Christchurch West Melton's special savannah
Drylands provide habitat for a range of specialised native insects and plant species. Protecting them is a priority for the Christchurch West Melton Water Zone Committee.
Dryland ecosystems are defined by their naturally low rainfall and free-draining soils, which are ideal growing conditions for native plants tolerant of harsh environments.
New Zealand native leafless and creeping pōhuehue, orange cushion plant, and the threatened fan-leaved mat daisy and turnip-rooted geranium are all present in Christchurch West Melton’s dryland areas.
Committee committed to advocacy for dryland habitat
The Christchurch West Melton Water Zone Committee is advocating for the protection and enhancement of dryland habitats in its zone to help these and other native species thrive.
In August the committee received a presentation from Environment Canterbury and Manaaki Whenua - Landcare Research staff, which focused on the remaining dryland areas in the zone, and the biodiversity they support.
“For years we’ve been aware of the special plant and insect species that exist in the drylands along the Waimakariri River corridor, north-west of the city, so it’s great to hear about the work that’s being done to protect and enhance it,” Committee Chair Kevin Brown said.
Species abundant in hostile environment
Christchurch-West Melton’s kōwhai savannah drylands, running along the southern side of the Waimakariri River, are home to the sun orchid and onion orchid and the at risk-declining dwarf broom. There are also native shrubs of kānuka, matagouri, porcupine shrub and critically endangered plains shrub daisy present in these drylands.
These plants all provide excellent habitat for indigenous moths and butterflies including the grass moth and copper butterfly, and the New Zealand blue butterfly.
“There are so many different insects living in dryland ecosystems. It’s quite mind boggling how many species can be hosted in such a small, hostile environment,” Greg Stanley, our Regional Biodiversity Officer said.
In some cases, dryland plants have been able to grow-through and replace gorse hedges, providing improved habitat for native insect species.
“All these different species help build an extremely complex and special dryland environment,” he said.
Lichen on stone in dryland reserve supports native species present.
Mat daisy in the dryland reserve provide habitat for native insects.
At risk-declining Southern grass skink at home in dryland habitat.
Dryland management methods not ‘one size fits all’
Although drylands were once present over a significant portion of the Canterbury Plains, land use change has meant only a small percentage of drylands remain in the Christchurch West Melton zone or elsewhere on the Canterbury Plains. This means the plant, insect and bird species living there are under threat.
Remaining intact dryland habitats on Environment Canterbury reserve land within the zone are mostly on short-term grazing licences, with conditions to protect areas identified as high value ecological sites within the leased area. They tend to be located on land that is well-drained, relatively unproductive, and prone to drought in summer. There are also some examples of native dryland vegetation and habitats within Lower Waimakariri River Regional Park.
“It’s not a one-size-fits-all approach when it comes to managing drylands. There’s a delicate balance between the different management methods that work so we’re monitoring each area to see which works best,” Stanley said.
“Our work in the drylands has focused on weed control, fencing and biosecurity. Protection of the remaining drylands is our number one priority, then we focus on enhancement and building on what’s already there,” he said.
“Several dryland enhancement projects are underway along the Waimakariri River, with remnant kānuka and kōwhai beneath pine being protected in a joint effort between our biodiversity and commercial forestry management teams.”
Recruitment of kōwhai and other native woody species, and rabbit fencing will be the priority for this area.
Taking action
Christchurch City Council has recently formalised a scenic reserve west of the airport that is almost as large as Hagley Park. The McLeans Grassland Reserve is 154 hectares and contains dryland habitat.
The Reserve complements around 3000 hectares of dryland areas managed by Environment Canterbury and other organisations.
The Christchurch West Melton Zone Committee has previously made recommendations for several dryland planting projects through our biodiversity funding, and these are establishing well.
“The Committee will continue advocating for the protection and enhancement of drylands ecosystems and encourage councils to allocate resource to this work,” Brown said.
“We’d also like to see some signage in these areas to inform the community about how unique and special these places are.
“Creating awareness of the challenges our drylands face will help people understand what looks like a barren, unproductive bit of dirt is actually home to lots of unique, special and sometimes rare species.
“I encourage the community to learn more and help us advocate for drylands across Canterbury. It’s imperative that we do what we can to retain and build on what’s there now,” he said.