By
Alison Craig
National Rural Fire Authority,
Wellington, New Zealand
Fire environment, fire regimes and the ecological role of fire
The vegetation cover of New Zealand has never been static. Indeed, even before the arrival of humans a thousand years ago, natural processes such as volcanism, glaciation, earthquakes and high winds caused landscape-wide changes in vegetative cover.
With the arrival of humans the pace and extent of vegetation cover changes increased dramatically, resulting in a large proportion of the natural forest being destroyed. Fire, both deliberate and accidental, played a large part in these changes.
Although changes in vegetative cover continue to occur, the overall outcome in terms of vegetation types and quantity of available fuels has been reversed in more recent times, from a reduction in overall biomass (or fuel) to an increase in biomass. Before the middle of the last century many of the native forest, tussock land, wetland and scrubland areas were generally converted to pasture lands. Today many of these pasture lands are economically non-viable and are either reverting to scrublands, or have been planted with exotic forest species.
Since 1951 the area in planted production forest has increased from 338 000 ha to 1 761 000 ha, an increase from 1.3 to 6.5 percent of the total land area of New Zealand. This area is predicted to increase to 2.5 million ha by 2010, equivalent to nine percent of the total land area.
Changes in the management of South Island tussock lands will see around one million hectares of these lands retired from the pastoral lease system and included in the conservation estate. This land use change will result in much greater volumes of fuel accumulating on these former grazing lands.
The vegetation changes in plantation forests and tussock lands, in addition to the reversion of previously productive pasturelands to scrublands, are significantly transforming the land cover of New Zealand. The change is now clearly from less complex to more complex fuel types, from low fuel loads to high fuel loads and from fragmented to continuous areas of fuel.
These changes have a two-fold impact on the consequences of wildfires on rural lands. First, the higher fuel loads and larger areas of continuous fuels will make fires harder to control and will result in larger areas being burned. Second, the increase in economically and ecologically valuable vegetation types will result in future fires having a greater overall impact in terms of loss of valuable assets.
The overall results of these fire environment and fire impact changes will not become apparent until a prolonged period of drought and extreme fire danger coincides with a number of fire ignitions. The average return period for these extremely damaging fire seasons, although difficult to quantify, is probably in the order of 15 to 25 years.
Narrative summary of major wildfire impacts on people, property and natural resources during the 1990s
Large and devastating wildfires occur relatively infrequently in New Zealand when compared with countries such as Canada, Australia and the USA.
The number of hectares that are burned annually by wildfires varies considerably, being driven predominantly by weather conditions during the summer season. The worst fire season since 1980 occurred in 1982-1983 when 45 000 ha were burnt. More recently, the 1998/1999 fire season resulted in 18 000 ha burnt, half of which can be attributed to two fires around Alexandra during February 1999 that destroyed two dwellings and many sheds and outbuildings. The average area burnt per annum since 1980 is 10 000 ha. Wildfire statistics for the decade 1990-1999 are given in Table 5-4.
The total economic and environmental cost that rural fires impose on New Zealand is not currently measured. This figure would have to include the loss of biodiversity, the destruction of production forests and other property and the reduction in water and soil quality following fire.
Table 5-4 Wildfire statistics of New Zealand for the fire seasons 1990-1991 to 1999-2000.
Year |
Total No. of Fires on Forest, Other Wooded Land and Other Land |
Total Area Burned on Forest, Other Wooded Land and Other Land |
Area of Forest Burned |
Area of Other Wooded Land and Other Land Burned |
Human Causes |
Natural Causes (lightning) |
Unknown Causes |
No. |
Ha |
Ha |
Ha |
No. |
No. |
No. | |
1990/1991 |
1 234 |
7 279 |
240 |
7 039 |
not available |
not available |
not available |
1991/1992 |
1 153 |
1 889 |
152 |
1 737 |
1 116 |
not available |
37 |
1992/1993 |
990 |
3 129 |
151 |
2 978 |
948 |
not available |
42 |
1993/1994 |
2 198 |
7 350 |
177 |
7 173 |
2 142 |
not available |
56 |
1994/1995 |
2 023 |
4 594 |
466 |
4 128 |
1 965 |
not available |
58 |
1995/1996 |
1 646 |
4 586 |
348 |
4 238 |
1 602 |
not available |
44 |
1996/1997 |
2 374 |
6 937 |
746 |
6 191 |
2 331 |
not available |
43 |
1997/1998 |
3 610 |
6 253 |
1 296 |
4 957 |
3 563 |
not available |
47 |
1998/1999 |
3 165 |
17 699 |
213 |
1 ,486 |
3 107 |
not available |
58 |
1999/2000 |
2 944 |
2 054 |
141 |
1 913 |
2 880 |
5 |
59 |
Notes:
Human Causes: includes "miscellaneous" causes of fire
Natural Causes (i.e. lightning): not recorded separately until 1999/2000
1990/1991: breakdown of causes not available
Operational fire management systems and Organizations present in the country
The New Zealand Fire Service Commission governs fire services in New Zealand by administering the Fire Service Act (1975) and the Forest and Rural Fires Act (1977). These two acts provide the framework within which the New Zealand Fire Service, the National Rural Fire Authority and Rural Fire Authorities carry out their responsibilities.
