Caladenia arenaria Fitzg. Recovery Plan
Threatened Species Unit, Western
The State of New South Wales, Department of Environment and Conservation, 2004
14 Recovery Actions
- 14.1 Action 1 Population monitoring
- 14.2 Action 2 Monitor population fecundity
- 14.3 Action 3 Weed control
- 14.4 Action 4 Monitor hybridisation
- 14.5 Action 5 Establish exclosures
- 14.6 Action 6 Hand pollination
- 14.7 Action 7 Survey
- 14.8 Action 8 Management Agreements
- 14.9 Action 9 Germplasm storage and germination
Monitor all populations each year to determine trends in mortality and recruitment. This requires the establishment of permanent plots, and the recording of the location of individuals so that mortality and recruitment can be followed over time.
Some understanding of population demography is developed.
Pollination and seed set is monitored for each of the populations. At present levels of seed set and year-to-year variation in fruiting numbers are not known. These measures are necessary to provide an understanding of reproductive output so that ameliorative actions can be implemented in the event that population numbers decline.
Reproductive output is known for each population.
The weed flora within each population is monitored. This can be undertaken when the populations are surveyed each year. The principal weeds among the population are introduced annual grasses and dicot herbs. Weed removal experiments will be undertaken to examine the influence of weeds on the populations.
The nature and significance of the impact of weeds or orchid plants as well as appropriate weed control techniques are understood.
The types and proportion of hybrids needs to be monitored in each of the populations. This can be conducted concurrently with the population monitoring.
Hybridisation as a potentially threatening process is better understood.
All populations are subject to grazing by native and introduced herbivores. To monitor the impact of vertebrate grazing exclosures must be established, which exclude rabbits, hares, stock (sheep, cattle and goats) and kangaroos.
The annual monitoring of plants, seed set, hybridisation, weed impacts and grazing impacts would be best incorporated in an experiment at three of the four sites. The populations are too large, and spread over too big an area at Buckingbong, Urana and Lonesome Pine to accurately monitor all individuals. The only practical means of monitoring to sample the population. There are insufficient plants at the roadside location to undertake experimental work. If sufficient plants are found through survey of Yarranjerry State Forest, the population could be incorporated into the experiment.
Four management regimes are needed:
- Exclosure that excludes all vertebrate herbivores with weed control
- Exclosure that excludes all vertebrate herbivores without weed control
- No exclosure, with weed control
- No exclosure, no weed control
The number of replicates and quadrat size will be constrained by the distribution of the orchid. Four replicates with a quadrat size of 5 metres square can probably be accommodated at Buckingbong, Urana and Lonesome Pine.
Exclosures are established to examine the influence of vertebrate herbivores on C. arenaria.
The effect of hand pollination in stimulating seedling recruitment is determined. Hand pollination has been shown to increase recruitment by one to several orders of magnitude in other endangered Caladenia. Several peripheral subsites at the Lonesome Pine SF and the Buckingbong SF populations will be selected where plant numbers are low (to avoid the masking of recruitment outcomes in denser sub-populations) and all flowers hand pollinated (outcrossed or cross-pollinated) each year. Seedling recruitment will be monitored and documented.
The effect of hand pollination as a method of increasing seedling numbers is understood.
The population in Yarranjerry State Forest, discovered in 2000, requires survey to establish the extent and size of the population or sub-populations. The potential locations near Ardlethan and Corowa are surveyed to determine if the populations are extant. Buckingbong State Forest needs survey to define the population boundaries.
Survey in the State Forests is undertaken and the distribution mapped so that forestry operations can be planned to account for the populations. One more season of survey in potential habitat is undertaken to determine if the species is extant at those locations.
State Forests and DEC negotiate appropriate strategies for the protection and recovery of C. arenaria in State Forests. This could be formalised in a Joint Management Agreement (JMA) which would stipulate buffer distances around populations, pre-logging survey intensities, and a protocol for thinning of cypress pine regrowth in potential habitat. Management and research responsibilities could be detailed as well. The JMA would be informed by the results of the experimental work, and so would be developed later in the life of the plan.
Develop strategies with the landowners of the Urana site to minimise the potential impact of farming practises on the population. Discussions be undertaken to enter some form of conservation agreement, preferably a VCA under the NPWS Act.
The impact of forestry operations and agricultural activities on C. arenaria is minimised, and management agreements developed that ensure long-term security.
Note: Cost of JMA shared between SF and DEC (in kind)
Note: Cost of VCA incurred by DEC (in kind)
The populations are separated by around 40-50 km and are isolated, both reproductively and by dispersal of seed. Two populations have a limited extent with the bulk of the individuals occupying less than 1 hectare. The other populations do not occupy more than 100 hectares in total. There is a possibility of the populations becoming extinct from chance events. To eliminate this possibility seed should be collected from a representative sample of individuals in each population and kept in the most appropriate conditions.
Storage in liquid nitrogen has been demonstrated to be optimal for orchid seed and mycorrhizal symbionts from four Western Australian species of Caladenia, Diuris, Pterostylis and Thelymitra (Batty et al 2001). There was considerable variation in response to storage methods, dessication, and the influence of cryoprotectants on the fungi. The knowledge is not yet available to establish a single best technique or routine procedure. As yet eastern Australian species have not been investigated. Study of Caladenia arenaria will be required to determine the most appropriate technique.
The efficacy of storage methods is best conducted by germination trials in conjunction with the fungal symbiont. Testing seed viability using histochemical staining procedures appears to overestimate the proportion of seed that will germinate in culture with the appropriate fungal symbiont (Batty et al 2001). Thus germination trials will need to be conducted with the germplasm storage study.
Optimal storage conditions are established and an adequate sample of seed and the fungal symbiont from each population is stored.