Abstract
Delayed seed release (serotiny) is a syndrome of adaptive significance in a randomly fluctuating environments such as fire-prone and arid ecosystems. Selective forces involving fire, rainfall and seed predators have been suggested as factors influencing serotiny. Callitris preissii is a conifer in the Cupressaceae found only in Australia and New Caledonia and it is regarded as “fire sensitive”. It has excellent potential for erosion control of sandy, alkaline coastal sites and has been used in revegetation in many region in Western Australia. We compared the degree of serotiny among different populations and related this to fire history, climate and seedling predators.The relative ages of cohorts of closed cones were determined on trees in populations ranging from arid interior sites to islands with much higher annual rainfall. The individuals with the greatest serotiny grow at inland sites (Kalgoorlie and Lake Grace), while the plants with the lowest serotiny were recorded at island sites. Seedling recruitment after fire at Boorabin National Park burnt in 2007 was dense and at Cape Le Grand National Park near the south coast of Western Australia a patchy fire produced many seedlings in burnt areas. However in both areas seedlings were absent from unburnt sections. The strong serotiny at these sites ensures an abundant seed rain after fire kills adult plants. The weaker serotiny at the island sites might be thought to relate to the possibility that there is interfire recruitment of the plants.