What climate change mitigation strategies are in place?

With temperature and rainfall patterns predicted to change across Australia, the potential impacts on forests and forestry are wide and varied.

Increasing carbon dioxide (CO₂) concentrations

General plant research already tells us that increasing CO₂ concentrations should result in increasing plant growth, provided trees are not water-deprived. For the impact of increasing CO₂ on the forestry industry, however, little research exists that can predict the impacts on whole forest ecosystems, and it is the whole forest ecosystem that allows continued tree growth.

There are many other factors that will influence the effect of increasing carbon dioxide concentrations on forest growth. These include pests, weeds, competition for resources; including soil nutrients and water, as well as air quality (Fairweather and Cowie, 2007).

Increasing temperatures and reduced rainfall

Increasing temperatures predicted by the CSIRO to be between 0.4 and 2.0°C  by 2030 will likely mean that the number of very high and extreme fire danger days could increase by as much as 25% by 2020, and 70% by 2050 (Fire and Rescue NSW).  This may impact on the period of time over which hazard reduction burns can be undertaken. Hazard reduction burning is an effective forest management tool as it helps to protect native forests and plantations from the threat of severe bushfires during the warmer and drier months.

Changes in the distributions of flora are likely to occur to some extent over time, as physical tolerances of plant species may prohibit them from occupying a place with less rainfall or more intense temperatures.

Pest incidence

Climate change is likely to affect the incidence and severity of pest and disease outbreaks in native forests and plantations (Fairweather and Cowie, 2007). Changing weather patterns and shifting maximum and minimum temperatures could have the potential to extend the geographic distribution of pests and pathogens, affecting forest communities not previously at risk (Cannon, 2007). For example, plant diseases or harmful insect distributions that are currently restricted to one area of the country due to temperature or rainfall limitations could become a problem for other forest areas in the future.

• Invertebrates can cause damage to forests. Invertebrate pests include insects such as leaf chewing beetles, sawflies, leaf skeletonising moth larvae and sap-sucking psyllids. For example, in pine plantations, the pine-killing wood wasp (Sinex noctilio), the Monterey pine aphid (Essigella californica) and the five-spined bark beetle (Ips grandicollis) all have the potential to reduce commercial productivity.
• Pathogens include diseases, fungal infestations and nematodes (microscopic worms). Pathogens have the potential to cause decreases in forest productivity. For example, the fungus Quambalaria pitereka affects spotted gum (Corymbia maculata) in NSW. Shoot blight and tip death occurs, resulting in loss of growth and tree death in severe cases. Further information on forest pests and diseases can be found at in the ‘Australian State of the Forests Report’ (DAFF, 2008).

Mitigation strategies for climate change

The industry is conducting research and implementing a range of adaptation strategies so that Australian forests can continue to provide wood products at a sustainable level into the future, while maintaining and enhancing forest health.

Before undertaking forestry operations, thorough plans are prepared. Information and observations that are linked to forest health are included in these plans. A survey may identify an insect infestation or tree disease that may influence how a section of forest is harvested so that no timber goes to waste, or so that harvesting in the future is not affected by a tree disease. A pre-operational survey may also find significant habitat of a threatened species or plant that needs to be protected and, as a result, exclusion zones, where no trees are to be harvested, are written into the harvest plan. The plan then provides a clear set of instructions for carrying out the operation.

These measures are what allow forests to be harvested in a sustainable manner.

Harvest plans can take into account early symptoms of physical environmental changes that might be associated with long-term climate change. For example, if there is reduced water availability in a land parcel, the harvest plan could recommend some thinning or the strategic removal of selected trees. Trees suffering from drought stress have reduced vigour, lose their leaves and are also more susceptible to dieback from insect attack. Thinning allows the remaining trees to have more access to water, which then allows those trees to reach their growth potential.