The spread of wildings
Many conifer species – such as pines and firs – benefit New Zealand . But certain species, and plantings in some places, can seed wilding trees that quickly spread.
Spreading wilding conifers on Clarence River, Marlborough
Conifer seeds can be blown many kilometres by wind, and have spread into areas such as farmland, the high country (including above the native bush line) and public conservation land. Seedlings quickly infest an area. If they aren’t removed, they can grow into dense, impenetrable wilding conifer forests. They often grow in mixed species groups, and their timber has either minimal or no value, or costs too much to remove because of access problems and density.
The spread of wilding conifers threatens productive farmland, New Zealand lifestyles, iconic landscapes and native ecosystems, tourism opportunities, and our national economy.
By the early 2000s, many individuals and groups saw the spread of wilding seedlings from conifer plantings as a serious problem. By 2016, this spread affected over 2 million hectares – an area larger than all our commercial forests combined.
Follow the links below to learn about wilding conifers effects on farmland, ecosystems, and biodiversity and water.
We can control wilding conifers
We can control wilding conifers
Despite the huge areas of land threatened by wilding conifers, these are one of New Zealand’s easiest weed problems to deal with. Their seedlings are easily spotted and seeds seldom survive in the soil beyond five years.
We are now making good progress with our national efforts to contain and control these weeds.
Many committed individuals and groups have already taken big steps to control New Zealand’s wildings, and they could use your help. See our Community groups page (quick link below) for groups in your area and other ways to help.
Ecosystem effects
These trees can quickly colonise and change ecosystems where there is no native forest, such as above the bush line, in mineral belts and in tussock grasslands. Once there, they outcompete other species. Their effects include:
- forming a closed canopy of shade and acidifying the soil, evicting native plant species and the animals that rely on these
- changing the distinctive look and conservation values of our New Zealand landscapes, such as iconic alpine tussock lands
- limiting eco-tourism and recreation opportunities
- fueling devastating wild fires.
Wilding conifer spread in 1998, 2004 and 2015 in Mid-Dome, Southland
Image: Environment Southland
Wilding conifer forests also don’t have firebreaks or ponds, so fires are difficult to manage and can quickly spread into neighbouring areas. And it’s even a big challenge just accessing the remote alpine areas that conifers often colonise.
Effects on water yield
Wilding conifers reduce surface flows and aquifer recharge in water-sensitive catchments.
Less flow means less water for farmers’ irrigation needs, hydroelectric generation, or outdoor recreation use. And less water for those plants and animals that live in and around the river.
Where pasture land becomes covered in wilding conifers, this reduction in annual water yield has been shown to range from 30 to 81 percent (with the upper end of that range recorded in dry South Island sites).
Environment Canterbury (regional council) has identified wilding conifer spread as something that might affect water yields in their region.
Effects on farmland
Wilding conifers affect our farmlands, livelihoods and ultimately our national economy.
Wilding conifers can quickly colonise farmland and significantly reduce the available grazing land, if seedlings aren’t managed through mob-stocking or other means. Spreading, wilding conifers can also:
- limit tourism and recreation-related activities
- harbour pests and diseases
- fuel devastating wild fires.
Unlike orderly commercial forests, where trees are thinned and there’s good road access, wilding conifer forests can be dense and impenetrable, and the trees can be different species, ages and shapes. All this makes removal difficult, with harvest costs being more than the trees are worth.
Not just a Kiwi problem
New Zealand is not alone with this wilding conifer crisis. Other southern hemisphere countries, including South Africa, Australia, Chile and Argentina, also introduced spread-prone conifer trees for forestry and erosion control. Now they’ve become invasive weeds in these countries too.
Wilding conifers threaten our productive farmland and economy, our uniquely Kiwi ways of life, and our iconic landscapes and native ecosystems, tourism opportunities and our national economy.
Preventing the spread
Despite the huge areas of land threatened by wilding conifers, these are one of New Zealand’s easiest weed problems to deal with.
Wilding conifer seedlings are easily spotted and seeds seldom survive in the soil beyond five years. We are now making good progress with our national efforts to contain and control these weeds - in 2016/17 we brought 1.2 million hectares of affected lands under control.
Many committed individuals and groups have already taken big steps to control New Zealand’s wildings, and they could use your help.
What can you plant and what are your obligations?
See our Community groups page to join a community group in your area.