Reproductive biology of one rare and three common Sydney Melaleuca species : Melaleuca deanei, Melaleuca nodosa, Melaleuca styphelioides and Melaleuca thymifolia

Abstract

This thesis presents work aimed at determining the reasons behind low reproductive success in Melaleuca deanei F. Muell., a vulnerable species in NSW. A series of comparative studies into the reproductive biology and regeneration niche are reported for M. deanei and three common Melaleuca species from the area: Melaleuca nodosa (Sol. ex Gaertn.) Sm., Melaleuca styphelioides Sm and Melaleuca thymifolia Sm. Measures of population structure were first quantified for each species and for replicate large and small populations of M. deanei; these include plant density, abundance and size class distributions, canopy seed loads and seed viability. The timing, frequency and synchrony of flowering of each species over three seasons were also documented. Smaller populations of M. deanei were found to contain lower quantities of viable seed per square metre, lower proportions of fruiting plants and to flower less frequently in comparison to plants from the larger populations of M. deanei or those of the common congeners. Flowering, when it occurred in M. deanei, was later than the common congeners, from mid-late October through to late November-early December. Increased flowering of M. deanei was documented along road edges and in years following fire. The work also confirmed significantly lower proportions of seedlings in all populations of M. deanei and M. styphelioides. Seedling recruitment in both species is rare and would appear to require specific conditions. These population level studies suggest that rarity in M. deanei is related to low recruitment success, infrequent flowering and low seed loads.

Date of Award	2016
Original language	English