A Study of the Nitrogen-fixing Microbiota of Macquarie Island Plant Communities

Highest rates of acetylene reduction (N-fixation) were found in the leafy lichen Peltigera sp. Colonising herbfields and short grasslands, and in the coastal angiosperm Colobanthus muscoides.

Significant rates of N-fixation were also associated with the liverwort Jamesoniella colorata commonly occurring in coastal and plateau mires, in a moss-bed of Dicranella cardotii colonising a land-slip face on the grassland slopes at 100m altitude, and within polsters of the mosses Ditrichum strictum and Andreaea sp. found in exposed localities on the plateau at 200-300m altitude. It was concluded that the common feature of plants supporting active N-fixation in dry habitats was the dense packing of stems and leaves, enabling water translocation to the cyanobacterial zone by wick action.