Recovery Plan for Three Orchid Species in South Australia and Victoria: Caladenia richardsiorum (Little Dip Spider-orchid) Caladenia calcicola (Limestone Spider-orchid) Pterostylis tenuissima

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List of Tables

Table 1. List of orchids covered in this Recovery Plan and current conservation status 5

Table 2. Morphological features, flowering and similar species 7

Table 3. Sub-population and individual numbers for the three orchid species 9

Table 4. Reserved and unreserved sub-populations of Caladenia richardsiorum 13

Table 5. Reserved and unreserved sub-populations of Caladenia calcicola 17

Table 6. Reserved and unreserved sub-populations of Pterostylis tenuissima 23

Table 7. Recovery objectives, actions and performance criteria 31

Table 8: List of national, state and regional stakeholders 37

Table 9. Estimated costs of implementing the recovery actions 38

List of Figures

Figure 1. Distribution of Caladenia richardsiorum, Little Dip Spider-orchid. 16

Figure 2. Current and historic distribution of Caladenia calcicola, Limestone Spider-orchid. 21

Figure 3. Current and historic distribution of Pterostylis tenuissima, Swamp Greenhood 27

Figure 1. Distribution of Caladenia richardsiorum, Little Dip Spider-orchid. 16

Figure 2. Current and historic distribution of Caladenia calcicola, Limestone Spider-orchid. 21

Figure 3. Current and historic distribution of Pterostylis tenuissima, Swamp Greenhood 27

Part A: Overview

1.1 Introduction

This recovery plan covers three nationally threatened terrestrial orchids endemic to mainland south-eastern Australia (Table 1). The nationally Endangered Caladenia richardsiorum (Little Dip Spider-orchid), and nationally Vulnerable Caladenia calcicola (Limestone Spider-orchid) and Pterostylis tenuissima (Swamp Greenhood) are small terrestrial orchids, which have highly fragmented and isolated sub-populations. Caladenia richardsiorum is endemic to the coastal vegetation of the South East NRM Region of South Australia, with an approximate population of 11,000 individuals occurring across 46 sub-populations. Caladenia calcicola consists of only 277 recorded individuals across eight sub-populations, which occur predominantly near Portland and Nelson, Victoria. In contrast, P. tenuissima has a relatively wide distribution, occurring in Silky Tea-tree (Leptospermum lanigerum) Scrub from near Robe in south-east South Australia, through to Wilson’s Promontory National Park in eastern Victoria. There are approximately 17,700 individuals of P. tenuissima distributed across 57 sub-populations. Although there are a high number of sub-populations of both C. richardsiorum and P. tenuissima, only 11 and 12 sub-populations respectively, occur on land reserved for conservation. Current threats to the remaining sub-populations include vegetation clearance, isolation and hence limited opportunity for genetic exchange, grazing, weed invasion, disturbance and destruction of plants from recreational activities.

This national recovery plan is the first for these species and details their taxonomy, ecology, distribution, current and potential threatening processes, as well as the existing and intended management actions required to prevent the further decline of the species.

Table 1. List of orchids covered in this recovery plan and current conservation status.

Scientific name

Common name


Conservation Status



South Australia^

Caladenia richardsiorum

Little Dip Spider-orchid

SA endemic




Caladenia calcicola

Limestone Spider-orchid

SA, Vic




Pterostylis tenuissima

Swamp Greenhood

SA, Vic




Abbreviations: EN = Endangered; VU = Vulnerable; TH = Threatened

*EPBC Act 1999; #FFG Act 1988; ^NPW Act 1972

1.2 Regional Context

The region covered by this plan is predominantly described by two Interim Biogeographic Regionalisation for Australia (IBRA) bio-regions (Environment Australia 2000); 1) the Naracoorte Coastal Plain, stretching across from the Coorong in the south-east of South Australia to Portland in south-west Victoria, and 2) the South East Coastal Plain, which occurs in three distinct segments, two of which, the Warrnambool Plain and Otway Plain, occur in the context of this plan. The remainder of the regions covered by the plan includes the eastern section of the Victorian Midlands, extending from the South Australian border to the Great Dividing Range’s lower inland slopes, and the eastern section of Victorian Volcanic Plain, which in its entirety stretches from Portland to west Melbourne.

