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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.
Kinchega National Park reserves significant stands of Eucalyptus largiflorens open woodland on the Darling River floodplain, low open Maireana pyramidata shrubland and Casuarina pauper/Alectryon oleifolius open woodland on dune systems. We identify four key issues for the conservation of flora in Kinchega National Park, western NSW. These are:
1) There is an urgent need to initiate regeneration in a number of long-lived perennial trees and shrubs. Failure to do so will lead to local population declines and extinction in a number of species. Reduction in grazing impacts of rabbits and goats is needed. Some degree of rabbit control has been achieved over the last few years through a combination of the effects of the rabbit calicivirus disease (RCD) and an extensive rabbit control program for the reserve.
2) The need to initiate a water plan of management for the reserve to overcome the problem of changes in water flows, flood periodicity and flood magnitude that have occurred in response to water regulation activities on the Darling River.
3) Management of several threatened species and ecological communities on the reserve, in particular the nationally vulnerable species Acacia carneorum and Solanum karsense. Kinchega NP is the only conservation reserve containing populations of these species and these populations are significant for both species.
4) Management of weeds, in particular those with bird-dispersed fruits as these species have the potential to become severe problems on the park.
Other issues that are likely to be significant in the future are salinity impacts and the interaction between grazing pressure, regeneration and climate change.
The flora of the Lord Howe Island Group (31°30’S, 159°05’E) comprises a unique mix of elements of Australian, New Zealand and New Caledonian floras. It is significant for its high degree of endemism and for its structural and biological (leaves, flowers, fruit) role in supporting a diverse array of fauna. Conservation of this flora is dependant upon: reducing current habitat degradation (mostly the result of exotic weeds); minimising any future impacts, in particular the effects of climate change on the unique cloud forests of the southern mountains and the continued introduction and spread of weeds and the pathogen Phytophthora cinnamomi.
We provide a description of the nature of the major threats to the flora and suggest an area-based scheme, focussed on the relative conservation significance of remaining vegetation, as a mechanism for developing priorities for threat mitigation activities. While a number of threat control works are in place, eg. weed control, some re-emphasis is needed. In addition, some new initiatives are required including: reducing the rate of introductions of new exotics; a system to remove potential environmental weeds from the settlement area; phytosanitary guidelines; pathogen quarantine measures; search and removal of environmental weeds from remote areas; and ex situ initiatives for plant species restricted to the cloud forests of the southern mountains.
The grass Elymus multiflorus subsp. kingianus (family Poaceae) is considered to be endemic to Lord Howe and Norfolk Islands. We assessed the conservation status of the taxon on Lord Howe Island, New South Wales, and undertook targeted field surveys across three years and several seasons in suitable habitat, based on the single previously recorded location. We found the species occurrence on Lord Howe Island was highly restricted, with only a few plants found at 2 locations in close proximity. A number of exotic grasses pose a threat to the long-term conservation of the taxon, which was assessed as being eligible for listing as critically endangered under the NSW Threatened Species Conservation Act 1995.
Seed production varies from year-to-year in most species. Factors influencing this variation can include pollination and dispersal mechanisms, seed predation and resource availability. Here we examine a long-term (12– year) photographic record of seed cone production for the Australian endemic conifer Wollemia nobilis (Araucariaceae). Coefficient of variation (a commonly used measure of variation in seed production) was low for the two trees analysed, compared with published values for other polycarpic plants. Nevertheless, cone production decreased with increasing spring minimum temperatures (during pollination) and increased with summer total rainfall (during cone initiation). Hence, Wollemia nobilis cone production was correlated with weather, in line with the resource-matching hypothesis. Impacts of variation in cone production on the Wollemia nobilis population are likely to be buffered by the shade-tolerant, slow-growing juvenile life stage of Wollemia nobilis.
Introduced perennial grasses are capable of altering the habitat of native species, causing reductions in population size and vigour, and potentially affecting life-history processes such as survival, pollination and seedling recruitment. We examined the utility of herbicide treatment on two exotic grasses, Pennisetum clandestinum (Kikuyu) and Stenotaphrum secundatum (Buffalo grass) to restore the habitat of Calystegia affinis, a critically endangered species endemic to Lord Howe and Norfolk Islands. Using two herbicides, Asset (designed to affect only grasses) and Glyphosate (a general herbicide), we compared effectiveness in reducing grass cover on a population of Calystegia affinis. We protected Calystegia plants from the herbicides by ensuring their leaves were covered by plastic bags during herbicide application. Both herbicides were similarly effective in reducing grass cover after four weeks and had no noticeable adverse affect on Calystegia (suggesting the plastic bag protection was effective). After 26 weeks, Glyphosate was more effective in maintaining a reduced grass cover. Plots treated with either herbicide had a greater relative increase in abundance of Calystegia stems compared to untreated controls. The Glyphosate treatment resulted in the greatest relative increase in stem abundance, but this was not significantly greater than in the Asset treatment. We consider that spraying with Glyphosate treatment, with follow-up monitoring and spot-spraying, will assist the recovery of the Calystegia affinis population. Ultimately, the maintenance of a weed-free zone at the forest edge will provide suitable habitat for additional recruitment of this and other native species.