Forest Fire Modifies Soil Free-Living Nematode Communities in the Biriya Woodland of Northern Israel

We hypothesized that differential tree damage caused by fire in a Mediterranean conifer forest would reduce soil free-living nematode abundances and species diversity and affect the nematode community's trophic structure. Nematode communities were examined in soil samples collected from 4 subsites according to damage caused by the fire: all trees completely burned; burned trees with some live canopy foliage; burned trees removed by salvage logging, and a patch of unburned forest. Abundances of 2 bacterium-feeding nematode genera (Cephalobus spp. and Acrobeloides spp.) were higher in burned forest soils than in unburned forest soils. Other species of bacteria-feeding nematodes were less abundant in burned forest soils than in unburned forest soils. There was no effect of fire on the abundances of fungus-feeding nematodes. Eight of 13 species of omnivore-predator nematode genera were more abundant in unburned forest soils than in burned forest soils. Only 2 omnivore-predators with very low abundances were found in soils of the burned forest but were absent from unburned forest soils. Fire resulted in a lower trophic diversity, lower generic diversity, and lower generic richness in burned forest soils than in unburned forest soils. The fungivore-bacterivore ratio was similar in burned and unburned areas. Maturity indices were lower in burned than in unburned forest soils. The reported increased abundance of bacterium-feeding nematodes 6 wk after the fire remained consistent in burned forest soils 2 yr post-burn in this study. Other short-term changes in nematode communities did not persist in this study during the 2nd year post-burn.