Flowering and flooding: factors influencing shoot production in a semelparous bamboo

Culm recruitment by semelparous bamboos has been reported to be severely depressed in the year prior to flowering, providing forewarning of flowering and subsequent die-off. However, supporting data are scant. We monitored productivity in 30 clumps in a wild stand of the riparian bamboo Bambusa arnhemica for four years, following which the clumps flowered and died. Stand-level productivity in the year prior to flowering was a minimum of 78% lower than previous years. However, the rate of depression was unevenly distributed, being close to 100% among clumps lower on the river bank and no more than 50% higher on the bank. This may be due to the impact of early and prolonged flooding in that year. Clumps high on the bank may have benefited from favourable conditions associated with above-average wet season rainfall, raising the possibility that resource allocation to vegetative growth and sexual reproduction in semelparous bamboos is flexible.