RECOVERY OF TALL OPEN EUCALYPT FOREST IN SOUTH-WESTERN AUSTRALIA FOLLOWING COMPLETE CROWN SCORCH

We investigated the response of overstorey and mid-storey trees in tall open forest of Eucalyptus diversicolor F. Muell., Eucalyptus jacksonii Maiden, and Corymbia calophylla (Lindl.) K.D. Hill & L.A.S. Johnson over an eight-year period following complete crown scorch by high intensity fire in March 2001. More than 90 % of E. diversicolor and E. jacksonii and 85 % of C. calophylla remained alive four years after fire, having replaced their crowns by re-sprouting from epicormic buds on the stems and larger branches. Mid-storey trees were more severely affected by fire with almost one third of Allocasuarina decussata (Benth.) L.A.S. Johnson stems and all above-ground stems of Agonis flexuosa (Willd.) Sweet killed back to ground level. Abundant seedling regeneration of E. diversicolor and E. jacksonii developed in the year following the fire but seedling density and stocking declined progressively over subsequent years. Survival of E. diversicolor seedlings was higher than for E. jacksonii seedlings, consistent with findings of earlier research. For both species, initial seedling densities were significantly greater within 25 m of potential seed trees, but seedling density was otherwise unrelated to the basal area of surrounding forest. Eight years after the fire, 38 % of sample quadrats (4 m(2)) were stocked with one or more eucalypt saplings, with saplings of E. diversicolor and E. jacksonii having a mean height of 5 m. Saplings established following the 2001 fire could add a further age class to the stand provided that this cohort persists during subsequent fires. The results of our study provide further evidence to support the view that tall open eucalypt forests in south-west Western Australia rarely experience complete stand replacement even following intense fires, and that multi-aged stands are common.