Giant sequoia  (Sequoiadendron giganteum)

Giant sequoias take around 20 years to reach maturity and start bearing cones, and the oldest known individuals are over 3,000 years old (2). Pollination occurs between December and May and cones develop during the spring and summer months (4). Seeds are only released as the cones dry out, shrinking and thus revealing gaps from which the seeds can fall; the process is therefore dependent on particular conditions and cones can lay dormant for many years (5). Each cone contains roughly 230 seeds and each tree will have around 11,000 cones at any one time; these tiny winged seeds are dispersed away from their parent tree by the wind, insects and rodents (2). The germination of seeds is, however, also dependent on particular conditions and these tiny, thin seeds require highly favourable soils with no overlying vegetation into which they can bury easily (4). As with other long-lived trees, fire seems to pay an important role in the life of a giant sequoia. A relatively high frequency of low intensity fires helps to rid the area of competitors whilst providing rich soils for the germination of seedlings. The heat generated by fires also helps to dry out the cones and open them. Mature trees are fairly indestructible; the loosely packed fibres in the thick bark are very poor conductors of fire (3).