5.0 Biodiversity

Key findings

At a national level, Western Australia has 8 of 12 Australian biodiversity hotspots.
At a global level, the South West is recognised as one of the world's 34 biodiversity hotspots.
WA currently has 362 threatened plants, 199 threatened animals and 69 threatened ecological communities.
Recovery plans have been developed for less than one-third of threatened species and ecological communities.
There is ongoing loss and degradation of biodiversity in WA.
Knowledge about many species and ecosystems and some threats to biodiversity remains inadequate.

Introduction

Biodiversity is defined as the variability within and among genes, species and ecosystems. It covers marine, terrestrial, subterranean and aquatic life and implies a highly complex system of interacting entities that occur over a range of temporal and geographic (from local to global) scales (Department of Environment and Conservation, 2006a). Biodiversity at the species and ecosystem levels are well-understood compared to genetic diversity. In this report, the term 'biodiversity' refers to organisms native to WA. Introduced species are considered threats to biodiversity, and treated as an environmental issue. Western Australia's rich biodiversity can be attributed to the State's large area which spans a huge range of geographical, soil and climatic conditions. Terrestrial ecosystems range from rainforest, savanna woodlands, grasslands, shrublands, heathlands, tall forests and woodlands. Inland water environments include permanent and seasonal waterways and wetlands (see 'Inland waters'). The marine environment is similarly diverse, including coral reefs, intertidal mangrove forests, seagrass beds, sandy beaches, coastal salt marshes, rocky shores, algal reefs and kelp forests (see 'Marine').

Western Australia is home to some of the most unusual and unique biodiversity on Earth. This includes over 11 500 known taxa of vascular plants which include flowering plants, ferns and conifers (Department of Conservation and Land Management, 2004d). This represents about 50% of known Australian vascular plants. Western Australia has eight of the 12 national biodiversity hotspots (defined by having high numbers of endemic species coupled with significant threats), which reflects the State's richness and high endemicity in biodiversity and significant threats. Western Australia also has one of the 18 tropical marine biodiversity global hotspots. Vertebrates are the best known animal group in WA with 220 mammal, 510 reptile, 3028 fish, 77 amphibian and 611 bird taxa formally described. Other groups, particularly fungi and invertebrates, are poorly understood. Marine and aquatic biodiversity is generally less well known and described than terrestrial taxa, and the lack of knowledge remains a significant shortcoming. Western Australia has 3747 islands that are recognised as important refuges for many species (13 fauna taxa are found only on offshore islands, and five are found on both the mainland and islands). The South West part of the State is also one of the world's 34 biodiversity hotspots (Conservation International, 2006). About 80% of native plant species are endemic, meaning that they are not native to any other parts of Australia or the world (Beard et al., 2000).

The conservation of biodiversity and maintenance of wider ecological functions is essential for long-term protection of the environment and human survival. The inter-relationships between plants, animals, microorganisms and the nonliving environment are complex and not well understood. In the absence of knowledge of these interrelationships, the potential for disrupting ecological function and services is significant. Many environmental issues presented in this report can have cumulative effects on the environment, placing biodiversity under increased pressure. Threats to biodiversity not only come from biological and physical processes, but from institutional issues too. Foremost amongst these problems is the failure to adequately value biodiversity in decision-making; but this is exacerbated by shortcomings in knowledge of biodiversity and the lack of commitment and capacity to manage ongoing threats.

Objectives

Improve understanding of biodiversity in WA.
Where possible, reduce or eliminate key threatening processes (both systemic and environmental) to biodiversity.
Conserve comprehensive, adequate and representative biodiversity at the genetic, species and ecosystem scales.
Improve community capacity to understand, manage and protect biodiversity for future generations of Western Australians.

Headline indicators

There is no overall indicator of the condition of biodiversity. This is because of the complexities in measuring diversity and health at genetic, species and ecosystem scales. Reservation of ecosystems can be used as interim headline indicators as it is very important for the long-term protection of the State's biodiversity. Conservation reserves form part of the national reserves system and aim to contain comprehensive, adequate and representative (often abbreviated to CAR) examples of ecosystems (see 'Conservation').

Indicator B1: Percentage of terrestrial biogeographical regions that meet the 15% reservation target.

The benchmark of 15% reservation has been increasingly recognised for terrestrial bioregions (Department of Conservation and Land Management, 2003b). It originates from the Nationally Agreed Criteria for the Establishment of a Comprehensive, Adequate and Representative Reserve System for Forests in Australia (ANZECC & MCFFA National Forest Policy Statement Implementation Sub-committee, 1997), but has been expanded to include other ecosystems as well as forests. The National Objectives and Targets for Biodiversity Conservation (Environment Australia, 2001) requires that a representative sample of each bioregion is protected within the National Reserve System, in the network of Indigenous Protected Areas, or as private land managed for conservation under a conservation agreement by 2005. No formal evaluation has yet been undertaken to assess the State's progress in meeting these targets.

As of June 2005, only 20% of the terrestrial subregions (as defined by the Interim Biogeographic Regionalisation for Australia) met the objective of 15% or more reserved and 11% of the subregions did not contain any formally reserved areas (Table B0.1). About 7% of WA's terrestrial area is currently reserved in the formal conservation estate, although other forms of informal conservation measures are present (see 'Conservation').

