Observations on the Floral and Vegetative Phenologies of North-Eastern Australian Mangroves

Abstract

The mangrove forests of north-eastern Australia are both species-rich and well developed but there is very little information available on their vegetative growth or flowering and fruiting behaviour. This account attempts to rectify this situation by presenting the results of at least 4 years of field studies and observations. Previous reports recorded no less than 35 mangrove species occumng along the north-eastern coast and observations of the flowering and fruiting status of all these species were made. The results are supported by some litter fall studies and overall they reflect the diversity of mangrove species by displaying a range of peak activity months. However, there are some common trends and most species flower mainly during the dry hot summer (September-December) prior to the rainy season when they drop their propaguies during the morniks of peak rainfall (around February).

Detailed studies of litter fall were camed out in Missionary Bay, Hinchinbrook Island (18° 16̸2S.,146° 13̸2E.), and care was taken to record components of floral development and vegetative growth. The results for five species (Rhizophora apiculata, R. stylosa, R. × lamarckii, Bruguiera gymnorhiza and Ceriops tagal var. tagal) include estimates of mean leaf longevity and also suggest that the floral and vegetative cycles are coordinated.