Choosing the wrong tree species can create an expensive problem for you and your neighbours.
If you plan to replace or plant conifer trees on your property, wherever possible choose species that won’t infest other areas of your (or your neighbours’) land and create an ongoing management problem.
There are several things to consider when thinking about what to plant and where you are planting.
Our The Right Tree for Your Place planting guide contains some trees and shrubs that are potentially good for shelter in the high country, have moderate-fast growth, and a comparatively low risk of wilding spread.
Landowners, consultants and planners should use the Wilding Spread Risk Calculator and associated guidelines to assess the wilding spread risk for proposed new conifer forests and shelterbelts.
The Wilding Spread Risk Calculator and the Associated Guidelines for new plantings helps landholders, consultants and planners assess the wilding spread risk for proposed new conifer forests and shelterbelts.
There are two Decision Support Systems (DSS) in the Associated Guidelines:
The calculator also predicts if wilding conifers might invade a site in the future.
Each DSS rates the spread risk using the following indicators.
Points are assigned to each of the five indicators when assessing a proposed site. When the points are summarised, this provides a total score that ranks the proposed planting according to risk levels.
The National Environmental Standards for Plantation Forestry (NES–PF, published May 2018) are nationally consistent regulations for managing the environmental effects of forestry under the Resource Management Act (RMA). A NES prevails over district or regional plans.
The NES-PF objectives are to:
The objectives are achieved through a single set of regulations under the RMA that apply to foresters throughout New Zealand.
Land owners and forest owners must apply the Wilding Conifer Risk Calculator whenever they are planting a new forest or are replanting in a different conifer species that carries a higher risk.
If the calculator shows that spread risk is high, the land or forest owner will need to talk with their local council and discuss the NES provisions in their plan.
For more information visit the NES for Plantation Forestry on the Ministry for Primary Industries' website.
Under the Emissions Trading Scheme (ETS) if a land owner deforests ‘pre-1990 forest’, they’re liable for the carbon that’s released. For an average forest at 2017 carbon prices ($20 per tonne of carbon) this may be $10,000 per hectare.
However, if wilding conifers on your land were established in 1990 or after, and you haven’t registered them in the Under the Emissions Trading Scheme (ETS), then you can remove them without ETS liability.
If your conifers were established before 1990, you may still be able remove them without incurring an ETS liability – for example, by applying for a Tree Weed Exemption. Find out more about exceptions to deforestation rules on the Ministry for Primary Industries (MPI) website. This website includes the publication 'Managing tree weeds and the Emissions Trading Scheme'.
Once wildings are removed, the site may be ripe for wilding re-infestation. For example, removing dense stands of conifers surrounded by shrubland creates light wells that may be quickly re-infested if not planted with another species.
Restoring and rehabilitating the site with desired plantings helps to prevent wilding conifers from returning, and accelerates creating the right conditions for a healthier ecosystem – and other land-use activities like grazing.
Dead standing trees can provide shelter and allow a quicker recovery of tussock grasses and other native vegetation – so sometimes a site is better left to recover naturally.
Note that assistance with site restoration (after wilding conifer removal) may be available through the One Billion Trees Programme.
Restoration planting options include:
Native species will often successfully colonise new sites, but may need some encouragement as some are not resilient to competition from introduced species. Options include:
As conifer seeds are viable for up to 5 years, after control it’s important to monitor the site during this period and hand-weed any wilding conifer seedlings.