Fire in the Tropics of Australia

Introduction

The use of fire in tropical regions is of increasing global significance. Conversion of forested land to pasture continues to contribute to deforestation on an unprecedented scale with severe implications in terms of habitat impoverishment, biodiversity loss, decreased soil fertility and global warming from greenhouse gas emissions and loss of carbon sequestration potential. For example, NASA satellite data indicates a 50-percent increase in the number of forest fires caused by fire-assisted pastoralism in the Brazilian Amazon between 1996 and 1997, representing one of the principal means of deforestation in the region. Burning as a land clearance tool is also thought to be one of the principal causes of the 1997-1998 Indonesian fires and, in Europe, the recent wild fires have been blamed by some scientists for the unprecedented rise in atmospheric carbon dioxide in 2002 and 2003 observed at the Mauna Loa Observatory, located 12,000ft up a mountain in Hawaii.

There is therefore increasing need to improve scientific knowledge regarding the ecological effects of fire, an area currently clouded by a high degree of uncertainty and disagreement among experts.

Study site map

This research aims to explore the ecological and economic implications of the use of fire as a land management tool in the wet-dry tropics of Australia. The project was established by Dr Jon Lovett of the University of York in 1997 whilst on a research leave with James Cook University in Cairns and since continued by David Ockwell. This work was carried out in partnership with the managers of Wattle Hills, a property in Cape York Peninsula, Queensland. The study assessed cross-sectional data from vegetation samples exposed to alternative burning regimes and enables monitoring of vegetative changes on burnt and unburnt sites. Vairous aspects of fire policy have also been analysed using social science techniques including discourse analysis and "Q Methodology" (see current work).

Fire in Cape York - some background

Cape York Peninsula is a remote area of wilderness in the tropical far-north of Australia. Roughly equivalent in size to England, Cape York has a population of around 18,000 people, less than in attendance at some third division football matches. The population is mostly concentrated within a few small mining settlements and Aboriginal communities. Despite its relative isolation from human settlement, an estimated 80% of Cape York burns each year as a direct result of human induced fires.

Fire has formed a natural part of the ecology of Australia for many millions of years. More recently, for at least the last 60,000 years, it has been used as a tool by Aboriginals to, for example, drive game into areas for hunting. Many species of trees, plants and animals have therefore become adapted to fire as part of their environment. There are also, however, many species, including most rainforest species, that have not adapted to fire.

Over the last 200 years, since European invasion of Australia, huge changes have taken place in human use of fire on the landscape. In Cape York, as in many parts of Australia, Aboriginal communities have been forcibly removed from their land and replaced by pastoralists who make a living rearing cattle. The pastoralists burn the land in the late stages of the dry season to encourage the growth of green grass for their cattle when food for these foreign introduced animals is most sparse. The early dry season burning practices of Aboriginals which result in cooler, low-intensity fires have, therefore, been replaced by the late dry season burning practices of pastoralists which result in hot, high-intensity fires. Conservation managers also tend to burn areas such as National Parks on an annual or bi-annual basis in order to avoid wildfires later in the dry season. This practice has raised concerns with the impact of such high frequency burning.

Some scientists believe that the changes in burning practices are causing an environmental problem but this is by no means a unanimously held view. Scientists are a long way from properly understanding the ecological impacts of fire. One key debate revolves around whether current burning practices on Cape York are impacting on "biodiversity". Biodiversity refers to biological diversity, or the diversity of living things. The exact rate of global biodiversity loss is not known, but scientists estimate current species extinction rates are between 1,000 and 10,000 times what would occur naturally without human influence. The global reduction of biodiversity is a key international concern as it is thought to threaten the healthy functioning of ecosystems which humans rely on to provide goods and services such as food, energy, building materials and medicines, and to assimilate the waste and pollution we produce as a result of our daily activities.

As well as impacting on biodiversity, fire can also contribute to global warming by killing trees and therefore releasing carbon dioxide back into the atmosphere from the carbon that trees otherwise store in their trunks, branches, roots and leaves. It is the increased levels of carbon dioxide in the atmosphere that are thought to cause global warming. Both in the public consciousness and in policy making an increasing significance is being attached to the potentially catastrophic future impacts global warming may have on global society.