Wellington Regional Council, Department of Conservation, Dairy NZ, and of course Ducks Unlimited. 
 
Threats to native biodiversity include:
 
Aquatic weeds: - hornwort, largarosiphon,  elodea, curled pond weed. These plants clog waterway and irrigation equipment and crowd out native species.
 
Invasive trees: alder, willow. Both fast growing and water tolerant they invade wetlands and lake edges and can dominate an entire ecosystem.
 
Invasive grasses: tall fescue, Mercer grass. Both introduced and out-compete native grasses and form an impenetrable barrier for native species the might try to establish.
 
Introduced mammals: Rabbits, hares, possums, stoats, ferrets, feral cats, rats. They eat pasture, native plants and/or native animals.
 
Introduced fish: Perch, tench, rudd, goldfish. Some of these eat our native fish, other outcompete them for food, while others eat plants and create more sediment in the water.
 
Poor water quality: Nutrients, effluent, waste water. Many native species will not tolerate nitrified water.
 
The clean-up work around the edge wetlands is just one part of the wider Wairarapa Moana Wetland Project. The prime focus is the publically owned land within the Wairarapa Moana catchment. The group is committed to working with the adjacent farmers and the users of the Moana. 
 
Each year a management team has been completing tasks within areas of recreation, marketing, relationships and biodiversity investigations and enhancement.
 
Photos: Ross Cottle.
 
 

 

Published in Issue 164
Tuesday, 27 February 2018 07:13

Wairio Wetland planting continues

The Wairio Wetland Restoration has taken another step forward with the completion of the 1.7 km Bund Wall linking Stage 1 and Stage 4. If it is as successful as the Bund in Stage 4 we will have another 15 to 20 hectares of shallow open water with low islands scattered throughout.

This type of habitat is an ideal breeding and feeding area for a wide variety waterfowl such as swan, geese, bittern, royal spoonbill and of course ducks.

The Bund has been fenced to keep stock out as well as protect planting.

A planting day, held on April 21 was attended by about 40 people including students from a local school and Taratahi Agricultural College, members of the South Wairarapa Rotary and a variety of people from DU, Greater Wellington Council and the local district.

We received $2500 worth of plants from the Honda Fund, as well as three people from Southey Honda in Masterton to help with the planting.

Start time was 10am and 2000 plants were in the ground by 12 noon, just in time for lunch provided by Greater Wellington Regional Council.

Special thanks go to The Game Bird Habitat Trust, Greater Wellington Regional Council, Nikau Foundation, Pharazyn Trust and South Wairarapa Rotary Club for their generous sponsorship.

It was an excellent day my thanks to all involved.

We now await rain to see just how successful we have been.

Ross Cottle
Published in Issue 164
Friday, 23 February 2018 06:55

Wairio scores again

Thanks to the Nikau Foundation, Wairio  wetland has again been granted a generous  amount toward development for the wetland.  The Richard and Doreen Evans Charitable  Trust provided $4000 in the 2015 Nikau  Foundation funding round. 

Conditions placed on the grant: 

  • It must be used for the purpose applied for. 
  • The Trust must receive a feedback form from within a year of the grant being made. 
  • The Trust requires an update of progress towards completion of the project. Also  forward two or three photos and an update  that can be used on their website / annual  report / newsletters. Before and after photos  are especially welcome with captions. Talent  release permissions are DUNZs responsibility. 
  • Please acknowledge Nikau Foundation contribution to DUNZ in any publications or  any other means of release – The Foundation  would like to become better known throughout  the Wellington region. 
  • Our logo is available to use in your  publications. 
  • Please keep informed through our website and  “Like” us on facebook

Should any of you wish to know more go to  the Foundation’s web site,  www.nikaufoundation.org.nz

New GM 

The Nikau Foundation has appointed a new General Manager who brings a wealth of  experience from the community and voluntary sector. Louise Parkin has had 25 years working  with charitable and philanthropic organisations  both in New Zealand and internationally. 

Ms Parkin had been at Nikau Foundation as  their Philanthropy Advisor for six months  before taking up the role of General Manager  in January this year. 

In her spare time, she teaches the Japanese martial art of aikido to adults and children. Her  personal philanthropy is for the benefit of the   environment and international aid. 

The Nikau Foundation is part of a world-wide   network of community foundations set up  to benefit a specific geographic area, in this  case the Wellington region. The Foundation manages 22 endowment funds that benefit the  arts, education, social and youth projects, the  environment and beyond. It does this through  the generosity of local donors. The funds it  manages grew 100 percent in the last year.

Published in Issue 166
Thursday, 22 February 2018 07:28

Wairio restoration planning and farewell

The presentation of DUNZ’s certificate “in recognition and appreciation of support to NZ’s waterfowl and wetland habitat” to Ian Gunn from Greater Wellington Regional Council (GWRC) – Manager of GWRC’s Wairarapa Moana Project and a great supporter  of the Wairio Wetland Restoration Project.

Ian was critical in securing a “step change” in funding for the project.  The presentation was made at the end of the meeting along with the small gift of a bottle of wine. DUNZ members may recall Ian joining us at our 2014 AGM in Martinborough.

The recent meeting was held at Fish & Game’s Kilmore Lodge, adjacent to the Wetland where the group planning the 2016 work programme was underway.

Funding currently tots up to around $30,000. Of this, about $20,000 is already funded by contributions from our supporters.

Published in Issue 167
Friday, 16 February 2018 07:23

Wairio wetland plant day – another success

June 21 work started at 9am for the organisers, supported by some strong lads from Taratahi Agricultural Training College and farm workers from a local sheep and beef station Palliser Ridge. Those strong farming trainees dug holes in pre-sprayed spots in rough, fescue infested terrain.   

Just after 10am we also had about 20 school children from Martinborough and Kahutara primary schools arrive to “assist” in planting flaxes in the holes prepared by the aforementioned lads and workers.  In all, around 65 folk helped with the planting and by 12 noon, 750 plants (about half of them kahikatea) were in the ground at the noreastern corner of the Wetland.

Greater Wellington Regional Council provided educational support and the school children, in addition to planting, were treated to a field class identifying plants common to the Wetland.  That and the hot sausages for lunch (again provided by GWRC) made a great day for the children who said they would be back next year to see how “their” plants were growing.

Jim Law.

Published in Issue 168
Friday, 16 February 2018 07:16

There is a long, long trail a winding…

Published in Issue 168
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