VEGETATION AND FLORA

The proposal involves clearing approximately 97 ha of native vegetation on the Whicher Scarp, of which about 86 ha will result from the mine pit, which will also disturb the soil structure. The affected vegetation includes one vegetation complex that has less than 30% of its pre-European extent remaining. The proposed disturbance area also includes one Declared Rare Flora (DRF) species and is also listed as vulnerable under the EPBC Act, (the Long-leafed Davesia Davesia elongata subsp. elongata) with one individual plant identified within the proposed disturbance area during the 2005 survey (Bennett 2006). Additional plants identified during a 2003 survey by Bennett were not recorded in the 2005 survey despite targeted searches. One species of Priority flora (Boronia humifusa) was also identified within the proposed disturbance area and from several locations nearby. Several other Priority species were identified in areas adjoining the proposed disturbance area.

The proposed disturbance areas lie across the interface between the Swan Coastal Plain and the Blackwood Plateau, and has the potential to reduce the ecological connectivity of the transitional landscape on a local scale.

Vegetation Surveys

Seven separate botanical surveys have been conducted, including those conducted at the direction of, or in consultation with, the EPA Services Unit.

1. Vegetation Assessment (ESM 1998) – floristic survey across project area. Vegetation complex types were compiled and distribution mapped
2. 1999 Assessment of landforms, vegetation and flora (ESM 1999) – comprehensive study by EMS involved soil sampling and profile studies, floristic survey (45 quadrats), field searches for conservation significant species and mapping of dieback spread. Floristic data was analysed using a statistical pattern analysis package (PATN).
3. 2001 Vegetation Survey, Location 215 (Bennett 2001) – Vegetation survey was undertaken on Location 215, north of Gavins Road. Eight quadrats were established, species presence, foliage cover, vegetation structure and map references were recorded.
4. 2003 Vegetation Unit Mapping (Bennett 2003) – At the request of the (then) Department of Environmental Protection the vegetation of the area was mapped at Vegetation Unit level, and field verification of the mapping outcomes undertaken.
5. 2004 Search for significant species (Bennett 2004) – A search of the Gwindinup and Happy Valley mining tenements for Declared Rare Flora (DRF), Priority flora and species conservation significance was undertaken.
6. 2006 Flora and Vegetation report (Bennett 2006) – Floristic survey of forty quadrats including those designed to form a continuum from the ‘Cartis’ lower slopes (Swan Coastal Plain) up the Whicher Scarp (Whicher slopes) and onto the lateritic uplands (Kingia ridges). Also surveyed were drainage lines and drainage depressions, areas on HVS and HVN orebodies and areas outside the proposed disturbance to determine if vegetation units or types were duplicated in the surrounding bushland. This data was then analysed by E. A. Griffin & Associated using PATN analysis.
7. 2007 Flora & Vegetation Selected Areas Happy Valley (Bennett, 2007) – Floristic survey of nine quadrats established in ephemeral creeks on the lease and resurvey of 15 quadrats established in 2005. Vegetation unit that included Daviesia nudiflora subsp. nudiflora was surveyed via eight temporary quadrats with an additional two quadrats established in a similar vegetation unit.

One DRF Daviesia elongata subsp. Elongata (Long-leafed Davesia) has been recorded from the HVS site. Surveys have found that all recorded plants were located outside the proposed area of clearing and will not be disturbed by mining. In addition to the one DRF found, six priority flora were recorded within the project area, with two species to be affected by the proposal. These species are Andersonia ferricola (P1), Hemigenia rigida (P1), Longania wendyae (P1), Boronia humifusa (P1), Stenanthemum sublineare (P2) and Franklandia triaristata (P4). Only Boronia humifusa and Logania wendyae will be impacted by the proposed clearing footprint at both HVS and HVN.

Regional significance: Vegetation Complexes

Guidance from the EPA establishes an objective for the representation of ecological communities in relation to the remaining areas of native vegetation of at least 30% of the pre-clearing extent of the ecological communities. The following vegetation complexes are located in the project area:

Whicher Slopes (WC) open forest of Eucalyptus marginata and Corymbia calophylla on escarpment with some Corymbia haemotoxylon, Banksia attenuata and Xylomelum occidentale. This vegetation is relatively restricted within existing reserves with 15.2% (588 ha) of the pre-European distribution represented. However, 74% of the pre-European distribution (2861 ha) still occurs.

