The most potent perils

Deforestation, logging and fire are among the most potent causes of rainforest loss and degradation globally. Alien species invasions associated with fragmented and damaged forests compounds the impacts. Climate change too will exacerbate these impacts as well as causing major damage in its own right.

High-resolution global maps of forest cover change show the highest rates of forest change globally occur in subtropical forests so primary forests are now rare.

Climate change

The rapid rise in concentrations of atmospheric carbon dioxide from pre-industrial levels of 280 ppm to the current 394 ppm has few precedents in Earth’s history, at least in the last 500 million years. Levels continue to increase at faster and faster rates. Deforestation generally accounts for approximately 17 per cent of global carbon emissions — around 1.5 times greater than those from the world’s air, road, rail and shipping traffic combined. Moreover, long-term studies are showing that increased drought-induced water stress followed by extreme weather patterns of heavy rains and wind in both the tropics and subtropics is changing the composition of forests — from ones dominated by larger trees to ones dominated by higher proportions of smaller individuals. This is because the larger trees, the forest giants, are more stressed than smaller trees by the increasingly warming and drying environments. The changes are ‘dwarfing’ our forests!

Logging

Industrial logging is also ‘dwarfing’ our forests. Our early work involved analysis of the industrial forestry paradigm. Logging in the Wet Tropics of Queensland was promoted in the 1980s by the then Department of Forestry as the best possible model for the world to emulate. Assisted by scientists such as Dr Mike Olsen we analysed and ground-truthed their data and found it seriously wanting. We presented our concerns effectively at world forums of the International Timber Trade Organisation, the United Nations Environment Program and the World Resources Institute in Washington DC. The plight of these forests is now well known, with global moves well advanced to protect all remaining primary forests. We continue to be integrally involved in progressing the agenda at these levels.

Fire

Fires are normally excluded from intact old-growth or primary rainforests by their moist microclimates. Exceptions occur during extreme droughts associated with the El Nino Southern Oscillation (ENSO) and other sea surface anomalies. Humans have changed this. Logged and fragmented forests are drier and vastly more ignition sources occur today. Mega-fires particularly in Indonesia and Brazil are having devastating impacts.