| Abstract: | The post-fire development of herbaceous understoreys of Tnodia/mallee burnt in different seasons was studied over a 3 year period in south-western New South Wales, Australia. Near Pooncarie, NSW, a 3 year sequence of above-average rainfall immediately following burning in either the spring, autumn or winter resulted in a substantial increase in species richness and herbage dry matter production. Plots burnt in the spring produced significantly more dry matter than either the autumn or the winter-burnt plots but only in the first growing season after burning. Some species such as Haloragis odontocarpa behaved as ephemerals, being abundant in the first post-fire season, particularly after spring fire, before becoming inconspicuous. Short-lived grasses, such as Stipa species, then became relatively abundant except during drought. Other experiments confirmed the potential of fire to increase herbage diversity and productivity when there was adequate rainfall. During drought, post-fire herbage production was low and the dominant perennials, viz. mallee Eucalyptus and Triodia irritans, regenerated at the expense of the herbs. There was a strong negative correlation between combined mallee and Triodia cover and total herbage cover over time. Seedling recruitment of Triodia irritans was significantly higher on plots burnt in the spring at Pooncarie. |