Whicher Valleys (WCv) open forest of Eucalyptus marginata and Corymbia calophylla on valleys dissecting escarpment, with some Xylomelum occidentale on escarpment slopes. This vegetation is inadequately represented within existing conservation reserves, with only 9.1% (37.2 ha) of pre-European distribution protected. However 54.4% (223 ha) of the pre-European distribution is still represented.

Cartis (CSs) low open forest of Eucalyptus marginata, Corymbia calophylla and Corymbia haemotoxylon with some Banksia attenuata and Xylomelum occidentale on escarpment slopes. 20.2% (294.5ha) of the pre-European distribution of this vegetation complex remains, with 80% of this within freehold land.

Kingia (KI) open forest of Eucalyptus marginata, Corymbia calophylla, Allocasuarina fraseriana, Banksia grandis and Xylomelum occidentale on lateritic uplands. The conservation value of the vegetation generally relates to its regional extent, representation within reserves and the uniqueness of its component flora. The Kingia vegetation complex occurs extensively on the uplands of the Blackwood Plateau between Bunbury and the Scott Coastal Plain. Approximately 95.8% (97,983ha) of the pre-European distribution remains, with 33.7% contained within formal¹ and informal² reserves.

Rosa (RO) woodland to open forest of Corymbia calophylla, Eucalyptus marginata and Xylomelum occidentale on slopes with a tall shrubland of Agonis linearifolia in valley floors. This vegetation is extensively represented in the landscape and adequately represented in reserves. Rosa vegetation is adequately represented with 78.8% of the pre-European distribution remaining and 84% of this within State Forest. No clearing of Rosa vegetation is proposed.

Of these vegetation complexes, only the Cartis vegetation complex is poorly reserved. The Kingia, Rosa and Whicher Scarp vegetation complexes are relatively well represented in a regional context. The Cartis complex is poorly represented and poorly reserved with only 20% of its pre-European extent remaining, nearly all occurring on privately owned land (80%). However, Bemax is proposing to clear only 1.6ha of the Cartis vegetation complex (0.1%) of its pre-European extent) and aims to investigate alternative protection mechanisms to improve the representation of this complex in formal reserves.

_{1 A formal reserve includes National Park, nature reserve, conservation park or CALM Act sections 5(1)(g) or 5(1)(h) reserves for the purpose of conservation}

_{2 An area set aside for conservation under a approved management plan: has had an opportunity for the public to comment on changes to reserve boundaries; able to be accurately defined on a map; and is of an area and design sufficient to sustain the values it seeks to protect.}

Floristic Community Types

As opposed to describing the structural variation and species dominance of vegetation communities, floristic analysis is a breakdown of the variation in vegetation communities based on the species present (similarity/dissimilarity). While the former method is more relevant to ecological function, particularly relating to fauna, floristic analysis is an excellent method for quantifying the differences in the species composition of vegetation communities between areas (Welker 2002). This is usually done using a statistical method, such as results extracted from the PATN software package (Belbin 1987), which are floristic based and, depending on the analysis technique, typically rely on the grouping of sites (ordinarily a 10 m by 10 m quadrat) to either presence/absence of species or quantitative data (such as density or cover). Under this approach, the similarity (and hence also dissimilarity) in the absence/presence of species is determined between all sample sites. These sites can now be grouped on this basis in a hierarchical manner depending on the level of dissimilarity to be examined. The approach will define hierarchically more and more homogeneous units, in terms of floristics, by further splitting groups of sites at increasing lower dissimilarity values. Work on the PATN analysis is continuing utilising data from quadrats within the Happy Valley tenement areas and those surveyed by the Wildflower Society of Western Australia for DEC across the broader Whicher scarp area.

Potential Impacts on Vegetation

• Dieback
• Introduced species
• Changes in hydrology affecting vegetation health
• Loss of vegetation through clearing
• Vegetation fragmentation

Management Strategies

A vegetation protection plan is being developed as part of the Happy Valley Environmental Management and Monitoring Program. The plan will address the following:

• Protection and enhancement of existing landscape values for those areas within the mining tenements and/or within the control of the proponent
• Management of offset areas
• Support for local programs, such as LandCare, dieback assessment / control
• Dieback assessment / control
• Weed assessment / control
• Pre-disturbance checks for unrecorded DRF or other species of conservation significance
• Monitoring program for vegetation surrounding the disturbance areas and also throughout areas that are the responsibility of Bemax
• Fire control and hazard reduction strategy
• Process for community involvement and reporting