The Wilding Pine Issue
Wilding conifers are the uncontrolled spread of conifer tree species. They are self-seeded conifers that have become weeds due to their vigor in spreading across many New Zealand landscapes, in particular invading our high country tussock grasslands. Wilding conifers are also referred to as wilding pines, or occasionally simply as wildings as most of the spreading species are pines, however Douglas Fir and European Larch are also major wilding species.
Why is this an issue?
In Central Otago wilding conifers have the potential to form dense stands of conifer forest over vast areas if left uncontrolled. This has major implications on landscape, water yield, biodiversity and tourism within the district as well as creating a huge fire risk at a landscape scale.
Central Otago is characterised by vast landscapes dominated by tussock grasslands and shrublands which are vulnerable to wilding conifer invasion. Consequently, about 70% of the Central Otago landscape is vulnerable to invasion by wilding conifers.
Landscape and Recreation:
Wilding conifers can have significant adverse effects on landscape values, especially on landscapes that are characterised by indigenous tussock grasslands and other low stature vegetation. Central Otago has a distinctive landscape much of which is characterised by tussock and shrublands. Our unique landscape is a major factor in attracting tourists to the district and is encapsulated in our tourism promotion slogan “A World of Difference”.
Additionally, many people come to Central Otago to live and as tourists because of the recreation opportunities that exist here. These opportunities include mountain biking, trout fishing, hunting, four wheel driving, kayaking, walking, picnicking and landscape and heritage photography. An appreciation of the outstanding landscape that exists in Central Otago is an important aspect of these recreation activities for many people. The adverse effect of uncontrolled wilding spread on landscape values will in turn have significant adverse effects on the quality and enjoyment of these recreation pursuits. There will also be other adverse effects such as the effect of wildings on stream ecosystems, stream flows, wild animal populations and impacts on physical access. The heightened fire risk that goes with an increasingly wooded landscape in the dry Central Otago climate may also have consequences in land owners declining public access.
Landscape and heritage values associated with our gold mining and pastoral history are important components of Central Otago’s tourism industry. Wilding spread has the potential to alter the landscape characteristics which Central Otago is renowned for and has direct adverse physical effects on historic heritage sites such as obscuring water races and damaging stone buildings.
Protecting landuse options:
Wilding conifer invasion reduces the viability of using high country land for pastoral farming. Because of the low grazing capacity of much of this country, the cost of wilding control can quickly exceed the economic return from the land, particularly in areas that are subjected to ongoing seed rain. While wilding spread does not generally effect more intensively grazed land, conifers have the potential to become the dominant vegetation on more extensive land eventually displacing grazing altogether and reducing other land use options. These more extensively grazed tussock grasslands are a significant proportion of Central Otago district. COWCCG works with landowners to assist them in getting on top of the wilding problem on these extensively grazed lands.
Protecting native biodiversity
Central Otago district is home to a significant proportion of the South Island dryland ecological zone. Within this zone 70% of the indigenous ecosystems have been lost and only 1.9% is formally protected. In Central Otago the native ecosystems are dominated by tussock grasslands, alpine herbfields, wetlands and grey shrubland.
Our native ecosystems are recovering and expanding naturally in many instances owing to less burning being carried out by farmers and lower rabbit numbers. Such areas also have the potential to be managed by active restoration such as is occurring at the Mokomoko Sanctuary in Conroy’s Gully and on QEII covenant land in the Waikerikeri Valley.
The spread of wilding conifers is a direct threat to the protection and restoration of native biodiversity values in Central Otago. Wilding conifers have the potential to totally displace native vegetation on most ecosystems within the district due to their higher stature and tolerance to low rainfall thus outcompeting native vegetation for light and moisture. . Unlike other parts of New Zealand where forestry can coexist with some native species, the low availability of water in Central Otago means that conifers tend to totally dominate as a monoculture if left uncontrolled.
Conserving water
Conifers, whether as plantations or wilding forests, decrease water yield from catchments. As Central Otago is the driest region in NZ, we are already water limited and consequently the uncontrolled spread of wilding conifers would have a more significant impact on our environment and economy than other regions.
Water is an important resource for sustaining a healthy aquatic environment for Central Otago rivers and streams which contain important native fish species endemic to this area and supports a popular sports fishery in trout. Water harvested from catchments within the district are important for irrigation for farming which sustains rural communities. The uncontrolled spread of wilding conifers would displace our extensive tussock grasslands that are important for water harvesting and would dramatically reduce water yield from our streams.
If left unchecked, wilding conifers are estimated to cover 20% of New Zealand, however in Central Otago, owing to our uniquely vulnerable landscape, up to 70% of the district could be dominated by wilding conifers. Although we are fortunate not to have the scale of infestation that is occurring in the Wakitipu or Mackenzie districts, there has been clear evidence that a similar pattern of spread was emerging in Central Otago. Through active management over the past 5 years we have been able to prevent this from occurring, however there is more work to be done in achieving lasting control.
Reducing fire risk
Domination of vegetation on our extensive hill and high country by wilding conifers would significantly increase wild fire risk by increasing the fire load of flammable material. In a seasonally dry region such as Central Otago, this risk is heightened so that without wilding control we would have a fire regime similar to California or New South Wales.
