A rate of spread index for fires in spinifex fuels

Fires in spinifex occur throughout arid and semi-arid parts of Australia and in some cases can affect large tracts of the landscape with associated environmental impacts. In response to this environmental challenge an empirical model for the prediction of fire spread rate in spinifex fuels has recently been developed, based on a number of experimental burns conducted in Western Australia. In other research related to fires in grasslands, a simple rate of spread index for quasi-equilibrium fire spread was developed and, despite its simplicity, was shown to provide practically identical output to current operational grassland fire spread prediction models. This simple rate of spread index for grasslands conceptualises the rate of fire spread as wind speed divided by fuel moisture content, where fuel moisture content is estimated using a fuel moisture index (FMI). Such a conceptualisation embodies the notion that fires will spread faster in windier conditions and in fuels that are drier. The rate of spread index, as it applied to grassfires, also incorporates a term that accounts for an intensity-dependent indraft that counters the prevailing winds at the fire line. As such, the rate of spread index can be viewed as a two parameter model for quasi-equilibrium fire sprea

How does ecological disturbance influence genetic diversity?

Environmental disturbance underpins the dynamics and diversity of many of the ecosystems of the world, yet its influence on the patterns and distribution of genetic diversity is poorly appreciated. We argue here that disturbance history may be the major

Complex responses of birds to landscape-level fire extent, fire severity and environmental drivers

Aim: To quantify bird responses to a large unplanned fire, taking into consideration landscape-level fire severity and extent, pre-fire site detection frequency and environmental gradients. Location: South-eastern Australia. Methods: A major wildfire in 2009 coincided with a long-term study of birds and provided a rare opportunity to quantify bird responses to wildfire. Using hierarchical Bayesian analysis, we modelled bird species richness and the detection frequency of individual species in response to a suite of explanatory variables, including (1) landscape-level fire severity and extent (2) pre-fire detection frequency, (3) site-level vegetation density and (4) environmental variables (e.g. elevation and topography). Results: Landscape-level fire severity had strong effects on bird species richness and the detection frequency of the majority of bird species. These effects varied markedly between species; most responded negatively to amount of severely burned forest in the landscape, one negatively to the amount of moderately burned forest and one responded negatively to the total area of burned forest. Only one species - the Flame Robin - responded positively to the amount of burned forest. Relationships with landscape-scale fire extent changed over time for one species - the Brown Thornbill - with initially depressed rates of detection recovering after just 2 years. The majority of species were significantly more likely to be detected in burned areas if they have been recorded there prior to the fire. Main conclusions: Birds responded strongly to the severity and spatial extent of fire. They also exhibited strong site fidelity even after severe wildfire which causes profound changes in vegetation cover - a response likely influenced by environmental features such as elevation and topography

Exploring the role of fire, succession, climate, and weather on landscape dynamics using comparative modelling

An assessment of the relative importance of vegetation change and disturbance as agents of landscape change under current and future climates would (1) provide insight into the controls of landscape dynamics, (2) help inform the design and development o

Fire, Science and Society at the Urban-Rural Interface

The drama of urban-rural interface fire is a feature of summer newscasts in south-eastern Australia. Fire-suppression agencies report on their activities and on threats to homes. At another level, scientists grapple with the problems of predicting fire spread, recommending house-construction methods, advocating human-safety measures and anticipating environmental effects. The householder can be largely unaware of a fire threat or have expectations of total protection from suppression agencies. Houses can burn down and fatalities can occur. This paper considers a number of the issues surrounding this 'bushfire problem'. Using examples based on the fire event experienced under extreme weather in Canberra, Australia, in 2003, simple models and calculations are presented for: the fire-awareness of householders; the proportion of 'knowledgeable' householders; the capacity of the brigade suppression system; demands for water from the mains; stay-or-go recommendations; and, house loss in relation to householder occupancy during fire. A set of testable hypotheses is suggested. The general sociopolitical problem is how to meet a rare, extreme, short-term demand for resources that far exceeds normal supply. The conclusion that householders need to be self reliant is apparent. The general scientific problem is one of too many variables and too few data for statistical analysis

Landscape fires as social disasters: An overview of the bushfire problem

The 'landscape', 'bushfire' or 'forest-fire' problem is exemplified by the destruction of homes and human lives by landscape fires raging out of control. The 'problem' involves a series of landscapes (e.g. wildland and suburb), a series of systems (e.g. biophysical system and environmental-effects system), and a series of time phases (e.g. planning phase). It is a multi-stakeholder, multi-variable, multi-scale problem. Land uses, like 'farmland', imply a set of specific assets and, therefore, particular perceptions of losses. In all land-use designations, at any one point, fire-proneness may be seen as a function of exposure to ignition sources (embers, burning brands or flame radiation and flame contact) and the ease of ignition. The landscape-fire problem has multiple partial 'solutions', not just one overall solution, and these involve social governance, land management (public and private), suppression capacity and personal preparedness. The problem needs to be addressed at multiple temporal and spatial scales in an integrated fashion for the outcome to be of maximal benefit. There will always be a residual risk of severe fire occurrence. Minimisation of residual risk requires effective land management, recurrent funding and the perpetual vigilance of all parties