Melaleuca deanei F.Muell. is a rare, serotinous shrub with a naturally restricted distribution centred over the sandstone ridges around Sydney. Sexual reproduction and seedling recruitment occur rarely, and plants appear to spread and persist largely by clonal root suckering. A potentially outcrossing breeding system, combined with extensive clonality, place M. deanei at a high risk of reproductive failure. Knowledge of the extent of its clonality and breeding system, and an understanding of the distribution and abundance of genetic diversity within and among its populations, will assist conservation management. The present study reports on the extent of clonality, breeding system, levels of genetic diversity, and population differentiation within small, medium and large populations of M. deanei from the northern and southern distribution regions. Multiple stems were found to comprise single genets up to ~10 m diameter on the ground and molecular evidence points to an outcrossing breeding system. Genetic diversity was positively correlated with population size and significant genetic differentiation was shown between northern and southern regions using clustering analyses. Recommendations for in situ and ex situ conservation management based on these results are provided.
Melaleuca deanei F.Muell. is listed under state and national protection legislation occurring as small, disjunct populations restricted to the Central Coast botanical district of New South Wales. This paper reports on the population structure, reproductive output and phenology of large and small field populations of M. deanei, compared with three common congeneric species in the area, namely, Melaleuca nodosa (Sol. ex Gaertn.) Sm., Melaleuca thymifolia Sm. and Melaleuca styphelioides Sm. Both M. deanei and M. styphelioides had few seedlings per population at the sites studied. Results indicated that seedling recruitment is rare and would appear to require specific conditions. In addition, M. deanei had a low incidence of flowering within the small populations, significantly fewer fruiting plants per population and significantly lower numbers of viable seeds per square metre, most likely compounding its limited recruitment. Flowering, when it occurred in M. deanei, was from mid to late October through to late November–early December with increased flowering in response to fire and along road edges. Further study is needed to determine reproductive success at the individual-plant level, the breeding system and recruitment requirements of these species.
Seed size and the regeneration niches of one rare (Melaleuca deanei) and three common (Melaleuca styphelioides, Melaleuca thymifolia and Melaleuca nodosa) Melaleuca (Myrtaceae) species of the Sydney region Abstract Melaleuca species occupy varied habitats across Australia with 16 members of the genus occurring in the Sydney district including the rare species Melaleuca deanei F. Muell. Little is known of their germination and recruitment requirements. This paper reports on experiments assessing the effects of temperature, water potential, fire cues, light and shade levels on germination in four species of Melaleuca native to the Sydney region. For the shade experiment, seedling survival at 12 months is also reported. The experiments tested the hypothesis that M. deanei, which exhibits few seedlings in the field, has limited seedling recruitment because of its particular requirements for germination and establishment. Further, that it differs in these requirements from three common congenerics: M. nodosa (Sol ex Gaertn.) Sm., M. thymifolia Sm. and M. styphelioides Sm. Results indicate that M. deanei has a substantially similar temperature and water potential range for germination to the common congeners from 15 to 35°C, and 0 to −0.65 ψ. Melaleuca nodosa displayed the broadest regeneration niche on all factors assessed. Germination of M. styphelioides was significantly reduced in the dark and M. styphelioides and M. deanei were most sensitive to shade in the seedling establishment/post-germination phase. Melaleuca deanei had significantly larger seed that was slower to germinate in all experiments. Germination of the four species was unaffected by the application of heat and smoke.The substantially similar germination parameters exhibited by the four species, despite differences in habitat, may reflect their close phylogenetic affinities. The effects of fire on stimulating seed release from the canopy, the high-light environment post-fire together with adequate follow-up rainfall may all be critical in seedling establishment for M. deanei.
This paper reports plant-level measures of reproductive performance from large and small field populations of the vulnerable species Melaleuca deanei F.Meull. compared with three common species within the genus: Melaleuca nodosa (Sol. ex Gaertn.) Sm., Melaleuca thymifolia Sm. and Melaleuca styphelioides Sm. Measures reported include average seed numbers per capsule and per plant; average fruit loads per plant; the proportion of buds that become flowers and thence fruits (fruit set); the number of ovules per flower and seed : ovule ratios (seed set); and floral morphologies. Results indicate that when M. deanei flowers, bud to flower ratios and flower to fruit ratios are not reduced compared with the congeners or between large and small populations. Seed loads per plant held by fruiting plants were comparable between the species and between large and small populations of M. deanei. Seed to ovule ratios were in the order of 5–9% in M. nodosa; 5–7% in M. styphelioides; 7–10% in M. deanei; and 12–15% in M. thymifolia. Larval herbivory of ovules was recorded in M. nodosa and pre-dispersal seed predation noted in M. thymifolia. Andromonoecy was recorded in two of the species at rates of 0.9–3.1% (M. deanei) and 2.9–7% (M. thymifolia). Results suggest that seed production within smaller populations of M. deanei is poor because of a low frequency of flowering and a low proportion of flowering plants per population, rather than plant-level pollination, fruit- or seed-set barriers. Further study is needed to determine the triggers to flowering, the breeding systems, the extent of clonality and the germination and establishment requirements in these species.
Abstract:The Duck River Reserve and Rookwood Cemetery in the highly urbanised Auburn district of western Sydney hold small but botanically valuable stands of remnant native vegetation. In the late 1970s, local resident G.A. (Tony) Price, recognised the value of these remnants, both for the species they held and the clues they could give us to the past, and spent three years surveying and collecting plants at these sites. Price recorded the species present and their abundance, and described the habitats in which they were found. He observed the ecology of plant interactions, moisture, shading and fire response, interpolating them into a picture of the landscape and vegetation of the district prior to European settlement. At a time when field botany was inaccessible to many, and the focus of conservation was largely on the broader scale, Price's local scale work at these sites was unusual and important. Though never formally published, Price's 1979 account 'The Vegetation of Duck River and Rookwood Cemetery, Auburn' has been cited in all subsequent work of consequence for the area. This paper presents and reviews Price's work and discusses his observations in relation to the current vegetation of these areas. Tony Price's contributions also highlight the value and role that ordinary citizens can play alongside professional botanists and plant ecologists in long term data collection, considered observation and environmental management. A copy of Price's original unpublished account has been included as an appendix to this paper.
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