This is a contentious area for two reasons: the continental datasets are poor, and the relationships between current fire regimes and biodiversity status are poorly understood.
Two simple descriptive statistics were derived for each landcover type: the relative distribution of area among the five fire seasons (Winter + Spring, Spring, Spring + Summer, Summer, Summer + Autumn) and among the three fire frequencies (1-3 years, 5-10 years, and > 10 years).
The translation of these statistics into indices of disturbance was based on the following reasoning that however plausible, is not yet supported by detailed evidence. We argue that for fire season, the greatest biodiversity disturbance is likely to result from fires in the hottest time of the year. Therefore the fire seasons were weighted for disturbance from Winter + Spring (0) to Summer and Autumn (4). A three-class rating and score of disturbance was then calculated as for feral density; low (0-25,*), moderate (25-50**) and high (> 50, ***).
For fire frequency, it was argued that the most frequent fires offer the largest disturbance to biodiversity. Therefore, the disturbance value of fire frequency classes was weighted as the frequency; from high (2) for the highest frequency to low (0) for the lowest frequency. In a similar manner, a numeric measure was calculated from the mean aggregate product of proportional areas and the disturbance rating; range 0-100. From this measure a three-class rating and score of disturbance was then calculated; low (0-25,*), moderate (25-50**) and high (> 50, ***). The respective fire disturbance scores are set out in Table 17.
Landcover Fire season Fire frequency _______________________________________________________________ xTML4 ** *** eTML3 ** ** wTML3 ** *** xTML3 ** ** eM2 ** ** wM2 * *** xM2 ** ** eL2 * *** wL2 ** * xL2 * ** eM1 ** ** eL1 * ** wL1 ** * xL1 ** * eS3 *** * wS3 *** * xS3 *** ** eS2 *** * wS2 ** * xS2 *** ** eS1 ** * wS1 ** * xS1 ** * xZ3 ** ** xZ2 *** * wZ1 ** * xH2 ** * xG4 * *** xG3 * ** xG2 ** * Littoral * ** xG1 ** * xF1 ** *
