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Burning Issues

Scientists will set fire to 12 hectares of tall-tussock grassland in Otago during the spring and summer to assess the effects of fire on the land's physical (soil fertility) and biological (native flora and fauna) resources.

"Large areas of tussock grassland are being retired from pastoral use and included within the Conservation Estate," project coordinator Dr Ian Payton says. "This raises questions about the extent to which an increase of flammable plant material in tussock grasslands -- that are no longer burned or grazed by stock -- poses an increased fire hazard during the dry summer months.

"Do accidental fires, such as occurred near Alexandra last summer, cause more long-term damage to the native flora and fauna than prescribed burns carried out in late winter or early spring when weather conditions are damp and cool?"

Payton's research involves staff of Landcare Research, Forest Research, AgResearch and DoC, supported by the Public Good Science Fund, DoC, the National Rural Fire Authority and the Hellaby Indigenous Grasslands Research Trust.

His team has completed its pre-burn assessments of the plant and animal populations and the quantities of plant material and nutrients at their two experimental sites in Otago.

"At each site we have nine one-hectare plots. Three plots will remain unburnt, three will be burned under damp spring conditions and the remaining three during summer or autumn when conditions are hot and dry. All we need now are ideal burning conditions [this] spring," Payton says.

The researchers were not able to burn last season because of the predominant northwest weather conditions during spring and the total fire ban in Otago during summer and autumn.

Meanwhile, the Building Research Association (BRANZ) is fighting fires inside computers.

The new BRANZFIRE computer program models overall fire development, and its predictions are being compared with Australian and Swedish experimental data.

Project leader Colleen Wade says BRANZ aims to reduce deaths and injuries by ensuring that fire does not spread prematurely downward through fire-rated floor-ceiling systems.

"This research project entailed a real-scale fire experiment in a 'firecell' [a specially constructed room] consisting of walls of timber frame with paper-faced gypsum plasterboard linings and a complete floor-ceiling system," says Wade.

Measurements during the experiment recorded the relative rates at which fire spread through the walls, floor and ceiling.

Another project aims to reduce fire deaths and injuries from uncontrolled fire spread on exterior cladding materials. Full-scale "flame-spread" experiments were done and, as a result, recommendations have been made for changes to the Building Code Acceptable Solutions.

A fourth project aims to reduce the cost of providing safe and effective lightweight fire barriers in buildings.