Cunninghamia : A Journal of Plant Ecology for Eastern Australia, Volume 7, Issue 2 (2001)
Refine
Year of publication
- 2001 (7)
Document Type
- Article (7)
Language
- English (7)
Has Fulltext
- yes (7)
Is part of the Bibliography
- no (7)
Germination of fresh seeds of the rare arid zone shrub Grevillea kennedyana F. Muell. (family Proteaceae) is most successful at 10°C with light, and 15°C with or without light. The seeds were non-dormant and did not require further germination enhancing substances, such as smoke or fire to achieve > 80% success. These results do not support the role of fire in the management strategies suggested in the Recovery Plan for this species. Grevillea kennedyana seeds are orthodox and can be dried at 15°C and 15% RH and stored at 4 and -18°C for a short period. In relating the results of this trial to the germination requirements of Grevillea kennedyana in the field, it appears that successful germination will require low temperatures (i.e. < 15°C in winter) at the time of seasonal rainfall. Further studies are required to determine the cause of the poor seedling recruitment observed in the field.
Doryanthes palmeri is a giant, flowering succulent herb endemic to north-east NSW and south-east Queensland. Prior to this study, only two D. palmeri sites had been reported in NSW. This study revealed a further nine sites, all of which are restricted to the Mt Warning caldera.
Doryanthes palmeri occurs on infertile lithosols or grows as a lithophyte on bare rock. It occurs in a narrow band of vegetation along the cliff-tops and on steep cliff-faces or rocky ledges in montane heath next to subtropical rainforest, wet sclerophyll forest or warm temperate forest. There are around 6000 mature D. palmeri plants in north-east NSW. Populations at each site occur as clusters on a relatively small amount of the available habitat. The area of occupancy of D. palmeri is less than 1 km2 with an average distance between sites of 6.3 km. However, the distribution consists of four groups of populations with an average of 15 km between the groups suggesting a poor ability to disperse.
There appear to be limits to the extent that plants can expand at some sites which are due mainly to low recruitment of juveniles into the population, illegal seed harvesting and the competition of faster growing native or weed species. The present populations, therefore, are restricted to their current exposed positions. The small restricted, fragmented distribution and current threats to the population suggests that D. palmeri should be regarded as a vulnerable species.
A 0.6 ha area in North Wahroonga, Sydney NSW, where the plant and soil cover had been completely removed to expose the underlying sandstone rock surface, was examined in 1997, c. 70 years after the disturbance ceased. The area has remained relatively undisturbed since the 1920s, and the revegetation has been allowed to proceed unhindered. In total, 146 species were encountered in and around the area, 126 of them occurring in the quarried area. Twenty-six of these species are not native to the area, but they occurred almost exclusively in the south-east quarry working, which is adjacent to the closest residential area. The three quarry workings were clearly floristically distinct from each other, with the south-east quarry working differing from the other two in having many unique species (mainly the introduced species) and the east working being floristically de-pauperate. None of the measured soil physical or chemical variables was particularly correlated with the variation in floristic composition. There was a partial distinction between the plant species composition of the quarried area and the adjacent undisturbed area, with 17% of the native species encountered not occurring in the quarried area and a further 10% showing a significantly lower abundance in this area. However, the distinctive south-east quarry working was floristically no more different from the rest of the quarry than was the native area last burnt in 1990 from the native area last burnt in 1968, and the quadrats in the long-unburnt native area were rather similar in species composition to those of the north and east quarry workings. However, many of the species in long-unburnt vegetation will be represented in the community solely by a soil seedbank, and so this comparison of above-ground vegetation may be artificial. The soil structure and fertility both showed no consistent differences between the native area and the quarried area.
Native plant species were recorded on a small mown remnant of Blue Gum High Forest in Observatory Park, Pennant Hills, in northwestern Sydney, in 1979 and 1988. In 1989 an area was set aside in the Park, in which mowing was stopped and bush regeneration commenced and is ongoing. Native species were recorded 5 times over the following 11 years, during which time the number of native species recorded rose from 47 to 126. The result demonstrates the potential for mown bushland sites containing native species to regenerate with appropriate treatment.
Ecological data in tabular form are provided on 325 plant species of the families Rutaceae to Zygophyllaceae, 236 native and 89 exotics, occurring in the Sydney region, defined by the Central Coast and Central Tablelands botanical subdivisions of New South Wales (approximately bounded by Lake Macquarie, Orange, Crookwell and Nowra). Relevant Local Government Areas are Auburn, Ashfield, Bankstown, Bathurst, Baulkham Hills, Blacktown, Blayney, Blue Mountains, Botany, Burwood, Cabonne, Camden, Campbelltown, Canterbury, Cessnock, Concord, Crookwell, Drummoyne, Evans, Fairfield, Greater Lithgow, Gosford, Hawkesbury, Holroyd, Hornsby, Hunters Hill, Hurstville, Kiama, Kogarah, Ku-Ring-Gai, Lake Macquarie, Lane Cove, Leichhardt, Liverpool, Manly, Marrickville, Mosman, Mulwaree, North Sydney, Oberon, Orange, Parramatta, Penrith, Pittwater, Randwick, Rockdale, Ryde, Rylstone, Shellharbour, Shoalhaven, Singleton, South Sydney, Strathfield, Sutherland, Sydney City, Warringah, Waverley, Willoughby, Wingecarribee, Wollondilly, Wollongong, Woollahra and Wyong. The study area falls within the Sydney Basin IBRA Bioregion.