Indicator B2: Percentage of marine biogeographical regions that have no formal reservation.

The National Objectives and Targets for Biodiversity Conservation requires that progress be made towards the establishment of a comprehensive, adequate and representative system of marine protected areas. However, no specific percentage targets for marine regions or ecosystem types have been set. Most marine bioregions have a very low level of reservation and 65% of bioregions had no marine reservation as of June 2005 (Table B0.1). The Ningaloo bioregion had the highest level of reservation (82% of its area).

Table B0.1: Terrestrial subregions and marine bioregions in WA that meet various levels of reservation, as of June 2005.

Data source: Department of Conservation and Land Management [ver. 2006]. Note: a) Includes the formal conservation reservation system only. Data from Indigenous protected areas and private land not included. b) Marine bioregions are defined by the Interim Marine and Coastal Regionalisation of Australia.

Overall condition

Indicator B3: Extent of native vegetation remaining.

Many WA terrestrial subregions have a high percentage of their native vegetation remaining (i.e. 41 of the 54 terrestrial subregions have 96% or more remaining) (Figure B0.1). Many South West bioregions have little native vegetation remaining (Department of Conservation and Land Management, unpublished data). For example the western Avon Wheatbelt subregion has 8.6% of its pre-European settlement vegetation remaining and the eastern Avon Wheatbelt subregion has 18.6%. Overall, about 40% of the pre-European settlement extent of native vegetation still remains in the South West.

In comparison, the rangelands retain a much higher percentage of native vegetation. The amount of native remaining vegetation is generally correlated with the amount of stress that those ecosystems are under (Figure B0.2). However, there are a number of landscape level threats (such as changed fire regimes, the impacts of introduced species and Phytophthora dieback) which are not directly related to the amount of remaining vegetation. In addition, the extent of fragmentation (or connectedness) of the landscape is as important as the area of vegetation cover. When small remnants of native vegetation remain but are not connected to other similar areas, they become islands of vegetation in a sea of agricultural land or urban development, and the genetic diversity and ecosystem resilience declines.

Figure B0.1: Percentage of pre-European vegetation that currently remains in terrestrial subregions.

Data source: Department of Conservation and Land Management [ver. 2005]. Analysis: Department of Agriculture; Department of Conservation and Land Management. Presentation: EPA.

Indicator B4: Continental stress class.

'Continental stress class' is a method of describing landscape health in Australia at bioregional scales (Morgan, 2001). Bioregions are areas defined by common natural characteristics, such as vegetation types, geology and landforms. The continental stress class is determined by a variety of factors including level of reservation, number of threatened species and communities, and number of pest and weed species. The continental stress classes have been adjusted in other publications using expert opinion (for example, see Department of Agriculture et al., 2003, and May & McKenzie, 2003).

The South West wheatbelt is the highest stress area for biodiversity in WA, due to widespread loss of native vegetation, fragmentation of habitat, land salinisation, and relatively small areas protected in the conservation estate (Figure B0.2). Other coastal parts of the South West and the Mid West also show high levels of stress on biodiversity. Land development and associated clearing and fragmentation, Phytophthora dieback and weeds are examples of pressures in these regions.

Much of the Kimberley region and the central desert areas have the lowest stress on biodiversity. It should be noted that continental stress is under-represented in some Pilbara and Kimberley subregions, especially those impacted by frequent and extensive fires, introduced species and overgrazing. Also, large areas of reserved land have skewed the assessment towards less stress than is otherwise observed on the ground. Some groups of organisms have undergone considerable decline, such as small and medium-sized mammals. However, many ecosystems in these areas have retained their pre-European vegetation and are in better condition than those in the South West.

Figure B0.2: Continental stress class of Western Australia's terrestrial subregions.

Data source: Morgan (2001). Presentation: EPA.

Indicator B5: Number of threatened species and ecological communities.

Threatened plants and animals are ranked as critically endangered (CR), endangered (EN) or vulnerable (VU), using criteria set out by the World Conservation Union (formerly known as the IUCN). Several criteria for listing plants, animals and threatened ecological communities in WA include having a low number of remaining individuals, populations or occurrences; a small or highly contracted range; susceptibility to known threats; and decline in habitat quality. Listed threatened plants and animals appear in wildlife conservation notices, published annually by the Western Australian Government Gazette. Currently there are 379 threatened plants, 204 threatened animals and 66 threatened ecological communities in WA (Table B0.2). Further there are 14 plants, 18 animals (mostly mammals) and 3 ecological communities that are thought to be extinct or destroyed (Table B0.2). Threatened plants are also known as Declared Rare Flora.

Table B0.2: Number of threatened flora, fauna and ecological communities.

Data source: a) Government of Western Australia (2006), b) Department of Environment and Conservation [ver. Feb 2007], c) Department of Environment and Conservation [ver. Jan 2007], d) Department of Conservation and Land Management [ver. Jan 2004] (no further communities have been endorsed since this time).

