Reproductive phenology in relation to fire and substrate in coastal Heath near Lancelin, Western Australia

Abstract

Barrett, S. & Ladd, P. G.: Reproductive phenology in relation to fire and substrate in coastal Heath near Lancelin, Western Australia. — Fl. Medit. 31 (Special Issue): 279-296. 2021. — ISSN: 1120-4052 printed, 2240-4538 online. Plant reproductive phenology has evolved to enable species to persist within the constraints of the environmental conditions in which they grow. Climate is an important control over phenology but other environmental factors such a disturbance will also influence when reproduction can occur. Quantitative reproductive phenology – flowering and fruiting, were examined in heath (kwongan) and coastal scrub near Lancelin, Western Australia. Two questions were addressed how is reproductive phenology affected by time since fire and do communities on different substrates under the same climate have different reproductive timing? In five sites with a range of fire histories differences were observed in both within-year reproductive patterns and total reproductive performance. The most prolific flowering occurred early in the season and preceded the time when the majority of species were flowering. Reproductive activity was more seasonally constrained in the most recently burnt site compared with more protracted flowering at the sites several years after fire. Flowering and fruiting were greatest at the longest unburnt site, more than 6 years post-fire. Life history characteristics and juvenile period of species were important influences on reproductive output, with annuals the main contributors to reproduction soon after fire while woody plants took longer to resume or begin reproduction. A comparison of reproductive phenology on a range of substrates showed the coastal dune scrub vegetation to have more protracted reproductive activity than coastal heathland vegetation. Differences of reproductive timing and intensity in heathland vegetation on different substrate types were not marked. Sites on different substrates but with similar fire histories appeared to be more strongly influenced by time since fire than by substrate.