BURNING IN A NEW-ZEALAND SNOW-TUSSOCK GRASSLAND - EFFECTS ON VEGETATION AND SOIL FAUNA

Soil conditions, vegetation features and soil fauna were recorded in m ontane tall tussock grassland dominated by narrow-leaved snow tussock Chionochloa rigida ssp. rigida up to 30 months after a spring fire. Bu rning reduced the stature of tussocks and the size and density of till ers in the first growing season. After two growing seasons, tussock ca nopy development and tiller size remained below those found in the unb urnt grassland nearby. New tillers and tussocks established following the prolific fire-induced flowering one year after burning. After the fire and sheep grazing, intertussock cover became progressively domina ted by introduced grasses and herbs. While soil pH, moisture content, bulk density, surface litter and total nematodes showed significant tr eatment (burning) effects, these properties also showed significant ye ar-to-year variation. The greatest increase in any nematode group was in Paratylenchus, a distinctive genus widespread in tussock grasslands and apparently responsive to environmental fluctuation and root devel opment; its population was 100x and 29x greater in the burned area tha n in the control area 16 and 30 months after burning. Subject to detai led testing, populations of mites and collembola may provide relativel y simple indicators of recovery of ecosystem function of such grasslan ds after burning.