Fire Futures in Australia:Integrating trajectories of change in climate, ecosystems and fire regimes.

[摘要] This report examines the potential effects of climate change on fire regimes and fire management.It follows on from Williams et al. (2011), which examined aspects of the potential effect of climate change on fuels and fire behaviour, the interactions between weather and fuels in relation to landscape scale patterns of fire, and implications for landscape fire management.Both reports are informed by preliminary work presented in Williams et al. (2009) which discussed potential impacts of climate change on fire regimes and biodiversity from a national perspective.The report examines five key aspects of climate change and fire by:1.Summarising existing knowledge of vegetation dynamics between and within plant communities, focussing on canopy and understorey compositional and structural dynamics in relation to fire frequency, fire intensity and fire severity. 2.Examining potential change in fire regimes across Australia by using an artificial neural network to classify environments, defined by climate, topography and soil variables, according to mapped fire regime classes and then using the classification to project how these environments change spatially under climate change scenarios. 3.Exploring the direction and extent of change in steady state litter fuel load and litter accumulation rate in the forests and grassy woodlands of the state of New South Wales in south eastern Australia using recently-developed empirical relationships between climate, vegetation and litter parameters.4.Investigating the effects of changing climate on fire behaviour using three climate models to consider best, most likely and worst case scenarios for changes to rainfall in a warming climate. 5.Considering adapting fire suppression to changing climate and fire behaviour by modelling the impacts of changing fire behaviour on fire suppression and canvasing options for adaptation.Key findings of our work are:1.The long term effects of the interaction between frequency and intensity on vegetation dynamics and therefore fuel dynamics remains poorly known for many vegetation types and is fundamental to an understanding of how vegetation and fuels will interact under a changing climate.2.Time-since-fire needs to be used in conjunction with severity-of-last- fire to enable a more realistic assessment of the state of vegetation and fuels for fire management planning. At present, there is a lack of data on the recovery time associated with different fire intensities.3.In many forest ecosystems, the compositional effects and dynamics initiated by even high intensity fire are likely to be only short term – ‘transient dynamics’. The largest changes in the short to medium term are likely to relate to structure rather than composition, driven by differential responses of canopy and understorey species to fires of different intensities.4.It is possible to have compositional change without structural change, structural change without compositional change, or both compositional and structural change and for each possibility to apply separately to canopy and understorey species. This will be a function of inherent traits such as resprouting and the interaction of these traits with fire frequency and fire intensity.5.Most landscapes of Australia will experience fire regime environments that are quite dissimilar to those that produce their current regimes, suggesting substantial changes in bush fire in the future driven by changing climate.6.There is a general trend toward drier less productive and less woody fire classes.7.Warmer and drier conditions, may lead to a decrease in litter fuel loads by the late 21st century. Predictions for the major fire-prone vegetation formations in particular, suggest there is potential for major declines in litter fuel.8.The inclusion of dynamic vegetation responses resulted in consistent major predicted declines in fuel in grassy woodlands, dry- and wet sclerophyll forests, relative to the predictio

[发布日期] 2015-02-02 [发布机构] CSIRO

[学科分类] 地球科学(综合)