Microbiology of Post Fire Soils.

Soils harvested from sites post fire possessed culturable microbes. Soils were from a coniferous wooded site with calcareous soils and from a granite-soil previously vegetated with juniper. The wood soils were 2-3 years post fire and were revegetated with almost a monoculture of naturally-seeded mountain hollyhock. At the one year old granite site, no revegetation had occurred. Microbes were cultured from water-based suspensions of the soils and from water washes from the holly hock roots. On a minimal medium, culturable colonies were higher from the burnt- than the control-sites. Colonies also grew on pyrene, used as a model hydrocarbon to mimic hydrophobic deposits in the fire soil, as the sole carbon source. Many of these cells had pink or yellow pigmentation that was not apparent when cells were transferred onto minimal medium.  Identification of these isolates is taking place. These findings suggest that microbial populations that possible can degrade hydrophobic components exist in the fired soils and these may play a role in reducing fire-induced hydrophobicity.