Listed species or communities are not necessarily the only ones in danger of extinction, and the listing process (especially for threatened ecological communities) is incomplete and is thought to under-represent the true number of threatened species and communities. In addition to threatened species and ecosystems, an additional list of 'priority' flora, fauna and ecosystems is used to reflect those which are poorly known, where special survey effort is needed, or to designate taxa that are considered naturally rare.

The number of threatened and priority flora and fauna has increased over time - a total of 2619 taxa (including 2309 flora and 310 fauna) were listed in 1998, while 3022 taxa (including 2625 flora and 397 fauna) were listed in 2006-07 (Table B0.2; Department of Conservation and Land Management, 1998 & 2006; Department of Environment and Conservation, unpublished data). This represents increases of 14% for flora and 28% for fauna being flagged as priority or threatened since 1998. However this may reflect increases in taxonomic revision, curation of collections, improved data management and field investigations, and may not necessarily represent a change in the conservation status of the State's wildlife (Department of Conservation and Land Management, 2005a).

Some taxa may improve categories following population recovery, or as surveys reveal more populations. Threatened plants, animals and communities are found throughout WA (Figures B0.3, B0.4, B0.5) but the Swan Coastal Plain and the South West have the highest density of threatened flora, fauna and ecological communities. The Kimberley area includes a large number of threatened fauna snails which are restricted to small areas of rainforest vegetation. Barrow Island stands out as having a very high number of threatened fauna (20 taxa) because it is home to many animals that are no longer found on the mainland, including a turtle, a bird and many cave-dwelling animals (such as a fish, snake, spider and many water-dwelling crustaceans).

Figure B0.3: Number of declared rare flora per terrestrial subregion.

Data source: Department of Environment and Conservation [ver. Jan 2007]. Presentation: EPA.

Figure B0.4: Number of threatened fauna per terrestrial subregion.

Data source: Department of Environment and Conservation [ver. Feb 2007]. Presentation: EPA.

Figure B0.5: Number of threatened ecological communities per terrestrial subregion.

Data source: Department of Conservation and Land Management [ver. Jan 2004]. Presentation: EPA. Note: These data are based on limited survey work that has only partially identified the number of threatened ecological communities likely to occur in WA.

Indicator B6: Number of recovery plans and their effectiveness.

A total of 649 species and communities are listed as threatened in WA (Table B0.3). About 39% have recovery plans developed (Table B0.3). Ideally each one should have a recovery or management plan and associated actions. At present, critically endangered species and ecological communities have priority for recovery plan development and implementation, followed by those that are endangered and then vulnerable.

Table B0.3 Number of Western Australian species threatened and ecological communities covered by endorsed recovery plans and interim recovery plans.

Data source: Department of Environment and Conservation [ver. 2007]. Note: RP - Recovery plan; IRP - Interim recovery plan; Some plans have been updated and replaced; Some fauna are covered within threatened ecological community interim recovery plans; Some plans cover more than one species or threatened ecological community.

The degree of implementation and effectiveness of recovery plans is limited. Seventy-four interim recovery plans for critically endangered plants and 33 for threatened ecological communities were assessed to determine progress during implementation of the plan. For plants under recovery plans, 55% improved, 32% remained stable and 12% declined. For threatened ecological communities under recovery plans, 15% improved, 57% remained stable and 27% declined (Department of Environment and Conservation, unpublished data, February 2007). Most threatened plants or communities have increased or remained stable under recovery plans but some species and communities have declined. It is possible that some of these would have become extinct or that their decline would have been much more rapid if they had not been covered by a plan. The development of a recovery plan does not guarantee the survival or improvement in condition of threatened species or ecosystems, but it does provide the best possible opportunity of doing so.

Effectiveness

Forty-eight actions for maintaining biodiversity were identified in the 1998 State of the Environment Report (Government of Western Australia, 1998). Of these 46% remained incomplete, 33% have been completed but not evaluated, and only 21% have been completed and evaluated. Evaluating the effectiveness of programs to maintain biodiversity is very difficult. Indicators of biodiversity condition still largely do not exist and so few environmental outcomes can be quantified. In addition, the effects of on-ground actions are difficult to detect and it may take many years of monitoring before environmental outcomes are evident. Consequently, even though a large proportion of these programs are underway or complete, it has been very difficult to evaluate actual environmental outcomes and increased monitoring and evaluation effort is urgently needed. The National Action Plan for Salinity and Water Quality and the Natural Heritage Trust programs may help to improve monitoring of biodiversity issues, such as introduced animals, weeds and Phytophthora dieback.

Suggested responses

5.1 Finalise and enact the Biodiversity Conservation Bill: the need for biodiversity conservation legislation is urgent as the existing legislation is outdated.

5.2 Finalise and implement the draft A 100-year Biodiversity Conservation Strategy for Western Australia. A draft version of the strategy has recently undergone public comment. The strategy will be an important complement to the proposed Biodiversity Conservation Act.

5.3 Ensure all potentially threatened species and communities are assessed and their status recognised within an appropriate time frame.

5.4 Assess the level of implementation and effectiveness of recovery plans.

Accessibility

State of the Environment Report 2007

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