Strategic Management Prospects v4.0 Species Forecast Report created on 18 July, 2024
A Species Forecast Report is a summary of currently available information, the predicted 50-year outlook for the species, and potential pathways to recovery through species-specific and landscape-scale actions.
The report collates data from a range of sources including the Victorian Biodiversity Atlas, Strategic Management Prospects (SMP), Specific Needs Assessments, Threatened Species Action Statements, the Genetic Risk Index, and the IUCN Common Assessment Method.
Species Forecast Reports are intended to be used in conjunction with SMP and other spatial outputs in NatureKit, and Action Statements where relevant.
For more information on Species Forecast Reports, SMP and other biodiversity decision support tools, including user guides, visit Choosing actions for nature webpage on the DEECA website.
| Taxon ID | 528595 |
| Scientific name | Caladenia bicalliata subsp. bicalliata |
| Common name | Limestone Ridge Spider-orchid |
| Group | Monocotyledons |
| FFG status | Endangered |
| EPBC status |
The taxon is a flowering plant 6-15 cm tall. Leaf narrow-linear, 10-20 cm long, 2-5 mm wide. Flowers 1 or 2; perianth segments 1-2.5 cm long, flat in basal half, margins inrolled in distal half, greyish white, sometimes with darker stripes, not spreading widely; dorsal sepal 1.2-2.5 cm long, 1.5-2.5 mm wide, incurved; lateral sepals 1.2-2.5 cm long, 2-3 mm wide, obliquely deflexed; petals 1-2 cm long, 1-2 mm wide, obliquely erect to horizontal. Labellum 6-8 mm long, 6-7 mm wide (when flattened), cream with reddish stripes breaking up into spots and blotches; margins with short blunt teeth, apex recurved, lamina calli in 2 rows, anvil-shaped. Flowers from September to October (VicFlora 2018). Caladenia bicalliata has short-lived flowers and is apparently self-pollinating, although flowers generally open freely, if only for a few days (Backhouse et al. 2016). Spider-orchids, in general, use either food deception or sexual deception for pollination, the usual pollinator is male wasps from the family Thynnidae. A scent that mimics female thynnid wasp pheromone is produced by the glandular tips of the sepals and acts as a sexual attractant for the pollinators. Once the pollinator reaches the flower, it attempts to copulate with the labellum of the flower, mistaking it for the female wasp, and effects pollination (DSE 2000). Spider-orchids generally reproduce from seed. The fruits normally take 5-8 weeks to reach maturity following pollination and each mature capsule may contain tens of thousands of microscopic seeds that are dispersed by the wind when the capsule dries out. Most spider-orchids grow in a complex relationship with mycorrhizal fungi which is critical for growth and development. The fungus assimilates some nutrients for the orchid, but the degree of nutritional dependence upon the fungus by spider-orchids is not clearly understood. Some spider-orchids have survived for at least 17 years in the wild, however longevity of most taxa is not known (DSE 2000). Most terrestrial orchids have evolved under conditions of hot summer fires, generally when the plants have been dormant. Some Caladenia taxa flower vigorously following hot summer fires, but this may be as much the result of the removal of surrounding vegetation and reduced competition as any chemical effect of the fire. The timing of fire is important, with the best time during late summer or early autumn, after seed dispersal but prior to new plant emergence. Rainfall and temperature also influences flowering. Flowering is often aborted when periods of sustained hot, dry weather follow flower opening (DSE 2000).
The taxon is known from just a single location and subpopulation of fewer than 100 plants, near Kentbruck in the Discovery Bay Coastal Park in south-western Victoria. The entire population is within a conservation reserve (VicFlora 2018). The taxon was only discovered in Victoria in 2009 and nothing is known of its previous distribution or abundance in Victoria, where it reaches the extreme eastern limit of its national range. Its specialised habitat is extremely limited in Victoria, so the taxon is likely to have always been rare.
The taxon occurs on low coastal scrub on consolidated sand dunes with exposed limestone rocks on sandy loam soils (Backhouse et al. 2016; VicFlora 2018).
No genetic risk information is currently available.
The Habitat Distribution Model (HDM) layer shows the modelled distribution of habitat for Limestone Ridge Spider-orchid in Victoria. Red shading indicates areas of habitat with relatively higher suitability, compared with yellow shaded areas. HDMs are developed by combining Victorian Biodiversity Atlas (VBA) occurrence records for the species with a range of environmental variables to predict where the most suitable habitat for the species is in Victoria. Species may not always occupy areas of suitable habitat. Threatening processes (prior or ongoing) and disturbance regimes (e.g. fire, timber harvesting) may stop species from occupying otherwise suitable habitat for periods of time. Management actions often focus on currently occupied areas, however management of unoccupied areas can also be important to allow populations to re-establish.
No Habitat Distrabution Model is currently available.
No Species Forecast data is available because Limestone Ridge Spider-orchid is not yet included in our decision-support tools.
A Species Forecast is the estimated likelihood of a species being present in 50 years time. The data for Species Forecasts is drawn from DEECA’s decision support tools, Strategic Management Prospects and Specific Needs Assessments.
Many species benefit from the management of widespread threats, such as weeds and pests, and the benefit of these landscape-scale actions to ~4,200 species is modelled in Strategic Management Prospects. In addition to landscape-scale actions, some species also need actions that improve or protect habitat at certain sites, such as nest boxes or hollow logs, or actions to improve certain populations, such as gene mixing or translocation.
As part of a continuous improvement program for our decision-support tools, we are working to expand the scope of actions modelled in Strategic Management Prospects, and to build the dataset of species benefits from location-specific and population-specific actions.
We can use this data to consider how different actions may benefit a species and examine how different types of on-ground management may contribute to a species’ recovery in 50 years, to develop a Species Forecast.
No Species Forecast data is available because Limestone Ridge Spider-orchid is not yet included in our decision-support tools.
The benefit data in SMP can be used to consider what the Limestone Ridge Spider-orchid’s prospects are if the landscape scale management actions in SMP are implemented.
No Species Prospects figure is available becuase Limestone Ridge Spider-orchid is not yet included in SMP.
For more information on the decision support tools, products and underlying data used in this report, and how the data is collected and developed into products, please visit the following links:
These links include information on how to provide data and feedback into these products.
The Species Forecast Reports will be updated periodically to reflect changes and improvements in the products and tools that inform them (e.g., following updates to SMP).
As the data contained in Species Forecast Reports is drawn from multi-species datasets, it is not currently possible to incorporate species-specific information or feedback directly.
For help or further information get in touch by visiting Choosing actions for nature webpage on the DEECA website.
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