Phenologies and Litter Fall of Two Mangrove Trees, Sonneratia alba Sm. And S. caseolaris (L.) Engl., And Their Putative Hybrid, S. × Gulngai N.C. Duke

Abstract

Litter fall studies were used to assess phenologies and productivity of Sonneratia alba, S. caseolaris and their putative hybrid, S. × Gulngai, in north-eastern Australia. Annual total litter falls (mean ± s.d.) were 2.5 × 0.5, 2.6 × 1.4 and 3.2 g dry weight m^-2 day^-1, respectively. Litter was partitioned into leaves (47, 61 and 50%), wood (12, 14 and 19%) and reproductive parts (41, 25 and 31%). In addition, monthly reproductive schedules were produced for each taxon. Differences between taxa were pronounced. For S. alba, flowering peaked in December and fruiting in February. For S. caseolaris, flowering peaked in late February and fruiting in June and July. S. × Gulngai was characterised by an apparent combination of events described for the two putative parental forms. This observation, along with a low (a%) fruiting success, provides further support for the hybrid status of this taxon.