Melaleuca deanei mostly occupies broad flat ridgetops, dry ridges and slopes (Benson & McDougall 1998). In southern Sydney, the species is most often found on flat broad ridge tops more than 100 metres wide (Travers Morgan 1990). The altitudinal range of M. deanei is between 20 and 410 metres above sea level, and annual rainfall in the species’ distribution ranges from 1,000 to 1,400 mm (Benson & McDougall 1998).
Melaleuca deanei is strongly associated with sandy loam soils that are low in nutrients, sometimes with ironstone present (Benson & McDougall 1998). In a study of ten populations in southern Sydney, Travers Morgan (1990) found that the species most frequently occurred on deep and well developed lateritic soils, i.e. soils where an indurated iron-rich layer usually overlies a mottled clay and a pallid clay (Murphy 1993).
* according to the vegetation mapping in Tindall et al. (2004)
**excludes 14 populations located in areas of Gosford, Hawkesbury, Hornsby, Liverpool, Sutherland and Campbelltown LGAs that are not covered by Tindall et al. (2004)
Specht (1981) describes the following four different vegetation associations for M. deanei: (1) forest, open forest, woodland and open woodland; (2) low open forest, low woodland and low open woodland; (3) scrub, open scrub and tall scubland; and (4) heathland, open heathland and shrubland.
Several authors state that there seems to be no obvious association between M. deanei and any particular components of the ridgetop flora (Specht 1981; Travers Morgan 1990; Felton 1993; Benson & McDougall 1998).
4.5.3 Habitat Critical to Survival
Habitat critical to the survival of M. deanei includes:
the area of occupancy of populations;
areas of similar habitat surrounding and linking populations;
additional occurrences of similar habitat that may contain undiscovered populations of the species or be suitable for future translocations.
Apart from the area of occupancy of known populations, the location of habitat critical to survival has not been mapped.
Melaleuca deanei is a single or multi-stemmed shrub to 3 metres high (Benson & McDougall 1998). The longevity of individuals is reported to be greater than 100 years (Benson & McDougall 1998). As a clonal species, M. deanei has the ability to re sprout from a swollen rootstock (lignotuber) to produce coppiced growth, and it can also sucker from its rootstock (Felton 1993).
The exact age at which M. deanei starts to produce flowers and seed is unknown. Some observers estimate this age as 3-4 years (Wrigley pers. comm. cited in Maryott-Brown & Wilks 1993), while others claim that it may take as long as 10 years (Ross Doig, Australian Plant Society, pers. comm.). Melaleuca seedlings, in general, take between 7 and 20 years to start flowering (Holiday 1999, cited in Virtue 1991).
4.2Pollination, flowering and seed production
It is not known how M. deanei is pollinated, though insects are the most likely group of pollinators (Turnbull & Doran 1997 cited in Virtue 1991). Self-fertilisation of M. deanei should also not be ruled out (Virtue 1991).
Clonal plants, such as M. deanei,are known to produce flowers and seed infrequently and at irregular periods of time (Benson & McDougall 1998). Flowering has been observed in spring (Fairley & Moore 1989; Wrigley & Fagg, 1993) and summer (Beadle et al., 1983; Maryott-Brown & Wilks 1993).
Infrequent flowering was evident when some populations did not flower for more than 4-5 years (Benson & McDougall 1998), for 15 years (R. Payne pers. comm., cited in Benson & McDougall 1998), or for many years (Doig & Thumm, pers. obs.). In contrast, one population in Royal National Park has flowered annually for a number of years (Felton 1993). In the populations surveyed for the present recovery plan, only approximately half (20 of 43 surveyed) showed evidence of flowering (including the presence of fruit; Table 6, Appendix 3).
Seed production is described as poor and infrequent by several authors (Virtue 1991; Travers Morgan 1990). For example, only 5 of 28 populations surveyed were carrying seed capsules (Felton 1993).
Low levels of flowering are apparently common in many other Melaleuca species (Travers Morgan 1990; Virtue 1991). Felton (1993) suggests that in M. deanei, thismay be a result of the following two factors: first, this species can re-sprout and hence often invests energy in vegetative reproduction rather than flower and seed production. Second, a specific stimulus (or set of stimuli) may need to trigger flowering in the species, e.g. fire or high/prolonged rainfall. However, Felton also observed that time since last fire did not influence flowering of M. deanei, nor did other variables, such as plant height.
The only variable of importance in Felton’s study was the size of M. deanei populations, as low density stands appeared less likely to flower than high density stands. The important role of population size is supported by Virtue (1991) who observed that seed set appeared to be greater in large populations. It is also supported by the data in this recovery plan (Appendix 3, analysed in Table 6): all populations with more than 100 ramets produced seed, and populations with less than 10 ramets were most likely to contain no seed.
Table 6. Presence of seed by population size class
The relationship between population size and fruit or seed production may be explained by crossbreeding. Virtue (1991) suggests a requirement for crossbreeding in the species, that is, for breeding between different individuals.
In summary, observations so far indicate that recruitment of M. deanei is more likely to result from vegetative reproduction rather than from seedlings. Further research is required to determine the detailed causes for the limited recruitment from seed in this species.