By early 2022 the Weed Strikeforce was on track to rid the lakeshore of Te Waihora/Lake Ellesmere of willows and some other really problematic weeds.
Grey willow (pussy willow), yellow flag iris, reed canary grass, blackberry, elderberry and gorse are all targets of Weed Strikeforce which is delivered by the Department of Conservation Te Papa Atawhai and jointly funded by Environment Canterbury and Te Papa Atawhai.
Invasive non-native willows, both grey and crack willow, are now present within nearly one third of the lakeshore freshwater wetlands. Grey willow (Salix cinerea) in particular, is a challenge on the west side of the lake, where the area of crack- and/or grey willow-dominant forest and scrub vegetation was found to have doubled over a 25 year period between the early 1980s and 2007.
Grey willow is considered one of the top ten most invasive weed species in seven of the thirteen the Department of Conservation Te Papa Atawhai conservancies around New Zealand and willow spread has been one of the main causes of reduced extent of native freshwater wetland vegetation around the lake shore.
Vegetation at risk from further spread includes any of the remaining harakeke/flax and raupō stands.
It takes two to four years to achieve total control of grey willow in an area but reseeding is often a problem if adjacent landowners are not controlling willow on their land. To gauge progress, monitoring is undertaken to assess how well willows have responded to spraying and if there have been any changes in native vegetation.
With the lakeshore work nearing completion, Once the lakeside work is complete, the team has started to will move onto willow and weed control along the tributaries.
Protecting our precious ecosystem
"With less than 1% indigenous vegetation cover remaining on the Canterbury Plains, our native ecosystems are incredibly vulnerable. Te Waihora is home to much of this indigenous vegetation cover and supports some of the most extensive wetland habitat in the eastern South Island. Our vision is for this environment to thrive and have the space to flourish and spread. Removing weed competition is a cost effective strategy in achieving this goal and the Weed Strikeforce project has the ability to take on the entire lake margin with a strategic and well planned approach," - Gary Boyd, of the Department of Conservation’s Weed Strike Force said.
Weeds are also controlled in ecologically sensitive areas of Lakeside and Harts Creek Wildlife Management Reserves.
These sites are home to some of New Zealand’s most special and secretive swamp birds, such as matuku/Australasian bittern and koitareke/marsh crake.
The Weed Strikeforce team helps stop the loss of their native habitat caused by willows invading wetlands.
If you think you have seen an unusual plant or aquatic animal in a waterway let us know. Contact a biosecurity officer through Environment Canterbury Customer Services on 0800 324 636.
Learn more about different weeds
Use these websites to identify and learn more about different weeds and how to tackle them:
- Weed list - Search from a list of over 100 weeds - Weedbusters
- Weed identification key - Identify over 650 weeds - Landcare Research
- Search for an exotic plant from a list of over 2,500 naturalised plants - NZ Plant Conservation Network
- Information on unwanted marine pests - Marine Biosecurity Porthole
- New Zealand Marine Pest ID Guide - Ministry for Primary Industries
- Be a warrior in the War on Weeds - Department of Conservation
- Weed Strikeforce in full swing at Te Waihora - Environment Canterbury
25 Jun 2020
Weed Strikeforce in full swing at Te Waihora
In 2020 Te Waihora/Lake Ellesmere’s Weed Strikeforce team aim to stop the spread of seed-producing female grey willow trees around the edges of Te Waihora/Lake Ellesmere.Learn more