Families are: Rutaceae, Salicaceae, Sambucaceae, Santalaceae, Sapindaceae, Sapotaceae, Scrophulariaceae, Selaginaceae, Simaroubaceae, Solanaceae, Stackhousiaceae, Sterculiaceae, Stylidiaceae, Symplocaceae, Thymelaeaceae, Tremandraceae, Tropaeolaceae, Ulmaceae, Urticaceae, Valerianaceae, Verbenaceae, Viburnaceae, Violaceae, Viscaceae, Vitaceae, Winteraceae, Zygophyllaceae.
Data are derived from herbarium collections, literature and field observations. It is hoped that the many, often alarming gaps in the information available will stimulate much-needed research into the ecology of more of the species. Information is provided so far as available to us for each plant species in the following categories:
Life History: Growth form, vegetative spread, longevity, primary juvenile period (time from germination to fruiting), reproduction, flowering and fruiting times, fruit/seed type, dispersal, establishment and growth, fire response, interaction with other organisms.
Distribution: Status/origin (native/naturalised), botanical subregions, distribution in Sydney area, selected locations.
Habitat: Habitat, altitude, annual rainfall, typical local abundance, vegetation, substrate, exposure.
Conservation: Conservation status.
Habitat details and population sizes are provided for six populations of the rare leafless saprophytic terrestrial orchid Cryptostylis hunteriana Nichols (family Orchidaceae) from the Wyong-southern Lake Macquarie area of New South Wales. The extent of potential habitat based on known sites on the Central Coast is examined in a regional context, and annual targeted surveys in similar habitat are suggested. Apart from a population of unknown size in Ku-ring-gai Chase National Park, no populations of Cryptostylis hunteriana are at present within conservation reserves on the Central Coast. The paucity of records in the region suggests that any information about ecology or habitat will be beneficial to conservation and management. Adoption of a landscape approach may be the most appropriate avenue to ensure long term conservation. Due to the limited records, the poor representation in reserves and the species' cryptic nature, assessment and survey of all known populations of Cryptostylis hunteriana in New South Wales should be undertaken, prior to a review of its current conservation status.
The Rutaceae is an important worldwide family. In Australia, members of the family have radiated across the landscape from rainforests, moist and dry eucalypt forests, heaths, alpine areas and deserts.
Some 71 native taxa (in 14 genera) of Rutaceae occur in the Sydney Region, representing some 3% of the native vascular plant flora of the region. Species richness is greatest in heaths, woodlands and dry forests on sandstone derived soils. A number of species occur in moist forest, while a few species occur in riparian forests, rainforests or forests on clay soils or soils derived from granite. The most species rich genera are Boronia and Zieria (both 18 species). Fifteen species in the region are rare or threatened at the state or national level, with a further 2 species poorly known and likely candidates as threatened species. There are 17 species endemic to the Sydney region, 11 of which are rare or threatened.
Most species flower in winter to spring with seeds released in October to December. There are two basic modes of dispersal in the family in the Sydney Region. Firstly, a few species, generally associated with rainforests, disperse seeds widely via fleshy fruits that are taken by birds and probably mammals. Secondly, most Rutaceae species have limited dispersal ability and have short range initial ballistic dispersal of seeds from fruits at maturity followed by secondary seed dispersal primarily by ants. In this latter group, seeds are generally dispersed less than a few metres. There is a high level of seed dormancy at seed release. Members of the Rutaceae are likely to have persistent soil seedbanks with germination linked to fire, except perhaps for species in rainforest or rainforest margins (where the nature of possible seedbanks is unknown). Heating of the soil during fire is one mechanism for breaking seed dormancy and allowing germination. Other mechanisms, i.e. smoke and the interaction of fire related germination cues may also be important. Fire is a widespread disturbance affecting vegetation in the Sydney Region. Within the Rutaceae in the Sydney region, a mixture of fire-sensitive and resprouting species occur, although details for many species are lacking. To maintain the floristic diversity in the family, effective management of such plant communities requires sufficient times between fires for seedlings to flower and replenish the soil seedbanks, as well as for juveniles of resprouting species to become fire-resistant.
The ecology of Rutaceae species remains poorly understood, a pattern typical across Australia, with a few notable exceptions. There have been no comprehensive demographic studies of members of the family in Sydney, and only limited attempts to examine aspects of the biology of the species in the family. In particular, the seed biology and ecology of the family and the impact of fire on species are poorly understood. This review poses a number of questions for research on members of the Rutaceae.