Impact of hazard reduction fire on the community structure of Trichocomaceae in dry sclerophyll forest soils

 

Anne-Laure Markovina1, John I. Pitt1, Ailsa D. Hocking1, Deidre A. Carter2, Peter A. McGee3

 

1Food Science Australia, PO Box 52, North Ryde, NSW 1670, Australia

2School of Molecular and Microbial Biosciences, University of Sydney, NSW 2006, Australia

3School of Biological Sciences, University of Sydney, NSW 2006, Australia

 

The effect of low-intensity fire on the community structure of Trichocomaceae was examined in two undisturbed dry sclerophyll forest sites in the Sydney Basin.  The first site (Katandra) had experienced a fire six weeks before sampling.  At the second study site (Tumbi Umbi), the effect of fire was examined a day after fire and subsequently at two and four weeks intervals.

 

Heat treatment is known to activate the germination of ascospores produced by the teleomorphic (sexual) states of some species of Trichocomaceae.  However, the immediate effect of fire on undisturbed fungal communities has not been clarified.  It has been suggested that fire also acts as a disturbance that reshapes fungal communities.

 

The results obtained at Katandra revealed a marked difference in fungal community structure between burnt and control samples.  Control soils supported a community of common, ruderal species typified by an absence of teleomorphic taxa.  Burnt soils, on the other hand, revealed an increase in species diversity and the presence of ascosporic fungi.  Opportunistic species were not encountered in burnt soils.

 

The impact of fire on community structure was immediate at Tumbi Umbi.  All common anamorphic (asexual) taxa isolated from control soils were again eradicated by fire and thus not recorded in burnt soils.  Instead, teleomorphic and heat tolerant fungi replaced many of the ruderals.

 

Common asexual fungi quickly recolonised burnt soils.  Within two weeks, a return of some of the widespread species was noted.  However, many species, including previously undescribed fungi, were not re-isolated from the four week samples.  Fire was found to stimulate the germination of ascospores which appeared immediately after fire and remained in the soil a month following fire.