Broom (Cytisus scoparius (L.) Link) and fire: management implications.

Fire is often employed to control populations of weeds especially over large and/or remote areas. However, how fire may favour subsequent re-invasion , either from the original or other weeds is poorly understood. There is a need to know how weed species respond to fire and to incorporate this knowledge into management strategies for both fire and weeds. This paper explores how broom (Cytisus scoparius ) responds to fire. Studies were conducted in New South Wales and Victoria, Australia.Fire can cause high seed mortality in broom seed banks reducing them to less than 10% of pre-fire levels, depending on the timing and intensity of the fire. It is the only potential management tool available that can directly target the seed bank, however, remaining viable seeds in the soil are sufficient for stand replacement. Any effects of fire on seed bank germination and subsequent seedling survival in the field had negligible consequences on recruitment 12 months after the fire. However, seed bank decline in burned soil samples potted out in the glasshouse showed a marked difference compared to unburned over the same period. Burned broom plants die, but lightly scorched plants have the capacity to resprout. Using fire to control broom should be avoided, unless intensive follow-up treatments are planned as part of an integrated weed management strategy.