Ontogeny and fire interact to affect competition between grass and shrubs

Abstract

We investigated the effects of fire, grass and acacia age on the relative growth rate (RGR), relative neighbour effect (RNE), height and biomass of acacia and grass in the greenhouse condition. The experiment was arranged a completely randomized design with 10 replicates. Grass and shrubs were grown 17 weeks after establishment, thereafter, fire was applied, and observations were done 16 weeks later. Old grass tussock suppressed acacia seedling and sapling, but young grass facilitated acacia seedling and sapling. Young acacia suppressed the young grass but older acacia facilitated the growth of mature grass tussocks. After remove of biomass and the application of fire there was no significant effect but the height and biomass of all acacia seedlings were negatively affected by grasses In contrast to acacia, the effects of fire on the grass tussocks were reduced the above ground biomass.