The Naracoorte Coastal Plain consists of a series of low coastal and inland dunes that run parallel to the present coastline. The calcarenite inland dunes were formed from marine sands and shell fragments that were subsequently consolidated into limestone. Low-lying flats which lie between the ancient dunes were seasonally inundated, forming extensive wetlands that covered much of the region. These areas have been significantly altered through drainage and agricultural development.

The Warrnambool Plain is characterised by low calcareous dune formations overlayed with nutrient poor soils, which terminate in distinctive coastal cliffs along the coastline. Similar to the Naracoorte Coastal Plain, fertile peat swamplands exist between the calcareous dunes, which are seasonally inundated. To the east of Warrnambool the land is dominated by deeper volcanic soils over limestone. The Otway Plain consists of river valleys, coastal plains and foothills. Much of the native vegetation of these sub-regions has also been cleared for agriculture.

The Victorian Midland is defined by isolated ranges and sloping foothills of the Great Dividing Range, which supports a variety of sclerophyll forests and woodlands. The Victorian Volcanic Plain supports extensive and fertile grassland over a gently undulating basaltic plain, occasionally interrupted by large shallow lakes, stony rises, and extinct low volcanic peaks. Similar to the other bioregions encompassed in this plan, the Volcanic Plains have been intensively used since European settlement for grazing and cropping purposes.

1.3 Relationship to other Management Documents

This recovery plan relates to a range of other regional, State and Federal documents that provide specific recommendations or regional objectives regarding the management of threatened species including;

  • Our Place, Our Future, State Natural Resources Management Plan 2012 - 2017 (Government of South Australia 2012) – the recovery plan meets Objective 12 of the State NRM Plan: “Improve the conservation status of species and ecological communities”.

  • No Species Loss – A Biodiversity Strategy for South Australia (DEH 2006) - contributes to the priority targets by eradicating or halting significant threats, reassessing the conservation status and securing key populations at priority threatened species sites.

  • Biodiversity Plan for the South East of South Australia (Croft et al. 1999) - discusses the importance of conserving a range of threatened species and significant habitat in the region including C. richardsiorum, P. tenuissima, the highly threatened Silky Tea-tree (Leptospermum lanigerum) Scrub in which P. tenuissima occurs, and coastal systems. The plan also prioritises specific coastal areas.

  • South East Natural Resource Management Plan (SENRMB 2010) – this recovery document supports the resource condition targets of the SENRM plan, which include: “Conservation status of threatened species and ecological communities occurring in the south-east will be maintained or improved”.

  • West Victoria Comprehensive Regional Biodiversity Assessment (CVRFASC 2000) - provides an overview of the biodiversity of the region and identifies 63 plant taxa of high regional priority for management, including C. calcicola.

  • Glenelg Hopkins Regional Catchment Strategy (GHCMA 2003) - recognises the high number of threatened plant species in the Lower Glenelg and Portland Coastal sub-catchments including C. calcicola and P. tenuissima. The strategy also sets out Interim Resource Condition Targets that aim to double the cover of depleted Ecological Vegetation Classes by 2030 and all three species are found in highly threatened ecological communities.

  • Corangamite Regional Catchment Strategy (CCMA 2003) - identifies Silky Tea-tree Scrub (habitat for P. tenuissima) as a priority Ecological Vegetation Class and endeavours to protect 2,500 hectares of high priority Silky Tea-tree Scrub remnant vegetation on private land. The strategy recognises the importance of Regional Biodiversity Action Plans, National Recovery Plans and State Action Statements in the planning of threatened species recovery.

1.4 International Obligations

The implementation of this recovery plan is consistent with the following international agreements:

  • 1992 United Nations Convention on Biological Diversity

  • 1992 Rio Declaration on Environment and Development (Agenda 21)

1.5 Storage of Spatial and Other Data

Data relating to the location and management of threatened species and communities are stored in a range of information systems within the South Australian Department of Environment, Water and Natural Resources (DEWNR) and the Victorian Department of Sustainability and Environment (DSE).

The impacts of excessive visitation and illegal orchid collection, although infrequent, remains a high risk to threatened orchid taxa where population sizes are low or where the habitat is very sensitive to trampling. As a result, data relating to exact site locations are not included in this document.

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