The New Zealand Fire Service, under the Fire Service Act (1975), is responsible for protecting life and property from fire, primarily within urban areas. Outside urban areas, the National Rural Fire Authority promotes and encourages rural fire coordination under the Forest and Rural Fires Act (1977), with the responsibility to prevent, detect and extinguish fires falling under the jurisdiction of Rural Fire Authorities.
Rural Fire Authorities are independent Organizations with responsibilities for fire control measures including prevention, restriction and suppression of fires in forest and rural areas.
Each Rural Fire Authority falls into one of the three following categories:
State Areas
The Minister of Conservation, through the Department of Conservation, is the Rural Fire Authority for the lands administered by the Department. This may include a one-kilometre fire safety margin around Conservation land.
Rural Fire Districts
Landowners looking to provide greater fire protection for their lands, or territorial authorities that wish to amalgamate their fire protection responsibilities with neighbouring authorities, may establish a Rural Fire District. Rural Fire Districts ranging in size from several thousand hectares to three million hectares are currently in existence. The New Zealand Defence Force is the Rural Fire Authority for eight Rural Fire Districts covering their lands.
Territorial Authorities
Areas that are not covered by an Urban Fire District, a Rural Fire District, or a State area are the responsibility of the Territorial Authority, who becomes the Rural Fire Authority.
The National Rural Fire Authority provides support and co-ordination to Rural Fire Authorities, including the following:
• Developing and managing the Rural Fire Management Code of Practice and conduction compliance audits of Rural Fire Authorities against this Code.
• Promoting and delivering rural fire training.
• Monitoring and reporting fire danger conditions throughout the country to Rural Fire Authorities and the media.
• Providing technical advice to Rural Fire Authorities.
• Providing grants to Rural Fire Authorities for equipment purchases.
Use of prescribed fire
Forestry
Little controlled forestry burning has been carried out in the last ten years.
Other vegetation management (grasslands, bushlands)
Little prescribed burning is carried out.
Agricultural maintenance burning
Burning is still used quite extensively in the high country areas of New Zealand as a land management tool, predominantly in tussock areas to encourage new growth and enable oversowing with grass species in an effort to improve the pasture. Burning is also carried out to remove weed species. Access for stock is also improved after burning.
Most high country burning is carried out in the spring when soil and moisture levels are generally high.
“Let burn” or integration of natural (lightning) and human-caused wildfires
Fires are extinguished rather than left to burn.
Research
Research burning trials are being undertaken.
Practices to reduce wildfire hazards
Fire hazard reduction and forest management preventive measures include construction of bulldozer track fuel breaks, windrowing of materials and silvicultural treatment of forests
Public policies concerning fire
The policies of the country are included in the following legislation:
• Fire Service Act (1975)
• Forest and Rural Fires Act (1977)
• Forest and Rural Fires Regulations (1979)
A National Fire Prevention Campaign is supported by local campaigns.
Fire management needs and challenges
Rural Fire Authorities are responsible for all aspects of fire management outside urban fire districts, including fire suppression. There are a number of options available for Rural Fire Authorities to carry out fire suppression, ranging from using their own staff or contractors, using Volunteer Rural Fire Forces, or contracting with the New Zealand Fire Service. Most Rural Fire Authorities use a combination of these options to effectively protect their area and meet their statutory responsibilities.
The New Zealand Fire Service attends all fires, including vegetation fires, inside urban fire districts. The Fire Service also responds to some fires outside the urban fire districts every year. There are, however, vast areas in New Zealand outside Fire Service coverage.
The Department of Conservation responds to approximately 150 to 200 fires per year, most of which are attended by the Department’s staff.
Other Rural Fire Authorities respond to approximately 2 000 to 3 000 fires per year, some of which are also attended by the New Zealand Fire Service.
Most Rural Fire Authorities have mutual aid agreements with their neighbouring authorities, recognising the fact that regional cooperation is the only efficient manner to deal with larger vegetation fires.
Continued changes in the rural area, the increased use of forest and rural lands and the greater emphasis on environmental protection necessitate the development of new strategies to adequately manage fire in the rural landscape.
These strategies need to be developed cooperatively with the rural fire sector to ensure ownership of the solutions, effective implementation and long term sustainability of any change.
Suggested strategies are:
• Develop rural fire risk management tools;
• Increase the level and focus of fire prevention and mitigation activities;
• Develop regional and national incident management teams;
• Establish seasonal firefighting teams.
Wildland fire research
The aim of the Forest and Rural Fire Research project is predicting where wildfires are most likely to break out, what fuels them and helps them burn and how fire managers can be best prepared to fight them.
The main aim is to develop a New Zealand fire danger rating system; a decision support tool that predicts likely fire behaviour based on weather, fuel and topographic variables. The programme has five main objectives:
• Development of fire behaviour models for New Zealand fuel types that predict how fast fires will spread under different weather conditions.
• Development of a method of assessing curing (or die-off) of grasslands, an essential element in grassland fire behaviour prediction.
• Describing New Zealand’s fire climate using historical weather and fire danger data from the network of remote automatic weather stations around the country.
• Using Geographic Information Systems (GIS) to combine the climatic and physical factors that influence fire behaviour so that maps of current and expected fire danger conditions can be produced.
• Combining this information into a decision support system that provides fire managers with the information to better prevent, predict and fight damaging wildfires.
Source
Craig, A. 2001. Wildland fires in New Zealand in the 1990s: Retrospective and challenges. Int. Forest Fire News 26.
