Factors affecting broom regeneration in Australia and their management implications
Andy SheppardA, Peter HodgeB and Quentin PaynterC
A CRC Weed Management Systems, CSIRO Entomology, GPO Box 1700, Canberra, Australian Capital Territory 2601, Australia.
B CRC Weed Management Systems, NSW Agriculture, c/o CSIRO Entomology GPO Box 1700, Canberra, Australian Capital Territory 2601, Australia.
C CSIRO, Tropical Ecosystems Research Centre, PMB 44, Winnellie, Northern Territory 0822, Australia
Summary
Broom regeneration following disturbance, with and without vertebrate herbivores, was studied at three contrasting sites with differing abundances of native plant species in the Shoalhaven River system in southern New South Wales. This study was part of a larger experiment replicated across four countries in both the native and exotic range of broom. In Australia broom seedbanks of 6000 to 20 000 seeds m-2 had a natural decay rate of 36% per annum. The proportion of the seedbank that germinated each year was highly variable, but sufficient to be the major cause of seedbank decline.
Seedling survival and broom height after three years were similar for all cohorts germinating during the first three years of this study. Seedling survival was higher following cultivation, with grazing and in immature broom stands versus mature broom stands, but lower in sites with a higher native component to the grassland. Broom height after three years was greater when broom was cut and/or the ground cultivated and in immature broom stands, but was unaffected by grazing. The age when broom first flowered varied from three to five years across sites and treatments and was influenced by competition within the grassland and by grazing. These preliminary results are compared with similar data from the native range of the weed. Implications of these results for broom management are also discussed.
Plant Protection Quarterly (2000) 15 (4) 156-161.